Spherical Equivalent Refractive Error Research Articles

Link between parental myopia and early-onset high myopia: Insights from a clinical retrospective analysis.

Genetic aetiology is suspected in the development of early-onset high myopia (spherical equivalent refractive error [SER] ≤-6.00 D at ≤6 years of age), considering that the role of environmental factors in inducing high myopia is improbable at an early age. Therefore, we aimed to understand if early-onset high myopia is associated with parental myopia in a clinical setting. A retrospective study was conducted in which information about demographics, age of apparent onset of myopia, refractive error, axial length, number of myopic parents, time spent outdoors and time spent on near-work was obtained from electronic medical records (EMR). It included 195 myopic individuals categorised into (1) Early-onset high myopes (EOHM): SER ≤ -6.00 D with age of presentation ≤6 years, (2) Early-onset low myopes (EOLM): SER > -6.00 D with age of apparent onset ≤6 years, (3) Late-onset high myopes (LOHM): SER ≤ -6.00 D with age of presentation and age of apparent onset >6 years and (4) Late-onset low myopes (LOLM): SER > -6.00 D with age of apparent onset >6 years. Overall, 63% of individuals were found to have parental myopia. The proportion of individuals with EOHM, EOLM, LOHM and LOLM with parental myopia was 57%, 74%, 53% and 64%, respectively. After adjustment for age, gender and environmental factors, the odds of development of EOHM (Odds ratio: 0.78, 95% confidence interval: 0.25-2.48), EOLM (1.54, 0.65-3.67) or LOHM (0.70, 0.30-1.65) were similar in the presence of myopic parents, when compared with LOLM. The SER and axial length did not differ based on the number of myopic parents in any of these categories. This retrospective analysis reveals that the presence of parental myopia, which was self-reported, did not induce additional risk for early-onset high myopia.

Refractive error accuracy and user perceptions of a smartphone home-based tester

Background: Uncorrected refractive error accounts for nearly half of the global burden of vision impairment. The EyeQue personal vision tracker (EPVT) was created as a convenient smartphone refractometer to be used at home and order spectacles online thereafter. However, its accuracy in diagnosing refractive error has not been fully established.Aim: This study aimed to determine the accuracy of the EPVT in measurement of refractive error and determine user perception on device use.Setting: University of KwaZulu-Natal optometry clinic, Westville campus.Methods: This was a comparative cross-sectional study using a double-blind design. Objective, non-cycloplegic refraction testing results using the EPVT were compared with gold standard ophthalmic subjective refraction (SR). Both eyes were considered for the analysis with comparisons being made between EPVT and gold subjective standard refraction for each eye. User perception was evaluated by means of a structured questionnaire.Results: The mean spherical equivalent refractive error was –0.18 ± 0.70 dioptre (D) and –1.12 ± 2.79 D for the gold standard ophthalmic SR and EPVT, respectively, with significant differences in visual acuities yielded by the two methods (p = 0.000). Participants preferred gold standard refraction testing over the EPVT.Conclusion: The EPVT was not accurate in measuring refractive error; therefore, the resultant prescription from EPVT alone should not be used to order spectacles. However, this digital tool presents promise as an autorefractor for screening refractive error rather than as a diagnostic device.Contribution: This study offered valuable insights into the prospective utility of home-based, self-administered smartphone refractive error testers as a tool for screening of refractive error. The study also provided cautions to the EPVTs limitations related to accuracy and limited ocular health assessment, which have broader implications for visual health and quality.

Complications, Visual Acuity, and Refractive Error Three Years After Secondary Intraocular Lens implantation for Pediatric Aphakia

