The development and maintenance of emmetropia

BCLA CLEAR presbyopia: Mechanism and optics

With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.

The significance of growth shells in development of symmetry, transparency, and refraction of the human lens

Human visual function depends on the biological lens, a biconvex optical element formed by coordinated, synchronous generation of growth shells produced from ordered cells at the lens equator, the distal edge of the epithelium. Growth shells are comprised of straight (St) and S-shaped (SSh) lens fibers organized in highly symmetric, sinusoidal pattern which optimizes both the refractile, transparent structure and the unique microcirculation that regulates hydration and nutrition over the lifetime of an individual. The fiber cells are characterized by diversity in composition and age. All fiber cells remain interconnected in their growth shells throughout the life of the adult lens. As an optical element, cellular differentiation is constrained by the physical properties of light and its special development accounts for its characteristic symmetry, gradient of refractive index (GRIN), short range transparent order (SRO), and functional longevity. The complex sinusoidal structure is the basis for the lens microcirculation required for the establishment and maintenance of image formation.

Outcome of intraocular lens exchange for the management of myopic shift in pseudophakic children

PURPOSE

To evaluate the visual outcome of intraocular lens (IOL) exchange for the management of myopic shift in pseudophakic children.

METHODS

The medical records of children who underwent IOL exchange for myopic shift were examined. The preoperative data, operative details and the postoperative outcome were analyzed.

RESULTS

Twenty-one eyes (16 patients) were identified. Mean age at cataract extraction was 20 ± 26 months (range, 2-84 months). Twelve patients (6 unilateral, 6 bilateral) had primary IOL implantation. Mean age at IOL exchange was 7.3 ± 3.2 years. Mean spherical equivalent (SE) at IOL exchange was -14 ± 5 D (range, -7 to -21 D): Mean SE at IOL exchange was -13.64 ± 4.99 D, -12 ± 1.53 D, and -15.5 ± 4.7 D in unilaterally pseudophakic cases (8 patients), in the eye that underwent unilateral IOL exchange (3 patients) in bilaterally pseudophakic cases, and in bilateral IOL exchange cases (5 patients), respectively. Mean axial length at IOL exchange was 24 ± 1.3 mm (range, 23 to 27 mm). Following IOL exchange, mean SE was reduced to -2 ± 1.8 D (range, -4 to +2.5 D). An average of three logMAR line improvement in the best-corrected visual acuity was observed in 12/16 eyes of patients for whom pre- and post-exchange visual acuity were available, while visual acuity remained unchanged in 4 eyes. Mean logMAR visual acuity improvement was 0.35 and 0.49 in unilateral and bilateral pseudophakic cases, respectively.

CONCLUSIONS

IOL exchange is a safe procedure that should be considered to improve visual rehabilitation in pseudophakic patients with myopic shift.

Bi-Gaussian analysis reveals distinct education-related alterations in spherical equivalent and axial length-results from the Gutenberg Health Study

PURPOSE

The aim of this study is to investigate the distribution of spherical equivalent and axial length in the general population and to analyze the influence of education on spherical equivalent with a focus on ocular biometric parameters.

METHODS

The Gutenberg Health Study is a population-based cohort study in Mainz, Germany. Participants underwent comprehensive ophthalmologic examinations as part of the 5-year follow-up examination in 2012-2017 including genotyping. The spherical equivalent and axial length distributions were modeled with gaussian mixture models. Regression analysis (on person-individual level) was performed to analyze associations between biometric parameters and educational factors. Mendelian randomization analysis explored the causal effect between spherical equivalent, axial length, and education. Additionally, effect mediation analysis examined the link between spherical equivalent and education.

RESULTS

A total of 8532 study participants were included (median age: 57 years, 49% female). The distribution of spherical equivalent and axial length follows a bi-Gaussian function, partially explained by the length of education (i.e., < 11 years education vs. 11-20 years). Mendelian randomization indicated an effect of education on refractive error using a genetic risk score of education as an instrument variable (- 0.35 diopters per SD increase in the instrument, 95% CI, - 0.64-0.05, p = 0.02) and an effect of education on axial length (0.63 mm per SD increase in the instrument, 95% CI, 0.22-1.04, p = 0.003). Spherical equivalent, axial length and anterior chamber depth were associated with length of education in regression analyses. Mediation analysis revealed that the association between spherical equivalent and education is mainly driven (70%) by alteration in axial length.

CONCLUSIONS

The distribution of axial length and spherical equivalent is represented by subgroups of the population (bi-Gaussian). This distribution can be partially explained by length of education. The impact of education on spherical equivalent is mainly driven by alteration in axial length.

Impact of ophthalmic clinical service use in mitigating myopia onset and progression in preschool children: a retrospective cohort study

BACKGROUND

Although school screenings identify children with vision problems and issue referrals for medical treatment at an ophthalmic hospital, the effectiveness of this approach remains unverified.

OBJECTIVE

To investigate the impact of ophthalmic clinical services on the onset and progression of myopia in preschool children identified with vision impairment.

METHODS

Using data from the Shanghai Child and Adolescent Large-scale Eye Study (SCALE), this retrospective cohort study evaluated the visual development of children from three districts-Jing'an, Minhang, and Pudong-which are representative of geographic diversity and economic disparity in Shanghai's 17 districts. Initially, in 2015, the study encompassed 14,572 children aged 4-6 years, of whom 5,917 needed a referral. Our cohort consisted of 5,511 children who had two or more vision screenings and complete personal information over the follow-up period from January 2015 to December 2020. We divided these children into two groups based on their initial spherical equivalent (SE): a High-risk group (SE > -0.5 D) and a Myopia group (SE ≤ -0.5 D). Within each of these groups, we further categorized children into Never, Tardily, and Timely groups based on their referral compliance to compare the differences in the occurrence and progression of myopia. Cox proportional models were applied to estimate hazard ratios (HRs) for myopia incidence per person-years of follow-up in High-risk group. Generalized additive models(GAM) was used to calculating the progression for annual spherical equivalent changes in all children.

RESULTS

Of the 5,511 preschool children (mean age, 5.25 years; 52.24% male) who received a referral recommendation, 1,327 (24.08%) sought clinical services at an ophthalmic hospital. After six years of follow-up, 65.53% of children developed myopia. The six-year cumulative incidence of myopia in the Never, Tardily, and Timely groups was 64.76%, 69.31%, and 57.14%, respectively. These percentages corresponded to hazard ratios (HRs) of 1.31 (95% CI, 1.10-1.55) for the Tardily group and 0.55 (95% CI, 0.33-0.93) for the Timely group, compared with the Never group. The HRs were adjusted for age, sex, and SE at study entry. Interestingly, the Timely group showed significantly less SE progression than the other groups (P < 0.001), and SE progression was higher in the High-risk group (-0.33 ± 0.37D/year) than in children with myopia (-0.08 ± 0.55D/year).

CONCLUSION

Timely utilization of ophthalmic clinical services among children aged 4 to 6 years who fail school vision screenings can significantly reduce the incidence of myopia and slow SE progression.

Longitudinal changes in crystalline lens thickness and power in children aged 6-12 years old

OBJECTIVES

To determine the three-year changes in crystalline lens power (LP) and thickness (LT) in children and their associated factors.

METHODS

Schoolchildren aged 6-12 years living in Shahroud, northeast Iran were examined in 2015 and 2018. The Bennett formula was used to calculate LP. Multiple generalized estimating equations (GEE) analysis was used for data analysis.

RESULTS

Among the 8089 examined eyes, the mean LP in Phase 1 and 2, and the three-year change were 21.61 ± 1.47D, 21.00 ± 1.42D, and -0.61 ± 0.52D, respectively. The GEE model showed that negative shifts in LP were less pronounced with increasing age (β = 0.176; p < 0.001), and were also less noticeable in hyperopes compared to emmetropes (β = 0.120; p < 0.001). The changes in LP decreased when outdoor activity increased among urban residents (β = 0.013; p = 0.039), while it increased in rural area (β = -0.020; p = 0.047). Mean three-year change in LT was 0.002 ± 0.13 mm. Female sex and aging by one year increased the LT by 0.022 mm (P < 0.001). However, LT decreased in 6-8-year-olds, while it increased in 10-12-year-old children, both in a linear fashion. The change in LT was less in myopes than in emmetropes (β = -0.018, P-value = 0.010).

CONCLUSION

LP decreases after three years in 6 to 12-year-old children. LT increases slightly after three years in 6 to 12-year-old children. The changes in LP and LT were associated with the refractive errors, place of residence, age and gender and outdoor activity time.

Dynamic changes in ocular shape during human development and its implications for retina fovea formation

The human fovea is known for its distinctive pit-like appearance, which results from the displacement of retinal layers superficial to the photoreceptors cells. The photoreceptors are found at high density within the foveal region but not the surrounding retina. Efforts to elucidate the mechanisms responsible for these unique features have ruled out cell death as an explanation for pit formation and changes in cell proliferation as the cause of increased photoreceptor density. These findings have led to speculation that mechanical forces acting within and on the retina during development underly the formation of foveal architecture. Here we review eye morphogenesis and retinal remodeling in human embryonic development. Our meta-analysis of the literature suggests that fovea formation is a protracted process involving dynamic changes in ocular shape that start early and continue throughout most of human embryonic development. From these observations, we propose a new model for fovea development.

