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

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 provides an overview of the evidence for the treatment profile, safety, and efficacy of the range of corneal techniques currently available 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. Presbyopia correction by conductive keratoplasty involves application of radiofrequency energy to the mid-peripheral corneal stroma which leads to mid-peripheral corneal shrinkage, inducing 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.

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.

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.

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.

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.

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.

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.

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.

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.

Refractive Lens Exchange Surgery in Early-Onset High Myopia Patients With Partial Cataract

Purpose

By reporting clinical characteristics and retinal image quality before and after refractive lens replacement surgery in early-onset high myopia (eoHM) patients presenting with partial cataract, we emphasized the need for an objective way to grade the severity of partial cataracts.

Methods

This retrospective, consecutive case series included six Chinese patients (nine eyes). Analysis of previous medical records, visual acuity, optometry, retinal image quality, and axial length (AXL) before surgery and after surgery was performed.

Results

Five females and one male (nine eyes) with a mean (± SD) age of 11.6 ± 7.9 years (range: 4–25 years) were included in this study. The preoperative spherical power ranged from −7.5 to −42 D. The mean follow-up time was 36 months (range: 24–48 months). Phacoemulsification was followed by in-the-bag implantation of intraocular lens. For patients who were under 6 years old, posterior capsulotomy + anterior vitrectomy were performed simultaneously. All surgeries were uneventful and no postoperative complications occurred during the entire follow-up period. All patients’ uncorrected visual acuity improved by ≥2 lines postoperatively(Snellen acuity). LogMAR best-corrected visual acuity was improved at 24-month (P = 0.042) and endpoint (P = 0.046) follow-ups. Modulation transfer function cutoff frequency (MTF_cutoff) and objective scatter index (OSI) was significantly improved at 12-month (P = 0.025, P = 0.038), 24-month (P = 0.005, P = 0.007) and endpoint (P = 0.005, P = 0.008) follow-ups. Postoperative AXL remained stable during 2–4 year follow-ups (P > 0.05).

Conclusion

Refractive lens replacement surgery is safe and effective for improving functional vision in eoHM patients presenting with partial cataract. Retinal image quality could provide a useful and objective way to facilitate partial cataract severity evaluation and surgery decision making.

Repeatability of i.Profiler for measuring wavefront aberrations in healthy eyes

PURPOSE

To evaluate the repeatability of wavefront aberration measurements and the correlation between corneal aberration and pupil size in normal eyes using a wavefront-based autorefractor (i.Profiler^Plus; Carl Zeiss Vision, Germany).

METHODS

A prospective cross-sectional study. Wavefront aberrations, including spherical aberration (SA) (Z₄⁰), coma (Z₃^-1, Z₃¹), trefoil (Z₃^-3, Z₃³) and total higher-order aberrations (tHOA), were measured at different pupil diameters. The repeatability was evaluated using one-way ANOVA method, and statistical indicators including within-subject standard deviation (S_w), test-retest repeatability (TRT), and intra-class correlation coefficient (ICC). The correlations between corneal aberrations and pupil sizes were evaluated by Pearson correlation analysis.

RESULTS

A total of 96 healthy young volunteers were enrolled. Corneal and ocular higher-order aberrations (HOA) measured by i.Profiler showed S_w < 0.01 μm, TRT < 0.10 μm, ICC > 0.90. There was a linear positive correlation between the corneal HOA and pupil size. The correlation coefficient between SA and tHOA was the largest (r = 0.996, P < 0.001).

CONCLUSIONS

The measurements of wavefront aberrations by i.Profiler are highly repeatable. Corneal HOA was significantly dependent on pupil size. SA was the most influential aberration for visual quality in this study.

Short-Term Effect of Wearing of Extended Depth-of-Focus Contact Lenses in Myopic Children: A Pilot Study

This pseudo-experimental, prospective, and longitudinal pilot study was conducted to characterize the optical and visual changes occurring in the short-term wear of a hydrophilic contact lens (CL) based on extended focus technology (EDOF). A total of 30 eyes of 15 children (age, 6–16 years) were fitted with the EDOF CL Mylo (Mark’ennovy Care SL), performing an exhaustive follow-up for one month evaluating changes in visual acuity (VA), accommodation, binocularity, ocular aberrometry, visual quality, pupillometry, keratometry and biometry. Far and near VA with the CL improved progressively (p < 0.001), obtaining mean final binocular values of −0.08 ± 0.01 and −0.07 ± 0.01 LogMAR, respectively. There was a mean reduction in the accommodative LAG of 0.30 D (p < 0.001), without associated alterations in the magnitude of the phoria and fusional vergences (p ≥ 0.066). A controlled but statistically significant increase (p ≤ 0.005) of ocular high order aberration (HOA) root mean square (RMS), primary coma RMS, primary spherical aberration Zernike term and secondary astigmatism RMS was found with the CL wear. In conclusion, the EDOF CL evaluated provides adequate visual acuity and quality, with associated increased of several HOAs and a trend to reduction in the accommodative LAG that should be confirmed in future studies.

