Effectiveness of repeated low-level red light in myopia prevention and myopia control

BACKGROUND/AIMS

To compare the effects of repeated low-level red light (RLRL) treatment on axial length growth and refractive error changes in myopic and premyopic children.

METHODS

Subjects were assigned randomly to four subgroups: myopia-RLRL group (M-RL), myopia-control group (M-C), premyopia-RLRL group (PM-RL) and premyopia-control group (PM-C). Subjects in the RLRL group completed a 12-month treatment composed of a 3 min RLRL treatment session twice daily, with an interval of at least 4 hours, for 7 days per week. Visits were scheduled before and at 1-month, 3-month, 6-month, 9-month and 12-month follow-up after the treatment. Repeated-measures analysis of variance was used to compare the spherical equivalent refractive errors (SE) and axial length (AL) changes between the groups across the treatment period.

RESULTS

After 12 months of treatment, in the myopia group, SE and AL changes were -0.078±0.375 D and 0.033±0.123 mm for M-RL and -0.861±0.556 D and 0.415±0.171 mm for M-C; in the premyopia group, the progression of SE and AL was -0.181±0.417 D and 0.145±0.175 mm for PM-RL and -0.521±0.436 D and 0.292±0.128 mm for PM-C. PM-RL indicated a lower myopia incidence than PM-C (2.5% vs 19.4%). Additionally, the percentage of AL shortening in the M-RL was higher than that in the PM-RL before the 9-month follow-up.

CONCLUSION

RLRL effectively delayed myopia progression in children with myopia and reduced the incidence of myopia in premyopic children. Moreover, RLRL exhibited a stronger impact on myopic children compared with premyopic individuals.

Influencing factors of effective lens position in patients with Marfan syndrome and ectopia lentis

AIMS

The aim of this study was to analyse the effective lens position (ELP) in patients with Marfan syndrome (MFS) and ectopia lentis (EL).

METHODS

Patients with MFS undergoing lens removal and primary intraocular lens (IOL) implantation were enrolled in the study. The back-calculated ELP was obtained with the vergence formula and compared with the theoretical ELPs. The back-calculated ELP and ELP error were evaluated among demographic and biometric parameters, including axial length (AL), corneal curvature radius (CCR) and white-to-white (WTW).

RESULTS

A total of 292 eyes from 200 patients were included. The back-calculated ELP was lower in patients undergoing scleral-fixated IOL than those receiving in-the-bag IOL implantation (4.54 (IQR 3.65-5.20) mm vs 4.98 (IQR 4.56-5.67) mm, p<0.001). The theoretical ELP of the SRK/T formula exhibited the highest accuracy, with no difference from the back-calculated ELP in patients undergoing in-the-bag IOL implantation (5.11 (IQR 4.83-5.65) mm vs 4.98 (IQR 4.56-5.67) mm, p=0.209). The ELP errors demonstrated significant correlations with refraction prediction error (PE): a 1 mm ELP error led to PE of 2.42D (AL<22 mm), 1.47D (22 mm≤AL<26 mm) and 0.54D (AL≥26 mm). Multivariate analysis revealed significant correlations of ELP with AL (b=0.43, p<0.001), CCR (b=-0.85, p<0.001) and WTW (b=0.41, p=0.004).

CONCLUSION

This study provides novel insights into the origin of PE in patients with MFS and EL and potentially refines existing formulas.

Role of lens in early refractive development: evidence from a large cohort of Chinese children

AIMS

To document longitudinal changes in spherical equivalent refraction (SER) and related biometric factors during early refractive development.

METHODS

This was a prospective cohort study of Chinese children, starting in 2018 with annual follow-ups. At each visit, children received cycloplegic autorefraction and ocular biometry measurements. Lens power (LP) was calculated using Bennett's formula. Children were divided into eight groups based on baseline age: the 3-year-old (n=426, 49.77% girls), 4-year-old (n=834, 47.36% girls), 6-year-old (n=292, 46.58% girls), 7-year-old (n=964, 43.46% girls), 9-year-old (n=981, 46.18% girls), 10-year-old (n=1181, 46.32% girls), 12-year-old (n=504, 49.01%) and 13-year-old (n=644, 42.70%) age groups.

RESULTS

This study included right-eye data from 5826 children. The 3-year-old and 4-year-old age groups demonstrated an inflection point in longitudinal SER changes at a mild hyperopic baseline SER (+1 to +2 D), with children with more myopic SER showing hyperopic refractive shifts while those with more hyperopic SER showing myopic shifts. The hyperopic shift in SER was mainly attributed to rapid LP loss and was rarely seen in the older age groups. Axial elongation accelerated in the premyopia stage, accompanied by a partially counter-balancing acceleration of LP loss. For children aged 3-7 years, those with annual SER changes <0.25 D were all mildly hyperopic at baseline (mean: 1.23 D, 95% CI 1.20 to 1.27 D).

CONCLUSION

Our findings suggest that during early refractive development, refractions cluster around or above +1.00 D. There is a pushback process in which increases in the rate of LP occur in parallel with increases in axial elongation.

Femtosecond laser-assisted astigmatic keratotomy versus toric IOL implantation for correcting astigmatism in cataract patients: a systematic review and meta-analysis with trial sequential analysis

AIMS

To compare the refractive and visual outcomes of femtosecond laser-assisted astigmatic keratotomy (FSAK) and toric intraocular lens (IOL) implantation for correcting astigmatism in cataract patients.

METHODS

Studies were retrieved from the Ovid-Medline, EMBASE, Cochrane Central Register of Controlled Trials and Scopus which compared FSAK and toric IOL for astigmatism correction in cataract patients. Outcome measures included postoperative refractive cylinder, correction index, uncorrected distance visual acuity (UDVA), the proportion of patients achieving a residual refractive cylinder of 1.00 dioptre or less, target-induced astigmatism (TIA) and surgically induced astigmatism (SIA). The trial sequential analysis (TSA) was used to collect firm evidence supporting our conclusion.

RESULTS

9 studies encompassing 590 participants were analysed. The meta-analysis revealed that toric IOLs could result in less postoperative refractive cylinder and provide better UDVA compared with FSAK. The TSA disclosed strong evidence of lower postoperative refractive cylinder in the toric IOL group compared with that of the FSAK group. FSAK showed a smaller correction index and lower mean TIA and SIA compared with toric IOLs.

CONCLUSIONS

For cataract patients, both FSAK and toric IOLs are effective methods for correcting astigmatism. However, toric IOLs offer less postoperative astigmatism and result in better postoperative UDVA compared with FSAK. In vector analysis of astigmatism, toric IOLs can also produce higher TIA and SIA. Additionally, neither method is associated with severe untreatable complications. Therefore, the conclusion is that toric IOLs are the preferred choice for astigmatism correction in cataract patients and FSAK serves as a viable alternative when toric IOLs are contraindicated.

Choriocapillaris flow features in children with myopic anisometropia

AIMS

To examine differences between the eyes in choriocapillaris perfusion and choroidal thickness in children with myopic anisometropia.

METHODS

In this observational and prospective study, 46 children with myopic anisometropia were enrolled. Choriocapillaris perfusion parameters, including the percentage of flow voids, the total number of flow voids and the average flow void area were obtained by optical coherence tomography angiography (OCTA). The OCTA image was divided into a 1 mm-diameter central circle (C1) and a 2.5 mm-diameter annulus (without the inner central 1 mm circle, C1-2.5). Both C1 and C1-2.5 are centred on the foveola. The C1-2.5 was divided into nasal (N1-2.5), temporal (T1-2.5), inferior (I1-2.5) and superior (S1-2.5) areas. Differences in these parameters in different regions between eyes were analysed.

RESULTS

There were no significant differences in the percentage of flow voids and the average flow void area between the fellow eyes. The total number of signal voids was significantly higher in the less myopic eyes in C1-2.5 (p=0.032), S1-2.5 (p=0.008) and N1-2.5 (p=0.019). Changes in spherical equivalent refraction and axial length were both correlated with the changes in the total number of flow voids in N1-2.5 (R=-0.431, p=0.03; R=-0.297, p=0.047).

CONCLUSIONS

The choroid in the macular region becomes thinner and the total number of flow voids in the nasal macular region decreased with the amplitude of myopia. This suggests that a decrease in total number of flow voids may indicate an early change in myopia.

One-year efficacy of myopia control by the defocus distributed multipoint lens: a multicentric randomised controlled trial

AIMS

To report the 1-year results of the efficacy of a defocus distributed multipoint (DDM) lens in controlling myopia progression in a multicentre, randomised controlled trial.

METHODS

Overall, 168 children aged 6-13 years were recruited and randomly assigned to wear a DDM lens (n=84) or single-vision (SV) lens (n=84) in three centres. Cycloplegic autorefraction (spherical equivalent refraction (SER)) and axial length (AL) were measured. Linear mixed model analysis was performed to compare between-group SER and AL changes. Logistic regression analysis was used to analyse the between-group difference in rapid myopia progression (SER increase≥0.75 D per year or AL growth≥0.40 mm per year).

RESULTS

After 1 year, mean changes in SER were significantly lower in the DDM group (-0.47±0.37 D) than in the SV group (-0.71±0.42 D) (p<0.001). Similarly, mean changes in AL were significantly lower in the DDM group (0.21±0.17 mm) than in the SV group (0.34±0.16 mm) (p<0.001). After adjusting for age, sex, daily wearing time and parental myopia, rapid myopia progression risk was higher in the SV group than in the DDM group (OR=3.51, 95% CI: 1.77 to 6.99), especially for children who wore a lens for >12 hours per day, boys and younger children (6-9 years) with ORs (95% CIs) of 10.82 (3.22 to 36.37), 5.34 (1.93 to 14.78) and 8.73 (2.6 to 29.33), respectively.

CONCLUSIONS

After 1 year, DDM lenses effectively retarded myopia progression in children. Longer daily wearing time of DDM lens improved the efficacy of myopia control. Future long-term studies are needed for validation.

TRIAL REGISTRATION NUMBER

NCT05340699.