Changes in anisometropia by age in children with hyperopia, myopia, and antimetropia

Anisometropia is a unique condition of both eyes and it is associated with vision problems such as amblyopia and reduced stereoacuity. Previous studies have not reported its change pattern by age and its correlation with the refractive condition of both eyes. This study aims to compare the changes in anisometropia by age in children with hyperopia, myopia, and antimetropia. In total, 156 children were included. Children aged 3-11 years with anisometropia ≥ 1.00 D were followed up for ≥ 1 year with ≥ 2 visits at two medical centers in Taiwan. Refractive errors by cycloplegic autorefractometry, best-corrected visual acuity, eye position, and atropine use were recorded. The children were divided into hyperopic, myopic, and antimetropic groups. The results showed that anisometropia decreased in children aged < 6 years (3.34-2.96 D; P = 0.038) and increased in older children (2.16-2.55 D; P = 0.005). In children aged 3, 4, 5, and 6 years, the mean anisometropia was higher in children with myopia and antimetropia than in those with hyperopia (P = 0.005, 0.002, 0.001, and 0.011, respectively). The differences were not significant in children aged > 6 years (all P > 0.05). The factors associated with changes in anisometropia were age, refractive group, amblyopia, and strabismus. Anisometropia decreased with age in children younger than 6 years, and the changes in anisometropia was found in children with myopia and antimetropia.

Distribution and Characteristics of Ocular Biometric Parameters among a Chinese Population: A Hospital-Based Study

INTRODUCTION

This study aimed to describe the distribution and characteristics of ocular biometric parameters among a large Chinese population.

METHODS

This retrospective cross-sectional study included 146,748 subjects whose ocular biometric parameters were measured at the ophthalmology clinic of West China Hospital, Sichuan University, and recorded in the hospital database. Ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, were recorded. Only monocular data for each subject were analyzed to avoid bias.

RESULTS

Valid data from 85,770 subjects (43,552 females and 42,218 males) aged 3-114 years were included in this study. The mean axial length, mean anterior chamber depth, average corneal keratometry, and mean keratometric astigmatism were 24.61 mm, 3.30 mm, 43.76 D, and 1.19 D, respectively. The stratification of the ocular parameters by age and gender showed significant inter-gender and inter-age differences.

CONCLUSIONS

Analysis of a large population of subjects in western China aged 3-114 years showed that the distribution and characteristics of ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, differed by age and gender. This study is the first to describe ocular biometric parameters in subjects aged > 100 years.

Predicting axial length in patients with Marfan syndrome and ectopia lentis after modified capsular tension ring and intraocular lens implantation

PURPOSE

To predict the growth of axial length (AL) in patients with Marfan syndrome (MFS) and ectopia lentis (EL).

SETTING

Eye and ENT Hospital of Fudan University, Shanghai, China.

DESIGN

Consecutive retrospective case series.

METHODS

Eyes were evaluated that had modified capsular tension ring and intraocular lens (IOL) implantation. The rate of AL growth (RALG) was calculated using AL divided by log10-transformed age. A multivariate linear regression model of RALG was developed after validation.

RESULTS

128 patients with MFS and EL were enrolled with a median follow-up duration of about 3 years. RALG was independent of age between 3 years and 15 years old ( P = .799) and decreased to 0 thereafter ( P = .878). Preoperative AL was associated with RALG in patients under 15 years old ( P = .003). Beta values for the final model of RALG were as below: intercept (-9.794) and preoperative AL (0.664). The postoperative AL was predicted as: postAL = preAL + RALG × log 10 ([postAge + 0.6]/[preAge + 0.6]). The mean prediction error was -0.003 (95% CI, -0.386 to 0.3791) mm and the mean absolute percentage error was 1.93% (95% CI, 0.73% to 3.14%). A Python-based calculator was developed to use the predicted AL in selecting IOL power and setting undercorrection.

CONCLUSIONS

The AL growth of patients with MFS followed a logarithmic pattern and ceased at about age 15. A prediction model of postoperative AL was established for individual MFS patients between 3 and 15 years old, which could potentially optimize the IOL power selection.

Age-Dependent Changes in the Water Content and Optical Power of the In Vivo Mouse Lens Revealed by Multi-Parametric MRI and Optical Modeling

Purpose

The purpose of this study was to utilize in vivo magnetic resonance imaging (MRI) and optical modeling to investigate how changes in water transport, lens curvature, and gradient refractive index (GRIN) alter the power of the mouse lens as a function of age.

Methods

Lenses of male C57BL/6 wild-type mice aged between 3 weeks and 12 months (N = 4 mice per age group) were imaged using a 7T MRI scanner. Measurements of lens shape and the distribution of T2 (water-bound protein ratios) and T1 (free water content) values were extracted from MRI images. T2 values were converted into the refractive index (n) using an age-corrected calibration equation to calculate the GRIN at different ages. GRIN maps and shape parameters were inputted into an optical model to determine ageing effects on lens power and spherical aberration.

Results

The mouse lens showed two growth phases. From 3 weeks to 3 months, T2 decreased, GRIN increased, and T1 decreased. This was accompanied by increased lens thickness, volume, and surface radii of curvatures. The refractive power of the lens also increased significantly, and a negative spherical aberration was developed and maintained. Between 6 and 12 months of age, all physiological, geometrical, and optical parameters remained constant, although the lens continued to grow.

Conclusions

In the first 3 months, the mouse lens power increased as a result of changes in shape and in the GRIN, the latter driven by the decreased water content of the lens nucleus. Further research into the mechanisms regulating this decrease in mouse lens water could improve our understanding of how lens power changes during emmetropization in the developing human lens.

Comparing the effects of highly aspherical lenslets versus defocus incorporated multiple segment spectacle lenses on myopia control

To compare spectacle lenses with highly aspherical lenslets (HAL) versus defocus incorporated multiple segments (DIMS) on myopia progression control in 1 year. This retrospective cohort study involved data from children prescribed HAL or DIMS spectacle lenses in Guangzhou Aier Eye Hospital, China. To address the discrepancy that some children followed up at less than or more than 1 year, the standardized 1-year spherical equivalent refraction (SER) and axial length (AL) changes from baseline were calculated. The mean differences in the changes between the two groups were compared with linear multivariate regression models. Age, sex, baseline SER/AL, and treatment were included in the models. A total of 257 children who qualified for the inclusion criteria were included for the analyses (193 in the HAL group and 64 in the DIMS group). After controlling baseline variates, the adjusted mean (standard error, SE) of the standardized 1-year changes in SER for HAL and DIMS spectacle lens users were - 0.34 (0.04) D and - 0.63 (0.07) D, respectively. HAL spectacle lenses reduced myopia progression by 0.29 D (95% confidence interval [CI] 0.13 to 0.44 D) at 1 year compared to DIMS lenses. Accordingly, the adjusted mean (SE) ALs increased by 0.17 (0.02) and 0.28 (0.04) mm for children wearing HAL lenses and DIMS lenses, respectively. HAL users had 0.11 mm less AL elongation (95% CI - 0.20 to - 0.02 mm) than DIMS users. Age at baseline was significantly associated with AL elongation. Chinese children wearing spectacle lenses designed with HAL had less myopia progression and axial elongation than those wearing spectacle lenses designed with DIMS.

A Proposed Method for Estimating Refractive Error in Primary School Children

Background This study aimed to evaluate consecutive measurements of biometric parameters, age, and refraction in a cohort of Turkish primary school-age children and to assess the correlation between biometric changes and refraction. Methodology The study population was seven and 12-year-old children (n = 197). The retrieved data consisted of three consecutive measurements with a one-year interval for each subject. Data from one eye (right) were used. Age, gender, body mass index, spherical equivalent (SE), axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), keratometry (K), and lens thickness (LT) were analyzed. The onset and final data were retrieved from the database in 2013 and 2016, respectively. Statistically, logistic and Cox regression models of all parameters were analyzed, and the significance level was set at 5%. Results The median of the onset and final SE values were -0.00 D (0.00-0.00) and 0.50 D (0.19-1.00), respectively. The onset AL (hazard ratio (HR) = 5.82, 95% confidence interval (CI) = 3.45-9.76, β = 1.76, p < 0.001), K_mean (HR = 2.28, 95% CI = 1.67-3.11, β = 0.82, p < 0.001), and age (HR = 0.77, 95% CI = 0.59-0.99, β = -0.26, p = 0.046) were correlated with myopia progression. To calculate the estimated SE, the onset data were included in the logistic regression model. The onset SE (β = 0.916, p < 0.001), AL (β = -0.451, p < 0.001), ACD (β = 0.430, p = 0.005), and K (β = -0.172, p < 0.001) were correlated with the mean final SE. An equation was generated using the regression model analysis. Conclusions The onset parameters of SE, AL, ACD, and K were confirmed to correlate with the final SE values in the proposed model. To confirm the use of the refractive calculator, a cross-validation analysis is needed to estimate three-year subsequent refractive error among seven and 12-year-old children.

Prevalence of myopia and associated risk factors among key schools in Xi'an, China

BACKGROUND

The aim of this study is to investigate the prevalence of myopia and high myopia and the associated risk factors in key schools in Xi'an, China.

METHODS

This cross-sectional study started in September 2021 and was conducted for one month. A total of 11,011 students from 10 key primary schools, five key junior high schools and five key high schools in Xi'an were randomly selected to undergo visual acuity measurement and non-cycloplegic autorefraction. The questionnaire was completed by the students and their parents together.

RESULTS

The prevalence of myopia and high myopia in key schools were 75.7% and 9.7%, respectively. The prevalence of myopia and high myopia rose significantly as grade or age increased (all P < 0.001), and the prevalence of myopia and high myopia in females was higher than that in males (P < 0.001, P < 0.5). According to the multivariable logistic regression analysis, older age (OR=1.42), female compared with male (OR=1.43), having one myopic parent (OR=1.64), having two myopic parent (OR=2.30) and often taking extracurricular tuition (OR=1.35) were more likely to be associated with develop myopia (P < 0.001). Older age (OR=1.39), having one myopic parent (OR=2.29), having two myopic parent (OR= 3.69), and often taking extracurricular tuition (OR=1.48) were more likely to be associated with high myopia (P < 0.001).