Simultaneous measurements of foveal and peripheral aberrations with accommodation in myopic and emmetropic eyes

The difference in peripheral retinal image quality between myopic and emmetropic eyes plays a major role in the design of the optical myopia interventions. Knowing this difference under accommodation can help to understand the limitations of the currently available optical solutions for myopia control. A newly developed dual-angle open-field sensor was used to assess the simultaneous foveal and peripheral ( 20 ∘ nasal visual field) wavefront aberrations for five target vergences from -0.31 D to -4.0 D in six myopic and five emmetropic participants. With accommodation, the myopic eyes showed myopic shifts, and the emmetropic eyes showed no change in RPR. Furthermore, RPR calculated from simultaneous measurements showed lower intra-subject variability compared to the RPR calculated from peripheral measurements and target vergence. Other aberrations, as well as modulation transfer functions for natural pupils, were similar between the groups and the accommodation levels, foveally and peripherally. Results from viewing the same nearby target with and without spectacles by myopic participants suggest that the accommodative response is not the leading factor controlling the amplitude of accommodation microfluctuations.

Effect of corneal incision features on anterior and posterior corneal astigmatism and higher-order aberrations after cataract surgery

PURPOSE

To evaluate the influence of 2.2 mm clear corneal incision (CCI) features in surgically induced astigmatism (SIA) and higher-order aberrations (HOAs) after cataract surgery.

METHODS

Right eyes of 92 subjects receiving 2.2 mm incision cataract surgery were involved. A total of 38 eyes were categorized as the intact incision group, and 54 eyes were the defective incision group. Pre- and postoperative (1 month and 6 months) corneal astigmatism and HOAs on anterior and posterior corneal surfaces, corneal volume, and corneal thickness (CT) were measured using Pentacam. The CCI features including incision length (IL), incision angles, distance from incision to central cornea (Dis-En/Ex), and CT at incision site were quantified using AS-OCT.

RESULTS

The defective incision group showed shorter IL and larger incision angles [false discovery rate (FDR) - p < 0.05]. Changes in CT at incision site were more pronounced for the defective incision group (FDR - p < 0.05). Some SIA parameters were related to the certain specific CCI features, especially IL (FDR - p < 0.05). Both groups exhibited significant increased 6 mm posterior corneal tHOAs at 1 month (Bonferroni corrected - p < 0.01) and the defective incision group showed increased 6 mm posterior tHOAs at 6 months (Bonferroni corrected - p = 0.023). There were characteristic correlations between Zernike terms and CCI features including IL, CT, Dis-En/Ex, and incision angles at 1 month, especially over 6 mm zone.

CONCLUSION

The CCI deformities can affect corneal recovery and induce more HOAs at 1 month postoperatively. Such effects became minor, but could persist until 6 months. The IL combined with Angle-En/Ex was important factor influencing CCI integrity and corneal optical quality.

Geometrical scaling of the developing eye and photoreceptors and a possible relation to emmetropization and myopia

In this study the role of vergence in relation to age-dependent scaling of eye and photoreceptor parameters is studied. The underlying hypothesis is that the size and packing of outer segments is matched to the pupil size outdoors in photopic conditions. Vergence is analysed in relation to the angular spectrum of waves being incident using age-dependent data from the literature for the actual geometry and density of photoreceptor cones and rods. This approach is used to derive simple relations for the angular confinement of light along outer segments. Only with a small photopic pupil can leakage and crosstalk for both central and peripheral photoreceptors be entirely ruled out due to the finite length of the outer segments. A limiting 3 mm pupil size is found for children in the school age. Larger pupils will increase the likelihood of leakage and crosstalk that may therefore impact on emmetropization. This study has introduced a new paradigm in myopia research by considering vergence across the 3-D retina as being matched to the angular spectrum of waves being incident from the eye pupil. Emmetropization suggests a delicate balance between photoreceptor outer segment length and density in relation to pupil size. Only when balanced will leakage and crosstalk between adjacent outer segments be effectively suppressed thereby ensuring the highest possible light capture efficiency by visual pigments in the outer segments whether an image is formed on the retina or not.