To report the cumulative incidence of complications and describe refractive error and visual acuity (VA) outcomes in children undergoing secondary intraocular lens (IOL) implantation following previous surgery for non-traumatic cataract. Pediatric cataract registry. 80 children (108 eyes: 60 bilateral, 48 unilateral) undergoing lensectomy at <13 years of age, followed by secondary IOL implantation at median age (range) of 2.7 (0.6 to 5.0) years for bilateral and 2.1 (0.5 to 6.4) for unilateral cases. Annual data collection from medical record review through 5 years following lensectomy. Cumulative incidence of newly emergent complications following secondary IOL implantation; refractive error and VA by 5 years after lensectomy. Median (interquartile range [IQR]) follow-up following secondary IOL implantation was 2.5 years (0.8 to 3.3 years). A common complication following secondary IOL implantation was a glaucoma-related adverse event (GRAE: glaucoma or glaucoma suspect); the cumulative incidence was 17% (95% CI: 3%-29%) in bilateral and 12% (95% CI: 0%-23%) in unilateral cases. The cumulative incidence of surgery for visual axis opacification was 2% (95% CI: 0%-7%) for bilateral and 4% (95% CI: 0%-10%) for unilateral cases. Median prediction error (IQR) within 90 days of implantation was 0.88 D (-0.50 D to +3.00 D) less hyperopic than intended among 21 eyes for bilateral cases and 1.50 D (-0.25 D to +2.38 D) less among 19 unilateral cases. Median (IQR) spherical equivalent refractive error at 5 years (median 5.1 years of age) in eyes receiving a secondary IOL was +0.50 D (-2.38 D to +2.94 D) for 48 bilateral and +0.06 D (-2.25 D to +0.75 D) for 22 unilateral cases. Median (IQR) monocular VA at 5 years was 20/63 (20/50-20/100) for bilateral (n=42) and 20/400 (20/160-20/800) for unilateral (n=33) cases. Eyes with secondary IOL implantation have an ongoing risk of new glaucoma-related adverse events. Five years after lensectomy (approximately 2.5 years after secondary IOL implantation), average refractive error was less hyperopic than desired given the anticipated further myopic shift before refraction stabilizes.

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

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. 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. 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. 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.

Following prevalence of myopia in a large Swiss military cohort over the last decade: where is the European "myopia boom"?

Myopia prevalence is increasing globally, with the highest rates found in Asia. Data from European countries is scarce. We aimed to investigate whether the prevalence of myopia is rising in our meridians. Data from male military conscripts for the recruitment period of 2008-2017 were retrospectively analyzed. Year of recruitment, conscripts' birth year, visual acuity, refractive status (spherical equivalent), and spectacle wear (yes/no) were available. The dataset contained data of a total of 355,657 male conscripts, who had been recruited in the years 2008 to 2017. The mean number of conscripts per year was 35,566 (MD = 35,440, SD = 1249), reaching a minimum number of 33,998 conscripts in 2017 and a maximum of 37,594 in 2011. Mean age at recruitment was 19.7years (MD = 19.0years, SD = 1.1years). Overall, the number of conscripts wearing spectacles remained stable over the observation time; on average 29.6% (n = 10,540; MD = 10,472; SD = 492) of conscripts wore glasses at recruitment. Of 21.8% (n = 77,698) of conscripts, data on the refractive status was available: The mean spherical equivalent for both right and left eyes was -2.3D (MD = -2 D, SD = 2.4 D). No decrease in mean spherical equivalent per recruitment year was noted over the observation period. Estimated myopia prevalence reached an average of 27.5% (SD = 0.8%) and did not increase during the observation period. In summary, no change in spherical equivalent refractive errors of male Swiss army conscripts was found for the years 2008-2017. Equally, the percentage of spectacle wearers (MN = 29.6%) and estimated myopia prevalence (MN = 27.5%) did not significantly increase during the observation time. BASEC 2019-00060 (18/01/2019).

Predicting the onset of myopia in children by age, sex, and ethnicity: Results from the CLEERE Study.

Clinicians and researchers would benefit from being able to predict the onset of myopia for an individual child. This report provides a model for calculating the probability of myopia onset, year-by-year and cumulatively, based on results from the largest, most ethnically diverse study of myopia onset in the United States. This study aimed to model the probability of the onset of myopia in previously nonmyopic school-aged children. Children aged 6 years to less than 14 years of age at baseline participating in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study who were nonmyopic and less hyperopic than +3.00 D (spherical equivalent) were followed up for 1 to 7 years through eighth grade. Annual measurements included cycloplegic autorefraction, keratometry, ultrasound axial dimensions, and parental report of children's near work and time spent in outdoor and/or sports activities. The onset of myopia was defined as the first visit with at least -0.75 D of myopia in each principal meridian. The predictive model was built using discrete time survival analysis and evaluated with C statistics. The model of the probability of the onset of myopia included cycloplegic spherical equivalent refractive error, the horizontal/vertical component of astigmatism (J0), age, sex, and race/ethnicity. Onset of myopia was more likely with lower amounts of hyperopia and less positive/more negative values of J0. Younger Asian American females had the highest eventual probability of onset, whereas older White males had the lowest. Model performance increased with older baseline age, with C statistics ranging from 0.83 at 6 years of age to 0.92 at 13 years. The probability of the onset of myopia can be estimated for children in the major racial/ethnic groups within the United States on a year-by-year and cumulative basis up to age 14 years based on a simple set of refractive error and demographic variables.