CONCLUSIONS

The overall rate of myopia and high myopia in key schools in Xi'an, China, is extremely high. Myopia and high myopia are associated with increasing age, parents' myopia, few outdoor exercises, and extracurricular tuition. Myopia is also associated with female and not having the habit of "one punch, one foot, one inch (when reading and writing, 10 cm from the chest to the table, 33 cm from the eye to the book and 3.3 cm from the tip of the pen to the finger)".

Myopia and axial length in school-aged children before, during, and after the COVID-19 lockdown-A population-based study

Background

Myopic shift had been observed during the COVID-19 lockdown in young school children. It remains unknown whether myopic shift is accompanied with increase in axial length. We aimed to evaluate the impact of the COVID-19 lockdown on myopia and axial length of school children in China by comparing them before, during and after the lockdown.

Methods

In this population-based cross-sectional study, school-based myopia screenings were conducted in the Fall of 2019, 2020, and 2021 (representing before, during and after COVID-19 lockdown respectively) in Chengdu, China. Myopia screenings were performed on 83,132 students aged 6 to 12 years. Non-cycloplegic refractive error was examined using NIDEK auto-refractor (ARK-510A; NIDEK Corp., Tokyo, Japan) and axial length was measured using AL-Scan (NIDEK Corp., Tokyo, Japan). Spherical equivalent (SER, calculated as sphere+ 0.5^*cylinder), prevalence of myopia (SER ≤ -0.50 D), and axial length were compared across 3 years stratified by age.

Results

Myopia prevalence rate was 45.0% (95% CI: 44.6-45.5%) in 2019, 48.7% (95% CI: 48.3-49.1%) in 2020, and 47.5% (95% CI: 47.1-47.9%) in 2021 (p < 0.001). The mean non-cycloplegic SER (SD) was -0.70 (1.39) D, -0.78 (1.44) D, and -0.78 (1.47) D respectively (p < 0.001). The mean (SD) axial length was 23.41 (1.01) mm, 23.45 (1.03) mm, and 23.46 (1.03) mm across 3 years respectively (p < 0.001). From the multivariable models, the risk ratio (RR) of myopia was 1.07 (95% CI: 1.06-1.08) times, the SER was 0.05 D (95% CI: 0.04 D to 0.06 D) more myopic and the mean axial length increased by 0.01 mm (95% CI: 0.01 mm to 0.02 mm) in 2020 compared to 2019. In 2021, the risk ratio (RR) of myopia was 1.05 (95% CI: 1.04-1.06), the mean SER was 0.06 D (95% CI: 0.05 D to 0.07 D) more myopic, and the mean axial length increased by 0.03 mm (95% CI: 0.02 mm to 0.04 mm) compared to 2019.

Conclusions

The COVID-19 lockdown had significant impact on myopia development and axial length, and these impacts remained 1 year after the lockdown. Further longitudinal studies following-up with these students are needed to help understand the long-term effects of COVID-19 lockdown on myopia.

Objectively measuring anterior segment alterations in the eyes of mucopolysaccharidoses: Its utility in early diagnosis of glaucoma

Purpose

Our study aimed to evaluate the utility of the anterior segment morphometry for objectively assessing anterior segment architectural changes of corneal clouding in the mucopolysaccharidoses (MPS) cohort and to investigate whether these measurements correlate with the slit-lamp findings on the cornea and early diagnosis of glaucoma.

Methods

This retrospective study involved 70 eyes of 35 children with cloudy cornea due to MPS variants. Anterior segment architectural alterations were measured using anterior segment imaging and biometry in MPS children and compared with controls.

Results

Mean age of the cohort at the time of assessment was 7.9 ± 4.5 years. Males constituted two-thirds of the cohort. Variants of MPS with cloudy cornea were as follows: Type I (62%), Type IV (11%), and Type VI (22%). Morphometric measurements were available in 22 eyes of 11 MPS children and an age-matched healthy control group. There were significant differences between MPS cohort and controls in refraction in Diopters (5.03 ± 0.39 and 0.01 ± 0.04; P < 0.0001), axial length (AXL) in mm (21.39 ± 0.28 and 23.04 ± 0.28; P = 0.0002), average keratometry in Diopters (40.67 ± 0.44 and 42.83 ± 0.44; P < 0.0001), anterior chamber depth (ACD) in mm (2.92 ± 0.07 and 3.65 ± 0.07; P < 0.0001), and intraocular pressure (IOP) in mmHg (25.2 ± 2.0 and 14.1 ± 2.3; P = 0.0003). Secondary glaucoma was observed in 28% of the MPS cohort.

Conclusion

The anterior segment morphometry in the cloudy cornea due to MPS provides an objective measurement of anterior segment architectural changes, thus diagnosing early-onset secondary glaucoma. These findings highlight that cloudy cornea due to MPS variants merits close monitoring throughout life.

Beijing Pinggu Childhood Eye Study: The Baseline Refractive Characteristics in 6- to 12-Year-Old Chinese Primary School Students

Purpose

To report the design and baseline data of a 3-year cohort study in Beijing Pinggu District primary school students in China after COVID-19.

Methods

Noncycloplegic and cycloplegic spherical equivalent refraction (SER) were measured, ocular biometry, including the axial length (AL), anterior chamber depth (ACD) and corneal power (CP), were collected before cycloplegia. Corneal radius (CR), AL-to-CR ratio, and lens power (LP) were calculated.

Results

Among the 4,806 (89.1%) eligible students (51.5% male), the prevalence of emmetropia, myopia, mild hyperopia, and mild-to-high hyperopia was 12.8, 30.8, 53.0, and 3.3% after cycloplegia, respectively. Myopia increased from 2.5% in 6- to 71.6% in 12-year-old students, with 9- and 10-year-olds showing the most prominent increases. The median of cycloplegic SER was 0.50 (IQR = 1.63), and the noncycloplegic SER was −0.38 D (IQR = 1.50), which is more negative than the cycloplegic refraction. The mean AL increased with age, from 22.46 ± 0.70 mm to 24.26 ± 1.07 mm. The ACD increased from 3.38 ± 0.28 mm to 3.70 ± 0.30 mm, and the AL-to-CR ratio increased from 2.91 ± 0.08 to 3.12 ± 0.13 between 6- and 12-year-old students. AL, CR and LP explained the SER variance with R² of 86.4% after adjusting the age and gender.

Conclusions and Relevance

The myopia prevalence since emergence of COVID-19 rapidly increased from 6- to 12-year primary school Chinese children, especially after 7 years of age. The non-cycloplegia SER overestimated the prevalence of myopia, and the cycloplegic SER is a more accurate and reliable method to assess the prevalence of refractive status.

Predictability of 6 Intraocular Lens Power Calculation Formulas in People With Very High Myopia

Purpose

To investigate the accuracy of 6 intraocular lens (IOL) power calculation formulas in predicting refractive outcomes in extremely long eyes.

Setting

Department of Ophthalmology, Far Eastern Memorial Hospital, Taiwan.

Design

Retrospective comparative study.

Methods

In this retrospective single-center study, we reviewed 70 eyes of 70 patients with axial length (AL) ≥ 28 mm who had received an uneventful 2.2 mm corneal wound phacoemulsification and in-the-bag IOL placement. The actual postoperative refractive results were compared to the predicted refraction calculated with 6 formulas (Haigis, Hoffer Q, Holladay 1, SRK/T, T2, Barrett Universal II formulas) using IOLMaster 500 as optical biometry in the User Group for Laser Interference Biometry (ULIB) constants.

Results

Overall, the Haigis and Barrett formulas achieved the lowest level of mean prediction error (PE) and median absolute error (MedAE). Hoffer Q, Holladay 1, SRK/T, and T2 had hyperopic prediction errors (p < 0.05). The Hoffer Q and Holladay 1 had significantly more MedAE between the 6 formulas. After the mean PE was zeroed out, the MedAE had no significant difference between each group. The absolute error tends to be larger in patients with longer AL. The absolute errors were 30.0–37.1% and 60.0–64.3% within 1.0 D of all patients compared to predicted refraction calculated using various formulas.

Conclusion

The Haigis and Barrett Universal II formulas had a better success rate in predicting IOL power in high myopic eyes with AL longer than 28 mm using the ULIB constant in this study. The postoperative refractive results were inferior to the benchmark standards, which indicated that the precision of IOL power calculation in patients with high myopia still required improvement.

Optical biometry and influence of media opacity due to cataract on development of axial length in NorthEast Indian paediatric patients- A prospective study

AIM

To study the influence of media opacity due to cataract on the development of axial length in paediatric patients from North-East India, using optical biometry.

METHOD

This is a prospective, observational study, including consecutive patients attending the paediatric ophthalmology clinic, over a period of 1 year. Patients with other ocular and systemic diseases, unfit for optical biometry measurements due to dense cataract, nystagmus and strabismus were excluded and rest divided into three groups after proper age matching - 1. Group A (Bilateral cataract) 2. Group B (Unilateral cataract) 3. Group C (Bilateral normal). The axial length of the various groups was analysed using independent sample test (for bilateral cataract group) and paired t-test (for unilateral cataract group). Linear regression analysis between age and axial length was done.

