Higher order aberrations, refractive error development and myopia control: a review

The association between subfoveal choroidal thickness and refractive error in Taiwanese children: A cross-sectional study

PURPOSE

The aim was to analyze the association of subfoveal choroidal thickness (SFCT) with age, best-corrected visual acuity, refractive error, and axial length in Taiwan pediatric population.

METHODS

A total of 374 eyes in 187 children were enrolled in this retrospective cross-sectional comparative study, who underwent examinations of best-corrected visual acuity (BCVA), cycloplegic refraction, and axial length (AL). Subfoveal choroidal thickness was assessed utilizing spectral domain enhanced depth imaging optical coherence tomography (EDI-OCT), with measurements taken at the subfovea, defined as the distance from the retinal pigment epithelium to the chorioscleral border.

RESULTS

The mean age was 5.6 ± 1.9 years (range 2-16 years). The cycloplegic spherical equivalent refractive error was between + 7.25 and - 15.25 diopters (D) and cycloplegic sphere power was between + 8.25 and - 11.5 diopters (D). The mean SFCT was 299.0 ± 69.80 μm. The mean axial length was 22.87 ± 1.29 mm. In univariate analysis, SFCT had significant positive correlations with spherical equivalent (SE) and sphere power (p < 0.05) and significant negative correlations with age, cylinder power, and axial length (p < 0.05). However, after adjusting in the multivariate regression analysis, spherical equivalent, sphere power and age were not independently associated with SFCT. In multivariate analysis, lower cylinder power and longer axial length have significant correlations with thinner SFCT. The relationship between best-corrected visual acuity and SFCT was not significant in both analyses.

CONCLUSIONS

This study showed that mean subfoveal choroidal thickness was 299.0 ± 69.80 μm among Taiwanese children. The SFCT was thinner in myopic, longer axial length, and lower cylinder power eyes.

Development and evaluation of machine learning models for individualized prediction of myopia control efficacy treated with overnight orthokeratology

Purpose

The primary objective of this study is to develop a predictive model utilizing fundamental clinical and ocular measurements to predict the effect of overnight orthokeratology on myopia control. Accordingly, this study aims to assist ophthalmologists in selecting adolescent myopia control methods.

Methods

This retrospective study used one-year follow-up data of 225 myopia children treated with orthokeratology. Using the random sampling method, 225 samples were randomly divided into a training set (n = 180) and a test set (n = 45). LASSO regression identified predictive factors correlated with controlling myopia. The final features are input into the machine learning model for prediction model construction to predict 1-year axial length elongation. The prediction performance was evaluated according to the accuracy and AUC of the training set and the test set. DCA was used to assess the clinical benefits of the model.

Results

Five features (age, diopter, flat keratometry, corneal higher-order aberrations (6 mm), and intraocular trefoil (6 mm) were used to build the machine learning model (p < 0.01)). Based on the accuracy, ROC, and DCA curves, the prediction performance and clinical practicability of five prediction models: KNN, SVM, RF, Extra Trees, and XGBoost were compared. In the DCA, all machine learning models consistently achieved greater net benefits within the clinical threshold range. SVM demonstrated the highest predictive quality with an AUC of 0.877 in the training and 0.828 in the external validation set.

Conclusion

We developed and validated several prediction models for individualized prediction of myopia control efficacy treated with overnight orthokeratology through machine learning, using easily obtained clinical and corneal topography features. This cost effective strategy helps ophthalmologists predict the effect of using orthokeratology in children, and make timely adjustments to myopia control methods. The differential features selected by this model can also provide insights for optimizing lens design.

Quantifying natural higher order aberration(s) in emmetropic human eyes and objectively evaluating retinal image quality

AIM

This study aimed to quantify the internal, corneal and total higher order aberrations (HOAs) in the healthy human eye using ray tracing technology in bright and dim light conditions. The study also aimed to evaluate the retinal image quality and contrast modulation at different spatial frequencies, objectively using image-quality metrics derived from wavefront aberrations.

METHODOLOGY

A cross-sectional prospective observational study was conducted on 521 emmetropic young adults. HOAs including coma, trefoil, spherical aberration and secondary astigmatism were measured separately for the cornea, internal and total eye using a ray-tracing wavefront aberrometer at mesopic and photopic pupil sizes. The Strehl ratio, derived from the point spread function (PSF), was used to evaluate the retinal image quality of the eye. Contrast modulation at spatial frequencies of 5, 10 and 15 cycles per degree was assessed through the modulation transfer function (MTF).

RESULTS

Mean age of participants was 25.4 ± 4.8 years (54.5% male). The total HOAs of internal, corneal and total eye were 0.186 ± 0.075, 0.191 ± 0.112 and 0.222 ± 0.075 μ, respectively for a 5-mm pupil (dim light condition), and 0.069 ± 0.031, 0.061 ± 0.094 and 0.076 ± 0.031 μ, respectively, for a 3-mm pupil (bright light condition). The Strehl ratio was 0.16 ± 0.124 (5 mm pupil) and 0.601 ± 0.19 (3 mm pupil). A normative database was created and correlations drawn for the HOAs, PSF and MTF (using image quality metrics) for the cornea, internal and total eye at mesopic and photopic pupil sizes.

CONCLUSION

These findings provide normal population (young healthy adults) reference ranges for HOAs, retinal image quality and contrast modulation at higher spatial frequencies using ray tracing technology. The presence of these natural wavefront aberrations enhances the visual performance and may not need to be corrected. The separate assessment of aberrations and derived image quality metrics for the cornea, internal and total eye can serve as a benchmark for diagnosing and monitoring ocular conditions and allows targeted treatment planning.

Differential impact of 0.01% and 0.05% atropine eye drops on visual performance in young adults

PURPOSE

The onset and progression of myopia can occur during adulthood, suggesting that myopia should be managed in young adults. Low-concentration atropine eye drops have shown promising efficacy in myopia control. This study aimed to evaluate the impact of 0.01% and 0.05% atropine eye drops on the visual performance of university students.

METHODS

Twenty-six myopic students aged 18-30 years received 0.01% and 0.05% atropine in random order. Atropine eye drops were administered once a night in both eyes for 14 days, with a minimum 14-day washout period between concentrations. Visual assessments, including the modulation transfer function (MTF) cut-off, Strehl ratio (SR), objective scattering index, contrast sensitivity (CS) and glare disability, were conducted 1, 2, 7 and 14 days after atropine administration and corresponding time points after cessation. A questionnaire was used to evaluate ocular and general symptoms.

RESULTS

After 1 day of treatment with 0.05% atropine, the MTF cut-off (β = -8.75, p < 0.001) and SR (β = -0.05, p < 0.001) decreased significantly to their lowest levels. The area under the log CS function also decreased significantly (all p < 0.05) during administration of the 0.05% eye drops, especially in the mesopic with glare condition, and reached its lowest point 1 day after administration (β = -0.20, p < 0.001). However, all parameters returned to baseline levels 2 weeks after 0.05% atropine was stopped (all p > 0.05). Additionally, 40.91% of the young adults reported experiencing excessive daytime sleepiness and nocturnal glare during 0.05% atropine use. Treatment with 0.01% atropine had minimal effects on both visual performance and subjective symptoms.

CONCLUSIONS

Administration of 0.05% atropine had a significant but temporary effect on the visual performance of young adult myopic patients, whereas 0.01% atropine had a minimal effect.

Association Between Inflammatory Cytokines and Refractive Errors: A Bidirectional Mendelian Randomization Study

Purpose

This investigation aimed to elucidate the causal role of inflammatory cytokines in the risk of developing refractive errors.

Methods

Genetic variants previously associated with inflammatory cytokines served as instrumental variables in genome-wide association studies (GWASs) of European ancestry. Bidirectional two-sample Mendelian randomization (MR) analyses were conducted using summary data from GWAS meta-analyses. Rigorous sensitivity analyses were performed to validate the reliability of the MR results.

Results

We found that, for every unit increase in interleukin 1 receptor antagonist (IL1RA) and interleukin 2 (IL2), there was a corresponding decrease in the prevalence of myopic refractive errors by 0.235 (95% confidence interval [CI], 0.050-0.419 for fixed effects; 95% CI, 0.125-0.345 for random effects) and 0.132 (95% CI, 0.032-0.231 for fixed effects; 95% CI, 0.044-0.220 for random effects), respectively. No substantial causal associations were observed for IL1α, IL1β, IL12p70, or monocyte chemoattractant protein 1 (MCP1) with refractive errors. Conversely, reverse MR analyses failed to indicate a causal influence of refractive errors on IL1RA and IL2.

Conclusions

The present study offers evidence for a causal link between inflammatory cytokines and refractive errors, which could have significant implications for the early detection, surveillance, and management of refractive errors.

Translational Relevance

Our study underscores the importance of IL1RA and IL2 in the prevention and management of refractive errors, suggesting the feasibility of strategies for early identification, continuous surveillance, and the deployment of focused therapeutic approaches.

Associations between refractive error components and higher-order aberrations in simple myopia and compound myopic astigmatism

Aim

To investigate associations between refractive error components and higher-order aberrations (HOAs) in adult myopic subjects.

Methods

A total of 1370 myopia right eyes, aged 18-40, were included in a cross-sectional study. Subjective cycloplegic refractions and distance aberrometry measured with a Shack-Hartmann device were analyzed. Zernike components of horizontal coma (Z3 1), vertical coma (Z3 -1), oblique trefoil (Z3 3), vertical trefoil (Z3 -3), spherical aberration, and total root-mean-square (RMS) wave-front error for 6 mm pupil were analyzed. Pearson's correlations were calculated between sphero-cylindrical components and HOAs based on vector analysis for the astigmatism axis. Total subjects were divided into two subgroups: simple myopia (SMY, 648 eyes) and compound myopic astigmatism (CMA, 722 eyes). HOAs were compared between the two subgroups.