Recalled Age of Myopia Onset May Predict Risk of High Adult Myopia in Chinese Adults

Introduction: This study aimed to investigate the relationship between the age of myopia onset and high myopia and to explore if age of onset mediated the associations of high myopia with parental myopia and time spent on electronics. Methods: This cross-sectional study enrolled 1,118 myopic patients aged 18–40. Information was obtained via a detailed questionnaire. Multivariable logistic regression and linear regression models were utilized to assess age of onset in relation to high myopia and spherical equivalent refractive error, respectively. Structural equation models examined the mediated effect of onset age on the association between parental myopia, time spent on electronics, and high myopia. Results: An early age at myopia onset was negatively correlated with spherical equivalent refractive power. Subjects who developed myopia before the age of 12 were more likely to suffer from high myopia than those who developed myopia after the age of 15. Age of myopia onset was the strongest predictor of high myopia, with an area under the curve in receiver operator characteristic analysis of 0.80. Additionally, the age of myopia onset served as a mediator in the relationships between parental myopia, electronic device usage duration, and the onset of high myopia in adulthood. Conclusions: Age of myopia onset might be the single best predictor for high myopia, and age at onset appeared to mediate the associations of high myopia with parental myopia and time spent on electronics.

Optical coherence tomography and optical coherence tomography angiography findings in optic nerve hypoplasia and their relationships with visual acuity

This study aimed to quantitatively assess the thickness of the peripapillary retinal nerve fiber layer (pRNFL) thickness, as well as the microvascular alterations in the macula and peripapillary regions, in optic nerve hypoplasia (ONH) patients compared to normal controls. This was achieved through the utilization of spectral-domain optical coherence tomography (SD-OCT) and optical coherence tomography angiography (OCTA), with a specific focus on elucidating the association between these structural alterations and visual acuity. We included a total of 17 eyes of 12 ONH patients, and 34 eyes of age-matched 34 healthy controls. The pRNFL thickness was quantified using SD-OCT, while OCTA facilitated the visualization and measurement of the microvascular structure images of the superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), and radial peripapillary capillary (RPC) segment in the macula and peripapillary area. pRNFL thickness was measured for eight sectors (superior, temporal, inferior, nasal, superotemporal, superonasal, inferotemporal, and inferonasal). SRCP, DRCP, and RPC were measured for four sectors (superior, temporal, inferior, and nasal). Age, gender, and spherical equivalent refractive errors were statistically adjusted for the analysis. Associations of structural parameters with visual acuity in ONH patients were analyzed using Spearman correlation analysis. pRNFL thickness was significantly thinner in ONH patients than in controls for all sectors. Vessel densities of temporal and nasal sectors in DRCP were significantly higher in ONH patients, but vessel densities of the inferior sector in RPC were significantly lower than those in controls. For all sectors, pRNFL thickness was strongly associated with visual acuity in ONH patients. ONH patients showed significant pRNFL thinning and microvascular alterations compared to controls, and pRNFL thickness was strongly associated with visual function. OCT and OCTA are useful tools for evaluating optic disc hypoplasia and its functional status.