RESULTS

A total of 177 patients were included.80 cases in Group A (bilateral cataract), 18 cases in Group B (unilateral cataract) and 79 in Group C (bilateral normal) The mean age of the patients in all the groups was 8.88 ± 3.51 years (range: 1-17 years). The bivariate analysis and simple linear regression revealed a statistically significant correlation between age and AL in case of cataractous eyes. (Pearson's coefficient: 0.341, p < 0.001). The mean AL was significantly longer (p = 0.013) in the cataractous eyes (mean = 23.38 ± 2.08 mm) of Group A(bilateral cataract) in the 7-12 years age group as compared to the bilaterally normal eyes (mean AL = 22.57 ± 0.70 mm) of patients in the same age group in Group C. The mean AL of cataractous eyes in group B (unilateral cataract) (mean = 22.46 ± 1.73 mm) as compared to the fellow normal eyes, (mean = 21.87 ± 0.97 mm) was not statistically significant.

CONCLUSION

Cataractous eyes have an abnormal axial length development. The influence of media opacity due to cataract on development of axial length in paediatric eyes in the North-East Indian population is variable, in line with global data on the same. Although there is some influence of media opacity, the exact nature is not clearly understood and may have a crucial interaction with genetic and other environmental factors. Genetic testing integrated with biometric analysis is recommended for further understanding of the ocular growth and development.

Distribution of Ocular Anterior and Posterior Segment Lengths Among a Cataract Surgical Population in Shanghai

Purpose: To investigate the distributions of the ocular anterior and posterior segment lengths among a cataract surgical population in Shanghai. Design: Cross-sectional study. Methods: Ocular biometric parameters of 23,462 eyes of 23,462 cataract surgery candidates were reviewed. Axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were obtained using IOL Master. Anterior segment length (ASL = ACD + LT), posterior segment length (PSL = AL - ASL) and the ratio of ASL to PSL (ASL/PSL) were calculated. Results: The mean ASL was 7.58 ± 0.39 mm, the mean PSL was 17.12 ± 2.64 mm. As the age grew, the ASL increased, and PSL increased firstly then decreased. Male subjects tended to have significantly longer ASL and shorter PSL than female subjects. With the increasing AL, the ASL was firstly decreased to trough at 20-22 mm AL group, then increased gradually, while the PSL increased rapidly. The ASL correlated positively with AL in normal, moderate and highly myopic eyes, negatively in short eyes. The PSL correlated positively with AL across the entire study population. The ASL/PSL was not constant in the eyes with different AL but had a relatively steep downward trend with the increasing AL in the short eyes, then decreased smoothly in normal, moderate and highly myopic eyes. Conclusions: In Chinese cataractous eyes, longer ASL and shorter PSL were associated with elder age and male gender. The change of ASL over AL was not linear, and the ASL was smallest in the eyes with AL of 20-22 mm. The elongation of the eyeball was mainly due to the extension of the posterior segment.

Age-Dependent Changes in Total and Free Water Content of In Vivo Human Lenses Measured by Magnetic Resonance Imaging

Purpose

To use magnetic resonance imaging (MRI) to measure age-dependent changes in total and free water in human lenses in vivo.

Methods

Sixty-four healthy adults aged 18 to 86 years were recruited, fitted with a 32-channel head receiver coil, and placed in a 3 Tesla clinical MR scanner. Scans of the crystalline lens were obtained using a volumetric interpolated breath-hold examination sequence with dual flip angles, which were corrected for field inhomogeneity post-acquisition using a B1-map obtained using a turbo-FLASH sequence. The spatial distribution and content of corrected total (ρlens) and free (T1) water along the lens optical axis were extracted using custom-written code.

Results

Lens total water distribution and content did not change with age (all P > 0.05). In contrast to total water, a gradient in free water content that was highest in the periphery relative to the center was present in lenses across all ages. However, this initially parabolic free water gradient gradually developed an enhanced central plateau, as indicated by increasing profile shape parameter values (anterior: 0.067/y, P = 0.004; posterior: 0.050/y, P = 0.020) and central free water content (1.932 ms/y, P = 0.022) with age.

Conclusions

MRI can obtain repeatable total and free water measurements of in vivo human lenses. The observation that the lens steady-state free, but not total, water gradient is abolished with age raises the possibility that alterations in protein-water interactions are an underlying cause of the degradation in lens optics and overall vision observed with aging.

Prediction of premyopia and myopia in Chinese preschool children: a longitudinal cohort

BACKGROUNDS

Myopia has become a global public health problem. Children with early onset of myopia are at particular risk of complications associated with myopia. Younger children and children with greater initial myopic refractive errors are at a greater risk of myopia progression. Therefore, it is essential to identify subjects at high risk of developing myopia to facilitate myopia prevention in the early stage, especially during the preschool period. The purpose of this study was to determine whether premyopia and myopia in preschool children can be predicted by easily obtainable parameters.

METHODS

Data was collected in a population-based cohort. Comprehensive examinations included height, weight, refraction, axial length (AL), and corneal radius of curvature (CR), with a follow-up of 2 years. Parental myopia history was obtained from a questionnaire. Myopia was defined as spherical equivalent (SE) ≤ - 0.50 D. Premyopia was defined as - 0.50 D < SE ≤ + 0.75 D. Multivariate linear regression models were fitted to determine the associations between these parameters at baseline and future SE. To predict premyopia and myopia, Cox proportional hazard regression analysis coupled with a nomogram was used.

RESULTS

A total of 830 children (433 boys and 397 girls) were included (40.83 ± 3.43 months old at baseline). A significantly negative relationship was observed in the multivariate analysis between baseline AL, AL/CR, two myopic parents, and the future SE after adjusting for age and gender (coefficient = - 0.291, coefficient = - 5.791, coefficient = - 0.273, respectively, both p <  0.001). Higher baseline AL, AL/CR (hazard ratio (HR) = 4.916, HR = 2.979, respectively, comparing the top quartile with the bottom quartile, both p <  0.001) and two myopic parents (HR = 1.756, compared to no myopic parents, p = 0.001) were associated with a higher risk of future onset of premyopia. From the nomogram, AL/CR was found to have the most enormous effect on survival. Different baseline AL and AL/CR values (both Log Rank p <  0.001) had different survival curves.

CONCLUSIONS

AL and AL/CR could be used as obtainable indicators for identifying subjects at high risk of developing premyopia and myopia in young preschool children.

The cause of myopia development and progression: Theory, evidence, and treatment

I review the key findings and our current knowledge of the cause of myopia, making the connections among the reliable observations on myopia development and theory to arrive at a summary of what we know about myopia, the proposed prevailing theory, and applicable action. Myopia is reaching epidemic proportions. It is estimated that half of the world's population will be myopic by 2050 unless new strategies to fight myopia are developed. Our high-level mathematical description of myopia is translated into clinical applications involving effective treatment and prevention. A regulating mechanism controlling the refraction of the eye is intimately related to myopia. The approach at hand is to review our knowledge about emmetropization, connecting myopia and emmetropization feedback theory to unveil the cause of myopia. Many observations discussed here test the validity of feedback theory positively. The cause of human myopia fits perfectly with the idea that emmetropization, in particular its feedback theory implementation, is the controlling mechanism behind myopia. They include near work, atropine, lenses, defocus, and outdoor versus indoor activities. The key findings in myopia research point the same way: myopia is the result of corrective lenses interfering with emmetropization. We have enough knowledge to answer the question of whether myopia can be reversed or prevented. There is no need to have mathematical skills to apply theory to real cases. It is enough to know the predictions of the feedback theory of emmetropization.

The associations of high academic performance with childhood ametropia prevalence and myopia development in China

Background

To assess associations of high academic performance with ametropia prevalence and myopia development in Chinese schoolchildren.

Methods

This multicohort observational study was performed in Guangdong, China. We first performed a cross-sectional cohort analysis of students in grades 1 to 9 from Yangjiang to evaluate the relationship between academic performance and refractive status on a yearly basis. We also performed longitudinal analyses of students in Shenzhen to evaluate the trend of academic performance with refractive changes over a period of 33 months. All refractive statuses were measured using noncycloplegic autorefractors.

Results

A total of 32,360 children with or without myopia were recruited in this study (mean age 10.08 years, 18,360 males and 14,000 females). Cross-sectional cohort analyses in Yangjiang showed that the prevalence of hyperopia was associated with lower academic scores in grade one, the year students entered primary school (β=-0.04, P=0.01), whereas the prevalence of myopia was associated with higher academic scores in grade six and grade eight, the years in which students were about to take entrance examinations for junior high school or senior high school (β=0.020, P=0.038; β=0.041, P=0.002). Longitudinal analysis showed that in Shenzhen, faster myopia development was associated with better scores in all grades even after adjustments for BMI, outdoor activity time, screen time, reading time, and parental myopia (grade two at baseline: β=0.026, P<0.001; grade three at baseline: β=0.036, P=0.001; grade four at baseline: β=0.014, P<0.001; grade five at baseline: β=0.039, P<0.001; grade six at baseline: β=0.04, P<0.001).

Conclusions

Refractive errors correlated significantly with academic performance among schoolchildren in China. Children with high academic performance were more likely to have faster myopia development.

Feasibility and repeatability of ocular biometry measured with Lenstar LS 900 in a large group of children and adolescents

PURPOSE

To evaluate the feasibility and repeatability of Lenstar LS 900 biometry measurements in a paediatric population.

METHODS

Children were examined as part of the LIFE Child Study (Leipzig Research Centre for Civilization Diseases), a population-based study in Leipzig, Germany. Altogether, 1917 children, aged from 3.5 to 17.5 years, were assessed with the Haag Streit Lenstar LS 900. Three consecutive measurements of the right eye were analysed for axial length, central corneal thickness, anterior chamber depth, aqueous depth, lens thickness and flat and steep corneal radii. The number of successful measurements and repeatability were evaluated for each parameter and three age bands (3.5 to 6.5 years, 6.5 to 10.5 years and 10.5 to 17.5 years).