Results

Total RMS wave-front error correlates with spherical equivalent myopia (r = -0.1, P<0.05) and J45 (r = 0.1, P<0.001). J0 correlates positively with vertical coma (Z3 -1) (r = 0.1 p <0.001) and negatively with oblique trefoil (Z3 3) and vertical trefoil (Z3 -3), (r = -0.1, p < 0.001; r = -0.1, P < 0.05). The total RMS wavefront-error was larger in the CMA (|0.37| ± 0.18 µm) compared to the SMY (|0.34| ± 0.16 µm, P <0.001). The mean values of vertical coma (Z3 -1), vertical trefoil (Z3 -3), and oblique trefoil (Z3 3) differed between the two subgroups.

Conclusion

Total RMS wave-front error increases with increasing myopia and astigmatism. Increasing myopia power does not show a systematic correlation with HOAs components. A weak systematic correlation is suggested between astigmatism direction and third-order aberrations.

Long-term changes in classified higher-order aberrations after implanting an EVO intraocular collamer lens

PURPOSE

To evaluate changes in intraocular, corneal, and whole-eye higher-order aberrations (HOAs) after EVO intraocular collamer lens (ICL) implantation.

METHODS

In this retrospective study, we enrolled 53 eyes of 53 patients and measured their refractive parameters and intraocular, corneal, and whole-eye HOAs using OPD scanning preoperatively and 1 month, and 3 years postoperatively. All statistical analyses were performed using SPSS software.

RESULTS

The safety index was 1.31 ± 0.15, and the efficacy index was 1.02 ± 0.24 3 years postoperatively. The best linear fit curve of the attempted versus achieved correction was y = 0.96x + 0.08 at 3 years postoperatively. The mean spherical equivalent decreased from - 8.53 ± 2.49 D preoperatively to -0.09 ± 0.25 D and - 0.34 ± 0.41 D at 1 month and 3 years postoperatively, respectively (P < 0.05). The whole-eye trefoil and total HOAs, intraocular trefoil, corneal trefoil increased significantly at 1 month (P < 0.05) but did not change significantly at 3 years (P > 0.05) postoperatively compared to the preoperative value. The intraocular spherical aberration and total HOAs increased significantly at 1 month and 3 years postoperatively (P < 0.05). The whole-eye coma or spherical aberration, intraocular coma, corneal coma or spherical aberration or total HOAs did not differ from those observed at 1 month and 3 years postoperatively (P > 0.05).

CONCLUSIONS

Long-term EVO-ICL implantation is safe, effective, predictable, and stable. The intraocular and corneal trefoils increased significantly in the early postoperative period but can be recovered to the preoperative level in the long term. The intraocular spherical aberration increases slightly in the long term postoperatively, but the whole-eye spherical aberration does not change significantly.

Analysis of preoperative ocular optical parameters in patients with cataract

This study aims to evaluate the distribution of preoperative corneal parameters obtained using the Pentacam anterior segment analyzer in Chinese male and female patients with cataracts and to investigate the correlation between these parameters and related factors. Preoperative examination data of the eyes of 1,255 patients who underwent cataract surgery were retrospectively analyzed. The Pentacam AXL was used to extract preoperative corneal measurements, and the total corneal measurement data were analyzed. The average age of the patients was 52.9 ± 21.3 years. The mean simulated keratometry values and corneal curvature of total corneal refractive power were positively correlated with age (both P < 0.01). Spearman's correlation analysis revealed a positive association between age and anterior corneal spherical aberration, posterior corneal spherical aberration, and total corneal spherical aberration changes. A negative correlation was found between age and with-the-rule astigmatism, and it was positively correlated with the ratios of against-the-rule and oblique astigmatism. A significant between-eye correlation was observed regarding spherical aberration (Z40), horizontal coma (Z31), vertical coma (Z3-1), and horizontal trefoil (Z33). The corneal curvature in females was significantly steeper than that in males (P < 0.01). Corneal curvature, corneal spherical aberration, and corneal astigmatism were found to change with age. Additionally, we found physiological differences between the sexes. Individual measurements could be taken preoperatively to facilitate the development of personalized surgical plans. By identifying age- and gender-related corneal variations, this study enables more personalized cataract surgery planning, potentially improving refractive outcomes and reducing postoperative complications through tailored surgical techniques and intraocular lens selection.

The effect of near work on the anterior eye and associations with myopia: a narrative review

The global prevalence of myopia has increased significantly in recent decades, and it is anticipated that half the population of the world will be myopic by 2050. The dramatic increase in myopia cannot be explained solely by genetic factors; hence, environmental factors such as near work may play an important role in myopia development. Near work activities involve accommodation, convergence, and pupil constriction, which lead to various mechanical changes that alter the structural and optical properties of the anterior eye. Mechanical changes associated with near work activities include ciliary body contraction, medial rectus contraction, lateral rectus relaxation, changes in the eyelid-cornea interaction, pupil size, and crystalline lens shape and position. These structural variations lead to optical changes including a change in spherical refractive power, astigmatism, accommodative convergence, higher order aberrations, and retinal image quality. Several differences in near work-related optical and structural changes have been observed between myopes and non-myopes. These differences elucidate mechanisms that potentially underpin near work-associated axial elongation and myopia development. This narrative review explores anterior segment structural and optical changes during near work and their potential mechanistic contribution to myopia development, while highlighting literature gaps that require further research.

The Peripheral Defocus Designed Spectacle Lenses Might Increase Astigmatism in Myopic Children

Purpose

This study aims to explore the impact of wearing peripheral defocus spectacle lenses (PDSL) on cylindrical refractive error (CYL) in myopic children.

Methods

This study included 1057 myopic children and divided the participants into three groups: the HAL group (spectacle lens with highly aspherical lenslets), the MPV group (spectacle lens based on manipulating peripheral vision), and a control group (without myopia control interventions). The study analyzed the effect of wearing PDSL on changes in spherical equivalent refraction, CYL, and corneal astigmatism (CA). The mediating effect between changes in spherical refractive errors (SPH) and CYL was also investigated.

Results

Compared to the control group (0.05 ± 0.33 D), the annual CYL progression was faster in the HAL group (-0.15 ± 0.33 D, P < 0.001) and the MPV group (-0.09 ± 0.27 D, P = 0.019). More children in the HAL group had an annual CYL progression ≥0.50 D (HAL: 23.6%, Control: 16.2%, P = 0.012). The annual CYL and CA progression were consistent within the PDSL groups (HAL: P = 0.677, MPV: P = 0.683). The total effect of CYL progression in the HAL group was primarily due to direct induction from wearing HAL and indirect induction through the SPH control effect.

Conclusions

The application of PDSL could cause increase in astigmatism in myopic children, which could mainly be contributed to cornea astigmatism change.

Translational Relevance

PDSL may passively affect the anterior ocular biomechanics during myopia control, leading to an increase in astigmatism.

Machine learning-based nomogram to predict poor response to overnight orthokeratology in Chinese myopic children: A multicentre, retrospective study

PURPOSE

To develop and validate an effective nomogram for predicting poor response to orthokeratology.

METHODS

Myopic children (aged 8-15 years) treated with orthokeratology between February 2018 and January 2022 were screened in four hospitals of different tiers (i.e. municipal and provincial) in China. Potential predictors included 32 baseline clinical variables. Nomogram for the outcome (1-year axial elongation ≥0.20 mm: poor response; <0.20 mm: good response) was computed from a logistic regression model with the least absolute shrinkage and selection operator. The data from the First Affiliated Hospital of Chengdu Medical College were randomly assigned (7:3) to the training and validation cohorts. An external cohort from three independent multicentre was used for the model test. Model performance was assessed by discrimination (the area under curve, AUC), calibration (calibration plots) and utility (decision curve analysis).

RESULTS

Between January 2022 and March 2023, 1183 eligible subjects were screened from the First Affiliated Hospital of Chengdu Medical College, then randomly divided into training (n = 831) and validation (n = 352) cohorts. A total of 405 eligible subjects were screened in the external cohort. Predictors included in the nomogram were baseline age, spherical equivalent, axial length, pupil diameter, surface asymmetry index and parental myopia (p < 0.05). This nomogram demonstrated excellent calibration, clinical net benefit and discrimination, with the AUC of 0.871 (95% CI 0.847-0.894), 0.863 (0.826-0.901) and 0.817 (0.777-0.857) in the training, validation and external cohorts, respectively. An online calculator was generated for free access (http://39.96.75.172:8182/#/nomogram).

CONCLUSION

The nomogram provides accurate individual prediction of poor response to overnight orthokeratology in Chinese myopic children.

Higher order aberrations according to spherical, and astigmatic refractive errors in children

CLINICAL RELEVANCE

The results of this study present novel insights into the impact of spherical and astigmatic refractive errors on overall, corneal and internal aberrations and may provide a clear understanding of the emmetropisation process and the development of visual function.

BACKGROUND

This study aimed to assess the association between overall, corneal and internal higher-order aberrations and the spherical and astigmatic components (magnitude and angle) of refractive error in a large sample of children.

METHODS

A total of 311 children aged 7 - 8 years old were classified based on spherical equivalent refraction (myopic, emmetropic and hyperopic); magnitude of astigmatism (none, low and moderate); and angle of astigmatism (with-the-rule, against-the-rule and oblique). Refractive error and overall, corneal and internal higher-order aberrations were measured using the OPD-Scan III workstation.

RESULTS

Regarding spherical equivalent refraction, myopic eyes had greater root mean square (RMS) overall higher-order values, total spherical, tetrafoil and secondary astigmatism aberrations, and internal higher-order, total spherical and tetrafoil aberrations in comparison to emmetropic eyes. The magnitude of astigmatism was positively associated with all overall RMS aberrations and with internal higher order, coma, total coma, total spherical and tetrafoil aberrations. Eyes with with-the-rule astigmatism showed higher RMS values of coma and total coma compared to eyes with against-the-rule and oblique astigmatism.

CONCLUSIONS

Higher-order aberrations are dependent on the spherical as well as astigmatic components of refractive error. These findings enhance the current understanding of the emmetropisation process and visual function development.

Longitudinal measures of peripheral optical quality in young children

PURPOSE

To assess longitudinal changes in optical quality across the periphery (horizontal meridian, 60°) in young children who are at high (HR) or low risk (LR) of developing myopia, as well as a small subgroup of children who developed myopia over a 3-year time frame.