Astigmatism and maternal myopia as important factors affecting success rate of DIMS lens treatment

OBJECTIVE

To assess the efficacy of myopia control spectacle lenses (defocus incorporated multiple segments/DIMS) in slowing myopia progression among a diverse Central European paediatric population and investigate the contribution of baseline parameters on treatment outcomes.

METHODS AND ANALYSIS

This retrospective observational study included 62 individuals aged 4-17 years (mean±SD: 10.21±2.70) with progressing myopia but without ocular pathology with a range of -0.88 to -8.25 D spherical equivalent refraction (SER) (-3.73±1.56), coupled with astigmatism up to -3.25 D cylindrical. All participants were prescribed DIMS (Hoya MiyoSmart) spectacles. Key outcome variables were cycloplegic SER, measured for all participants and axial length (AL), assessed in a subset of patients, recorded at baseline, 6 months and 12 months. Quality of life assessments were conducted at baseline, at 2 weeks, and 3, 6, 9 and 12 months. Additionally, parental myopic dioptre was recorded when applicable.

RESULTS

At the 12-month mark, myopia progression in patients (mean±SE: -0.40±0.05) mirrored findings from prior European DIMS studies, but with 50% of patients showing no progression. A multivariate analysis of covariance model revealed that baseline astigmatism and younger age adversely affected therapy outcomes in both SER and AL, while severe maternal myopia led to greater SER progression. In contrast, only young age but not astigmatism was associated with AL increase in a comparable group of children with myopia, part of the LIFE Child Study, wearing single-vision spectacles. Patients reported consistent satisfaction with treatment, with minimal side effects, which diminished over the year.

CONCLUSION

In the European population, astigmatism, young age and severe maternal myopia are risk factors for suboptimal outcomes following DIMS therapy. Further research is necessary to elucidate the impact of astigmatism on myopic defocus therapy.

Method comparison and overview of refractive measurements in children: implications for myopia management

OBJECTIVE

This study investigated the agreement between objective wavefront-based refraction and subjective refraction in myopic children. It also assessed the impact of cyclopentolate and refraction levels on the agreement.

METHODS

A total of 84 eyes of myopic children aged 6-13 years were included in the analysis. Non-cycloplegic and cycloplegic objective wavefront-based refraction were determined and cycloplegic subjective refraction was performed for each participant. The data were converted into spherical equivalent, J0 and J45, and Bland-Altman plots were used to analyse the agreement between methods.

RESULTS

Linear functions were used to determine the dependency between the central myopic refractive error and the difference between the method of refraction (=bias). The influence of central myopia was not clinically relevant when analysing the agreement between wavefront results with and without cyclopentolate (comparison 1). The bias for wavefront-based minus subjective spherical equivalent refraction (comparison 2) was ≤-0.50 D (95% limits of agreement -0.010 D to -1.00 D) for myopia of -4.55 D and higher when cycloplegia was used (p<0.05). When no cyclopentolate was used for the wavefront-based refraction (comparison 3), the bias of -0.50 D (95% limits of agreement -0.020 D to -0.97 D) was already reached at a myopic error of -2.97 D. Both astigmatic components showed no clinically relevant bias.

CONCLUSION

The spherical equivalent, measured without cycloplegic agents, led to more myopic measurements when wavefront-based refraction was used. The observed bias increased with the amount of myopic refractive error for comparisons 2 and 3, which needs to be considered when interpreting wavefront-refraction data.

TRIAL REGISTRATION NUMBER

NCT05288335.

Sympathetic nervous system activity is associated with choroidal thickness and axial length in school-aged children

BACKGROUND/AIMS

We aim to explore the effect of sympathetic nervous system (SNS) on choroid thickness (ChT) and axial length (AL).

METHODS

Students of grade 2 and 3 from a primary school were included and followed for 1 year. Visual acuity, refraction, AL and ChT were measured. Morning urine samples were collected for determining SNS activity by analysing concentrations of epinephrine, norepinephrine and dopamine using the liquid chromatography-tandem mass spectrometry. The most important factor (factor 1) was calculated using factor analysis to comprehensively indicate the SNS activity.

RESULTS

A total of 273 students were included, with an average age of 7.77±0.69 years, and 150 (54.95%) were boys. Every 1 µg/L increase in epinephrine is associated with 1.60 µm (95% CI 0.30 to 2.90, p=0.02) decrease in average ChT. Every 1 µg/L increase in norepinephrine is associated with 0.53 µm (95% CI 0.08 to 0.98, p=0.02) decrease in the ChT in inner-superior region. The factor 1 was negatively correlated with the ChT in the superior regions. Every 1 µg/L increase in norepinephrine was associated with 0.002 mm (95% CI 0.0004 to 0.004, p=0.016) quicker AL elongation. The factor 1 was positively correlated with AL elongation (coefficient=0.037, 95% CI 0.005 to 0.070, p=0.023).

CONCLUSIONS

We hypothesised that chronic stress characterised by elevated level of the SNS, was associated with significant increase in AL elongation, probably through thinning of the choroid.

Paediatric norms for photopic electroretinogram testing based on a large cohort of Chinese preschool children

OBJECTIVE

Full-field electroretinogram (ffERG) is an objective test to determine the electroretinal activities in response to light stimulation for investigating retinal physiology and diagnosing retinal diseases. This study aimed to establish a reference data set of photopic electroretinogram (ERG) of Chinese preschool children in Hong Kong to facilitate clinical and research studies.

METHODS AND ANALYSIS

Preschool children aged 3-7 years with normal vision were recruited from local kindergartens. Eye examinations, including cycloplegic spherical equivalent refraction (SER), axial length (AL) and keratometry (K) measurements, were performed. ffERGs of the International Society for Clinical Electrophysiology of Vision (ISCEV) standard photopic flash and 30-Hz flicker protocols were measured using RETeval with Sensor Strip skin electrodes. ERG waveform characteristics were extracted, and relationships between ERG, age, SER, AL and K were evaluated.

RESULTS

A total of 479 children completed the measurements (mean age: 5.0±0.9 years, 45.5% female). Mean, 95% CIs, 5th-95th percentile range of the ERG parameters were reported. Age was positively associated with amplitudes of b-wave and 30-Hz flicker (p<0.01), but negatively associated with implicit times of b-wave and 30-Hz flicker (p<0.01). AL was significantly associated with all amplitudes of a-wave, b-wave and 30-Hz flicker (p≤0.01) and implicit time of both a-wave and 30-Hz flicker (p<0.05). K was positively associated only with 30-Hz flicker amplitude (p=0.01), and no association between all responses and SER.

CONCLUSION

Reference data set of photopic ERG of Chinese preschool children was established. Cross-sectional investigations revealed associations between ERG, age, SER and AL, which were speculated to further implicate the role of retina in refractive error development.

Pathologic myopia in highly myopic patients with high axial anisomyopia

PURPOSE

To determine prevalence of anisomyopia (axial length (AL) difference ≥2.5 mm) among high myopes ((HMs), defined by spherical equivalent of ≤6.0 diopters or AL ≥ 26.5 mm). To characterise the shorter anisomyopic eye (SAE) and evaluate if pathologic myopia (PM) in the longer anisomyopic eye (LAE) was associated with increased risk of PM in the SAE.

METHODS

1168 HMs were recruited from Singapore National Eye Centre clinic for this cross-sectional study. Biometry, fundus photography and swept-source optical coherence tomography were performed. Patients with high axial anisomyopia were identified. Structural characteristics and presence of PM were described. Stepwise multivariate regression explored associations between PM in the LAE and pathology in the SAE, controlling for confounding variables.

RESULTS

Prevalence of anisomyopia was 15.8% (184 of 1168 patients). Anisomyopic patients (age 65.8±13.5 years) had mean AL of 30.6±2.0 mm and 26.2±2.3 mm in the LAE and SAE, respectively. 52.7% of SAEs had AL < 26.5 mm. Prevalence of myopic macular degeneration, macula-involving posterior staphyloma (PS), myopic traction maculopathy (MTM) and myopic choroidal neovascularisation (mCNV) in the SAE was 52.2%, 36.5%, 13.0% and 8.2%, respectively. Macular hole in the LAE was associated with increased risk of MTM in the SAE (OR=4.88, p=0.01). mCNV in the LAE was associated with mCNV in the SAE (OR=3.57, p=0.02). PS in the LAE was associated with PS in the SAE (OR=4.03, p<0.001).

CONCLUSIONS

Even when controlled for AL, PM complications in the LAE predict similar PM complications in the SAE. Patients with high axial anisometropia with PM in the LAE should be monitored carefully for complications in the SAE.

Eyecare practitioner perspectives and attitudes towards myopia and myopia management in the UK

OBJECTIVE

Many children with progressive myopia are still prescribed single-vision correction. An investigation into UK eyecare practitioners' (ECPs) perceptions of myopia management was carried out to ascertain factors which may be limiting its implementation and uptake within clinical practice.

METHODS AND ANALYSIS

Online focus groups were held with UK ECPs. Participants were encouraged to discuss their knowledge of the available myopia management options, their perception of how myopia management is being delivered in the UK and any barriers limiting ECPs' prescribing of these management options in practice. The discussions were transcribed and analysed thematically.

RESULTS

Focus groups were held with 41 ECPs from primary and secondary eyecare. ECPs felt that provision of myopia management in the UK is variable. Most ECPs believe they have sufficient knowledge, but felt a lack of confidence in decision-making and practical experience. Less experienced ECPs sought more definitive guidance to support their decision-making. ECPs desired clarity on their duty of care obligations and were concerned over possible future litigation if they had not offered, or referred for, myopia management when indicated. The greatest barrier appears to be financial-treatment is expensive and ECPs are uncomfortable communicating this to parents. Many barriers were indicative of systemic problems within UK eyecare, such as commercial pressures, inadequate National Health Service funding and poor public awareness of paediatric eyecare.

CONCLUSION

Myopia management is not implemented consistently across the UK. To improve accessibility, changes are required at multiple levels, from individual ECPs through to wider stakeholders in UK eyecare provision.

Effect of mount location on the quantification of light intensity in myopia study

PURPOSE

To investigate how the mounting location of wearable devices affects the measurement of light intensity.