Refractive Error Change and Overminus Lens Therapy for Childhood Intermittent Exotropia

Increased myopic shift was found to be associated with 1 year of overminus spectacle treatment for children with intermittent exotropia (IXT). Persistence of myopic shift after discontinuing overminus spectacles is unknown. To compare refractive error change over 3 years in children with IXT originally treated with overminus vs nonoverminus spectacles. This study was an 18-month extension of the Trial of Overminus Spectacle Therapy for Intermittent Exotropia cohort, which previously randomized children aged 3 to 10 years with IXT and baseline spherical equivalent refractive error (SER) between -6.00 diopters (D) and 1.00 D to overminus spectacles (-2.50 D for 12 months, -1.25 D for 3 months, and nonoverminus for 3 months) or nonoverminus spectacles. Children were recruited from 56 sites from July 2010 to February 2022. Data were analyzed from February 2022 to January 2024. After trial completion at 18 months, participants were followed up at 24 and 36 months. Treatment was at investigator discretion from 18 to 36 months. Change in SER (cycloplegic retinoscopy) from baseline to 36 months. Of 386 children in the Trial of Overminus Spectacle Therapy for Intermittent Exotropia, 223 (57.8%) consented to 18 months of additional follow-up, including 124 of 196 (63.3%) in the overminus treatment group and 99 of 190 (52.1%) in the nonoverminus treatment group. Of 205 children who completed 36-month follow-up, 116 (56.6%) were female, and the mean (SD) age at randomization was 6.2 (2.1) years. Mean (SD) SER change from baseline to 36 months was greater in the overminus group (-0.74 [1.00] D) compared with the nonoverminus group (-0.44 [0.85] D; adjusted difference, -0.36 D; 95% CI, -0.59 to -0.12; P = .003), with 30 of 112 (26.8%) in the overminus group having more than 1 D of myopic shift compared with 14 of 91 (15%) in the nonoverminus group (risk ratio, 1.8; 95% CI, 1.0-3.0). From 12 to 36 months, mean (SD) myopic shift was -0.34 (0.67) D and -0.36 (0.66) D in the overminus and nonoverminus groups, respectively (adjusted difference, -0.001 D; 95% CI, -0.18 to 0.18; P = .99). The greater myopic shift observed after 1 year of -2.50-D overminus lens treatment remained at 3 years. Both groups had similar myopic shift during the 2-year period after treatment weaning and cessation. The risk of myopic shift should be discussed with parents when considering overminus lens treatment. ClinicalTrials.gov Identifier: NCT02807350.

Altering optical zone diameter, reverse curve width, and compression factor: impacts on visual performance and axial elongation in orthokeratology

PurposeTo investigate the effects of modifications in back optical zone diameter (BOZD), reverse curve width (RCW), and compression factor (CF) on refractive error changes and axial elongation in myopic children undergoing orthokeratology (ortho-k) over a 12-month period. MethodIn this retrospective study, data from 126 myopic children undergoing ortho-k fitting were analyzed. Subjects were categorized into four distinct groups based on lens design parameters: Group A (BOZD 6.0 mm, RCW 0.6 mm, CF 0.75 D); Group B (BOZD 6.0 mm, RCW 0.6 mm, CF 1.25 D); Group C (BOZD 5.4 mm, RCW 0.9 mm, CF 1.25 D); and Group D (BOZD 5.0 mm, RCW 1.1 mm, CF 1.25 D). The study evaluated uncorrected visual acuity (UCVA), corneal topography, and axial length (AL) at intervals, using Linear Mixed Models (LMMs) for time-based changes, and ANOVA or Kruskal-Wallis tests for group differences in AL elongation. A multivariable regression analysis identified factors independently associated with AL elongation. ResultsWithin the first day and week, all four groups displayed significant improvements in UCVA and alterations in corneal curvature, which subsequently stabilized. Although UCVA variations between groups were subtle, Group D had less corneal curvature change than Groups A and B initially and exhibited significantly less AL elongation after one year. No significant difference in corneal curvature change or AL elongation was observed between Group C and the other groups. Multiple regression analysis indicated that older baseline age, greater baseline spherical equivalent refractive error, and smaller BOZD were associated with less AL elongation. ConclusionThe study reveals a positive correlation between BOZD and axial length growth over the 12-month period. A pure 0.5 D CF increment demonstrates a nonsignificant impact. This study provides new ideas into optimizing the parameters of ortho-k lenses.