METHODS

Aberrations were measured every 6 months in 92 children with functional emmetropia at baseline. Children were classified into HR or LR based on baseline refractive error and parental myopia. Zernike polynomials were calculated for 4 mm pupils, accounting for the elliptical shape of the pupil in the periphery. Various metrics were computed, including Strehl Ratios with only high-order aberrations (HO-SR). Primary spherical aberration (SA), horizontal coma and defocus were also analysed given their relevance in emmetropisation. The areas under the image quality metrics for various regions of interest were computed.

RESULTS

HO-SR were higher in children at HR and children with myopia, even when SA was removed from the Strehl Ratio (SR) calculation. SA was less positive in children at HR and children with myopia. Defocus was more negative in children at HR and children with myopia at all eccentricities and was even more negative when computed relative to the fovea, an effect that increased in the mid periphery. Relative peripheral defocus also became more negative over time in children at HR and children with myopia at the mid temporal retina. The other aberrations showed no significant changes in time overall.

CONCLUSIONS

This longitudinal study showed differences in HO-SR, SA and defocus in the central and near-peripheral retina (±20°) of young children at HR before they develop myopia compared with children at LR for myopia. The results may indicate these eccentricities are significant in providing signals for emmetropisation. The small changes noted over time may indicate that the differences are a cause of myopia development.

Impact of back optic zone diameter (BOZD) in orthokeratology on axial length elongation: A meta-analysis and systematic review

PURPOSE

Myopia has emerged as a significant public health concern. Recent studies have demonstrated that Orthokeratology (Ortho-K) can effectively decelerate axial length (AL) growth, with eyes possessing smaller back optical zone diameters (BOZD) exhibiting greater effectiveness compared to those with larger BOZD. This study aims to analyze the impact of Ortho-K with varying BOZD.

METHOD

This systematic review involved the retrieval of articles from eight databases: PubMed, Embase, Web of Science, Cochrane, CNKI, Wanfang, Sinomed, and VIP, covering the period from each database's inception to January 2024. It compared axial length (AL) changes between smaller and larger back optic zone diameters (BOZD). Review Manager 5.4 was used to statistical analysis and the results presented as weighted mean differences and 95% confidence intervals (CI). This review adheres to the PRISMA guidelines.

RESULT

This systematic review included two randomized controlled trials (RCTs) and five cohort studies (CS), analyzing a total of 702 eyes (352 eyes are treated with Ortho-K and BOZD ≤ 5.5 mm, 350 eyes are treated with Ortho-K and BOZD ≥ 6.0 mm). The findings indicate that the Ortho-K with smaller BOZD significantly reduces AL growth [WMD = -0.13, 95 %CI (-0.16 to -0.10), P < 0.001].

CONCLUSION

The Ortho-K with smaller BOZD prove more effective in controlling myopic AL growth compared with larger BOZD. However, in clinical practice, it is necessary to comprehensively evaluating factors such as patient age, myopia diopter, pupil diameter, higher-order aberration, treatment zone area, and corneal eccentricity to achieve optimized outcomes in improving naked-eye vision and myopia controlling.

Contact Lenses in Therapeutic Care: A Comprehensive Review of Past Innovations, Present Applications, and Future Directions

Contact lenses have become integral tools in the realm of ocular therapeutics, extending beyond their primary function of refractive correction to encompass a diverse array of therapeutic applications. This review explores the evolving role of contact lenses in managing various ocular conditions, highlighting their efficacy in enhancing patient outcomes. Initially developed to correct refractive errors, contact lenses now serve as effective vehicles for delivering medications directly to the ocular surface, offering targeted treatment for conditions such as dry eye syndrome and corneal ulcers. Their ability to provide sustained moisture and facilitate drug absorption makes them indispensable in promoting corneal healing and managing chronic ocular surface diseases. Specialized contact lenses designed for irregular corneas, such as those affected by keratoconus, provide both optical correction and structural support, significantly improving visual acuity and patient comfort. Additionally, orthokeratology lenses have shown promise in controlling myopia progression in children by reshaping the cornea overnight, thereby reducing reliance on corrective eyewear during waking hours. In post-surgical settings, therapeutic contact lenses aid in epithelial regeneration and minimize discomfort, accelerating recovery and improving surgical outcomes. They also play a crucial role in protecting the cornea from external irritants and promoting a stable tear film, crucial for maintaining ocular health. Looking ahead, ongoing advancements in contact lens materials and designs promise further innovation in ocular therapeutics, paving the way for personalized treatment strategies and improved patient care. As such, contact lenses continue to evolve as essential therapeutic tools, offering tailored solutions for a spectrum of ocular conditions and contributing to enhanced quality of life for patients worldwide.

Research Tendency and Frontiers of Multifocal Lenses in Myopic Control in the Past Two Decades: A Bibliometric Analysis

Background: This study aimed to analyze the research progress on the use of a multifocal lens for myopic control throughout the 21st century, utilizing bibliometric analysis. Methods: Publications related to multifocal lenses from 2001 to 2024 were searched on the Web of Science core collection (WoSCC) database. VOSviewer (Version 1.6.19) and Bibliometrix package (Version 4.3.0) were used to perform the bibliometric analysis. Primary information including the publication number per year, country or region, journal, keyword, and title of the literature was extracted and analyzed. Results: A total of 234 articles from 31 countries were retrieved. The number of publications related to multifocal lenses had a rapid growth phase from 2016 to 2024. The United States, Australia, China, and Spain emerged as leading contributors to the research landscape. Ophthalmic and Physiological Optics was the most popular journal in this field, and the most frequently cited article was published in Optometry and Vision Science. Myopic progression was the main topic in this research field as well as the principal keywords of emerging research hotspots. Conclusions: Our bibliometric study provides a pioneering overview of the research trends and evolution in the application of a multifocal lens for myopic control. These findings provide a deep insight into current research frontiers and hot directions, offering a valuable reference for further research.

Refractive development II: Modelling normal and myopic eye growth

PURPOSE

During refractive development, eye growth is controlled by a combination of genetically pre-programmed processes and retinal feedback to minimise the refractive error. This work presents a basic differential model of how this process may take place.

METHODS

The description starts from two bi-exponential descriptions of the axial power Pax (or dioptric distance) and total refractive power Peye, the difference between which corresponds with the spherical refractive error S. This description is rewritten as an ordinary differential equation and supplemented by a retinal feedback function that combines retinal blur (closed loop) with a term describing excessive axial growth (open loop). This model is controlled by a total of 18 parameters that allow for a wide variety of developmental behaviours.

RESULTS

The proposed model reproduces refractive development growth curves found in the literature for both healthy and myopic eyes. An early onset of myopisation, a large growth term and a high minimum for the crystalline lens power all lead to higher degrees of myopia. Assigning more importance to the feedback than to the pre-programmed growth makes the model more sensitive to myopogenic influences. Applying refractive corrections to the model, undercorrection is found to produce more myopia. The model compensates for a low-powered imposed lens and can return to (near) emmetropia if that imposed lens is removed quickly thereafter. Finally, simulating the effect of a diffuser leads to high myopia.

CONCLUSION

Using a series of basic assumptions, the proposed model recreates many well-known experimental and clinical results about refractive development from the literature while placing them in a standardised context. This contributes to a broader understanding of the origins of refractive errors, and future versions may help in the development of solutions for myopia control.

The Influence of Accommodative Demand on Ocular Aberrations: A Study of Zernike Coefficients Repeatability and Variability

PURPOSE

To evaluate the repeatability of the Zernike coefficients in healthy eyes when monocular accommodation was stimulated at different vergences demands.

METHODS

A total of 36 right eyes from healthy volunteers were prospectively and consecutively recruited for this study. Wavefront aberrometry was conducted to objectively characterize the ocular optical quality during accommodation, from the individual's far point to a 5 D accommodation demand in steps of 0.5 D. The repeatability of Zernike coefficients up to the fourth order was assessed by calculating the within-eye repeatability (Sw), the coefficient of repeatability (CR), the coefficient of variation (CV), and the intraclass correlation coefficient (ICC) as an indicator of measurement reliability.

RESULTS

Correlation among repeated measurements showed high reliability (ICC > 0.513) for all parameters measured except some fourth-order Zernike coefficients, C(4, -4) (ICC < 0.766), C(4, -2) (ICC < 0.875), C(4, 2) (ICC < 0.778) and C(4, 4) (ICC < 0.811). Greater repeatability and less variability were obtained for high-order Zernike coefficients (CR < 0.154), although an increase in CR in the coefficients analyzed was observed with increasing accommodative demand. No clear trend was evident in CV; however, it was observed that the low-order Zernike coefficients exhibit lower CV (CV < 1.93) compared to the high-order Zernike coefficients (CV > 0).

CONCLUSIONS

The reliability of Zernike coefficients up to the fourth order in healthy young individuals demonstrated a strong consistency in measuring terms up to the fourth order, with more variability observed for high-order terms. The Zernike coefficients up to the third order exhibited the highest level of repeatability.

Effects and Related Factors of Short-time Accommodation Training on Measuring Consistency of InnovEyes Sitemap, Autorefraction, and Subjective Refraction

PURPOSE

To evaluate effects and related factors of short-time accommodation training on measuring consistency of InnovEyes Sitemap (Alcon/WaveLight; Alcon Laboratories, Inc), NIDEK ARK-1 autorefractor (Nidek Corporation), and subjective refraction (SR).

METHODS

One hundred adults (100 eyes) with myopia aged 17 to 40 years were enrolled. Refraction was obtained by InnovEyes Sitemap, autorefraction, and SR in a randomized order. Refractive data of InnovEyes Sitemap were grouped into two groups without and with application of a 2.00 diopter (D) flipper before InnovEyes Sitemap.