METHODS

Two commercially available wearable devices, HOBO and Clouclip, were used to compare the effects of different mount locations on light intensity measurement. We assessed the consistency of the measurements of the two devices by placing a HOBO and a Clouclip simultaneously in 26 different light environments and measuring the light intensity. To simulate the real-life usage scenarios of the two devices, we had 29 participants wear two HOBOs-one on the wrist and the other on the chest-along with a Clouclip on their spectacles for 1 day; meanwhile, the light intensity was measured and analysed.

RESULTS

When under the same light environments, the light intensity measured by the Clouclip was 1.09 times higher than that by the HOBO, with an additional 82.62 units (r2=1.00, p<0.001). When simulating the real-life scenarios, the mean light intensity at the eye-level position was significantly lower than that at the chest position (189.13±665.78 lux vs 490.75±1684.29 lux, p<0.001) and the wrist position (189.13±665.78 lux vs 483.87±1605.50 lux, p<0.001). However, there was no significant difference in light intensity between the wrist and chest positions (483.87±1605.50 lux vs 490.75±1684.29 lux, p=1.00). Using a threshold of 1000 lux for outdoor exposure, the estimated light exposure at the eye-level position was significantly lower than that at the chest position (3.9% vs 7.8%, χ2=266.14, p<0.001) and the wrist position (3.9% vs 7.7%, χ2=254.25, p<0.001).

CONCLUSIONS

Our findings revealed significant variations in light exposure among the wrist, chest and eye position. Therefore, caution must be exercised when comparing results obtained from different wearable devices.

Prevalence of refractive errors among school-going children in a multistate study in India

AIM

Much existing data on childhood refractive error prevalence in India were gathered in local studies, many now dated. The aim of this study was to estimate the prevalence, severity and determinants of refractive errors among school-going children participating in a multistate vision screening programme across India.

METHODS

In this cross-sectional study, vision screening was conducted in children aged 5-18 years at schools in five states using a pocket vision screener. Refractive error was measured using retinoscopy, and subjective refraction and was defined both by spherical equivalent (SE) and spherical ametropia, as myopia ≤-0.5 diopters (D), hyperopia ≥+1.0 D and/or astigmatism as >0.5 D. Data from the eye with less refractive error were used to determine prevalence.

RESULTS

Among 2 240 804 children (50.9% boys, mean age 11.5 years, SD ±3.3), the prevalence of SE myopia was 1.57% (95% CI 1.54% to 1.60%) at 5-9 years, 3.13% (95% CI 3.09% to 3.16%) at 10-14 years and 4.8% (95% CI 4.73% to 4.86%) at 15-18 years. Hyperopia prevalence was 0.59% (95% CI 0.57% to 0.61%), 0.54% (95% CI 0.53% to 0.56%) and 0.39% (95% CI 0.37% to 0.41%), respectively. When defined by spherical ametropia, these values for myopia were 0.84%, 2.50% and 4.24%, and those for hyperopia were 2.11%, 2.41% and 2.07%, respectively.Myopia was associated with older age, female gender, private school attendance, urban location and state. The latter appeared to be driven by higher literacy rates.

CONCLUSIONS

Refractive error, especially myopia, is common in India. Differences in prevalence between states appear to be driven by literacy rates, suggesting that the burden of myopia may rise as literacy increases.

Light exposure therapy for myopia control: a systematic review and Bayesian network meta-analysis

AIMS

To compare and rank the myopia control effects of different light wavelengths in children using a systematic review and Bayesian network meta-analysis (Bayesian NMA).

METHODS

The review protocol was registered with PROSPERO. We searched PubMed, EMBASE and MEDLINE for relevant clinical and animal studies published as of 2 February 2023. We included studies comparing red, violet or full-spectrum light with controls. Data extracted included descriptive statistics and study outcomes (axial length (AL) elongation and progression of spherical equivalent (SE) refraction). After quality assessment, estimates of treatment effect outcomes (mean differences (MDs) and 95% CIs) were first pooled for the animal and clinical studies in a traditional meta-analysis. To compare and rank the different light wavelengths, the Bayesian NMA was then conducted for all the included clinical studies (12 studies) and separately for only randomised controlled trials (8 studies). MDs, 95% credible intervals (CrIs) and ranks of the various light wavelengths were estimated in the Bayesian NMA.

RESULTS

When all clinical studies were included in the Bayesian NMA (12 studies), only red-light significantly slowed AL elongation, MD (95% CrI), -0.38 mm (-0.59 mm to -0.16 mm)/year and SE refraction progression, 0.72D (0.35D to 1.10D)/year compared with controls. It remained the only significant intervention when effect sizes from only RCTs (eight studies) were separately combined, (-0.28 mm (-0.40 mm to -0.15 mm)/year and 0.57D (0.22D to 0.92D)/year, for AL and SE refraction, respectively).

CONCLUSION

Myopia control efficacy varied among different wavelengths of light, with red light ranked as the most effective.

PROSPERO REGISTRATION NUMBER

Clinical studies: CRD42022368998; animal studies: CRD42022368671.

Long-term effect of orthokeratology on choroidal thickness and choroidal contour in myopic children

PURPOSE

To investigate the long-term effect of orthokeratology (ortho-k) on the choroidal thickness and choroidal contour in myopic children.

METHODS

Subjects were from a conducted 2-year randomised clinical trial. Children (n=80) aged 8-12 years with spherical equivalent refraction of -1.00 to -6.00D were randomly assigned to the control group (n=40) and ortho-k group (n=40). Optical coherence tomography images were collected at the baseline, 1-month, 6-month, 12-month, 18-month and 24-month visits, then the choroidal thickness and choroid contour were calculated. Axial length (AL) and other ocular biometrics were also measured.

RESULTS

During 2 years, in the control group, the choroidal thickness became thinning and the choroidal contour became prolate with time at all visits (all p<0.001). Ortho-k can improve the choroidal thickness (all p<0.001) and maintain the choroidal contour at all visits (all p<0.05). In the ortho-k group, the choroidal contour was less changed in the temporal than nasal (p=0.008), and the choroidal thickness was more thickening in the temporal 3 mm (p<0.001). Two-year change in choroidal thickness was significantly associated with the 2-year AL change in the control group (r=-0.52, p<0.001), however, this trend was broken by ortho-k (r=-0.05, p=0.342). After being adjusted by other variables in the multivariable regression model, the effect of ortho-k on choroidal thickness was stable.

CONCLUSIONS

In the current 2-year prospective study, ortho-k can improve the choroidal thickness and maintain the choroidal contour, but this effect diminished in a long term. Further study with larger sample size and longer follow-up is warranted to refine this issue.

Prediction of spectacle refraction uncertainties with discrete IOL power steps and manufacturing tolerances according to ISO using a Monte Carlo model

PURPOSE

The purpose of this study was to develop a concept for predicting the effects of both discrete intraocular lens (IOL) power steps (PS) and power labelling tolerances (LT) on the uncertainty of the refractive outcome (REFU).

DESIGN

Retrospective non-randomised cross-sectional Monte Carlo simulation study.

METHODS

We evaluated a dataset containing 16 669 IOLMaster 700 preoperative biometric measurements. The PS and the delivery range of two modern IOLs (Bausch and Lomb enVista and Alcon SA60AT) were considered for this Monte Carlo simulation. The uncertainties from PS or LT were assumed to be normally distributed according to ±½ the IOL PS or the ISO 11979 LT. REFU was recorded and analysed for all simulations.

RESULTS

With both lenses the REFU from discrete PS ranged from 0.11 to 0.12 dpt. Due to the larger PS for low/high power lenses with the enVista/SA60AT, REFU is more dominant in initially myopic/hyperopic eyes. REFU from LT ranged from 0.18 to 0.19 dpt for both lenses. Since LT increases stepwise with IOL power, REFU is more prevalent in initially hyperopic eyes requiring high IOL power values, and for lenses with a wide delivery range towards higher powers.

CONCLUSIONS

Since surgeons and patients are typically aware of the effect of discrete PS on REFU, these might be tolerated in cataract surgery. However, REFU resulting from LT is inevitable while the true measured IOL power is not reported on the package, leading to background noise in postoperative achieved refraction.

Age-matched analysis of axial length growth in myopic children wearing defocus incorporated multiple segments spectacle lenses

BACKGROUND/AIMS

Defocus incorporated multiple segments (DIMS) spectacle lenses are known to be able to inhibit axial length (AL) growth in myopic children compared with single vision (SV) spectacle lenses. However, it is not known whether AL growth is sufficiently inhibited to achieve the treatment goal of physiological AL growth.

METHODS

Of the data already collected in 2014-2017 by Lam et al, the AL growth with DIMS and SV spectacle lenses was re-evaluated according to the age-matched myopia control system. The individual AL growth after the first year of treatment of each eye was plotted against the corresponding age of the same time point in a colour-coded scheme. The two treatment groups were further subdivided based on their age and their baseline AL.

RESULTS

Overall, 65% (61% of male, 70% of female) of eyes with DIMS spectacle lenses and 16% (16% of male, 16% of female) of eyes with SV spectacle lenses are within range of physiological AL growth rate. Median AL growth rate of eyes with DIMS spectacle lenses is also within the range of physiological growth. In the subgroups, eyes with DIMS spectacle lenses were also superior to the ones with SV spectacle lenses regarding this treatment goal. Of the children with SV spectacle lenses, older children and children with eyes with high baseline AL were least likely to achieve physiological AL growth rate.

CONCLUSIONS

DIMS spectacle lenses can bring the AL growth rate of myopic children to the level of physiological AL growth rate, indicating 100% reduction of excessive myopic AL growth, independent of age and baseline AL. Older children and children with eyes with high AL have the risk to have increased AL growth without treatment.

Multivariate analysis of repeatability for the Near Eye Tool for Refractive Assessment (NETRA)

OBJECTIVE

To investigate repeatability of refractive state using a smartphone-based assessment tool, the Near Eye Tool for Refractive Assessment (NETRA).