RESULTS

Best measurement feasibility was found for axial length and central corneal thickness (91% to 100%), followed by flat and steep corneal radii (86% to 100%), anterior chamber and aqueous depth (76% to 92%) and lens thickness (50% to 81%), with higher numbers for older children. Repeatability values (in mm) were: axial length 0.025 to 0.035; central corneal thickness 0.003 to 0.027; aqueous depth 0.024 to 0.058; anterior chamber 0.024 to 0.054; lens thickness 0.034 to 0.067. An overall trend showed better repeatability for older children, especially for central corneal thickness, aqueous depth and lens thickness.

CONCLUSIONS

For ocular biometry in the paediatric population, axial length, central corneal thickness, flat and steep corneal radii can be measured very reliably even in children from 4 years old onward using the Lenstar LS 900. Lens thickness can be quantified in a limited number of younger children. Repeatability was high for all variables investigated. Repeatability improved with age, reaching adult values in the adolescent age band. Established repeatability limits can be applied in future studies as a quality parameter.

Eyes of Aniso-Axial Length Individuals Share Generally Similar Corneal Biometrics with Normal Eyes in Cataract Population

AIMS

To determine the characteristics of corneal biometrics in eyes from aniso-axial length cataract patients compared with eyes from non-aniso-axial length individuals.

METHODS

This is a retrospective case series. Cataract patients with preoperative binocular measurements were recruited. A binocular axial difference of ≥1 mm was considered to indicate aniso-axial length. The anterior segmental biometrics were measured using Pentacam HR (Oculus, Wetzlar, Germany) and IOLMaster 500 (Carl Zeiss Meditec, Jena, Germany). Comparisons of biometrics were made among 4 eye conditions: the longer eyes from aniso-axial length patients, the shorter eyes from aniso-axial length patients, the longer eyes from non-aniso-axial length patients, and the shorter eyes from non-aniso-axial length patients. The aniso-axial length eyes were also stratified into 8 subgroups with axial length (AL) increments of 1 mm, and the biometrics of the subgroups were compared.

RESULTS

There was smaller anterior corneal astigmatism in the shorter aniso-axial length group than those in the longer aniso-axial length group (1.01 ± 0.70 D vs 1.12 ± 0.76 D, P=0.031). The longer aniso-axial length eyes had greater anterior corneal steep curvature (44.13 ± 1.69 D vs 43.87 ± 1.69 D, P=0.009) and anterior corneal astigmatism (1.12 ± 0.76 D vs 1.02 ± 0.69 D, P=0.023) compared with longer non-aniso-axial length subjects. Other corneal biometrics were similar between the aniso-axial length eyes and the non-aniso-axial length eyes. In the longer aniso-axial length group, the posterior corneal aberrations of eyes in the ≥5 mm subgroups were greater than those in the <5 mm subgroups (0.879 ± 0.183 μm vs 0.768 ± 0.178 μm for total aberrations, P < 0.001; 0.228 ± 0.086 μm vs 0.196 ± 0.043 μm for high-order aberrations, P=0.036; 0.847 ± 0.173 μm vs 0.741 ± 0.179 μm for low-order aberrations, P=0.001).

CONCLUSION

Eyes of aniso-axial length individuals share generally similar corneal biometrics with normal eyes in cataract population. Anterior corneal astigmatism of the longer eyes from the aniso-axial length cataract patients was higher than that of the longer eyes from the non-aniso-axial length individuals. Total posterior corneal aberrations of the longer aniso-axial length eyes increased when the binocular axial difference was over 5 mm.

Adult onset unilateral high myopia in a female patient: A case report

Purpose

We report a rare case of unilateral progressive adult-onset myopia in a healthy 27 year old female patient.

Observations

The patient presented to our clinic in 2014 with gradual decrease in vision in the right eye since one and a half years. Her uncorrected visual acuity (UCVA) in the right eye was 0.05, improving to 1.0 with −2.25 Diopter Sphere (DS). The left eye uncorrected visual acuity was 1.0 partial improving to 1.0 with −0.50 Diopter Cylinder (DC) at 10°. The myopia in her right eye continued to increase steadily until her last detailed ophthalmic examination in November 2018, at the age of 31 years, showed a refractive error of −6.75 Diopter Sphere with −0.5 Diopter Cylinder at 170°. Ocular biometry readings showed an axial length (AL) of 25.79mm in the right eye compared to 25.05mm in 2015. The ocular examination of both eyes including clinical examination of anterior and posterior segment, corneal topography, lens densitometry, ultrasound B scan all were within normal limits. Over the last two years she has gradually developed moderate constant esotropia in the right eye, currently +30 Prism Diopters. A short visit to the clinic in December 2019, showed a refraction of −6.75DS with −0.5DC at 170° in the right eye and −0.50DC at 10° in the left eye.

Conclusions and importance

The abrupt onset of myopia in one eye in a healthy individual in this case, the degree of myopia, the nature and rate of progression, absence of risk factors, and otherwise normal ocular examination except for progressive increase in axial length is unusual. Our case brings us to conjecture the role of powerful local factors in the intrinsic regulation of eyeball growth going askew. We believe more and more reporting of myopia cases deviating from natural history and their study might provide clues in a new direction about myopia pathogenesis and our understanding and tackling of one of the oldest eye disease with an ever increasing prevalence.

Refractive Error and Retinopathy Outcomes in Type 1 Diabetes: The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study

PURPOSE

To determine the relationship between refractive error and diabetic retinopathy (DR).

DESIGN

Clinical trial.

PARTICIPANTS

Type I diabetes individuals with serial refractive error and DR stage measurements over 30 years in the Diabetes Control and Complications Trial (DCCT) and Epidemiology of Diabetes Interventions and Complications (EDIC) follow-up study.

METHODS

Stage of DR was measured every 6 months from standard fundus photographs, and refractive error was measured annually during the 6.5 years of DCCT; then, both were staggered every fourth year during EDIC with the full cohort measured at EDIC years 4 and 10. Outcomes of DR were 2- or 3-step progression, presence of proliferative DR (PDR), clinically significant macular edema (CSME), diabetic macular edema (DME), or ocular surgery. Myopia, emmetropia, and hyperopia were defined as a spherical equivalent of ≤-0.5, >-0.5 and <0.5, and ≥0.5, respectively.

MAIN OUTCOME MEASURES

For each outcome separately, Cox proportional hazard (PH) models assessed the association between the refractive error status and the subsequent risk of that outcome, both without and with adjustment for potential risk factors.

RESULTS

Hyperopia was associated with a higher risk of 2-step progression (hazard ratio [HR], 1.29; 95% confidence interval [CI], 1.05-1.59), 3-step progression (HR, 1.35; 95% CI, 1.05-1.73), and PDR (HR, 1.40; 95% CI, 1.02-1.92) compared with emmetropia in unadjusted models. These associations remained significant after adjustment for DCCT treatment group, cohort, age, sex, smoking, duration of diabetes, systolic and diastolic blood pressures, pulse, low-density lipoprotein, high-density lipoprotein, triglycerides, albumin excretion rate, and DCCT/EDIC mean updated hemoglobin A1c (HbA1c) (2-step progression: HR, 1.28; 95% CI, 1.03-1.58; 3-step progression: HR, 1.30; 95% CI, 1.00-1.68; PDR: HR, 1.38; 95% CI, 1.00-1.90). Myopia was not associated with any of the 5 DR outcomes in the unadjusted models and only marginally associated with 2-step progression (HR, 1.11; 95% CI, 1.00-1.24) in the adjusted models.

CONCLUSIONS

Myopia is not associated with DR progression risk. Hyperopia is an independent risk factor for 2-step and 3-step DR progression and PDR.

Using the Lens Paradox to Optimize an In Vivo MRI-Based Optical Model of the Aging Human Crystalline Lens

Purpose

To optimize our in vivo magnetic resonance imaging (MRI)-based optical model of the human crystalline lens, developed with a small group of young adults, for a larger cohort spanning a wider age range.

Methods

Subjective refraction and ocular biometry were measured in 57 healthy adults ages 18 to 86 years who were then scanned using 3T clinical magnetic resonance imaging (MRI) to obtain lens gradient of refractive index (GRIN) and geometry measurements. These parameters were combined with ocular biometric measurements to construct individualized Zemax eye models from which ocular refractive errors and lens powers were determined. Models were optimized by adding an age-dependent factor to the transverse relaxation time (T₂)-refractive index (n) calibration to match model-calculated refractive errors with subjective refractions.

Results

In our subject cohort, subjective refraction shifted toward hyperopia by 0.029 diopter/year as the lens grew larger and developed flatter GRINs with advancing age. Without model optimization, lens powers did not reproduce this clinically observed decrease, the so-called lens paradox, instead increasing by 0.055 diopter/year. However, modifying the T₂-n calibration by including an age-dependent factor reproduced the decrease in lens power associated with the lens paradox.

Conclusions

After accounting for age-related changes in lens physiology in the T₂-n calibration, our model was capable of accurately measuring in vivo lens power across a wide age range. This study highlights the need for a better understanding of how age-dependent changes to the GRIN impact the refractive properties of the lens.

Translational Relevance

MRI is applied clinically to calculate the effect of age-related refractive index changes in the lens paradox.

Puberty could regulate the effects of outdoor time on refractive development in Chinese children and adolescents

Aim

To explore the impact of puberty on refractive development and its interaction with outdoor time in children and adolescents.