RESULTS

The average difference in spherical equivalent (SE) between InnovEyes Sitemap and SR (autorefraction) decreased from -0.56 ± -0.41 D in the without accommodation training group to -0.29 ± -0.14 D in the with accommodation training group, with 95% CI of limits of agreement (LOA) shrinking dramatically (InnovEyes Sitemap-SR: -1.39 to 0.27 vs -0.71 to 0.14 D; InnovEyes Sitemap-autorefraction: -1.23 to 0.40 vs -0.69 to 0.40 D). Furthermore, short-time accommodation training significantly improved the consistency of myopia measurements, with the proportion of SE differences within 0.50 D between InnovEyes Sitemap and SR significantly increasing from 56% to 88% (P < .001). Meanwhile, J0 and J45 showed no significant difference (P > .05) with similar LOA among three techniques in both groups. SE difference of InnovEyes Sitemap (with accommodation training group minus without accommodation training group) was significantly correlated to SE difference between SR and habitual glass refraction (β = -0.312, P = .001), lens thickness (β = 0.262, P = .006), and axial length (β = 0.199, P = .037).

CONCLUSIONS

Short-time accommodation training could promote spherical consistency but not deteriorate cylindrical agreement among InnovEyes Sitemap, autorefraction, and SR, and this effect showed more effective in eyes with more undercorrected myopia in habitual prescription, thicker lens, and longer axial length. [J Refract Surg. 2024;40(12):e941-e955.].

Comparison of the axial growth with multifocal and monofocal intraocular lenses in unilateral pediatric cataract surgery

PURPOSE

To compare axial growth in pediatric cataract patients who underwent multifocal intraocular lens (IOL) implantation without anterior vitrectomy (AV) with that in pediatric patients who underwent monofocal IOL implantation with or without AV.

METHODS

Patients who had unilateral pediatric cataracts and underwent surgery at 3-6 years of age from June 6, 2019, to June 30, 2020, at our institution were prospectively analyzed. The patients were categorized into Group A: multifocal IOL implantation with optic capture in Berger's space without AV; Group B: monofocal IOL implantation with optic capture in Berger's space without AV; and Group C: bag-in-the-lens monofocal IOL implantation with AV. Groups A', B' and C' consisted of the fellow eyes from the respective groups. Axial growth and monthly growth rates were compared among the 3 treatment groups, as well as between the treated eyes and the fellow eyes.

RESULTS

Thirty-one, 23, and 14 children fulfilling the inclusion criteria, respectively, were included in the final analysis. There were no significant differences in patient age at the time of surgery or preoperative axial length (P > 0.05). After a mean follow-up of 35.57 ± 3.78 months, significant differences in the axial growth and the monthly growth rate were observed (P < 0.05), and Group A had the least axial elongation. Comparing treated eyes with fellow eyes, the amount and rate of axial growth were lower in Group A than in Group A' (P < 0.05), no significant differences were found in Group B (P > 0.05), and Group C had greater growth than did Group C' (P < 0.05).

CONCLUSIONS

The implanting multifocal intraocular lenses and maintenance of vitreous body integrity may be protective factors against excessive axial growth in pediatric cataract patients. Clinical trial registration (prospective study): chiCRT1900023155; 2019-05-14.

Corneal higher-order aberrations and their relationship with choroid in myopic patients

BACKGROUND

To investigate corneal higher-order aberrations (HOAs) and choroidal characteristics in myopic individuals and explore the association between HOAs and choroidal parameters.

METHODS

Myopic participants were categorized into three groups based on axial lengths (ALs). We compared corneal HOAs, including spherical (Z40), comatic (Z3 - 1 and Z31), and trefoil (Z3 - 3 and Z33) aberrations, as well as choroidal vascularity index (CVI) and choroidal thickness (CT). Linear regression analysis was used to assess the relationships among corneal HOAs, CVI, CT, spherical equivalent, and AL.

RESULTS

Groups 1, 2, and 3 included 105, 98, and 118 eyes, respectively. Group 3 exhibited lower spherical HOA root mean square and Z40 values than group 1(p < 0.05). Group 1 showed lower Z31 levels than other groups (p < 0.001). Groups 1 and 2 had higher mean, central, and I2 vertical CVIs than group 3 (p < 0.05). Group 1 had a larger vertical S1 CVI than group 3 (p < 0.05). Group 3 had smaller horizontal CVI values in all regions except N2 (p < 0.05). Both the mean and CT in all regions decreased as AL increased (p < 0.001). The comatic (Z31) and trefoil (Z33) components were predictors of mean horizontal CVI, and the comatic (Z31) component was correlated with both mean vertical and horizontal CT.

CONCLUSION

Longer AL myopic patients exhibited lower absolute values of spherical aberration and horizontal coma. Alterations in choroid in myopic patients correlated with corneal HOAs. Our results suggest a potential connection between the optical quality and ocular perfusion in myopia.

Comparing the Early Changes in Classified Higher-Order Aberrations Before and After Non-Toric and Toric Implantable Collamer Lens V4c Implantation

PURPOSE

This study aimed to compare early changes in classified higher-order aberrations (HOAs) pre- and postsurgery in patients who received nontoric versus toric implantable collamer lenses (ICL; ICL Model V4c; STAAR Surgical, Monrovia, CA, USA).

METHODS

This prospective study included 124 eyes of 64 patients: 49 eyes were treated using a nontoric implantable collamer lens (ICL), and 75 eyes were treated using a toric implantable collamer lenses (TICL). Refractive parameters and ocular aberrations were examined before and 1 month after surgery.

RESULTS

At one month, the safety indices were 1.24 ± 0.17 in the ICL group and 1.20 ± 0.25 in the TICL group (p = 0.39). The efficacy indices were 1.07 ± 0.17 in the ICL group and 1.15 ± 0.26 in the TICL group (p = 0.02). The root mean square (RMS) values of whole-eye total HOAs, trefoil, corneal total HOAs, spherical aberration, and intraocular spherical aberration significantly increased postoperatively in both groups. The RMS of intraocular total HOAs in the TICL group significantly increased 1 month postoperatively. No statistically significant differences were observed in HOA changes between the ICL and TICL groups.

CONCLUSIONS

The dominant increases in short-term aberrations after ICL and TICL V4c implantation were in corneal trefoil and intraocular spherical aberrations, which were related to the corneal incision and implanted lens. The HOA changes post-surgery were not statistically different between the two lens types.

Retrospective diagnosis of naked eye visual acuity (UCVA) variations in patients with refractive errors treated with SMILE, LASIK, and WF-LASIK refractive surgery

A retrospective assessment of the visual acuity (UCVA) variations in bare eyes of the refractive error cases treated with SMILE, LASIK and WF-LASIK. A retrospective selection of 126 patients with refractive error treated by refractive surgery admitted to our hospital between January 2019 and December 2021 were divided into three separate sets of patients according to their surgical methods: the SMILE cohort, the LASIK cohort, and the WF-LASIK cohort, and the three sets of patients were analyzed for bare eye visual acuity, refraction, higher-order aberration, BUT, SIt index, and complications, and the recovery effects of patients with the three surgical procedures. All three types of refractive surgery, SMILE, LASIK and WF-LASIK, can yield good surgical results in the reduction of refractive error, and patients with SMILE have better postoperative tear film stability, while patients with WF-LASIK have the best postoperative visual quality.

[Visual Performance of School-age Children Wearing Dual-Focus Soft Contact Lenses: A Randomized Controlled Trial]

Objective

To investigate the effect of wearing dual-focus soft contact lenses (DFSCL) on the visual performance of school-age children.

Methods

In this randomized controlled clinical trial, 64 children aged 8 to 12 years with spherical equivalent refraction between -0.75 D and -4.00 D were recruited in our hospital in October 2022. Using the envelope method, the subjects were evenly and randomly assigned to the control group wearing single vision spectacles (SVS) or the intervention group wearing MiSight dual-focus soft contact lenses (DFSCL) from CooperVision. Follow-up examinations were conducted once every 3 months. The corrected visual acuity, contrast sensitivity function (CSF), and the scores for National Eye Institute Refractive Error Quality of Life Instrument-42 (NEI-RQL-42) were compared between the control and intervention groups.

Results

By December 2023, a total of 58 subjects completed follow-up (30 in the SVS group and 28 in the DFSCL group). No significant difference in corrected visual acuity was observed between subjects wearing DFSCL and those wearing SVS. The CSF of the DFSCL group was comparable to that of the SVS group across the spatial frequencies of 3, 6, 12, and 18 cpd (P>0.05). According to the results of the NEI-RQL-42 survey at the 6-month follow-up, the score for ocular discomfort symptoms was 89±14 in the SVS group and 79±16 in the DFSCL group (P=0.008), reflecting that the DFSCL group had a 12.66% higher level of discomfort. For appearance, the score was 70±32 in the SVS group and 92±22 in the DFSCL group (P=0.002), showing a 31.43% improvement in the DFSCL group.

Conclusion

In addition to providing the normal visual acuity and CSF, wearing MiSight DFSCL also leads to better satisfaction with the appearance.

Changes in the Objective Vision Quality of Adolescents in a Mesopic Visual Environment After Wearing Orthokeratology Lenses: A Prospective Study

PURPOSE

This study aimed to investigate changes in objective vision quality in mesopic environments in teenagers with myopia after wearing orthokeratology (OK) lenses.

METHODS

This prospective clinical study included 45 patients (80 eyes) who received OK lenses at the First Affiliated Hospital of Jinan University from March 2021 to September 2021. An Optical Path Difference-Scan III refractive power/corneal analyzer was used to determine the corneal topographic parameters (corneal e, corneal Q, surface asymmetry index (SAI), and surface regularity index (SRI)), higher-order aberrations (HOAs), axial length (AL) change, lens decentration, induced astigmatism, target power, and Strehl ratio (SR) in a mesopic visual environment after wearing OK lenses for 6 months. In addition, corneal morphological parameters, HOAs, and SR were analyzed in a mesopic visual environment. Finally, we investigated the correlations among corneal morphology, HOAs, AL change, lens decentration, induced astigmatism, and SR.