METHODS AND ANALYSIS

This study included 279 participants, predominantly female (66.7%) of African descent (49.1%). The age range was 9-63 years with mean age (s) 22.6 (8.9) years. Two consecutive measurements per eye with the NETRA were measured for both eyes of all participants. However, analyses for the right eyes only are included here. Multivariate statistical analysis included stereo-pair comets and scatterplots with 95% surfaces of constant probability density. Correlation coefficients for repeated samples were determined. Repeatability and agreement for NETRA were assessed with Bland-Altman plots, coefficients of repeatability ([Formula: see text] ; [Formula: see text] is the SD of differences) and intraclass correlation coefficients (ICCs).

RESULTS

Bland-Altman plots, within-subject SD (sw ), coefficients of repeatability and ICC indicated that repeated measurements were similar for many but not all eyes and there was good agreement (ICC=0.96) for the spherical coefficient (F I=M) but less so for antistigmatic coefficients (F J=J 0 and F K=J 45) of power. Although mean differences for repeated samples were almost zero, 95% limits of agreement widths were larger for the stigmatic coefficients. Without cycloplegia, repeatability (2.77sw ) was 1.63 D, 0.58 D and 0.56 D for the stigmatic and antistigmatic coefficients, respectively.

CONCLUSION

NETRA is a potentially useful and inexpensive portable method in clinical and primary health settings, and especially in less-developed regions of the world. The subjective nature of the self-refraction task can be challenging for younger individuals, and cycloplegia is recommended for NETRA with such patients.

Effect of spectacle lenses with aspherical lenslets on choroidal thickness in myopic children: a 2-year randomised clinical trial

OBJECTIVE

Spectacle lenses with highly aspherical lenslets (HAL) and slightly aspherical lenslets (SAL) showed effective myopia control. This study was to investigate their effects on macular choroidal thickness (ChT) in myopic children.

METHODS

Exploratory analysis from a 2-year, double-masked, randomised trial. 170 children aged 8-13 years with myopia between -0.75D and -4.75D, astigmatism of 1.50D or less, and anisometropia of 1.00D or less were recruited. Participants were randomly assigned in a 1:1:1 ratio to receive HAL, SAL or single vision spectacle lenses (SVL). The subfoveal, parafoveal and perifoveal ChT were evaluated every 6 months.

RESULTS

154 participants completed all examinations. The ChT showed significant changes over time in all three groups in all regions (all p<0.05). The ChTs continuously decreased in the SVL group (ranging from -20.75 (SD 22.34) μm to -12.18 (22.57) μm after 2 years in different regions). Compared with the SVL group, ChT in the SAL group decreased less (ranging from -16.49 (21.27) μm to -5.29 (18.15) μm). In the HAL group, ChT increased in the first year and then decreased in the second year (ranging from -0.30 (27.54) μm to 8.92 (23.97) μm after two years). The perifoveal ChT decreased less than the parafoveal ChT, and the superior region decreased the least.

CONCLUSIONS

The ChT of the macula decreased after 2 years of myopia progression with SVL. Wearing spectacle lenses with aspherical lenslets reduced or abolished the ChT thinning and HAL had a more pronounced effect.

TRIAL REGISTRATION NUMBER

ChiCTR1800017683.

Effect of atropine, orthokeratology and combined treatments for myopia control: a 2-year stratified randomised clinical trial

PURPOSE

To investigate the 2-year efficacy of atropine, orthokeratology (ortho-k) and combined treatment on myopia. To explore the factors influencing the efficacy.

METHODS

An age-stratified randomised controlled trial. Children (n=164) aged 8-12 years with spherical equivalent refraction of -1.00 to -6.00 D were stratified into two age subgroups and randomly assigned to receive placebo drops+spectacles (control), 0.01% atropine+spectacles (atropine), ortho-k+placebo (ortho-k) or combined treatment. Axial length was measured at baseline and visits at 6, 12, 18 and 24 months. The primary analysis was done following the criteria of intention to treat, which included all randomised subjects.

RESULTS

All interventions can significantly reduce axial elongation at all visits (all p<0.05). Overall, the 2-year axial elongation was significantly reduced in combined treatment than in monotherapies (all p<0.05). After stratification by age, in the subgroup aged 8-10, the difference between combined treatment and ortho-k became insignificant (p=0.106), while in the subgroup aged 10-12, the difference between combined treatment and atropine became insignificant (p=0.121). A significant age-dependent effect existed in the ortho-k group versus the control group (p for interaction=0.013), and a significant age-dependent effect existed in the ortho-k group versus the atropine group (p for interaction=0.035), which indicated that ortho-k can achieve better efficacy in younger children.

CONCLUSIONS

Atropine combined with ortho-k treatment can improve the efficacy of myopia control compared with monotherapy in children aged 8-12. Younger children might benefit more from ortho-k.

TRIAL REGISTRATION NUMBER

ChiCTR1800015541.

Modelling ready-made spectacle coverage for children and adults using a large global database

BACKGROUND/AIMS

To model the suitability of conventional ready-made spectacles (RMS) and interchangeable-lens ready-made spectacles (IRMS) with reference to prescribing guidelines among children and adults using a large, global database and to introduce a web-based application for exploring the database with user-defined eligibility criteria.

METHODS

Using refractive power and interpupillary distance data for near and distance spectacles prescribed to children and adults during OneSight clinics in 27 countries, from 2 January 2016 to 19 November 2019, we modelled the expected suitability of RMS and IRMS spectacle designs, compared with custom-made spectacles, according to published prescribing guidelines.

RESULTS

Records of 18 782 presbyopic adult prescriptions, 70 619 distance adult prescriptions and 40 862 paediatric prescriptions were included. Globally, 58.7%-63.9% of adults could be corrected at distance with RMS, depending on the prescribing cut-off. For presbyopic adult prescriptions, coverage was 44.1%-60.9%. Among children, 51.8% were eligible for conventional RMS. Coverage for all groups was similar to the above for IRMS. The most common reason for ineligibility for RMS in all service groups was astigmatism, responsible for 27.2% of all ineligible adult distance prescriptions using the strictest cut-off, 31.4% of children's prescriptions and 28.0% of all adults near prescriptions globally.

CONCLUSION

Despite their advantages in cost and convenience, coverage delivered by RMS is limited under current prescribing guidelines, particularly for children and presbyopic adults. Interchangeable designs do little to remediate this, despite extending coverage for anisometropia. Our free application allows users to estimate RMS coverage in specific target populations.

Accuracy of using the axial length of the fellow eye for IOL calculation in retinal detachment eyes undergoing silicone oil removal

PURPOSE

Evaluate whether the axial length of the fellow eye can be used to calculate the intraocular lens (IOL) in eyes with retinal detachment.

DESIGN

Retrospective, consecutive case series.

METHODS

Our study was conducted at the Goethe University and included patients who underwent silicone oil (SO) removal combined with phacoemulsification and IOL implantation. Preoperative examinations included biometry (IOLMaster 700, Carl Zeiss). We measured axial length (AL) of operated eye (OE) or fellow eye (FE) and compared mean prediction error and mean and median absolute prediction error (MedAE) using four formulas and AL of the OE (Barrett Universal II (BUII)-OE). Additionally, we compared the number of eyes within ±0.50, ±1.00 and ±2.00 dioptre (D) from target refraction.

RESULTS

In total, 77 eyes of 77 patients met our inclusion criteria. MedAE was lowest for the BUII-OE (0.42 D) compared with Kane-FE (1.08 D), BUII-FE (1.02 D) and Radial Basis Function 3.0 (RBF3.0)-FE (1.03 D). This was highly significant (p<0.001). The same accounts for the number of eyes within ±0.50 D of the target refraction with the BUII-OE (44 eyes, 57%) outperforming the RBF3.0-FE (20 eyes, 25.9%), Kane-FE and BUII-FE formula (21 eyes, 27.2%) each.

CONCLUSION

Our results show a statistically and clinically highly relevant reduction of IOL power predictability when using the AL of the FE for IOL calculation. Using the AL of the SO filled eye after initial vitrectomy results in significantly better postoperative refractive results. A two-step procedure using the AL of the OE after reattachment of the retina is highly recommended.

Oral administration of caffeine metabolite 7-methylxanthine is associated with slowed myopia progression in Danish children

PURPOSE

Myopia is associated with an increased risk of permanent vision loss. The caffeine metabolite 7-methylxanthine (7-MX), licensed in Denmark since 2009 as a treatment to reduce the rate of childhood myopia progression, is the only orally administered therapy available. The purpose of the current study was to assess the rate of myopia progression in children taking 7-MX.

METHODS

Longitudinal cycloplegic refraction and axial length data for 711 myopic children from Denmark treated with varying doses of oral 7-MX (0-1200 mg per day) were analysed using linear mixed models.

RESULTS

The median age at baseline was 11.1 years (range 7.0 -15.0 years). Children were followed for an average of 3.6 years (range 0.9-9.1 years) and the average myopia progression was 1.34 dioptres (D) (range -6.50 to +0.75 D). Treatment with 7-MX was associated with a reduced rate of myopia progression (p<0.001) and axial elongation (p<0.002). Modelling suggested that, on average, an 11-year-old child taking 1000 mg 7-MX daily would develop -1.43 D of myopia over the next 6 years, compared with -2.27 D if untreated. Axial length in this child would increase by 0.84 mm over 6 years when taking a daily dose of 1000 mg of 7-MX, compared with 1.01 mm if untreated. No adverse effects of 7-MX therapy were reported.

CONCLUSIONS

Oral intake of 7-MX was associated with reduced myopia progression and reduced axial elongation in this sample of myopic children from Denmark. Randomised controlled trials are needed to determine whether the association is causal.

Comparison of biometric and refractive changes in intermittent exotropia with and without overminus lens therapy

BACKGROUND

Overminus lens is an effective non-surgical treatment of intermittent exotropia (IXT). Whether this treatment causes development of myopia is recently debated. This study evaluated ocular biometric changes in IXT children treated with and without overminus lens.

METHODS

Children with IXT were randomly assigned to control and overminus groups. Cycloplegic refraction, axial length and other parameters (keratometry, anterior chamber depth and lens thickness) were evaluated for up to 30 months and compared between the groups. Axial length to corneal curvature (AL/CR) ratio was examined as an indicator of myopia progression. Changes prior to and after overminus were also assessed in a subgroup.