Exemplifying practice-based research: the influence of age on myopia progression

ABSTRACT Clinical relevance The electronic storage of patient records and modern-day search engines present private practitioners with a unique opportunity to extract valuable data for investigative research purposes. However, practitioners seldom harness this resource and consequently a vast repository of clinical data remains largely unexplored. Background This study, based on real-world data from an optometric practice, stands as an example of how clinicians can actively contribute to research. In doing so it underscores the role played by age in determining the rate of natural myopia progression. Methods A retrospective data analysis of the refractive status, age and optical correction type of participants, was conducted over six years. Forty-four participants were recruited (25 contact lens and 19 spectacle wearers), with a presenting age varying from 5 to 20 years (median, 11 years). Non-cycloplegic, monocular foveal refractions were completed using a ShinNippon open-field autorefractor, corroborated with subjective refraction. The mean spherical equivalent refractive error was calculated for the participants’ initial visit (baseline measure) and for a six-year follow-up visit (progression measure), with myopia progression defined as the difference between these measures. Statistical analyses were computed using Decision Tree Analysis, with a significance level set at 95%. Results The participant age at first visit exerted a significant influence on natural myopia progression over the assessment period (F 1,42 = 17.11, p < 0.001). Individuals aged ≤ 10 years had approximately twice the myopic progression (mean, −2.27 D) of those aged > 10 years (mean, −1.13 D). Neither degree of myopia at the initial visit nor optical correction type had a significant effect on progression (p > 0.05). Conclusions Utilizing the advantage of small real-world data samples, the benefit of research by private practitioners was demonstrated, providing evidence that the age at which a child first presents for an eye examination is highly influential in determining their rate of myopia progression.

Longitudinal changes of refractive error in preschool children with congenital ectopia lentis.

Congenital ectopia lentis (CEL) is a hereditary eye disease which severely impacts preschool children's visual function and development. This study aimed to evaluate the longitudinal changes in spherical equivalent (SE) refractive error in preschool children with CEL. A retrospective cohort study was conducted at Zhongshan Ophthalmic Center, Guangzhou, China. Medical records of CEL patients under 6-year-old who were diagnosed with Marfan syndrome at the initial visit from January 2014 to March 2022 were collected and were divided into surgery and non-surgery groups. Mean change rate of SE in the two groups was evaluated, and the potential associated factors of SE change rate were investigated by mixed-effect regression model. A total of 94 preschool patients from 14 provinces of China were included. Among the 42 children of the surgery group, the mean age with standard deviation (SD) was 5.02 ± 0.81years and patients experienced a myopic shift of -0.05 ± 0.09D/month in average. The mean age with SD of the 52 children of the non-surgery group was 4.34 ± 1.02years, and the mean myopic shift was -0.09 ± 0.14D/month. The mixed-effect regression model identified that higher degree of myopia at baseline was associated with slower myopic shift both in surgery (β = 0.901, 95% CI: 0.822 ~ 0.980, P < 0.001) and in non-surgery group (β = 1.006, 95% CI: 0.977 ~ 1.034, P < 0.001) in CEL patients. Surgical treatment (β = 2.635, 95% CI: 1.376 ~ 3.894, P < 0.001) was associated with slower myopic shift in all participants CEL patients. Myopic progression was slower in the surgery group than in the non-surgery group of CEL. Preschool CEL patients who met the surgical indication are suggested being performed with timely surgery to slow down the myopic progression.

Intraocular Straylight and Multifocal Soft Contact Lens Fit With a Myopia Control Approach.

Center-distance multifocal contact lenses (MFCLs) are used to slow myopia progression. We examined the effect of two MFCLs on intraocular straylight values in myopic individuals. Twenty-five young myopic adults were enrolled and were fit with three contact lenses (Biofinity sphere, Biofinity Multifocal, and NaturalVue Multifocal) in a random order over two study visits. Pupil size (NeurOptics VIP-300, Laguna Hills, CA) and contact lens centration were measured. Right eye intraocular straylight measurements were collected (OCULUS C-Quant; Wetzlar, Germany) and compared with a spectacle trial lens. Log straylight (LogSL) values and straylight residuals were analyzed using repeated-measures analyses of variance with Tukey-corrected post hoc t -tests. The mean participant age (±SD) was 24.1±1.5 years, and right eye spherical equivalent refractive error was -3.38±1.53 DS. There was no difference in mesopic pupil size between visits ( P =0.68) and no difference in contact lens centration between lenses ( P =0.99). LogSL values differed by lens type ( P =0.004). LogSL with the spectacle trial lens was significantly greater than with each contact lens type (all P <0.05), but there were no significant differences in LogSL between the three contact lenses (all P >0.05). There was no difference between the three contact lens designs for straylight residuals ( P =0.33). Measured intraocular straylight for both MFCLs was not different than with a spherical soft contact lens. A significant increase in intraocular straylight with spectacle trial lens correction was observed compared with all contact lenses.