Effect of the Optical Zone Ablation Diameter on Higher Order Aberrations After Transepithelial Photorefractive Keratectomy: A Cohort Study

OBJECTIVES

To study the effect of the optical zone diameter of ablation on higher order aberrations after transepithelial photorefractive keratectomy for myopia and myopic astigmatism.

METHODS

In this historical cohort study in 2019, patients were grouped into 7-mm (Gr-1) and 6.5-mm optical zones of ablation (Gr-2). Topographic and higher order aberrations at analysis diameters of 2, 4, and 6 mm were measured before and six months after transepithelial photorefractive keratectomy. The changes in the five types of higher order aberrations in the 6.5 mm and 7 mm groups were compared. The pupillary diameter was correlated with the change in the higher order aberrations.

RESULTS

We had 24 eyes of 12 patients in Gr-1 and 80 eyes of 40 patients in Gr-2. The trefoil type of higher order aberrations at 6 mm was significantly more prevalent in Gr-2 than in Gr-1 before surgery (p = 0.038). The change in spherical aberration six months after surgery compared with before was significantly more at 6 mm in the eyes of Gr-2 patients (p = 0.02). For the eyes managed by the 7-mm optical zone of ablation for transepithelial photorefractive keratectomy, the decline in the different types of higher order aberrations was significant. The pupillary diameter was positively correlated with the change in the third-order coma in Gr-2 (Spearman coefficient, p = 0.005). All the eyes had an uncorrected visual acuity of 0.0 LogMAR in Gr-1 and 95% in Gr-2 after surgery.

CONCLUSIONS

The higher order aberrations six months after transepithelial photorefractive keratectomy were similar in eyes managed with 7-mm and 6.5-mm optical zone for ablation. But a lower aberration coefficient in eyes was managed by the 7-mm zone than the 6.5-mm zone of optical ablation at 6-mm analysis diameter.

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

Changes in higher order aberrations (HOA's) and retinal image quality during accommodation have not previously been examined in children. This study measured ocular HOA's in ninety non-myopic, school-aged children during short-term accommodation tasks at 0, 3, 6, and 9 D demands presented via a Badal optometer mounted to a Hartmann-Shack wavefront aberrometer (COAS-HD, Wavefront Sciences). Eighty-four participants who exhibited active accommodation were included in the analyses. An eighth order Zernike polynomial was fit across a 2.3 mm, 4 mm, and natural pupil diameter to evaluate changes in refractive power vectors (M, J₁₈₀, and J₄₅), accommodation errors (lags and leads), HOA root mean square (RMS) variables, individual Zernike coefficients, and the visual Strehl ratio based on the optical transfer function (VSOTF). All HOA RMS variables changed significantly with accommodation, with the greatest change observed for the 9 D demand. Of the individual Zernike coefficients, primary (C₄⁰) and secondary spherical aberration (C₆⁰) exhibited the greatest magnitude of change, becoming negative and positive with increasing accommodation, respectively. The VSOTF changed significantly with greater accommodation for both the 4 mm and natural pupil size, becoming significantly worse for the 9 D demand. HOA's increase and retinal image quality decreases significantly during higher levels of accommodation in children, similar to adults. These findings provide a greater understanding of the optical properties of children's eyes and insights into possible mechanisms for the association between accommodation, near work, and refractive error development.

Functional integration of eye tissues and refractive eye development: Mechanisms and pathways

Refractive eye development is a tightly coordinated developmental process. The general layout of the eye and its various components are established during embryonic development, which involves a complex cross-tissue signaling. The eye then undergoes a refinement process during the postnatal emmetropization process, which relies heavily on the integration of environmental and genetic factors and is controlled by an elaborate genetic network. This genetic network encodes a multilayered signaling cascade, which converts visual stimuli into molecular signals that guide the postnatal growth of the eye. The signaling cascade underlying refractive eye development spans across all ocular tissues and comprises multiple signaling pathways. Notably, tissue-tissue interaction plays a key role in both embryonic eye development and postnatal eye emmetropization. Recent advances in eye biometry, physiological optics and systems genetics of refractive error have significantly advanced our understanding of the biological processes involved in refractive eye development and provided a framework for the development of new treatment options for myopia. In this review, we summarize the recent data on the mechanisms and signaling pathways underlying refractive eye development and discuss new evidence suggesting a wide-spread signal integration across different tissues and ocular components involved in visually guided eye growth.