Methods

In this 2-year observational study, students aged 7–13 years were selected with cluster sampling. All participants underwent cycloplegic refraction and axial length measurements once every year. Information of related factors was acquired through proper questionnaire or inquiry. The level of testosterone/estradiol was detected from the saliva of the subjects using the ELISA kit. Multiple linear regression and generalised estimating equation (GEE) were used to analyse the relationship among puberty, outdoor activities and refractive indicators.

Results

A total of 776 children and adolescents were included, with an average baseline age of 9.64±1.54 years and 53.6% boys. There were 350 myopes (55.2% of the 634 cyclopleged subjects) at baseline. There was a significant difference in the mean axial length changes and outdoor time among different puberty groups (for axial length: p=0.017, for outdoor time: p=0.015). Myopic parents, less outdoor time and more changes in estradiol were associated with greater changes in axial length and spherical equivalent (SE) (axial length changes: parental myopia β=0.230, outdoor time β=−0.250, changes in estradiol β=0.261; SE changes: parental myopia β=−0.267, outdoor time β=0.256, changes in estradiol β=−0.297). In the GEE model, the interaction between outdoor time and puberty was significantly associated with axial length (p=0.024, β=1.199).

Conclusions

This study implies puberty may play a regulating role on the relationship between outdoor time and refractive development among Chinese children and adolescents, which provides clues for in-depth mechanism interpretation and efficient intervention strategies.

Characteristics of Corneal Biomechanics in Chinese Preschool Children With Different Refractive Status

PURPOSE

To investigate the characteristics of corneal biomechanics in Chinese preschool children with different refractive status.

METHODS

Study participants were 108 Chinese children (216 eyes) aged 4 to 6 years with a spherical equivalent refraction between -9.00 and +9.00 diopters (D). Cycloplegic refraction was measured using an autorefractor, axial length using an IOL Master (Zeiss, Oberkochen, Germany), and corneal biomechanical metrics and corneal power using an ultra-high-speed camera (Corvis ST; Oculus, Wetzlar, Germany) and Pentacam (Oculus; Menlo Park, CA). Differences in corneal biometry and biomechanical characteristics among myopia, emmetropia, and hyperopia eyes were analyzed by SPSS 17.0.

RESULTS

The spherical equivalent refraction was significantly positively correlated with the stiffness parameter at the first applanation (SP-A1, r = 0.22, P < 0.01) and corneal velocity at the second applanation (A2 velocity, r = 0.25, P < 0.001), whereas it was negatively correlated with the peak distance (r = -0.32, P < 0.001) and deformation amplitude ratio (DA ratio, r = -0.34, P < 0.001). In the hyperopia, emmetropia, and myopia groups, the SP-A1 successively decreased (108.70 ± 22.93 vs. 100.50 ± 18.98 vs. 97.97 ± 18.91, P < 0.01), whereas the peak distance progressively increased (4.39 ± 0.32 vs. 4.56 ± 0.30 vs. 4.63 ± 0.34 mm, P < 0.001). In the same order of groups, an increasing trend was found for the axial length (21.11 ± 0.76 vs. 22.39 ± 0.72 vs. 24.09 ± 1.37 mm, P < 0.001), central anterior chamber depth (CACD, 3.04 ± 0.41 vs. 3.21 ± 0.33 vs. 3.37 ± 0.40 mm, P < 0.001) and flat meridian keratometry (K1, 41.92 ± 1.59 vs. 42.73 ± 1.39 vs. 42.98 ± 1.60 D, P < 0.001). Central corneal thickness significantly decreased in the same order of groups (565.46 ± 33.22 vs. 551.97 ± 24.66 vs. 543.36 ± 37.74 µm, P < 0.001).

CONCLUSIONS

Corneal stiffness is reduced in myopia and increased in hyperopia compared with emmetropia in children aged 4 to 6 years. Corneal biometry and biomechanical characteristics in preschool children seem to depend on refractive status.

Growth in foetal life, infancy, and early childhood and the association with ocular biometry

PURPOSE

Ocular biometry varies within groups of emmetropic, hyperopic or myopic children. The aim of this study was to quantify the effect of foetal and infant growth on ocular biometry in early childhood, to determine the most important period for this association, and to examine genetic overlap with height and birth weight.

METHODS

5931 children (50.1% girls) from a population-based prospective birth cohort study underwent intra-uterine and infant growth measurements at second and third trimester, and from birth to 72 months. An ophthalmic examination including axial length (mm) and corneal radius of curvature (mm) was performed at 6 years of age. The associations between prenatal and postnatal growth variables and axial length and corneal radius of curvature were assessed with conditional linear regression analyses. Weighted genetic risk scores for birth weight and height were calculated and causality was tested with Mendelian randomisation.

RESULTS

Weight and length from mid-pregnancy to 2 years of age were most important prognostic factors for axial length and corneal radius of curvature at age 4.9-9 years (mean 6.2 years S.D. 0.5). For height (Standard deviation score), the association with axial length and corneal radius of curvature was highest for the measurement at 12 months (β 0.171 p < 0.001 and 0.070 p < 0.001). The genetic height and birth weight risk scores were both significantly associated with ocular biometry.

CONCLUSIONS

Larger neonates had longer axial length and greater corneal radius of curvature. Growth during pregnancy and 2 years postnatally is the most important period underlying this association and may be partly genetically determined by genes associated with height.

Morphological changes of human crystalline lens in myopia

Ocular biometric parameters, including full shape crystalline lens, were assessed in myopes and emmetropes using 3-D optical coherence tomography. The anterior chamber depth, the radius of the curvature of the anterior cornea, anterior lens, and posterior lens, lens thickness, lens equatorial diameter, surface area, equatorial position, volume, and power, were evaluated as functions of refractive errors and axial lengths while controlling for age effects. The crystalline lens appears to change with myopia consistent with lens thinning, equatorial, and capsular stretching while keeping constant volume. Axial elongation appears counteracted by a crystalline lens power reduction, while corneal power remains unaffected.

Correlations between ocular biometrics and refractive error: A systematic review and meta-analysis

The understanding of correlations between different biometric parameters is essential for personalized eye care in the field of cataract and refractive surgery. This systematic review offers a clear overview of the previous literature assessing these correlations including a meta-analysis. The review is focused on the following five correlations: (1) axial length and refractive error; (2) anterior chamber depth and refractive error; (3) axial length and anterior chamber depth; (4) corneal power and refractive error; (5) corneal power and axial length. An expected strong correlation between axial length and refractive error was found. Correlations including corneal power were weak and might be clinically insignificant.

Longitudinal Analysis of Ocular Disease in Children with Mucopolysaccharidosis I after Hematopoietic Cell Transplantation

Corneal clouding, causing visual impairment, is seen in nearly all patients with mucopolysaccharidosis type 1 (MPS-1). Hematopoietic cell transplantation (HCT) is able to stabilize disease in many organs. Residual disease in several tissues is being increasingly recognized, however. Data on the effect of HCT on ocular disease in patients with MPS-1 are contradictory. With this study, we aim to clarify the long-term effects of HCT on ocular disease in these patients. Best corrected visual acuity (BCVA), refraction, intraocular pressure (IOP), and slit-lamp biomicroscopic and fundoscopic examinations, including corneal clouding, were collected prospectively from 24 patients with MPS-1 who underwent HCT successfully between 2003 and 2018 (92% with >95% chimerism and normal enzyme activity after HCT). The course of corneal clouding and BCVA after HCT were analyzed using a linear mixed model. Other parameters studied were clinical phenotype, age at time of transplantation, and hematologic enzyme activity after transplantation. Outcomes of additional ophthalmologic tests were described. In addition, IDUA and α-galactosidase A (AGAL) enzyme activity and glycosaminoglycan (GAG) concentration in tear fluid were determined. Corneal clouding stabilized in the first years after HCT but increased rapidly beyond 3 years (P < .0001). BCVA and IOP also worsened over time (P = .01 and P < .0001, respectively). IDUA activity in tear fluid remained very low (P < .0001). After initial stabilization in the cornea, ongoing ocular disease and low IDUA activity in tear fluid is seen in patients with MPS-1 despite treatment with HCT, unveiling a weak spot of current standard therapy. New therapies that overcome these shortcomings are needed to improve the late outcomes of patients.

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

Evidence from animal and human studies suggests that ocular growth is influenced by visual experience. Reduced retinal image quality and imposed optical defocus result in predictable changes in axial eye growth. Higher order aberrations are optical imperfections of the eye that alter retinal image quality despite optimal correction of spherical defocus and astigmatism. Since higher order aberrations reduce retinal image quality and produce variations in optical vergence across the entrance pupil of the eye, they may provide optical signals that contribute to the regulation and modulation of eye growth and refractive error development. The magnitude and type of higher order aberrations vary with age, refractive error, and during near work and accommodation. Furthermore, distinctive changes in higher order aberrations occur with various myopia control treatments, including atropine, near addition spectacle lenses, orthokeratology and soft multifocal and dual-focus contact lenses. Several plausible mechanisms have been proposed by which higher order aberrations may influence axial eye growth, the development of refractive error, and the treatment effect of myopia control interventions. Future studies of higher order aberrations, particularly during childhood, accommodation, and treatment with myopia control interventions are required to further our understanding of their potential role in refractive error development and eye growth.

Changes in axial length in accommodative esotropia patients with minimal hyperopic correction

Purpose

To compare the changes of spherical equivalent refractive error (SER) and axial length (AL) for three years in hyperopic children with minimal undercorrection according to the presence of accommodative esotropia (AE).