COMPARISON OF NONCONTACT A-SCAN AND ULTRASOUND A-SCAN IN THE MEASUREMENT OF AXIAL LENGTH IN MYOPIC SUBJECTS

Introduction: Myopia, which is also known as nearsightedness, is a common type of refractive error among the majority of the population. It is characterized by clear vision up close but blurry vision at a distance. Myopia is caused by an eyeball that is abnormally longer than normal and cornea that is too steeply curved. In both cases, images are focused in front of the retina instead of on it. With abnormal axial length of the eyeball, myopia has developed into a condition that threatens eyesight. Methodology: In this study, we compared the axial length measurements between non-contact biometry, and ultrasound A-scan among young myopic adults in UKM Kuala Lumpur campus. A total of 90 healthy myopic subjects (14 male and 76 female) with mean age of 22.03 ± 1.14 years were enrolled in this cross-sectional study. Clinical investigations that included visual acuity, refraction and axial length measurement using optical and ultrasound biometry were carried out. Results: The mean spherical equivalent refractive error, axial length measured by optical biometry and ultrasound were found to be -3.04 ± 1.61 D, 24.74 ± 0.90 mm and 24.50 ± 0.86 mm respectively. Paired sample t-test showed that subjects’ axial length measured by ultrasound A-scan were significantly lower than optical biometry (p &lt; 0.05). Negative and strong correlations were found between degree of myopia and axial length (rs = -0.609, p &lt; 0.001). Regression showed that axial length measurement accounted for a significant 33.5% of the degree of myopia, R² = 0.335, adjusted R² = 0.328, F = (1, 88) = 44.38, p &lt; 0.01. Conclusion: The results of this study demonstrated a significant difference in measurements of axial length using non-contact A-scan and ultrasound A-scan in myopic subjects, which must be considered during management of myopic patients.

Are red/green colour vision deficient individuals at altered risk of myopia?

Aims/Purpose: To investigate the association between red/green colour vision deficiency (CVD) and myopia in Irish and Australian participants.Methods: Data from the Ireland Eye Study (IES; age 12–13 years), Raine Study Gen2 cohort (Australia; age 18–22 years) and Kidskin Study (Australia; age 25–30 years) were used. Colour vision was assessed with the Hardy‐Rand‐Ritler (IES) or Ishihara colour vision test (Raine, Kidskin). Right eye spherical equivalent refractive error (SER; myopia defined as SER ≤ −0.50 dioptres [D]) was measured with cycloplegic autorefraction and right eye axial length (AXL) with interferometry. Participants who were female, or with incomplete colour vision or refraction data, tritanomaly, monochromacy, previous surgery or condition‐altering refraction were excluded. Linear and logistic regression were used for analysing binary and continuous outcomes, respectively, with an interaction between study country and CVD.Results: After exclusions (n = 56), there were 2488 participants of whom 1286 (51.7%) were male (IES: n = 503, Raine: n = 676 and Kidskin: n = 107). The prevalence of CVD across the IES, Raine and Kidskin studies, respectively, was 5.8% (16 deutan, 9 protan, 5 unclassified), 5.5% (18 deutan, 3 protan, 16 unclassified) and 6.5% (6 deutan, 1 unclassified). After adjusting for age, any red/green CVD was not associated with myopia risk (odds ratio [OR] = 1.31, 95% confidence interval [95%CI]: 0.86–2.32, p = 0.36), SER or AXL. However, when analysed by CVD type, deutan CVD was associated with higher odds of myopia (OR = 2.31, 95% CI 1.19 to 4.44, p = 0.01) and a more myopic SER (difference = −0.61D, 95% CI: −1.09 to −0.12, p = 0.02; AXL: difference = 0.09 mm, 95%CI: −0.19 to 0.37, p = 0.51), compared to non‐CVD participants, while other CVD types were not associated with myopia (protan: OR = 0.94, 95% CI 0.20–4.41, p = 0.94; unclassified: OR = 0.36, 95% CI 0.08–1.56, p = 0.17), SER or AXL.Conclusions: In contrast to previous findings in Chinese school students, participants with a deutan CVD in this study had a higher risk of myopia.