RESULTS

Mean age of the total 84 subjects (58% women) was 7.2 years (range 4-15 years). Baseline refractive and biometric parameters of 39 control and 45 overminus subjects were not significantly different. Mean±SD change in refraction was -0.34±0.45D in controls and -0.41±0.66D in overminus group (p=0.527). AL increased by 0.29±0.20 millimetre (mm) in controls and 0.28±0.23 mm in overminus group (p=0.766). In the subgroup, the changes before and after overminus therapy was not significantly different (p>0.05). AL/CR ratio was maintained from baseline to follow-up visit (p=0.298) in both groups.

CONCLUSION

No significant differences in biometry or refraction were found between the two groups and before and after the therapy. We conclude that the overminus therapy in children, not accounting for other myopia risk factors, does not affect normal refractive growths.

Normative value of hyperopia reserve and myopic shift in Chinese children and adolescents aged 3-16 years

BACKGROUND

This research aims to generate normative values of hyperopia reserve and refractive progression as effective tools to estimate the risk of myopia.

METHODS

A 1-year follow-up study was conducted among Chinese children and adolescents aged 3-16 years selected from schools and kinder gardens using cluster sampling. All participants underwent examinations including visual acuity, axial length and cycloplegic autorefraction (1% cyclopentolate). Percentiles of spherical equivalent (SE) were calculated using Lambda-Mu-Sigma (LMS) method. Age-specific refractive progression and hyperopia reserve were determined by backward calculation.

RESULTS

Of 3118 participants, 1702 (54.6%) were boys with a mean baseline age of 7.30 years. The 50th percentile of SE estimated by LMS decreased from 1.04 D at 3 years to -2.04 D at 16 years in boys, while from 1.29 D to -2.81 D in girls. The 1-year refractive progression of myopes (0.81 D) was greater than that of non-myopes (0.51 D). The normative value of hyperopia reserve was 2.64 (range: 2.40 D-2.88 D) at 3 years and -0.35 (range: -0.50 to -0.17) D at 16 years, with the maximum progression of 0.35 D at the age of 6 years.

CONCLUSION

Age-specific normative values of hyperopia reserve and yearly myopic shift in children and adolescents aged 3-16 years were provided, helping identify and monitor myopia and giving prevention in advance.

Establishing a method to estimate the effect of antimyopia management options on lifetime cost of myopia

BACKGROUND

Informed decisions on myopia management require an understanding of financial impact. We describe methodology for estimating lifetime myopia costs, with comparison across management options, using exemplars in Australia and China.

METHODS

We demonstrate a process for modelling lifetime costs of traditional myopia management (TMM=full, single-vision correction) and active myopia management (AMM) options with clinically meaningful treatment efficacy. Evidence-based, location-specific and ethnicity-specific progression data determined the likelihood of all possible refractive outcomes. Myopia care costs were collected from published sources and key informants. Refractive and ocular health decisions were based on standard clinical protocols that responded to the speed of progression, level of myopia, and associated risks of pathology and vision impairment. We used the progressions, costs, protocols and risks to estimate and compare lifetime cost of myopia under each scenario and tested the effect of 0%, 3% and 5% annual discounting, where discounting adjusts future costs to 2020 value.

RESULTS

Low-dose atropine, antimyopia spectacles, antimyopia multifocal soft contact lenses and orthokeratology met our AMM inclusion criteria. Lifetime cost for TMM with 3% discounting was US$7437 (CI US$4953 to US$10 740) in Australia and US$8006 (CI US$3026 to US$13 707) in China. The lowest lifetime cost options with 3% discounting were antimyopia spectacles (US$7280, CI US$5246 to US$9888) in Australia and low-dose atropine (US$4453, CI US$2136 to US$9115) in China.

CONCLUSIONS

Financial investment in AMM during childhood may be balanced or exceeded across a lifetime by reduced refractive progression, simpler lenses, and reduced risk of pathology and vision loss. Our methodology can be applied to estimate cost in comparable scenarios.

Evaluation of the Nallasamy formula: a stacking ensemble machine learning method for refraction prediction in cataract surgery

AIMS

To develop a new intraocular lens power selection method with improved accuracy for general cataract patients receiving Alcon SN60WF lenses.

METHODS AND ANALYSIS

A total of 5016 patients (6893 eyes) who underwent cataract surgery at University of Michigan's Kellogg Eye Center and received the Alcon SN60WF lens were included in the study. A machine learning-based method was developed using a training dataset of 4013 patients (5890 eyes), and evaluated on a testing dataset of 1003 patients (1003 eyes). The performance of our method was compared with that of Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, PearlDGS and SRK/T.

RESULTS

Mean absolute error (MAE) of the Nallasamy formula in the testing dataset was 0.312 Dioptres and the median absolute error (MedAE) was 0.242 D. Performance of existing methods were as follows: Barrett Universal II MAE=0.328 D, MedAE=0.256 D; EVO MAE=0.322 D, MedAE=0.251 D; Haigis MAE=0.363 D, MedAE=0.289 D; Hoffer Q MAE=0.404 D, MedAE=0.331 D; Holladay 1 MAE=0.371 D, MedAE=0.298 D; PearlDGS MAE=0.329 D, MedAE=0.258 D; SRK/T MAE=0.376 D, MedAE=0.300 D. The Nallasamy formula performed significantly better than seven existing methods based on the paired Wilcoxon test with Bonferroni correction (p<0.05).

CONCLUSIONS

The Nallasamy formula (available at https://lenscalc.com/) outperformed the seven other formulas studied on overall MAE, MedAE, and percentage of eyes within 0.5 D of prediction. Clinical significance may be primarily at the population level.

Repeatability and reproducibility of a new fully automatic measurement optical low coherence reflectometry biometer and agreement with swept-source optical coherence tomography-based biometer

AIMS

To assess the repeatability and reproducibility of the ocular measurements obtained with the Suoer SW-9000 μm Plus, a new fully automatic biometer based on optical low coherence reflectometry (OLCR) biometer, and to compare them to those obtained by a swept-source optical coherence tomography (SS-OCT)-based biometer.

METHODS

This prospective study consisted of 115 eyes of 115 healthy subjects. The measurements were taken by the two optical biometers in random order. The measured parameters were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), mean keratometry (Km), lens thickness (LT) and corneal diameter (CD). To evaluate the intraobserver repeatability and interobserver reproducibility, the within-subject SD, test-retest variability, coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were adopted. The Bland-Altman plot was drawn to assess the agreement.

RESULTS

The repeatability and reproducibility of all parameters for the new device were excellent (ICC>0.960 and CoV<0.71%). The Bland-Altman plots showed high agreement between the OLCR-based and SS-OCT-based devices for AL, CCT, AQD, ACD, Km and LT, with narrow 95% limit of agreements (LoAs) (-0.08 mm to 0.06 mm, -15.91 µm to -1.01 µm, -0.09 mm to 0.09 mm, -0.09 mm to 0.08 mm, -0.47 D to 0.35 D, -0.05 mm to 0.16 mm, respectively) and moderate agreement for CD (95% LoA: -0.67 mm to -0.01 mm).

CONCLUSIONS

The new Suoer SW-9000 μm Plus biometer showed excellent repeatability and reproducibility. All the parameters obtained by this biometer were similar to those measured by SS-OCT-based biometer.

Change of peripapillary retinal nerve fiber layer and choroidal thickness during 4-year myopic progress: Boramae Myopia Cohort Study Report 4

AIMS

To investigate the longitudinal changes of peripapillary retinal nerve fibre layer (RNFL) and choroidal thickness during myopic axial elongation.

METHODS

Peripapillary RNFL and choroidal thickness were prospectively evaluated by spectral-domain optical coherence tomography (SD-OCT) in 46 eyes of 23 myopic children over the course of 4 years. Using serial OCT images acquired based on a fixed scan circle in the glaucoma progression analysis mode, general and sectoral RNFL thicknesses were acquired at the same position and the angular location of the peak was measured. The peripapillary choroidal thickness likewise was measured at eight positions in serial OCT images.

RESULTS

The mean age at the baseline was 9.6±1.7 years. The mean axial length increased from 24.80±1.28 mm to 25.64±1.35 mm. The global peripapillary RNFL thickness was 98.54±12.06 µm at baseline. The global and sectoral RNFL thicknesses did not change during the 4 years. The angular location of RNFL peaks was also stable and was located in the superotemporal (64.18±10.85°) and inferotemporal (293.98±11.62°) sectors. The global peripapillary choroidal thickness was 145.40±28.67 µm at the baseline. The global and sectoral choroidal thicknesses did not change during the 4 years.

CONCLUSIONS

The peripapillary RNFL and choroidal thicknesses as well as the locations of the RNFL peaks had been preserved, during the 4-year follow-up on myopic children, when traced and measured from the same location.

Comparison of intraocular lens calculation methods after myopic laser-assisted in situ keratomileusis and radial keratotomy without prior refractive data

AIM

To compare intraocular lens (IOL) calculation methods not requiring refraction data prior to myopic laser-assisted in situ keratomileusis (LASIK) and radial keratotomy (RK).

METHODS

In post-LASIK eyes, the methods not requiring prior refraction data were Hagis-L; Shammas; Barrett True-K no-history; Wang-Koch-Maloney; 'average', 'minimum' and 'maximum' IOL power on the American Society of Cataract and Refractive Surgeons (ASCRS) IOL calculator. Double-K method and Barrett True-K no-history, 'average', 'minimum' and 'maximum' IOL power on ASCRS IOL calculator were evaluated in post-RK eyes. The predicted IOL power was calculated with each method using the manifest postoperative refraction. Arithmetic and absolute IOL prediction errors (PE) (implanted-predicted IOL powers), variances in arithmetic IOL PE and percentage of eyes within ±0.50 and ±1.00 D of refractive PE were calculated.

RESULTS

Arithmetic or absolute IOL PE were not significantly different between the methods in post-LASIK and post-RK eyes. In post-LASIK eyes, 'average' showed the highest and 'minimum' showed the least variance, whereas 'average' and 'minimum' had highest percentage of eyes within ±0.5 D and 'minimum' had the highest percentage of eyes within ±1.0 D. In the post-RK eyes, 'minimum' had highest variance, and 'average' had the least variance and highest percentage of eyes within ±0.5 D and ±1.0 D.