Greater higher order aberrations induced by toric orthokeratology versus soft toric multifocal contact lens wear

PURPOSE

Spherical orthokeratology and soft multifocal contact lenses are commonly used for myopia control and correction, but have been shown to increase spherical aberration, coma and total higher order root mean square (HORMS) aberrations. There are limited myopia control contact lens options for patients with moderate to high astigmatism. The purpose of this study was to quantify changes in higher order aberrations (HOA) in myopic astigmatic eyes fitted with toric orthokeratology (TOK) and soft toric multifocal (STM) contact lenses.

METHODS

Ocular wavefront aberrations were measured in both eyes of 30 adult subjects and are reported through the 6th radial order over a 5 mm, dilated pupil. All eyes met refractive criteria of myopia (-5.00 D to plano) and cylinder (-3.50 to -1.25 D). Three measurements were taken at baseline and after 10 ± 2 days of lens wear (TOK, STM). Sixteen subjects achieved logMAR high contrast visual acuity of 0.30 or better in both eyes and were included in this analysis. Repeated measures analysis of variance and post-hoc paired t-tests were used, as appropriate, with Benjamini-Hochberg correction.

RESULTS

Higher order root mean square, spherical aberration (C12), and coma RMS (C7, C8) increased with TOK (0.641 [0.222], 0.409 [0.157], 0.426 [0.187] µm, respectively) and STM (0.481 [0.107], 0.223 [0.139], 0.320 [0.130] µm, respectively) from baseline (all p < 0.001). TOK was elevated compared to STM for HORMS (p = 0.03), spherical aberration (p = 0.001) and coma RMS (p = 0.04).

CONCLUSIONS

Toric orthokeratology induced more HORMS, spherical aberration and coma RMS than STM in myopic astigmats; however, both lens types showed an increase in HOA compared to baseline, which placed patients outside the age and pupil size matched normative ranges. While the optical changes that accompany these modalities are helpful for myopia management, the induction of HOAs may have unintended consequences on visual performance.

Compression Factor and Visual Performance in Adults Treated With Orthokeratology

OBJECTIVES

To investigate the effect of compression factor on visual performance in orthokeratology (ortho-k).

METHODS

Myopic adults were fitted with ortho-k lenses with either a 0.75 diopter (D) or 1.75 D compression factor. Higher-order aberrations (HOAs), corneal topography, and responses to the National Eye Institute/Refractive Error Quality of Life Instrument-42 questionnaire were measured at baseline and 6-month and 12-month follow-up along with a satisfaction questionnaire. Subjective refraction, high-contrast, and low-contrast visual acuity were measured at baseline and 1-day, 1-week, 6-month, and 12-month follow-up.

RESULTS

Forty-four myopic (mean spherical equivalent refraction: -3.66±0.84 D) adults (median age 25 years) completed the 12-month follow-up. After ortho-k lens wear, levels of satisfaction of vision after waking were significantly higher than vision before sleep for both compression factors (both P<0.01). The increased compression factor (ICF) resulted in less myopia at the 1-week visit (P=0.04) and better high-contrast unaided visual acuity at the 1-day visit (P=0.03) compared with the conventional compression factor (CCF). No other significant differences were observed for the compression factor for treatment zone diameter, lens decentration, or any subjective measurements. Individual HOA terms , , , and were significantly higher in the CCF group (0.75 D) (all P<0.05). The HOA visual Strehl ratio decreased significantly after lens wear (P<0.001) but did not vary with the compression factor.

CONCLUSIONS

An ICF did not result in clinically significant differences in subjective refraction, visual acuity, unaided vision, or the total ocular HOA profile compared with a CCF (0.75 D) in myopic adults after long-term ortho-k lens wear.