RESULTS

The SAI value was significantly higher ( P <0.01), and the corneal e was significantly lower ( P <0.01), in a mesopic visual environment after wearing OK lenses for 1 week than baseline. A significant increase was observed in total HOAs and spherical aberrations, compared with before the OK lenses were worn ( P <0.01). In addition, SR in the mesopic visual environment decreased significantly after wearing the lenses ( P <0.01). No significant differences were observed ( P >0.05) among the 1-week, 1-month, 3-month, and 6-month follow-up findings. After 6 months, AL and lens decentration did not differ significantly compared with before ( P >0.05), whereas induced astigmatism significantly increased ( P <0.05). Negative correlations were observed between corneal Q, SAI, SRI, HOAs, induced astigmatism, and SR, and positive correlations were found between corneal e, AL change, lens decentration, and SR, after wearing OK lenses.

KEY POINTS

• Wearing orthokeratology lenses significantly altered corneal morphology and HOAs in myopic teenagers within 1 week. • The changes that we observed in the eyes of adolescents with myopia after wearing orthokeratology lenses decreased vision quality in mesopic environments. • Strehl ratio is significantly correlated with multiple parameters, including HOAs, AL change, and lens decentration.

CONCLUSIONS

In teenagers with myopia wearing OK lenses, significant changes in vision quality and corneal morphology were observed, leading to increased aberrations and affecting optical imaging quality. Furthermore, SR is significantly correlated with multiple parameters, including HOAs, AL change, and lens decentration.

REGISTRATION NUMBER

This study is registered with the United States Clinical Trials Registry under registration number NCT04929119.

BCLA CLEAR Presbyopia: Management with corneal techniques

Corneal techniques for enhancing near and intermediate vision to correct presbyopia include surgical and contact lens treatment modalities. Broad approaches used independently or in combination include correcting one eye for distant and the other for near or intermediate vision, (termed monovision or mini-monovision depending on the degree of anisometropia) and/or extending the eye's depth of focus [1]. This report reviews the evidence for the treatment profile, safety, and efficacy of the current range of corneal techniques for managing presbyopia. The visual needs and expectations of the patient, their ocular characteristics, and prior history of surgery are critical considerations for patient selection and preoperative evaluation. Contraindications to refractive surgery include unstable refraction, corneal abnormalities, inadequate corneal thickness for the proposed ablation depth, ocular and systemic co-morbidities, uncontrolled mental health issues and unrealistic patient expectations. Laser refractive options for monovision include surface/stromal ablation techniques and keratorefractive lenticule extraction. Alteration of spherical aberration and multifocal ablation profiles are the primary means for increasing ocular depth of focus, using surface and non-surface laser refractive techniques. Corneal inlays use either small aperture optics to increase depth of field or modify the anterior corneal curvature to induce corneal multifocality. In presbyopia correction by conductive keratoplasty, radiofrequency energy is applied to the mid-peripheral corneal stroma, leading to mid-peripheral corneal shrinkage and central corneal steepening. Hyperopic orthokeratology lens fitting can induce spherical aberration and correct some level of presbyopia. Postoperative management, and consideration of potential complications, varies according to technique applied and the time to restore corneal stability, but a minimum of 3 months of follow-up is recommended after corneal refractive procedures. Ongoing follow-up is important in orthokeratology and longer-term follow-up may be required in the event of late complications following corneal inlay surgery.

Influence of a long-distance optical imaging workbench on accommodation and choroidal response in myopic children

CLINICAL RELEVANCE

Optical approaches to modulating near work may be beneficial in arresting the progression of myopia.

BACKGROUND

To explore whether a long-distance optical image workbench (LOIW) can replace traditional near-distance reading and has beneficial influences on accommodation and choroidal parameters.

METHODS

This self-control study included two sessions. In session 1, an open-field autorefractor measured sustained accommodative response and pupil diameter when participants viewed virtual images from 3.42 m away through LOIW with + 0.50 D over-correction lenses (3.42 m/+0.50 D), LOIW with full-correction lenses (3.42 m/FC), or the visual target at a given distance of 0.33 m with + 0.50 D over-correction lenses (0.33 m/+0.50 D), with full-correction lenses (0.33 m/FC). In session 2, swept-source optical coherence tomography angiography assessed subfoveal choroidal thickness (SFChT), choroidal volume (CV), and choriocapillaris flow void percentage (FV%) at baseline and before and after reading via LOIW with + 0.50 D over-correction lenses (Far/+0.50 D) or in habitual near distance with full-correction (Near/FC) for a sustained 30-min period.

RESULTS

Thirty-five myopic (mean spherical equivalent refraction: -1.11 ± 0.78 D) children (median [range] age: 8.36 [8-10] years) were analysed. Children viewing virtual images in 3.42 m/+0.50 D exhibited mild-degree accommodative leads (-0.54 ± 0.17 D), much smaller pupil diameter (3.39 ± 0.63 mm) and microfluctuations (0.13 ± 0.04 D); accommodative lags (0.88 ± 0.04 D), larger pupil diameter (5.05 ± 0.75 mm) and microfluctuations (0.88 ± 0.16 D) were observed in 0.33 m/+0.50 D, and the microfluctuations were unstable (F = 2.185, p = 0.038). Compared with baseline data, SFChT, CV, and FV% changed by 13.40 ± 4.71 μm, 0.26 ± 0.21 mm3, and - 0.14%±3.66% in Far/+0.50 D, respectively, while changes under Near/FC were - 10.19 ± 7.48 μm, -0.15 ± 0.22 mm3 and 1.95%±2.92%, respectively. All changes differed significantly between these two conditions (all p < 0.001).

CONCLUSION

The long-distance working mode may exert beneficial effects on accommodative and choroidal parameters in myopic children compared with traditional near work.

In vivo assessment of human corneal epithelial cells in orthokeratology lens wearers: A pilot study

SIGNIFICANCE

Central corneal epithelial thinning associated with midperipheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet, the cellular mechanism governing the regional change in refractive power remains elusive.

PURPOSE

This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers.

METHODS

A new human prototype of a polarization-dependent optical coherence microscope was developed to enable noncontact and noninvasive in vivo imaging of corneal epithelial cells in ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and midperipheral corneal locations in four ortho-k wearers and four spectacle wearers serving as controls.

RESULTS

Polarization-dependent optical coherence microscope achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view of 0.5 × 0.5 mm 2 with an isotropic resolution of ~2.2 mm. The central epithelial thinning and midperipheral epithelial thickening were consistent across all ortho-k wearers. However, the inconsistency in their regional epithelial cell density highlighted a great variability in individual response to ortho-k treatment. There was no strong correlation between epithelial thickness and cell density, especially at the midperipheral cornea, in ortho-k participants.

CONCLUSIONS

This study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cells before and during ortho-k treatment to identify factors governing individual response to ortho-k treatment and ultimately inform the dynamics of epithelial cells taking place during the ortho-k treatment.

Efficacy of Soft Contact Lenses for Myopia Control: A Systematic Review

PURPOSE

To summarize and analyze critically the scientific evidence focused on the effectiveness of the use of hydrophilic contact lenses (HCLs) in myopia control, as well as their impact on visual quality and the involvement on the accommodative and binocular function.

METHODS

This systematic review was developed selecting all original studies which evaluated HCLs for myopia control with follow-up of at least 1 year. Eligible randomized controlled trials (RCTs) were retrieved from PubMed MEDLINE and Scopus. Methodological quality of the studies was assessed using the Critical Appraisal Skills Programme (CASP) for RCTs.

RESULTS

The search provided a total of 276 articles, selecting 13 according to the inclusion and exclusion criteria. The majority of studies evaluating the effectiveness of HCL showed a good efficacy in myopia progression, providing a good quality of vision. The quality of these studies was found to be suitable according to the CASP tool. The accommodative and binocular function with these lenses was evaluated in few studies, reporting a trend to an increase in the accommodative response and exophoria in near vision, while maintaining good level of stereopsis. Aberrometry and pupillometry were only studied in one trial, in which the authors did not find changes in these variables after the use of a myopia control HCL.

CONCLUSIONS

There is a strong evidence about the effectiveness of different HCLs designs for slowing down myopia progression in children, providing all of them good levels of visual quality. However, there is still poor evidence about changes in accommodation and binocular function, as well as in pupil size and aberrometry with myopia control HCLs, being necessary more studies focused on this issue.

Assessing the rebound phenomenon in different myopia control treatments: A systematic review

PURPOSE

To review the rebound effect after cessation of different myopia control treatments.

METHODS

A systematic review that included full-length randomised controlled studies (RCTs), as well as post-hoc analyses of RCTs reporting new findings on myopia control treatments rebound effect in two databases, PubMed and Web of Science, was performed according to the PRISMA statement. The search period was between 15 June 2023 and 30 June 2023. The Cochrane risk of bias tool was used to analyse the quality of the selected studies.

RESULTS

A total of 11 studies were included in this systematic review. Unifying the rebound effects of all myopia control treatments, the mean rebound effect for axial length (AL) and spherical equivalent refraction (SER) were 0.10 ± 0.07 mm [-0.02 to 0.22] and -0.27 ± 0.2 D [-0.71 to -0.03] after 10.2 ± 7.4 months of washout, respectively. In addition, spectacles with highly aspherical lenslets or defocus incorporated multiple segments technology, soft multifocal contact lenses and orthokeratology showed lower rebound effects compared with atropine and low-level light therapy, with a mean rebound effect for AL and SER of 0.04 ± 0.04 mm [0 to 0.08] and -0.13 ± 0.07 D [-0.05 to -0.2], respectively.

CONCLUSIONS

It appears that the different treatments for myopia control produce a rebound effect after their cessation. Specifically, optical treatments seem to produce less rebound effect than pharmacological or light therapies. However, more studies are required to confirm these results.

Comparison of optical aberrations in keratoconus with scleral versus rigid gas permeable lenses

PURPOSE

to assess optical aberrations under scleral (SL) versus rigid gas permeable (RGP) lenses in patients with keratoconus.

METHODS

A prospective study including 25 eyes of 14 patients. The best-corrected visual acuity (BCVA) with corrective glasses, RGP and SL, stage of keratoconus (Amsler-Krumeich classification), minimum pachymetry, maximum keratometry, and corneal higher-order aberrations (i.e, total HOAs, coma, and trefoil) with RGP and with SL were collected. Aberrometry was performed using iTrace® aberrometer (Tracey Technologies, USA).