CONCLUSION

In post-LASIK and post-RK eyes, there are no significant differences in IOL PE between the methods not requiring prior refraction data. 'Minimum' showed least variance in PEs and more chances of eyes to be within ±1.0 D postoperatively in post-LASIK eyes. 'Average' had least variance and more chance of eyes within ±1.0 D in post-RK eyes.

Accuracy of common IOL power formulas in 611 eyes based on axial length and corneal power ranges

AIMS

To provide clinical guidance on the use of intraocular lens (IOL) power calculation formulas according to the biometric parameters.

METHODS

611 eyes that underwent cataract surgery were retrospectively analysed in subgroups according to the axial length (AL) and corneal power (K). The predicted residual refractive error was calculated and compared to evaluate the accuracy of the following formulas: Haigis, Hoffer Q, Holladay 1 and SRK/T. Furthermore, the percentages of eyes with ≤±0.25, ≤±0.5 and 1 dioptres (D) of the prediction error were recorded.

RESULTS

The Haigis formula showed the highest percentage of cases with ≤0.5 D in eyes with a short AL and steep K (90%), average AL and steep cornea (73.2%) but also in long eyes with a flat and average K (65% and 72.7%, respectively). The Hoffer Q formula delivered the lowest median absolute error (MedAE) in short eyes with an average K (0.30 D) and Holladay 1 in short eyes with a steep K (Holladay 1 0.24 D). SRK/T presented the highest percentage of cases with ≤0.5 D in average long eyes with a flat and average K (80.5% and 68.1%, respectively) and the lowest MedAE in long eyes with an average K (0.29 D).

CONCLUSION

Overall, the Haigis formula shows accurate results in most subgroups. However, attention must be paid to the axial eye length as well as the corneal power when choosing the appropriate formula to calculate an IOL power, especially in eyes with an unusual biometry.

Prevalence and risk factors of pseudomyopia in a Chinese children population: the Anyang Childhood Eye Study

AIMS

To investigate the prevalence and predictors of pseudomyopia in Chinese children and its association with myopia progression.

METHODS

A prospective, school-based, cohort study of 6- and 13-year-old children was conducted in Anyang, China. Pre-cycloplegic and post-cycloplegic autorefraction were performed at baseline and 1 year later. Pseudomyopia was defined as spherical equivalent refractive (SER) error in the better-seeing eye ≤-0.50 D before cycloplegia and >-0.50 D after cycloplegia. Among pseudomyopic children, pseudomyopic power was defined as non-cycloplegic SER subtracted from cycloplegic SER. Market survey was collected in all optometry stores in Anyang city to investigate how cycloplegia is used for refracting children.

RESULTS

A total of 2612 children aged 6 years and 1984 children aged 13 years were included. Of the two cohorts, median cycloplegic SER (IQR) was 1.00 D (0.50, 1.38) and -1.13 D (-2.63, 0.13) respectively, myopia prevalence was 5.2% and 61.0%, pseudomyopia prevalence was 24.1% and 18.9%, and median pseudomyopic power was 1.13 D (0.63, 1.63) and 0.38 D (0.13, 0.88). In both cohorts, greater baseline hyperopia was the strongest predictor of pseudomyopia (p<0.001), whereas time spent on near work was not associated with pseudomyopic power (p>0.05). After 1 year, 15.6% (98/629) of 6-year-olds and 10.7% (40/374) of 13-year-olds with pseudomyopia developed myopia. Compared with myopes, pseudomyopic children with the same pre-cycloplegic SER had slower myopic progression (p<0.001). Among all 127 optometry stores in Anyang, only 4 (3.15%) used cycloplegia for refracting children.

CONCLUSION

Pseudomyopia is more prevalent in younger, more hyperopic children. Pseudomyopia is not an independent risk factor for myopic progression in this setting.

What can anisometropia tell us about eye growth?

BACKGROUND/AIMS

Both eyes of one individual share the same environment and genes. We examined interocular differences in biometry to determine the potential role of other factors in refractive development.

METHODS

362 subjects (6-7 years) from the Northern Ireland Childhood Errors of Refraction study were studied. Cycloplegic autorefraction was measured with a Shin-Nippon open-field autorefractor. Axial length and corneal curvature were measured with a Zeiss IOLMaster.

RESULTS

257 subjects had an interocular difference of <0.50 D (ISO group) and 105 (29%) a difference of ≥0.50 D (ANISO group). Twenty-five subjects (6.9%) had anisometropia ≥1.00 D and 9 (2.5%) had anisometropia ≥1.50 D. The two groups, ISO and ANISO, showed different refractive distributions (p=0.001) with the ISO group showing a nearly Gaussian distribution and the ANISO group showing positive skew, a hyperopic shift and a bi-Gaussian distribution. A marker of emmetropisation is the poor correlation between refraction and corneal curvature seen in older children. There was no significant correlation between refraction and corneal curvature of each eye in the ISO group (r=0.09, p=0.19), but these parameters were significantly correlated in the ANISO group (r=0.28, p=0.004).

CONCLUSION

In young children, small degrees of anisometropia (≥0.5 D) are associated with impaired emmetropisation. This suggests that anisometropia is a marker for poorly regulated eye growth, indicating that, in addition to environmental and genetic influences on eye growth, stochastic processes contribute to refractive outcomes.

Progression of diffuse chorioretinal atrophy among patients with high myopia: a 4-year follow-up study

AIMS

To investigate the progression pattern of diffuse chorioretinal atrophy (DCA) among Chinese participants with high myopia.

METHODS

This is a longitudinal, non-interventional study. Participants with high myopia, defined as ≤-6 diopters spherical power, were included and followed up for 4 years, and underwent cycloplegic autorefraction, best-corrected visual acuity (BCVA) and fundus photography examinations. Newly established DCA, enlargement of existing DCA and development of other lesions of myopic maculopathy were regarded as DCA progression.

RESULTS

Of the 484 participants with a mean age of 21.5±12.7 years (range, 6.8-69.7 years), 68 eyes (14.0%) showed DCA progression, with 88 lesion changes. The first appearance of DCA was identified in 21 eyes (23.9%). Of 88 eyes with DCA at baseline, 47 eyes (53.4%) showed progression, with 67 lesion changes, including 45 eyes (67.2%) with enlargement of DCA, 17 (25.3%) with a first appearance of lacquer cracks, 4 (6.0%) with development of patchy chorioretinal atrophy and 1 (1.5%) with increased numbers of lacquer cracks. Longer axial length (p<0.001), baseline DCA (p=0.005) and baseline DCA closer to the fovea (p=0.013) predicted DCA progression. Eyes had poorer BCVA at the follow-up if DCA was enlarging (p<0.001) or DCA was closer to the fovea at baseline (p=0.028) after adjusting for age,gender and cataract.

CONCLUSION

Approximately half of the participants with DCA had progression over a 4-year follow-up. Enlargement and newly developed DCA were common progression patterns. Larger areas of DCA and foveal involvement with DCA could be indicators of a worse BCVA later.

Genetic associations of myopia severities and endophenotypes in children

OBJECTIVE

To investigate the associations of multiple single-nucleotide polymorphisms (SNPs) with the severities and endophenotypes of myopia in children.

METHODS

A total of 3300 children aged 5-10 years were recruited: 137 moderate and high myopia (SE≤-3.0D), 670 mild myopia (-3.0D<SE≤-0.5D) and 2493 controls (SE>-0.5D). 13 SNPs in 13 genes/loci were selected for genotyping in all subjects using TaqMan assays. Associations between each SNP with myopia severities and ocular traits (spherical equivalent (SE), axial length (AL) and corneal radius (CR)) were analysed.

RESULTS

When compared with controls, SNPs ZC3H11B rs4373767 (OR=1.15, p=0.038), BICC1 rs7084402 (OR=1.18, p=0.005) and GJD2 rs524952 (OR=1.14, p=0.025) showed nominal associations with overall myopia. ZC3H11B rs4373767 and BICC1 rs7084402 showed stronger associations with moderate and high myopia (rs4373767: OR=1.42, p=0.018; rs7084402: OR=1.33, p=0.025), while GJD2 rs524952 had a stronger association with mild myopia (OR=1.14, p=0.025). GJD2 rs524952 also showed a difference between emmetropia and hyperopia (p=0.018). In quantitative trait locus analysis, ZC3H11B rs4373767, KCNQ5 rs7744813 and GJD2 rs524952 were correlated with both myopic SE (β=-0.09, p=0.03; β=-0.12, p=0.007; β=-0.13, p=0.0006, respectively) and AL (β=0.07, p=0.002; β=0.09, p=0.0008; β=0.07, p=0.0003, respectively). SNTB1 rs7839488 was correlated with both AL (β=0.07, p=0.005) and CR (β=0.02, p=0.006). Moreover, ZC3H11B rs4373767-T (β=0.006; p=0.018), KCNQ5 rs7744813-A (β=0.007; p=0.015) and GJD2 rs524952-T (β=0.009; p=0.0006) were correlated with AL-CR ratio.

CONCLUSIONS AND RELEVANCE

ZC3H11B and BICC1 are genetic risk factors for moderate and high myopia, while ZC3H11B, KCNQ5, SNTB1 and GJD2 confer risk to excessive AL in children.

Impact of spectacles wear on uncorrected visual acuity among urban migrant primary school children in China: a cluster-randomised clinical trial

OBJECTIVE

To estimate the effect of providing free spectacles on uncorrected visual acuity (VA) among urban migrant Chinese school children.

DESIGN

Exploratory analysis from a parallel cluster-randomised clinical trial.

METHODS

After baseline survey and VA screening, eligible children were randomised by school to receive one of the two interventions: free glasses and a teacher incentive (tablet computer if ≥80% of children given glasses were wearing them on un-announced examination) (treatment group) or glasses prescription and letter to parents (control group). The primary outcome was uncorrected logarithm of the minimal angle of resolution (LogMAR) VA at study closeout, adjusted for baseline uncorrected VA.