Binocular dynamics of accommodation, convergence, and pupil size in myopes

The purpose of this work is to study the dynamics of the accommodative response as a function of the subject's refractive error, as a first step in determining whether an anomalous accommodative function could affect emmetropization or trigger myopia progression. A secondary goal was to establish potential relationships between the speed of accommodation and other parameters in the accommodation process. Parameters related to the speed and amplitude of accommodation, convergence, miosis, and change in high-order aberrations were measured during the accommodative process for 2.8 D demand in 18 young healthy subjects (mean age 25.0 ± 4.7 years) with a range of refractive errors between 0 and -7.5 D (spherical equivalent). Measurements were performed in real time (25 Hz) with an open-view binocular Hartmann-Shack (HS) sensor using a GPU-based processing unit. Correlation coefficients were calculated between refractive error and each computed variable. Additionally, the speed of accommodation was correlated with all the other parameters in the study. Correlation coefficients with refractive error had non-zero values for several parameters of the accommodative response but p-values were higher than 0.05 except in two cases: with pupil miosis speed (R = -0.49, p = 0.041) and with lag of accommodation (R = -0.57, p = 0.014). Additionally, correlation values with p-value < 0.05 were found between accommodation speed and convergence duration (R = 0.57, p = 0.014), convergence speed (R = 0.48, p = 0.044), and pupil miosis amplitude (R = 0.47, p = 0.049). We did not find strong evidence of a link between myopia and altered dynamics of the accommodation process. Only miosis speed was found to be correlated to refractive error with p < 0.05, being slower for myopes. On the other hand, increased lag of accommodation tends to be associated to larger refractive errors. Additionally, our data suggests that the faster the accommodation, the faster and longer the convergence and the larger the pupil miosis.

IMI Accommodation and Binocular Vision in Myopia Development and Progression

The role of accommodation in myopia development and progression has been debated for decades. More recently, the understanding of the mechanisms involved in accommodation and the consequent alterations in ocular parameters has expanded. This International Myopia Institute white paper reviews the variations in ocular parameters that occur with accommodation and the mechanisms involved in accommodation and myopia development and progression. Convergence is synergistically linked with accommodation and the impact of this on myopia has also been critiqued. Specific topics reviewed included accommodation and myopia, role of spatial frequency, and contrast of the task of objects in the near environment, color cues to accommodation, lag of accommodation, accommodative-convergence ratio, and near phoria status. Aspects of retinal blur from the lag of accommodation, the impact of spatial frequency at near and a short working distance may all be implicated in myopia development and progression. The response of the ciliary body and its links with changes in the choroid remain to be explored. Further research is critical to understanding the factors underlying accommodative and binocular mechanisms for myopia development and its progression and to guide recommendations for targeted interventions to slow myopia progression.

Atropine in topical formulations for the management of anterior and posterior segment ocular diseases

INTRODUCTION

Atropine is an old-known drug which is gaining increasing attention due to the myriad of therapeutic effects it may trigger on eye structures. Nevertheless, novel applications may require more adequate topical formulations.

AREAS COVERED

This review aims to gather the existing knowledge about atropine and its clinical applications in the ophthalmological field when administered topically. Atropine ocular pharmacokinetics is paid a special attention, including recent evidences of the capability of the drug to access to the posterior segment. Ocular bioavailability and systemic bioavailability are counterbalanced. Finally, limitations of traditional dosage forms and potential advantages of under investigation delivery systems are analyzed.

EXPERT OPINION

Mydriasis and cyclopegia have been widely exploited for eye examination, management of anterior segment diseases, and more recently as antidotes of chemical weapons. Improved knowledge on drug receptors and related pathways explains atropine repositioning as an outstanding tool to prevent myopia. The ease with which atropine penetrates ocular tissues is a double edged sword, that is, while it ensures therapeutic levels in the posterior segment, the unspecific distribution causes a wide variety of untoward effects. The design of formulations that can selectively deliver atropine to the target tissue for each specific application is an urgent unmet need.

Ocular and corneal aberrations changes in controlled randomized clinical trial MiSight® Assessment Study Spain (MASS)

Background

To compare ocular and corneal inherent aberrations in the naked eyes of randomly selected children fitted with MiSight contact lenses (CL) for myopia control, versus children corrected with single-vision spectacles (control), over a 24-months period.

Methods

Children aged 8 to 12 years, with myopia (-0.75 to -4.00 D sphere) and astigmatism (< -1.00 D cylinder) were randomly assigned to the lens study group (MiSight) or the control group (single-vision spectacles). The root mean square aberration (RMS) was determined as corneal (RMS_C), corneal high order RMS (HO_RMS_C), corneal low order RMS (LO_RMS_C), ocular (total) RMS (RMS_T), ocular high order RMS (HO_RMS_T), ocular low order RMS (LO_RMS_T), corneal spherical aberration (SA_C) and ocular SA (SA_T) were calculated by aberrometry measures at the baseline, on 12-months and 24-months visits. A 5 mm diameter was defined for the analysis in all visits for all subjects. Only the dominant eye was analyzed.