RESULTS

80% of the included keratoconus patients were stage 4, with a mean age of 34.3 years (±8.8). There were no significant differences in mean BCVA (logMAR) between SL and RGP. The mean BCVAs were significantly better both with SL (p < 0.0001) and RGP (p < 0.0001) compared with corrective glasses. Total HOAs (p = 0.01), coma (p = 0.003) and trefoil (p = 0.008) were significantly lower with SL compared with RGP. The BCVA decreased with the stage of keratoconus in SL (p = 0.01) and RGP (p = 0.02). The BCVA decreased with decreasing minimum pachymetry in SL (p = 0.02) and RGP (p = 0.002), and with increasing maximum keratometry in SL (p = 0.02) and RGP (p = 0.01). Significant correlations were found between BCVA, total HOAs (p = 0.008), and coma (p = 0.02) in SL.

CONCLUSION

For the same keratoconus patients, total higher order, coma and trefoil optical aberrations were reduced with scleral lenses compared to rigid gas permeable lenses.

The effect of multifocal contact lenses on the dynamic accommodation step response

PURPOSE

To measure the dynamic accommodation response (AR) to step stimuli with and without multifocal contact lenses (MFCLs), in emmetropes and myopes.

METHODS

Twenty-two adult subjects viewed alternating distance (0.25D) and near (3D) Maltese crosses placed in free space, through two contact lens types: single vision (SVCL) or centre-distance multifocal (MFCL; +2.50D add). The AR level was measured along with near to far (N-F) and far to near (F-N) step response characteristics: percentage of correct responses, magnitude, latency, peak velocity and duration of step response.

RESULTS

There was no difference between N-F and F-N responses, or between refractive groups in any aspect of the accommodation step response dynamics. The percentage of correct responses was unaffected by contact lens type. Through MFCLs, subjects demonstrated smaller magnitude, longer latency, shorter duration and slower peak velocity steps than through SVCLs. When viewing the near target, the AR through MFCLs was significantly lower than through SVCLs. When viewing the distance target with the MFCL, the focal points from rays travelling through the distance and near zones were approximately 0.004D behind and 2.50D in front of the retina, respectively. When viewing the near target, the respective values were approximately 1.89D behind and 0.61D in front of the retina.

CONCLUSION

The defocus error required for accommodation control appears not to be solely derived from the distance zone of the MFCL. This results in reduced performance in response to abruptly changing vergence stimuli; however, these errors were small and unlikely to impact everyday visual tasks. There was a decrease in ocular accommodation during near tasks, which has previously been correlated with a reduced myopic treatment response through these lenses. With MFCLs, the estimated dioptric myopic defocus was the largest when viewing a distant stimulus, supporting the hypothesis that the outdoors provides a beneficial visual environment to reduce myopia progression.

Effects on radius of curvature and refractive power of the cornea and crystalline lens by atropine 0.01% eye drops

PURPOSE

The morphological changes in the cornea and crystalline lens have not been closely evaluated after the administration of atropine 0.01%. This study aims to evaluate the radii of curvature and refractive power of the cornea and lens in myopic eyes during atropine 0.01% treatment.

METHODS

Children aged 6-14 years with myopia <-6.0 D were randomized to receive atropine 0.01% once nightly with single vision lenses or simply wear single vision lenses. Ocular biometric parameters were measured using the IOLMaster 700 biometry and the radii of corneal and lenticular curvature were simulated using a customized program.

RESULTS

At the 9-month visit, 69 atropine-treated eyes and 50 control eyes were included in the final analyses. In atropine-treated eyes, the posterior corneal surface steepened (-0.05 ± 0.13 mm) and the anterior lenticular surface flattened (0.20 ± 0.69 mm) significantly within 3-6 months, whereas the posterior corneal surface and anterior lenticular surface gradually flattened (0.07 ± 0.23 and 0.32 ± 0.80 mm respectively) in the control eyes over 9 months. The difference in the change of corneal refractive power was significant between groups (-0.03 ± 0.18 D vs. 0.11 ± 0.24 D, p = 0.001), while that in the change of lenticular refractive power was statistically insignificant (0.01 ± 0.92 D vs. -0.22 ± 0.86 D, p = 0.161).

CONCLUSIONS

The administration of atropine 0.01% exhibited a clinically short and subtle impact on the cornea and lens, which may shed light on new targets of action for atropine in inhibiting myopia.

Changes in Corneal Higher-Order Aberrations and Ocular Biometric Measurements after Phacoemulsification Combined with Goniosynechialysis in Primary Angle Closure/Glaucoma Patients

Purpose

To compare corneal higher-order aberrations (HOAs), refractive error, and ocular biological parameters before and after phacoemulsification combined with goniosynechialysis (Phaco-GSL) in primary angle closure/glaucoma (PAC/PACG) patients with different axial lengths (ALs).

Methods

In this prospective study, cataract patients diagnosed with PAC/PACG were categorized into two groups based on their ALs: the short AL group (AL ≤ 22.5 mm) and the normal AL group (22.5 < AL ≤ 24.5 mm). The pre- and postsurgery measurements of intraocular pressure (IOP) and best-corrected visual acuity (BCVA) were conducted at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months. Additionally, the assessments included corneal HOAs, the number of antiglaucoma medications, visual field parameters, manifest refraction, and other ocular biological parameters before surgery and at the final follow-up.

Results

Prior to surgery, the two groups exhibited no significant differences, except for AL, curvature value, and Z (4, 0) of the posterior corneal surface (all P < 0.01). Following surgery, BCVA improved, and IOP decreased significantly in both groups (P < 0.01). Both anterior and total corneal HOAs, along with Z (3, -3), increased in the two groups (all P < 0.05), with the normal AL group exhibiting a significantly greater increase in total cornea Z (3, -3) than the short AL group (P=0.047). The normal AL group also exhibited a slight tendency towards hyperopia (P < 0.01). Significant changes were observed in the visual field index and mean deviation in both groups (P < 0.05).

Conclusions

Phaco-GSL resulted in an increased corneal HOAs, particularly trefoil, with variations based on the patient's AL. Patients with normal ALs tended to shift towards hyperopia after surgery.

Comparison of visual performance and image quality between a myopia-control contact lens and a single-vision contact lens

OBJECTIVE

This study aimed to evaluate the visual performance and image quality of concentric dual-focus-designed contact lenses (CLs) compared with single-vision CLs in myopic Chinese people.

METHODS

Twenty myopic volunteers aged between 18 and 26 years were recruited at a university eye hospital to wear both defocus-incorporated soft contact (DISC) lenses and single-vision CLs for 1 week in random order. High- and low-contrast visual acuity (VA), contrast sensitivity (CS), ocular higher-order aberrations (HOA), Strehl ratio and the Quality of Vision (QoV) questionnaire were assessed with each type of CL at weekly follow-up.

RESULTS

Distance VA was not affected by DISC lenses compared to single-vision CLs in either high (p = 0.414) or low contrast (p = 0.431). However, there was a significant reduction in low-contrast near VA with DISC lenses compared with single-vision CLs (p = 0.011). The differences of CS between DISC lenses and single-vision CLs were significantly associated with lighting conditions and spatial frequencies (F = 128.81, P < 0.001). Compared with single-vision CLs, wavefront aberrations of DISC lenses were significantly increased in total HOA, trefoil, and spherical aberrations for either 3.0 mm or 6.0 mm pupil size. The Strehl ratio wearing DISC lenses reduced significantly compared to the single-vision CLs (p < 0.001) at a pupil diameter of 6.0 mm. QoV scores were higher overall (p = 0.026) and frequency (p = 0.019) with DISC lenses than with single-vision CLs, indicating poorer visual performance.

CONCLUSION

DISC lenses provide satisfactory distance VA. However, the higher scores of the QoV questionnaire with DISC lenses may be related to decreased CS at medium or high spatial frequencies and increased higher-order aberrations.

Long-term variations and influential factors of the treatment zone of wearing orthokeratology lenses

PURPOSE

To investigate the variation trend of the treatment zone (TZ) during 12 months of Orthokeratology (Ortho-K) from the perspective of the treatment zone size (TZS), decentration (TZD) and the weighted Zernike defocus coefficient of the treatment zone (Cweighteddefocus).

METHODS

94 patients were included in this retrospective study, who were fitted with a 5-curve vision shaping treatment (VST) lens (n = 44) or a 3-zone corneal refractive therapy (CRT) lens (n = 50). The TZS, TZD and Cweighteddefocus up to 12 months were analyzed.

RESULTS

TZS (F(4,372) = 10.167, P＜0.001), TZD (F(4,372) = 8.083, P＜0.001) and Cweighteddefocus (F(4,372) = 7.100, P＜0.001) were significantly increased with time during overnight Ortho-K treatment. The TZS increased sharply from 1 week to 1 month of overnight Ortho-K (F = 25.479, P <.001) and stayed smooth then. It showed growing tendency from 6 to 12 months (F = 8.407, P =.005). The TZD (F = 16.637, P <.001) and Cweighteddefocus (F = 13.401, P <.001) increased significantly until 1 month and kept stable until 12 months (all P＞0.05). The univariant linear regression analysis showed that TZS of the last visit was correlated with baseline myopia (β = 0.219, P =.034). Also, the greater final Cweighteddefocus was correlated with higher baseline myopia (β = -0.589, P＜0.001) and higher corneal astigmatism (β = -0.228, P =.007) at the onset of lens wear with the multiple linear regression.

CONCLUSION

The TZS, TZD and Cweighteddefocus kept stable after 1 month of Ortho-K while the TZS had an increasing trend after 6 months. Children with higher myopic eyes or higher corneal astigmatism at baseline tended to have smaller TZS and greater Cweighteddefocus at 12 months.

Choroidal vasculature act as predictive biomarkers of long-term ocular elongation in myopic children treated with orthokeratology: a prospective cohort study

BACKGROUND

Despite receiving orthokeratology (ortho-k), the efficacy of retarding ocular elongation during myopia varies among myopic children. The current study aimed to investigate the early changes of choroidal vasculature at one month after ortho-k treatment and its association with one-year ocular elongation, as well as the role of such choroidal responses in predicting the one-year control efficacy of ortho-k treatment.