Methods

A total of 67 hyperopic children were enrolled. The patients were divided into 3 groups and matched by initial age upon examination; esotropic eyes with AE (AE group), fellow eyes with AE (FE group), and right eyes without esotropia (HE group). Changes of SER and AL were serially measured every six months for three years and collected data were compared among the groups.

Results

All three groups underwent significant myopic shift and AL elongation during the follow-up period. However, the least amount of change was found in the AE group. The AE group (-0.96 ± 1.38D) exhibited significantly less change in SER compared to the HE group (-1.76 ± 1.11D) and the FE group (-1.57 ± 1.33D) (both p<0.001). Meanwhile, smaller changes of AL were noticeable in the AE group (0.62 ± 0.88mm) compared to the other two groups (HE 0.99 ± 0.29mm; p<0.001, FE 0.73 ± 0.65mm; p = 0.04). The SER and AL changes were not significantly different between the HE group and FE group.

Conclusions

Esotropic eyes with AE patients with minimal undercorrection exhibited little negative shift of SER and AL elongation compared to not only hyperopic eyes without AE but also fellow eyes with AE.

Presbyopia: Effectiveness of correction strategies

Presbyopia is a global problem affecting over a billion people worldwide. The prevalence of unmanaged presbyopia is as high as 50% of those over 50 years of age in developing world populations, due to a lack of awareness and accessibility to affordable treatment, and is even as high as 34% in developed countries. Definitions of presbyopia are inconsistent and varied, so we propose a redefinition that states "presbyopia occurs when the physiologically normal age-related reduction in the eye's focusing range reaches a point, when optimally corrected for distance vision, that the clarity of vision at near is insufficient to satisfy an individual's requirements". Strategies for correcting presbyopia include separate optical devices located in front of the visual system (reading glasses) or a change in the direction of gaze to view through optical zones of different optical powers (bifocal, trifocal or progressive addition spectacle lenses), monovision (with contact lenses, intraocular lenses, laser refractive surgery and corneal collagen shrinkage), simultaneous images (with contact lenses, intraocular lenses and corneal inlays), pinhole depth of focus expansion (with intraocular lenses, corneal inlays and pharmaceuticals), crystalline lens softening (with lasers or pharmaceuticals) or restored dynamics (with 'accommodating' intraocular lenses, scleral expansion techniques and ciliary muscle electrostimulation); these strategies may be applied differently to the two eyes to optimise the range of clear focus for an individual's task requirements and minimise adverse visual effects. However, none fully overcome presbyopia in all patients. While the restoration of natural accommodation or an equivalent remains elusive, guidance is given on presbyopic correction evaluation techniques.

Incidence of myopia and biometric characteristics of premyopic eyes among Chinese children and adolescents

Background

To determine the one-year incidence and progression rates of myopia and its association with baseline ocular biometric parameters in school-based samples of children and adolescents in China.

Methods

Two thousand four hundred thirty two grade 1 and 2346 grade 7 students living in the southwest part of China participated in the baseline survey. After 1 year, 2310 (95.0%) grade 1 and 2191 (93.4%) grade 7 students attended the follow-up examination. Refractive error was measured after cycloplegia using the same autorefractor and by the same optometrists in the baseline and follow-up examination. Myopia was defined as spherical equivalent of less than − 0.50 diopter.

Results

The overall one-year incidence of myopia was 33.6% (95% confidence interval [CI]: 31.7–35.5) among grade 1 students and 54.0% (95% CI: 51.5–56.5) for grade 7 students. The one-year myopia progression rate was − 0.97 D (95% CI: -1.22 to − 0.71) in grade 1 students and − 1.02 D (95% CI: -1.07 to − 0.96) in grade 7 students. Per mm increase in baseline axial lengths increased the risk of myopia onset by 28% among grade 1 students and 22% among grade 7 students after 1 year. The incidence rates of myopia were found to be higher in grade 7 students with thinner premyopic lenses.

Conclusions

The incidence and progression rates of myopia were very high in Chinese children and adolescents in recent years. Premyopic eyes were characterized with longer axial lengths and thinner lenses. These data had considerable implications for formulating myopia prevention strategies in China.

Ocular biometric characteristics of cataract patients in western China

BACKGROUND

We aimed to measure ocular biometric characteristics in older cataract patients from western China.

METHODS

Ocular biometry records were retrospectively analyzed for 6933 patients with cataracts (6933 eyes) at least 50 years old who were treated at West China Hospital of Sichuan University.

RESULTS

Partial coherence laser interferometry gave the following population averages: axial length (AL), 24.32 ± 2.42 mm; anterior chamber depth (ACD), 3.08 ± 0.47 mm; keratometric power (K), 44.23 ± 1.66 diopters; and corneal astigmatism (CA), 1.00 ± 0.92 diopters. The percentage of individuals with AL > 26.5 mm was 13.66%, while the percentage with CA > 1.0 diopters was 35.54%. Mean AL and ACD showed a trend of decrease with increasing age (P < 0.001). AL correlated positively with ACD (Spearman coefficient, 0.542) and CA (0.111), but negatively with K (- 0.411) (all P < 0.01). K also correlated negatively with ACD (- 0.078, P < 0.01).

CONCLUSIONS

These results show, for the first time, that older cataract patients from western China have similar ocular biometric characteristics as other populations. The high prevalence of severe axial myopia warrants further investigation.

Refraction and Ocular Biometry of Preschool Children in Shanghai, China

Purpose

To investigate the refraction and ocular biometry characteristics and to examine the prevalence of refractive errors in preschool children aged 3 to 6 years in Shanghai, China.

Methods

A school-based cross-sectional study was conducted in Jiading and Xuhui District, Shanghai, in 2013. We randomly selected 7 kindergartens in Jiading District and 10 kindergartens in Xuhui District, with a probability proportionate to size. The children underwent comprehensive eye examinations, including cycloplegic refraction and biometric measurements. Myopia, hyperopia, astigmatism were defined as spherical equivalent (SE) ≤ −0.50 D, SE ≥ +2.00 D, and cylindrical diopters ≤ −1.00 D.

Results

The mean SE for 3- to 6-year-old children was +1.20 D (standard deviation [SD] 1.05), and the mean axial length (AL) was 22.29 mm (SD 0.73). The overall prevalence of myopia and astigmatism was 3.7% and 18.3%, respectively. No difference in prevalence of astigmatism was found across age groups. There was a statistically significant association between lower cylindrical diopters and higher spherical diopters (Spearman's correlation: −0.21, P < 0.001).

Conclusion

Chinese children aged 3 to 6 years in the Shanghai area were mostly mildly hyperopic, with a low prevalence of myopia. Refractive astigmatism for children may be relatively stable throughout the preschool stage. Astigmatism was significantly associated with refractive error.

Prevalence and risk factors for myopia in older adult east Chinese population

BACKGROUND

To determine the prevalence and associated factors for myopia and high myopia among older population in a rural community in Eastern China.

METHODS

A community-based, cross-sectional survey was conducted in the Weitang town located in Suzhou, an urban metropolis in East China. A total of 5613 Chinese residents aged 60 years and older were invited to complete a questionnaire and participated in a detailed eye examination,including measurements of visual acuity and refractive error using autorefraction and subjective refraction. Myopia and high myopia was defined as SE < -0.5 diopters (D) and < -5.0 D, respectively.

RESULTS

Among the 5613 participating individuals, 4795 (85.4%) complete refraction data of phakic right eye was included for analysis. The age-adjusted prevalence was 21.1% (95% confidence interval [CI], 19.9-22.2) for myopia and 2.5% (95% CI, 2.1-2.9) for high myopia. The prevalence of myopia tended to increase significantly with age(p < 0.001),and women had a higher rate of myopia than men (p < 0.001). According to multivariate logistic regression analysis, adults who were older (odds ration[OR]:1.05; 95% CI:1.04-1.07), spent more time for sleeping at night (OR:1.12;95% CI: 1.06-1.18),or had cataract (OR:1.60;95% CI:1.36-1.88) and family history of myopia (OR:1.47;95% CI:1.23-1.77), are more susceptible to myopia (p < 0.001). People who had older age, family history, cataract and specially longer night-time sleep duration, would have a higher risk of myopia.

CONCLUSION

Myopia and high myopia among rural old adult population in Eastern China presents common. The current literature unanticipated suggests that there was a positive significant association between prevalence of myopia and night-time sleep duration among adult. Our data provide some evidence of this relationship and highlight the need for larger studies to further investigate this relationship longitudinally and explore mechanism therein.

Lens power in Iranian schoolchildren: a population-based study

Aims

To evaluate lens power (LP) in schoolchildren aged 6–12 years.

Methods

This cross-sectional study was conducted in Shahroud, northeast Iran. The students were selected through random cluster sampling and underwent the measurements of biometry, uncorrected and corrected visual acuity, non-cycloplegic and cycloplegic refraction. The LP was calculated using the Bennett formula.

Results

Of 6624 invited children, 5620 (84.8%) participated in the study and data of 4870 children were finally analysed. The mean age of the participants was 9.7 years and 2277 participants (46.02%) were girls. The mean LPs were 22.86 dioptres (D) in total study population, 23.91 D in 6 and 22.10 D in 12-year-old children. The mean LP was higher in girls than boys (23.48 D vs 22.34 D), in rural children than urban children (23.17 D vs 22.83 D) and in children with hyperopia (23.25 D) than children with myopia or emmetropia (22.64 D and 22.86 D, respectively). In the multiple linear regression model, lens thickness (β=1.59, p<0.001), anterior chamber depth (β=2.21, p<0.001) and female sex (β=0.016, p=0.015) were associated with an increase in the LP, while axial length (AL) (β=−4.41, p<0.001), corneal power (CP) (β=−1.47, p<0.001), spherical equivalent (SE) (β=−1.50, p<0.001) and age (β=−0.005, p=0.001) were associated with a decrease in the LP. AL and sex had the highest and lowest impact on LP, respectively.