RESULTS

Among 4376 randomly selected children, 728 (16.6%, mean age 10.9 years, 51.0% boys) at 94 schools failed VA screening and met eligibility criteria. Of these, 358 children (49.2%) at 47 schools were randomised to treatment and 370 children (50.8%) at 47 schools to control. Among these, 679 children (93.3%) completed follow-up and underwent analysis. Spectacle wear in the treatment and control groups was 68.3% and 29.3% (p<0.001), respectively. Uncorrected final VA for eyes of treatment children was significantly better than control children, adjusting only for baseline VA (difference of 0.039 LogMAR units, 95% CI: 0.008, 0.070, equivalent to 0.39 lines, p=0.014) or baseline VA and other baseline factors (0.040 LogMAR units, 95% CI 0.007 to 0.074, equivalent to 0.40 lines, p=0.020).

CONCLUSION

We found no evidence that spectacles wear worsens children's uncorrected VA among urban migrant Chinese school children.

Fifteen-year incidence rate and risk factors of pterygium in the Southern Indian state of Andhra Pradesh

PURPOSE

To report 15-year incidence rate and associated risk factors of pterygium among people aged 30 years and above at baseline in the rural clusters of longitudinal Andhra Pradesh Eye Disease Study (APEDS III).

METHODS

The baseline APEDS I included 7771 participants of which 6447 (83%) were traced and 5395 (83.7%) were re-examined in APEDS III. To estimate the incidence of pterygium, we selected participants who were 30 years and above at baseline (4188), of which 2976 were traced and 2627 (88.3%) were examined, and based on inclusion criteria, 2290 participants were included in the study. The incidence rate of pterygium was defined as the proportion of people free of pterygium at baseline who had developed the condition at 15-year follow-up (range 13-17 years). Univariate and multivariable analyses for risk factors were undertaken.

RESULTS

The sex-adjusted incidence rate of pterygium was 25.2 per 100 person-years (95% CI 24.8 to 25.7) which was significantly higher for men than women (26.3 per 100 person-years (95% CI 25.6 to 27.0) and 24.7 (95% CI 24.1 to 25.3) respectively). At the multivariable analysis, male gender (RR: 1.35, 95% CI 1.0 to 1.83), no formal education (RR: 2.46, 95% CI 1.22 to 4.93), outdoor occupation (RR: 1.47, 95% CI 1.14 to 1.9) and lower body mass index (BMI) (<18.5) (RR: 1.25, 95% CI 1.02 to 1.55) were associated with increased risk of pterygium.

CONCLUSIONS

The overall incidence rate of pterygium was high in this rural population, especially in men and those engaged in outdoor activities, lack of formal education and with lower BMI. It is likely that greater exposure to ultraviolet light is a major contributing factor, thus warranting preventive strategies.

Late-term topical tacrolimus for subepithelial infiltrates resistant to topical steroids and ciclosporin secondary to adenoviral keratoconjunctivitis

PURPOSE

Investigation of the efficacy and safety of 12 months of topical tacrolimus 0.03% ointment treatment against the subepithelial infiltrates (SEIs) due to adenoviral keratoconjunctivitis (AKC) resisting at least 2 years was aimed.

METHODS

This case series included consecutive patients with SEIs secondary to AKC who were resistant to topical steroid and ciclosporin-A (CSA) treatment and treated with topical 0.03% tacrolimus (Protopic; Fujisawa Healthcare, Teva, Deerfield, Illinois, USA) for 12 months, at least 2 years after AKC. For the evaluation of treatment efficacy, best-corrected visual acuity (BCVA), Fantes score, corneal subepithelial infiltrate score (CSIS), Oxford score, Schirmer and tear breakup time results were evaluated. Intraocular pressure and complaints of the patients were followed for evaluating the safety profile of the treatment. The patients were followed after the baseline visit at the 1st, 3rd, 6th and 12th month.

RESULTS

15 eyes of 11 patients with SEIs and 16 eyes of 16 healthy controls were included in this study. 1 patient (9.1%) could not tolerate the treatment. Significant improvements in BCVA, CSIS, Fantes score and Schirmer results were observed in the study group starting from the 3rd-month visit, and the improvements persisted until the end of 12 months of treatment.

CONCLUSION

Topical 0.03% tacrolimus might show efficacy against the SEIs persisting at least 2 years despite corticosteroid and/or CSA treatment without any prominent side effect. While at least a period of 3 months was necessary for a significant improvement in the BCVA, SEIs and Schirmer results, a period of 6 months was necessary for a decrease in Oxford score.

Microinterventional endocapsular nucleus disassembly: novel technique and results of first-in-human randomised controlled study

Aim

To assess the safety and efficacy of microinterventional endocapsular nuclear fragmentation in moderate to severe cataracts.

Methods

This was a prospective single-masked multisurgeon interventional randomised controlled trial (ClinicalTrials.gov NCT02843594) where 101 eyes of 101 subjects with grade 3‒4+ nuclear cataracts were randomised to torsional phacoemulsification alone (controls) or torsional phacoemulsification with adjunctive endocapsular nuclear fragmentation using a manual microinterventional nitinol filament loop device (miLOOP group). Outcome measures were phacoemulsification efficiency as measured by ultrasound energy (cumulative dispersed energy (CDE) units) and fluidics requirements (total irrigation fluid used) as well as incidence of intraoperative and postoperative complications.

Results

Only high-grade advanced cataracts were enrolled with more than 85% of eyes with baseline best corrected visual acuity (BCVA) of 20/200 or worse in either group. Mean CDE was 53% higher in controls (32.8±24.9 vs 21.4±13.1 with miLOOP assistance) (p=0.004). Endothelial cell loss after surgery was low and similar between groups (7‒8%, p=0.561) One-month BCVA averaged 20/27 Snellen in miLOOP eyes and 20/24 in controls. No direct complications were caused by the miLOOP. In two cases, capsular tears occurred during IOL implantation and in all remaining cases during phacoemulsification, with none occurring during the miLOOP nucleus disassembly part of the procedure.

Conclusions

Microinterventional endocapsular fragmentation with the manual, disposable miLOOP device achieved consistent, ultrasound-free, full-thickness nucleus disassembly and significantly improved overall phaco efficiency in advanced cataracts.

Trial registration number

NCT02843594

Accelerated transepithelial corneal cross-linking for progressive keratoconus: a prospective study of 12 months

BACKGROUND/AIMS

To evaluate the clinical results of accelerated transepithelial corneal cross-linking (CXL) in Japanese patients with progressive keratoconus (KCN).

METHODS

Thirty eyes of 19 patients (16 male, 3 female patients) with progressive KCN were included. The mean age was 24.9±7.0 (range 16-38) years. All patients received ultraviolet A radiation for 3 min at an irradiance of 30 mW/cm². Patients were followed up on the first day, at 1 week and 2 weeks, and at 1 month, 3 months, 6 months and 12 months postoperatively. Clinical examinations included measures of uncorrected visual acuity, best corrected visual acuity (BCVA), average keratometry (AveK), maximum keratometry (Kmax), central corneal thickness, thinnest corneal thickness (TCT), endothelial cell density, intraocular pressure and non-mydriatic indirect fundus examination. Patients were asked to report any pain or discomfort at each visit.

RESULTS

There were no intraoperative or postoperative complications. All 30 eyes finished the follow-up. After 12 months, there was a significant decrease in Kmax (p<0.0001), AveK (p=0.003) and TCT (p=0.002), and a significant improvement in BCVA (p=0.001). There were no other significant changes. Pain or foreign-body sensation following CXL appeared in the first 2 days, but lasted no more than 1 week in all cases.

CONCLUSIONS

There were no complications associated with accelerated transepithelial corneal CXL, and the clinical outcomes were appraisable in a 12-month follow-up.

TRIAL REGISTRATION NUMBER

UMIN000009372.

Single-step transepithelial versus alcohol-assisted photorefractive keratectomy in the treatment of high myopia: a comparative evaluation over 12 months

BACKGROUND/AIMS

To evaluate refractive outcomes of single-step transepithelial photorefractive keratectomy (TransPRK) versus alcohol-assisted PRK (EtOH-PRK) for the correction of high myopia.

METHODS

This was a retrospective non-randomised comparative study conducted at the American University of Beirut Medical Center, Beirut, Lebanon. Eyes with myopia (spherical equivalent (SE) larger than -6.00 D) that had undergone EtOH-PRK treatment combined with mitomycin C and TransPRK (SE: -7.53±0.90 D and -7.24±0.77 D, p=0.062), using the Schwind Amaris excimer laser, were included. 59 eyes (37 patients) that had single-step TransPRK were compared with 59 eyes (36 patients) that had EtOH-PRK. Visual and refractive outcomes, including analysis of astigmatism, and corneal higher order aberrations (HOAs) at 6.0 mm optical zone, were compared for 12 months postoperatively.

RESULTS

Baseline characteristics were similar between the two groups (p>0.05). The SE deviation from target (SEDT) at 1 week, 1, 3, 6 and 12 months follow-up visits were similar between groups (p=0.428). At 12 months, 81.3% and 73.3% of eyes that had undergone TransPRK and EtOH-PRK, respectively, were between ±0.50 D SEDT (p=0.381). Mean cylinder power was 0.33±0.26 D versus 0.41±0.30 D at 12 months follow-up (p=0.140). The mean success index was 0.50±0.50 for the TransPRK group and 0.49±0.52 for the EtOH-PRK group (p=0.939), while the absolute mean angle of error was 7.81°±61.98° vs 13.12°±71.86° (p=0.667), respectively. The change in total, spherical and comatic corneal HOAs were similar in both groups at 12 months (p>0.05). Haze was similar between both groups; two eyes had +1 haze at 12 months in the TransPRK group versus zero eyes among the EtOH-PRK group (p=0.154).

CONCLUSIONS

Single-step TransPRK for high myopia with or without astigmatism appears to yield similar visual, refractive and safety results as EtOH-PRK.

Integrating a novel concept of sentence optotypes into the RADNER Reading Charts

PURPOSE

To add a new set of 24 sentence optotypes to the German version of the RADNER reading charts and to investigate whether sentences constructed based upon an optimised concept of sentence optotypes can be used together with the original 38 sentences.