METHODS

A prospective cohort study was conducted in myopic children treated with ortho-k. Myopic children aged between 8 and 12 years who were willing to wear ortho-k lenses were recruited consecutively from the Eye Hospital of Wenzhou Medical University. Subfoveal choroidal thickness (SFCT), submacular total choroidal luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow deficit (CcFD) were evaluated by optical coherence tomography (OCT) and OCT angiography over a one-year period.

RESULTS

Fifty eyes from 50 participants (24 males) who finished one-year follow-ups as scheduled were included, with a mean age of 10.31 ± 1.45 years. The one-year ocular elongation was 0.19 ± 0.17 mm. The LA (0.03 ± 0.07 mm²), SA (0.02 ± 0.05 mm²) increased proportionally after one-month of ortho-k wear (both P < 0.01), as did the SFCT (10.62 ± 19.98 μm, P < 0.001). Multivariable linear regression analyses showed that baseline CVI (β = - 0.023 mm/1%, 95% CI: - 0.036 to - 0.010), one-month LA change (β = - 0.009 mm/0.01 mm², 95% CI: - 0.014 to - 0.003), one-month SFCT change (β = - 0.035 mm/10 µm, 95% CI: - 0.053 to - 0.017) were independently associated with one-year ocular elongation during ortho-k treatment after adjusting with age and sex (all P < 0.01). The area under the receiver operating characteristic curve of prediction model including baseline CVI, one-month SFCT change, age, and sex achieved 0.872 (95% CI: 0.771 to 0.973) for discriminating children with slow or fast ocular elongation.

CONCLUSIONS

Choroidal vasculature is associated with ocular elongation during ortho-k treatment. Ortho-k treatment induces increases in choroidal vascularity and choroidal thickness as early as one month. Such early changes can act as predictive biomarkers of myopia control efficacy over a long term. The utilization of these biomarkers may help clinicians identify children who can benefit from ortho-k treatment, and thus has critical implications for the management strategies towards myopia control.

Retinal image quality in myopic children undergoing orthokeratology alone or combined with 0.01% atropine

BACKGROUND

The retinal image quality derived from lower-order (LOA) and higher-order aberrations (HOA) for fixed 3-mm and photopic pupil diameters, in children undergoing combined 0.01% atropine and orthokeratology (AOK) versus those receiving orthokeratology alone (OK) over two years was evaluated.

METHODS

The visual Strehl ratio based on the optical transfer function (VSOTF), derived from 2nd- to 4th-order terms (LOA and HOA combined), 2nd-order terms (LOA only), and 3rd- to 4th-order terms (HOA only) for fixed 3-mm and natural photopic pupil diameters, was compared between the two treatment groups. The individual Zernike coefficients for a fixed 3-mm pupil size of 2nd- to 4th-orders, root mean square (RMS) of LOA ([Formula: see text], [Formula: see text], and [Formula: see text] combined), HOA (3rd to 4th orders inclusive), and Coma ([Formula: see text] combined) were also compared between the two groups.

RESULTS

Right eye data of 33 AOK and 35 OK participants were analysed. Under photopic conditions, significantly lower VSOTF based on HOA only was observed in the AOK group compared with that in the OK group at all post-treatment visits (all P < 0.05); however, interactions between HOA and LOA resulted in comparable overall retinal image quality (i.e., VSOTF based on LOA and HOA combined) between the two groups at all visits (all P > 0.05). For a fixed 3-mm pupil size, the VSOTF based on HOA only, LOA only, or HOA and LOA combined, were not different between the two groups (all P > 0.05). AOK participants had slower axial elongation (mean ± SD, 0.17 ± 0.19 mm vs. 0.35 ± 0.20 mm, P < 0.001), a larger photopic pupil size (4.05 ± 0.61 mm vs. 3.43 ± 0.41 mm, P < 0.001) than OK participants, over two years.

CONCLUSIONS

HOA profile related to an enlarged pupil size may provide visual signal influencing eye growth in the AOK group.

Higher order aberrations and retinal image quality during short-term accommodation in myopic and non-myopic children

INTRODUCTION

Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation-induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood.

METHODS

Ocular HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences) in 18 myopic and 18 age- and sex-matched non-myopic children during short-term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J₁₈₀ and J₄₅ ) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only.

RESULTS

Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with-the-rule astigmatism (J₁₈₀ ), higher order and third order RMS values, primary vertical ( C 3 - 1 $$ {C}_3^{-1} $$ ) and horizontal coma ( C 3 1 $$ {C}_3^1 $$ ), and several other individual Zernike coefficients compared with non-myopic children (all refractive error group by demand interaction p-values of ≤0.02). Non-myopic children exhibited a greater negative shift in primary ( C 4 0 $$ {C}_4^0 $$ ) and positive shift in secondary spherical aberration ( C 6 0 $$ {C}_6^0 $$ ) (both refractive error group by demand interaction p-values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of -0.274 (0.048) for the 9 D demand, compared with -0.131 (0.052) for the non-myopic children (p = 0.001).

CONCLUSION

These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks.

Atropine-eluting silicone contact lenses for myopia control

Myopia, also known as nearsightedness, is one of the prime reasons for vision impairment worldwide. Atropine in topical ophthalmic solutions (e.g., 0.01% atropine sulfate eye drops) is the primary medical treatment for controlling myopia, especially for pseudomyopia or true myopia in rapid progress. However, aqueous atropine solution is unstable and easily breaks down to tropic acid, which will result in vision blur. Drug-eluting contact lenses (CLs) have been explored as a potentially superior alternative to effectively control the drug release and improve the drug efficacy. In this work, an atropine-eluting contact lens was developed by encapsulating an atropine implant in a silicon-based contact lens, towards functioning in vision correction and controlling myopia. The safety and effectiveness of this atropine-eluting contact lens were verified with rabbit and guinea pig models. The results showed that the lenses reduced the side effects like mydriasis and no other adverse events were observed in rabbit eyes. More importantly, atropine-loaded lenses could effectively delay the progress of form-deprivation myopia with guinea pig eyes as the model. Thus, we concluded that atropine-eluting CLs prepared by implantation technology may be an option for the treatment of myopia.

Higher order aberrations and visual function in a young Asian population of high myopes

Purpose

To examine the associations between higher order aberrations (HOAs), visual performance, demographics, and ocular characteristics in a young Asian population with high myopia.

Methods

This was a retrospective review of military pre-enlistees conducted between March 2014 to September 2018. Visual acuity and contrast sensitivity were tested under photopic, mesopic and simulated night conditions. Ocular, corneal and internal HOAs were measured with a Hartmann-Shack wavefront aberrometer (KR-1W, Topcon Co., Tokyo, Japan).

Results

522 eyes of 263 consecutive subjects with severe high myopia (defined as spherical equivalent refraction [SER] ≤ -10.00D) in at least one eye, and high myopia (SER ≤ -6.00D) in the fellow eye, [mean (SD) SER -11.85 (2.03D)] were analysed. The mean (SD) age of subjects was 18.5 (1.6) years. Chinese eyes had significantly greater internal total HOA root-mean-square (RMS) compared to Malay eyes [mean difference (SD) 0.0246 (0.007) μm, p < 0.001). More negative SER was associated with greater ocular total HOA (p = 0.038), primary coma (p = 0.003) and tetrafoil (p = 0.025) RMS, as well as more positive ocular (p = 0.003) and internal primary spherical aberration (p = 0.009). Greater ocular total HOAs was associated with reduced visual acuity in simulated night conditions and low contrast, decreased contrast sensitivity under mesopic and simulated night conditions (all p < 0.05).

Conclusions

Greater HOAs were associated with Chinese ethnicity and more negative SER in a young Asian population with high myopia. Greater HOAs were associated with poorer visual performance in low luminance and reduced contrast conditions.

Effects of exogenous retinoic acid on ocular parameters in Guinea pigs with form deprivation myopia

Aim: Myopia is a common chronic eye disease, this study is to investigate the effects of exogenous retinoic acid (RA) on intraocular parameters, especially choroidal thickness (CT) and retinal thickness (RT), in guinea pigs with form deprivation myopia (FDM).

Methods: A total of 80 male guinea pigs were divided randomly into 4 groups: Control, FDM, FDM + RA, and FDM + Citral groups. The FDM + RA group was given 24 mg/kg RA dissolved in 0.4 mL peanut oil; the FDM + Citral group was given citral 445 mg/kg dissolved in 0.4 mL peanut oil; The other two groups were given 0.4 mL peanut oil. After 4 weeks, the refractive error (RE), axial length (AL), and intraocular pressure (IOP) of all guinea pigs were measured, and the parameters of RT and CT were obtained using enhanced depth imaging optical coherence tomography (EDI-OCT).

Results: After 4 weeks, both the RE and AL in the FDM and FDM + RA groups were increased, and the RT and CT in both groups were smaller than those in the Control group (p &lt; 0.05). Only the IOP of the right eye in the FDM + RA group increased significantly (p &lt; 0.05). The RT of the right eye of the 4 groups was compared: Control group &gt; FDM + Citral group &gt; FDM group &gt; FDM + RA group. Compared with the RT of the left eye and the right eye among the 4 groups, the RT of the right eye in the FDM and FDM + RA groups was significantly less than that in the left eye (p &lt; 0.05). Moreover, the CT of the right eye in the Control group was greater than that in the other three groups (p &lt; 0.0001). There was no significant difference in the CT among the FDM, FDM + RA, and FDM + Citral groups (p &gt; 0.05). In contrast to the RT results, the CT results of the left and right eyes in the FDM + Citral group showed statistically significant differences (p &lt; 0.05).

Conclusion: RA participates in the progression of FDM as a regulatory factor. Exogenous RA can increase the RE, AL, and IOP of FDM guinea pigs, and might aggravate the retinal thinning of FDM guinea pigs. Citral can inhibit these changes, but RA might not affect the thickness of the choroid.