Conclusion

LP decreased with age between 6 and 12 years and was associated with a shorter AL, deeper ACD, higher SE, thicker lens and lower CP.

Significant Axial Elongation with Minimal Change in Refraction in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study

PURPOSE

To document the distribution of ocular biometry and to evaluate its associations with refraction in a group of Chinese preschoolers.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

A total of 1133 preschoolers 3 to 6 years of age from 8 representative kindergartens.

METHODS

Biometric measurements including axial length (AL), anterior chamber depth (ACD), and corneal radius of curvature (CR) were obtained from partial-coherence laser interferometry (IOL Master; Carl Zeiss Meditec, Oberkochen, Germany) before cycloplegia. Lens power (LP) and AL-to-CR ratio were calculated. Cycloplegic refraction (3 drops of 1% cyclopentolate) was measured using an autorefractor (KR8800; Topcon Corp., Tokyo, Japan), and spherical equivalent refraction (SER) was calculated. Biometric and refractive parameters were assessed as a function of age and gender. Multiple regression analysis was performed to explore the associations between refraction and ocular biometry.

MAIN OUTCOME MEASURES

Ocular biometric distributions and their relationships to refraction.

RESULTS

Among the 1127 children (99.5%) with successful cycloplegic refraction, mean SER was 1.37±0.63 diopters (D). Prevalence of myopia increased from 0% at 3 years of age to 3.7% (95% confidence interval, 1.0%-6.5%) at 6 years of age. Biometric parameters followed Gaussian distributions with means of 22.39±0.68 mm for AL, 7.79±0.25 mm for CR, and 24.61±1.42 D for calculated LP; and non-Gaussian distributions with means of 3.34±0.24 mm for ACD and 2.88±0.06 for AL-to-CR ratio. Axial length, ACD, and AL-to-CR ratio increased from 3 to 6 years of age, CR remained stable, whereas LP declined. Overall, SER declined slightly. For the SER variance, AL explained 18.6% and AL-to-CR ratio explained 39.8%, whereas AL, CR, and LP accounted for 80.0% after adjusting for age and gender.

CONCLUSIONS

Young Chinese children are predominantly mildly hyperopic, with a low prevalence of myopia by the age of 6 years. An increase of 1 mm in AL was associated with only 0.45 D of myopic change. Decreases in LP reduce the myopic shifts that normally would be associated with increases in AL, and thus play a key role in refractive development in this age group.

The Relationship between Crystalline Lens Power and Refractive Error in Older Chinese Adults: The Shanghai Eye Study

Purpose

To report calculated crystalline lens power and describe the distribution of ocular biometry and its association with refractive error in older Chinese adults.

Methods

Random clustering sampling was used to identify adults aged 50 years and above in Xuhui and Baoshan districts of Shanghai. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by IOL Master. The crystalline lens power of right eyes was calculated using modified Bennett-Rabbetts formula.

Results

We analyzed 6099 normal phakic right eyes. The mean crystalline lens power was 20.34 ± 2.24D (range: 13.40–36.08). Lens power, spherical equivalent, and anterior chamber depth changed linearly with age; however, axial length, corneal power and AL/CR ratio did not vary with age. The overall prevalence of hyperopia, myopia, and high myopia was 48.48% (95% CI: 47.23%–49.74%), 22.82% (95% CI: 21.77%–23.88%), and 4.57% (95% CI: 4.05–5.10), respectively. The prevalence of hyperopia increased linearly with age while lens power decreased with age. In multivariate models, refractive error was strongly correlated with axial length, lens power, corneal power, and anterior chamber depth; refractive error was slightly correlated with best corrected visual acuity, age and sex.

Conclusion

Lens power, hyperopia, and spherical equivalent changed linearly with age; Moreover, the continuous loss of lens power produced hyperopic shifts in refraction in subjects aged more than 50 years.

Distribution of Ocular Component Measures and Refraction in Brazilian School Children

PURPOSE

To describe ocular component values and refraction in 6-17-year-old school children in Campinas, Brazil.

METHODS

To obtain a representative sample, a total of 1100 6-17-year-old public school students in Campinas, Brazil, were randomly selected and divided into groups according to median ages 6 years (range 5-7 years), 10 years (range 9-11 years), 14 years (range 13-15 years), and 17 years (range 16-18 years). Cycloplegic autorefraction and ocular biometry were performed on each child.

RESULTS

Parental consent for participation was obtained for 778 of the 1100 students (70.7%). Of these, 440 (56.6%) were female and 330 (44.4%) male. Sex distributions were similar for each median age group. Median age groups 6, 10, 14, and 17 years displayed significant trends of decreasing mean spherical equivalent refraction (SER; 0.96, 0.89, 0.57, and 0.23 diopters, D, respectively), mean lens thickness (3.50, 3.42, 3.41, and 3.45 mm, respectively), and mean lens power (23.6, 22.7, 21.8, and 21.2D, respectively), but significant trends of increasing mean anterior chamber depth (ACD; 3.00, 3.12, 3.16, and 3.15 mm, respectively), mean vitreous chamber depth (VCD; 16.0, 16.4, 16.6, and 16.8 mm, respectively), and mean axial length (22.5, 23.0, 23.2, 23.4 mm, respectively; all p for trend <0.001).

CONCLUSIONS

Significant trends towards lower refractive power, increased prevalence of myopia, increased ACD, VCD, and axial length, and decreased lens power were associated with increasing age in these children. There were no significant changes in corneal thickness or corneal curvature.

Age-related differences in ocular biometry in adult Korean population

Background

To evaluate the relationship between age, axial length (AL), anterior chamber depth (ACD) and corneal steepness (K) in patients with cataract.

Methods

In this retrospective study, medical records of 800 patients (800 eyes) who were diagnosed with cataract and received preoperative ophthalmologic examination were reviewed. Data including age, gender and ocular biometric data including AL, ACD and K were collected and analyzed using univariate and multivariate analyses.

Results

Univariate analysis showed increased age has significant correlation with shorter AL (P < 0.001), shallower ACD (P < 0.001) and steeper K (P < 0.001). K value has a negative correlation with AL (P < 0.001). In multivariate analysis, increasing age has a significant association with shorter AL (P < 0.001) and ACD (P < 0.001), although the association between age and K was not significant (P = 0.398). Negative correlation between AL and K remained significant in multivariate analysis (P < 0.001).

Conclusion

In patients with cataract, older age had significant association with shorter AL and ACD. AL and K had negative correlation.

An Analysis of Morphometric Qualities of Bulbus Oculi in Cataract Patients: A Comparative Biometric Study

Cataract is considered to be the primary reason for curable blindness that is caused by progressive loss of lens transparency and affects millions of people around the world. This study aims to analyze the changes in morphometric qualities of bulbus oculi (BO) as well as its morphometric measurements such as anterior chamber depth (ACD), lens thickness (LT), vitreous length (VL), axial length (AL), etc. depending on age and gender in cataract patients through comparison with healthy eyes. 200 eyes with cataract were separately analyzed in five different categories of ages for males and females at the ages of 40-89. Biometric measurements of a total of 128 eyes (64 males and 64 females) were used as the control group. The study revealed a strong negative relation between age and ACD and a strong positive relation between age and LT in males and females for healthy eyes and eyes with cataract (P < 0.05). No significant relation was found for VL and AL in either gender (P > 0.05). A significant decrease was observed in ACD with aging while a positive correlation with age was detected in LT. We believe that the data obtained from this study will serve as a guide for BO interventions, diagnose and treatment stages and training of physician assistants. Anat Rec, 299:1308-1312, 2016. © 2016 Wiley Periodicals, Inc.

Effects of epiblepharon surgery on higher-order aberrations

PURPOSE

To quantify and compare higher-order aberrations (HOAs) in children after epiblepharon surgery.

METHODS

The medical records of children (mean age, 7.3 years [range, 2-13 years]) who underwent surgery for epiblepharon were reviewed retrospectively. Aberrometry was conducted before surgery and at 1 month's and 3 months' follow-up using the Wavefront Analyzer KR-1W. Corneal HOAs in the 4 mm and 6 mm optical zones were compared. Classification of the severity of epiblepharon was based on the degree of cilia touching the cornea and corneal erosion.

RESULTS

A total of 120 eyes of 60 patients were included. Corneal total HOAs in the 4 mm and 6 mm optical zone decreased significantly at 1 and 3 months after surgery (P = 0.001 and 0.000, resp.. in the 4 mm zone; P = 0.006 and 0.006 in the 6 mm zone). Surgery induced a significant reduction of fourth-order aberrations, with decrease of tetrafoil in the 4 mm zone and coma, tetrafoil, and secondary astigmatism in the 6 mm zone 3 months after surgery; the differences were statistically significant (P = 0.038 and 0.006 in the 4 mm zone; P = 0.018 and 0.000 in the 6 mm zone). Although there was no significant association between epiblepharon severity and total HOAs, reduction of corneal staining grade and decrease of total HOAs at 3 months were significantly correlated (P = 0.03 in the 6 mm zone).

CONCLUSIONS

In this patient cohort, total HOAs decreased significantly after epiblepharon surgery. The correlation of reduction of corneal staining grade and decrease of total HOAs may be helpful in deciding the timing of surgery in children who have no specific visual symptoms.