Results

Seventy-four subjects completed the clinical trial: 41 subjects from the MiSight group (age: 11.01 ± 1.23 years) and 33 from the single-vision group (age: 10.12 ± 1.38 years). RMS_T significantly changed (0.57 ± 0.20 µm, p = 0.029) after 24-months in the control group. In the MiSight group no significant changes were registered (p > 0.05). The SA_C and SA_T did not reveal significant changes between visits or between groups (p > 0.05).

Conclusions

Along 2 years, MiSight CL did not induce significant changes in RMS of anterior cornea or total ocular RMS. Contrary, in control group the RMS_T significantly changed as response of greater eye growth and myopia progression. The results obtained in present study allow to predict corneal or total aberration changes, in children, in response of wearing of MiSight lens along the time.

Trial registration

: ClinicalTrials.gov Identifier: NCT01917110.

The human axial length and choroidal thickness responses to continuous and alternating episodes of myopic and hyperopic blur

PURPOSE

To investigate the change in axial length (AxL) and choroidal thickness (ChT) in response to continuous and alternating episodes of monocular myopic and hyperopic defocus.

METHODS

The right eye of sixteen young adults was exposed to 60 minute episodes of either continuous or alternating myopic and hyperopic defocus (+3 DS & -3 DS) over six separate days, with the left eye optimally corrected for distance. During alternating defocus conditions, the eye was exposed to either 30 or 15 minute cycles of myopic and hyperopic defocus, with the order of defocus reversed in separate sessions. The AxL and ChT of the right eye were measured before, during and after each defocus condition.

RESULTS

Significant changes in AxL were observed over time, dependent upon the defocus condition (p < 0.0001). In general, AxL exhibited a greater magnitude of change during continuous than alternating defocus conditions. The maximum AxL elongation was +7 ± 7 μm (p = 0.010) in response to continuous hyperopic defocus and the maximum AxL reduction was -8 ± 10 μm of (p = 0.046) in response to continuous myopic defocus. During both 30 and 15 minute cycles of alternating myopic and hyperopic defocus of equal duration, the effect of opposing blur sessions cancelled each other and the AxL was near baseline levels following the final defocus session (mean change from baseline across all alternating defocus conditions was +2 ± 10 μm, p > 0.05). Similar, but smaller magnitude, changes were observed for ChT.

CONCLUSIONS

The human eye appears capable of temporal averaging of visual cues from alternating myopic and hyperopic defocus. In the short term, this integration appears to be a cancellation of the effects of the preceding defocus condition of opposite sign.

Higher order aberrations and axial elongation in combined 0.01% atropine with orthokeratology for myopia control

PURPOSE

To compare the changes in higher order aberrations (HOA's) for photopic and mesopic pupil diameters in children undergoing orthokeratology treatment (OK) or combined 0.01% atropine with orthokeratology treatment (AOK), and their association with axial elongation.

METHODS

Children aged 6 to <11 years with 1.00-4.00 D of myopia were randomly assigned to each treatment group. Photopic and mesopic pupil diameters were quantified using automated pupillometry and HOA's were measured with a Hartmann-Shack aberrometer and Badal system to control for accommodation. HOA's were rescaled to photopic and mesopic pupil diameters and fitted with a 6^th order Zernike polynomial expansion. Axial length was measured using an optical biometer under cycloplegia.

RESULTS

Baseline and six-month data from 25 AOK and 28 OK participants were analysed. At the six-month visit, pupil diameter was larger in the AOK group under photopic conditions (3.70 ± 0.42 vs 3.12 ± 0.33 mm, p < 0.001), along with a range of HOA metrics [3^rd to 6^th order and higher order root mean square error values (HO RMS), all p ≤ 0.003] and individual Zernike terms (primary spherical aberration, and oblique quadrafoil, both p ≤ 0.03). Axial elongation was greater in the OK treatment group (0.05 ± 0.08 vs -0.01 ± 0.12 mm, p = 0.02). In the AOK group, axial elongation was correlated with the increase in photopic pupil diameter (r = -0.45, p = 0.02) and with several HOA metrics; however, these associations were not observed in the OK group.

CONCLUSION

AOK treatment resulted in increased photopic pupil size and HOA's, and significantly less axial elongation over a six-month period compared to OK treatment alone. The improved myopia control observed with combination 0.01% atropine and orthokeratology may be a result of an enhanced optical effect due to a larger photopic pupil size.