METHODS

Twenty-eight optimised sentence optotypes were constructed based upon the concept of sentence optotypes as established for the RADNER Reading Charts, with words having the same number of characters and syllables being placed in the same positions. The best comparable sentences were statistically selected in 30 volunteers. Reading speed and the number of errors were determined. Validity was analysed in comparison to a 111-word long standardised paragraph and 7 of the 38 original sentence optotypes.

RESULTS

The mean reading speed obtained with the 28 sentences was 192.30±26.69 words per minute (wpm), as compared with 192.47±25.32 wpm for the 7 original sentence optotypes and 165.28±20.82 wpm for the long paragraph; 24 of the 28 optimised sentences met our selection criteria for reading speed/time (mean reading speed: 192.41±26.58). The mean number of reading errors was 0.10±0.30. The correlation between the 24 optimised sentence optotypes and the long paragraph was r=0.90. Reliability analyses yielded an overall Cronbach's α coefficient of 0.992.

CONCLUSION

The 24 new sentence optotypes can be integrated into the existing set of 38 original sentences. Since all the statistical results obtained were similar to those of the original sentences, the best possible reliability had apparently already been achieved with the original sentence optotypes.

Treatment of type I ROP with intravitreal bevacizumab or laser photocoagulation according to retinal zone

AIMS

To investigate the outcome of intravitreal bevacizumab (IVB) compared with laser photocoagulation in type I retinopathy of prematurity (ROP).

METHODS

Case records of 54 consecutive very low birth weight (VLBW) infants with type I ROP (posterior ROP, n=33; peripheral zone II, n=21) who were treated either with IVB (n=37) or laser photocoagulation (n=17) between 2011 and 2015 were retrospectively evaluated.

RESULTS

Patients with posterior ROP displayed significantly faster regression of active ROP within 12 days (range 9-15 days) if treated with IVB compared with laser photocoagulation, where active ROP regressed within 57 days (range 28-63 days) (p>0.001). No difference was observed in peripheral zone II.Five of seven patients (12%) who developed a recurrence in both eyes after IVB required additional laser photocoagulation within a mean of 12.7 weeks (11.3-15.6 weeks) after the previous treatment. After laser photocoagulation one patient with posterior ROP developed macular dragging and another patient developed a temporary exudative retinal detachment in both eyes. 12 months after treatment the spherical equivalent was not statistically significant different between IVB and laser photocoagulation in posterior ROP patients. However, IVB lead to a significant lower spherical equivalent in infants with posterior ROP (+0.37 dioptres, range -0.5 to +1.88 dioptres) compared with peripheral zone II (+3.0 dioptres range +2.0 to +4.0 dioptres, p<0.001).

CONCLUSIONS

IVB leads to faster regression of active ROP in infants with posterior ROP compared with laser photocoagulation. Spherical equivalent after 12 months was comparable in those treated with IVB and laser photocoagulation, but it was significantly lower in posterior ROP than in peripheral zone II.

Objective and subjective visual quality after implantation of all optic zone diffractive multifocal intraocular lenses: a prospective, case-control observational study

BACKGROUND AND AIMS

To evaluate the objective and subjective optical quality of all optic zone diffractive multifocal intraocular lens (IOL).

METHODS

Fifty patients (50 eyes) having phacoemulsification and IOL implantation surgery were enrolled. 25 patients were implanted with all optic zone diffractive multifocal IOL and 25 patients with monofocal IOL. Objective optical quality parameters under 4 mm pupil using Optical Quality Analysis System (OQAS), subjective visual acuity (VA) at 85 cd/m² luminance and questionnaire concerning halo and visual function were assessed.

RESULTS

The multifocal group gained similar objective optical outcomes, such as OQAS values at contrast 100%, 20%, 9%, modulation transfer function cut-off and Strehl ratio, as the monofocal group. Objective scatter index (OSI) was significantly better in the monofocal group. Distance corrected near VA, uncorrected near VA, distance corrected intermediate VA and uncorrected intermediate VA were significantly better in the multifocal group. The difference in uncorrected distance VA and best corrected distance VA between the monofocal and multifocal groups was not significant. Mild halos and glare were reported in both groups and a significant difference between the two groups was not observed; however, moderate glare and halos were reported only in the multifocal group (2/25). There was no significant difference between the two groups when visual function was compared.

CONCLUSIONS

All optic zone diffractive multifocal IOLs provided almost the same objective optical quality as monofocal IOLs did under 4 mm pupil besides good all distance visual performance, but with greater OSI, indicating that implantation provides good optical quality in daytime but with more intraocular scatter light.

TRIAL REGISTRATION NUMBER

NCT02234635, post-results.

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adjusting for study design factors. 143 published articles (42 countries, 374 349 subjects aged 1–18 years, 74 847 myopia cases) were included. Increase in myopia prevalence with age varied by ethnicity. East Asians showed the highest prevalence, reaching 69% (95% credible intervals (CrI) 61% to 77%) at 15 years of age (86% among Singaporean-Chinese). Blacks in Africa had the lowest prevalence; 5.5% at 15 years (95% CrI 3% to 9%). Time trends in myopia prevalence over the last decade were small in whites, increased by 23% in East Asians, with a weaker increase among South Asians. Children from urban environments have 2.6 times the odds of myopia compared with those from rural environments. In whites and East Asians sex differences emerge at about 9 years of age; by late adolescence girls are twice as likely as boys to be myopic. Marked ethnic differences in age-specific prevalence of myopia exist. Rapid increases in myopia prevalence over time, particularly in East Asians, combined with a universally higher risk of myopia in urban settings, suggest that environmental factors play an important role in myopia development, which may offer scope for prevention.

Corneal powers measured with a rotating Scheimpflug camera

BACKGROUND/AIM

Keratometry measures the anterior corneal curvature only. Corneal power is calculated by multiplication with the keratometric refractive index, which takes into account the average negative posterior corneal power. The aim of this study was to calculate and compare various expressions for total corneal power assessed with Scheimpflug camera techniques, which also measure the posterior corneal curvature.

METHODS

We used the Pentacam rotating Scheimpflug camera to measure the equivalent power, total corneal refractive power (based on Snell's law ray tracing), and simulated keratometry (keratometric refractive index=1.3375) over the central 3.0 mm zone in 951 eyes. The keratometric refractive index of the equivalent power and the total corneal refractive power was calculated as the ratio between these values and the anterior corneal curvature.

RESULTS

The equivalent power, total corneal refractive power, and simulated keratometry all differed statistically significantly (analysis of variance, p<0.001) and averaged 42.26 (±1.46) dioptres (D), 42.78 (±1.51) D and 43.42 (±1.49) D. The calculated keratometric refractive indices for equivalent and total corneal refractive power averaged 1.3284 (±0.0009) and 1.3324 (±0.0015). The error of using these calculated keratometric refractive indices rather than the measured values for equivalent and total corneal refractive power averaged 0 (±0.11 D) and -0.01 D (±0.19).

CONCLUSIONS

Pentacam rotating camera assessment of total corneal power over the central 3.0 mm zone differed significantly for simulated keratometry, equivalent power and Snell's law ray tracing.

Evaluation and comparison of the new swept source OCT-based IOLMaster 700 with the IOLMaster 500

Purpose

To compare the measurements and failure rates obtained with a new swept source optical coherence tomography (OCT)-based biometry to IOLMaster 500.

Setting

Eye Clinic, Baskent University Faculty of Medicine, Ankara, Turkey.

Design

Observational cross-sectional study and evaluation of a new diagnostic technology.

Methods

188 eyes of 101 subjects were included in the study. Measurements of axial length (AL), anterior chamber depth (ACD), corneal power (K1 and K2) and the measurement failure rate with the new Zeiss IOLMaster 700 were compared with those obtained with the IOLMaster 500. The results were evaluated using Bland–Altman analyses. The differences between both methods were assessed using the paired samples t test, and their correlation was evaluated by intraclass correlation coefficient (ICC).

Results

The mean age was 68.32±12.71 years and the male/female ratio was 29/72. The agreements between two devices were outstanding regarding AL (ICC=1.0), ACD (ICC=0.920), K1 (ICC=0.992) and K2 (ICC=0.989) values. IOLMaster 700 was able to measure ACD AL, K1 and K2 in all eyes within high-quality SD limits of the manufacturer. IOLMaster 500 was able to measure ACD in 175 eyes, whereas measurements were not possible in the remaining 13 eyes. AL measurements were not possible for 17 eyes with IOLMaster 500. Nine of these eyes had posterior subcapsular cataracts and eight had dense nuclear cataracts.

Conclusions

Although the agreement between the two devices was excellent, the IOLMaster 700 was more effective in obtaining biometric measurements in eyes with posterior subcapsular and dense nuclear cataracts.

Correlation of central visual function and ROP risk factors in prematures with and without acute ROP at the age of 6-13 years: the Giessen long-term ROP study

AIM

To correlate light increment sensitivity (LIS) and visual acuity (VA) with birth weight (BW), gestational age (GA) and stage of acute retinopathy of prematurity (ROP) (STG) in premature children at school age.

METHODS

180 children (150 former prematures and 30 age-matched term-born children) were enrolled at age 6-13 years. Former prematures were categorised by the results of the initial ROP screening based on digital wide-field fundus imaging: absence of ROP (n=100) and spontaneously resolved ROP (n=50). The latter group was further subdivided according to their STG (Stg 1; Stg 2; Stg 3). Both groups were categorised into sectors by BW (<1000 g; 1000-1500 g; >1500 g), and GA (≤28 weeks; >28<32 weeks; ≥32 weeks). VA was assessed with Early Treatment of Diabetic Retinopathy Study letters, LIS was measured at 0°, 2.8° and 8° in the visual field (Microperimeter MP1, Nidek Technologies), and spherical equivalent refraction assessed with a Nidek autorefractor (Nidek, Italy).

RESULTS

Central and pericentral LIS (0° and 2.8°) and VA were significantly lower in all groups and sectors compared with term-born controls except for BW >1500 g for LIS and GA >28 to <32 W for VA. No significant differences were found for LIS at 8° in all groups. No correlation was found between LIS and VA on an individual basis.

CONCLUSIONS

Low BW, GA and increasing severity of spontaneously resolving ROP were associated with significantly decreased central visual function. In addition to VA, LIS measurement further describes foveal function and is a unique parameter to assess parafoveal function.