Intraocular composition of higher order aberrations in non-myopic children

This study examined anterior corneal, internal ocular, and total ocular higher order aberrations (HOA's), and retinal image quality in a non-myopic, paediatric cohort. Anterior corneal aberrations were derived from corneal topography data captured using a Placido disk videokeratoscope (E300, Medmont International), and whole eye HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences). The associations between HOA's and age, sex, refractive error, and axial length were explored using correlation analyses. Data for 84 children aged between 5 and 12 years (mean ± standard deviation spherical equivalent refraction (SER), +0.63 ± 0.35 D; range 0.00 to +1.75 D) were included, and an eighth order Zernike polynomial was fit for 4 and 6 mm pupil diameters for both the anterior corneal and total ocular HOA's, from which internal ocular HOA's were calculated via subtraction following alignment to a common reference axis (pupil centre). Internal ocular HOA's were of greater magnitude than previous studies of adolescents and adults, however partial internal "compensation" of HOA's was observed, which resulted in reduced levels of HOA's and excellent retinal image quality. Few significant associations were observed between HOA's and age, SER, and axial length (all correlations, p > 0.001), and there were minimal sex-based differences (all comparisons, p > 0.005). Coefficients for vertical coma ( C 3 - 1 and C 5 - 1 ) and spherical aberration ( C 4 0 and C 6 0 ), were most strongly associated with the visual Strehl ratio based on the optical transfer function (VSOTF), which indicated that the absolute magnitudes of these Zernike coefficients have the greatest impact on retinal image quality in this paediatric cohort. These findings provide an improved understanding of the optics and retinal image quality of children's eyes.

One-year myopia control efficacy of cylindrical annular refractive element spectacle lenses

PURPOSE

To evaluate the 1-year myopia control efficacy of a spectacle lens with annular cylindrical microstructures.

METHODS

A total of 118 consecutive eligible children aged 8-12 years with -1.00 D to -4.00 D of spherical component myopia and <1.50 D astigmatism were enrolled between August 2020 and November 2020 at the Eye Hospital of Wenzhou Medical University. Participants were randomly assigned to wear cylindrical annular refractive element (CARE) (n = 61) or single-vision (n = 57) spectacle lenses. Cycloplegic autorefraction (spherical equivalent refraction [SER]) and axial length (AL) were measured at baseline and 6-month intervals. Adaptation and compliance questionnaires were administered during all visits.

RESULTS

Among 118 randomized participants, 96 (81.4%) were included in the analyses (mean [SE] age, 10.4 [0.6] years; 49 [51.0%] were female; mean [SE] spherical equivalent refractive error, -2.67 [0.66] D; mean [SE] axial length, 24.75 [0.77] mm). Adjusted 1-year myopia progression was -0.56 D for CARE and -0.71 D for single-vision spectacle lenses. The difference in progression was 0.14 D (95% CI, -0.04 to 0.32) for CARE vs single vision. Adjusted 1-year eye growth was 0.27 mm for CARE and 0.35 mm for single vision. The difference in eye growth was 0.09 mm (95% CI, -0.15 to -0.02) for CARE vs single vision. All groups adapted to their lenses with no reported adverse events, complaints, or discomfort.

CONCLUSIONS

Among children with myopia, treatment with cylindrical annular refractive element spectacle lenses significantly reduced the rate of axial elongation over 1 year compared with single-vision spectacle lenses.

Visual function assessment of Chinese cataract patients after individual aspheric intraocular lens implantation according to preoperative cornea spherical aberration

BACKGROUND: Aspheric intraocular lens (IOLs) implantation has been widely applied in cataract surgery. However, there is no consensus on the optimal guidance for the operations in IOLs implantation. OBJECTIVE: This study evaluated the visual function of Chinese cataract patients six months after cataract surgery with two different guiding ideologies. METHODS: We evaluated 50 patients (61 eyes) with implantation of different aspheric IOLs (SN60WF IOLs, ZCB00 IOLs, PY-60AD IOLs, AO IOLs) 6 months after cataract surgery. Twenty-four patients (30 eyes) under individual implantation were ascribed to group 1 and 26 patients (31 eyes) with randomized implantation were ascribed to the control group (group 2). Postoperatively parameters included monocular best-corrected visual acuity (BCVA), contrast sensitivity (CS), total spherical aberration Z (4, 0) at 5 mm pupil size, and patient satisfaction. The quality of life after operation was assessed through the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). RESULTS: Six months after cataract operation, the contrast sensitivity with glare of group 1 at 2.5∘ was 0.697 ± 0.027, and 0.532 ± 0.049 in group 2. Besides, there was no significant difference at any other special frequency. The mean spherical aberration Z (4, 0) at 5 mm pupil size in group 1 was 0.015 ± 0.028 um, and in group 2 was 0.043 ± 0.109 um, with a significant difference (p< 0.01). The mean scores obtained from NEI VFQ-25 were not significantly different. CONCLUSION: It is effective to implant aspheric IOLs individually according to preoperative corneal spherical aberration. Patients obtained better contrast sensitivity with glare at 2.5∘, but there was no significant difference in BCVA, contrast sensitivity at other special frequency, and subjective visual function.

Short-term tear film stability, optical quality and visual performance in two dual-focus contact lenses for myopia control with different optical designs

Purpose

To assess and compare short‐term visual and optical quality and tear film stability between two dual‐focus (DF) prototype myopia control contact lenses (CLs) having different inner zone diameters.

Methods

Twenty‐eight myopic subjects were included in this randomised, double‐masked crossover study. Refraction, best‐corrected visual acuity (VA) and tear film stability were measured at baseline (i.e., when uncorrected). Subjects were then binocularly fitted with the DF CLs, with only the sensorial dominant eye being assessed. Lenses were of the same material and had inner zone diameters of either 2.1 mm (S design) or 4.0 mm (M design). Visual and physical short‐term lens comfort, over‐refraction, best‐corrected VA, stereopsis at 40 cm, best‐corrected photopic and mesopic contrast sensitivity (CS), size and shape of light disturbance (LD), wavefront aberrations, subjective quality of vision (QoV Questionnaire) and tear film stability were measured for each lens.

Results

Both CL designs decreased tear film stability compared with baseline (p < 0.05). VA and photopic CS were within normal values for the subjects' age with each CL. When comparing lenses, the M design promoted better photopic CS for the 18 cycles per degree spatial frequency (p < 0.001) and better LD (p < 0.02). However, higher‐order aberrations were improved with the S design (p = 0.02). No significant difference between the two CLs was found for QoV scores and tear film stability.

Conclusions

Both DF CLs provided acceptable visual performance under photopic conditions. The 4.0 mm inner zone gave better contrast sensitivity at high frequencies and lower light disturbance, while the 2.1 mm central diameter induced fewer higher‐order aberrations for a 5 mm pupil diameter. Both CLs produced the same subjective visual short‐term lens comfort.

Multifocal contact lens myopia control: central and peripheral retinal image quality

CLINICAL RELEVANCE

That myopic defocus, even if restricted to the peripheral retina, inhibits eye growth in young monkey eyes has motivated the therapy of myopia control through multifocal contact lens wear in children.

BACKGROUND

To understand how eye-length regulating mechanisms are triggered by light requires knowledge of retinal light spread. That is largely lacking for the multifocal contact lenses used in the therapy because empirical methods identifying just the defocus in dioptres are inadequate.

METHODS

"Through-focus" diffraction computations in contact lens/eye models with typical normal eye parameters, including polychromatic light, the chromatic aberrations and an M-cone phototransduction layer, offer estimates of retinal image spread for a range of viewing distances.

RESULTS

Point- and edge-spread distributions of activation of phototransduction in the central retina show that the addition of multifocal zones produces some veiling for in-focus viewing and substantial improvement of image quality for near targets in the unaccommodated eye. These effects are much reduced in the retinal periphery.

CONCLUSION

Whatever therapeutic value there is in prescribing multifocal contact lenses for myopia control, it is not particularly dependent on the precise configuration of the multifocal zones, nor can it be ascribed to changes in image quality specific to the retinal periphery; its origin is more likely less blur for near targets, reducing the stimulus to accommodation.

Corneal morphology correlates with choriocapillaris perfusion in myopic children

AIMS

The present study investigated the difference in choriocapillaris (CC) perfusion between different AL/K ratio groups with similar spherical equivalent refraction (SER) and analyzed factors affecting CC perfusion.

METHODS

This cross-sectional study included 129 children with low-to-moderate myopia. Axial length (AL), average K-reading (Ave-K), and SER were measured. Choroidal vascularity, including the total choroidal area (TA), choroidal luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), CC flow voids (FVs), and FVs%, was obtained using optical coherence tomography angiography.

RESULTS

Participants with similar SER were divided into two groups (high AL/K ratio, n = 57; low AL/K ratio, n = 72). The high AL/K group had lower LA, TA, and CVI (P < 0.01) and lower FVs (inner ring and fovea, P < 0.05) and FVs% (outer ring, inner ring, and fovea, P < 0.05). The AL/K ratio and FVs% were negatively correlated in the outer ring (r =  - 0.174, P < 0.05) and inner ring (r =  - 0.174, P < 0.05). The Ave-K and inner FVs (r = 0.178, P < 0.05), outer FVs% (r = 0.175, P < 0.05), and inner FVs% (r = 0.196, P < 0.05) were positively correlated. In stepwise multiple regression for the outer ring, the horizontal CVI was related to FVs (β = 0.175, P < 0.05), and the vertical CVI was related to FVs% (β = 0.232, P < 0.01). Independent risk factors associated with inner FVs area were vertical CVI (β = 0.329; P < 0.001) and SER (β =  - 0.196, P < 0.05); FVs% was also associated with vertical CVI (β = 0.360, P < 0.01) and SER (β =  - 0.196, P < 0.05).

CONCLUSION

With a similar SER, myopic eyes with a higher AL/K ratio maintained more CC perfusion and lower CVI, which may indicate rapid myopic progression. Low K-reading eyes had more CC perfusion and less CVI, which may explain the relatively poor myopia control efficacy in the clinic.