Axial length to corneal radius of curvature ratio and refractive error in Chinese preschoolers aged 4–6 years: a retrospective cross-sectional study

ObjectiveThis study aims to investigate the associations of axial length to corneal radius of curvature (AL/CRC) ratio with refractive error and to determine the effect of AL/CRC ratio on hyperopia...

Characteristics of ciliary muscle profile in high myopes measured by swept-source anterior segment optical coherence tomography.

To characterize and compare the ciliary muscle thickness (CMT) between low and high myopes using swept-source anterior segment optical coherence tomography (AS-OCT). Forty visually healthy young Chinese adults aged 18-25 years were divided into two groups based on refractive errors: low myopia (n = 20, spherical-equivalent refractive error (SER) between -0.50 D to -3.00 D) and high myopia (n = 20, SER ≤ -6.00 D). Cycloplegic refractions were performed before axial length (AL) and CMT were measured using a partial coherence laser interferometer and an AS-OCT respectively. CMT was measured perpendicularly to the sclera-ciliary muscle interface at 1 mm (CMT_1), 2 mm (CMT_2), and 3 mm (CMT_3) posterior to the scleral spur, and at the location with maximal thickness (CMT_MAX). High myopes demonstrated thicker CMT at 2 mm (CMT_2, p = 0.035) and 3 mm (CMT_3, p = 0.003) posterior to the scleral spur, but thinner maximal CMT (CMT_MAX, p = 0.005) than low myopes. The apical CMT_1 and CMT_MAX were also thinner in high myopes than in low myopes (both p< 0.001). CMT_MAX, apical CMT_1, and apical CMT_MAX correlated directly with SER and inversely with AL; in contrast, CMT_2 and CMT_3 showed inverse correlations with SER but direct correlations with AL. Our findings revealed significant differences in CMT between low and high myopes, with high myopes showing thicker CMT at 2 mm and 3 mm posterior to the scleral spur, but thinner maximal CMT. These results provide new evidence of the potential structural differences in ciliary muscles during myopia development and progression.

Intraretinal microvascular alterations in indirect traumatic optic neuropathy using optical coherence tomography angiography.

To quantitatively evaluate macular and peripapillary microvascular alterations in patients with indirect traumatic optic neuropathy (TON) compared to normal controls using optical coherence tomography angiography (OCT-A) and determine their associations with other ocular parameters. We enrolled 33 eyes of 33 patients with TON and 34 eyes of 34 healthy controls. OCT-A was used to generate microvascular structure images of the superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), and radial peripapillary capillary (RPC) segment in the macula and peripapillary area. Functional and structural parameters such as best-corrected visual acuity, visual field, peripapillary retinal nerve fibre layer (pRNFL) thickness, macular ganglion cell-inner plexiform layer (mGCIPL) thickness, OCT-A variables were compared between TON patients and controls. Age, gender, and spherical equivalent refractive errors were statistically adjusted for the analysis. OCT-A revealed a significant reduction of the average vessel density in the RPC segment in TON patients compared to controls (48.5% ± 6.28 vs. 57.88% ± 3.06%, P < 0.0001, corrected P < 0.0001). When comparing sectors, the vessel density of the RPC segment in TON patients was also significantly lower in all four quadrants compared to healthy controls. The inferior sector vessel density of the RPC segment was significantly associated with visual field defects (P = 0.0253) and visual acuity (P = 0.0369). The temporal sector vessel density of DRCP was also associated with visual field defects (P = 0.0377). The RPC segment in the superior and inferior sector vessel density displayed a significant association with the corresponding regional pRNFL thickness (P = 0.0248 and <0.0001, respectively). Patients with indirect TON exhibit significant microvascular alterations compared to controls. This study confirms that TON can induce intraretinal microvascular changes and suggests that OCT-A may serve as a useful biomarker for assessing visual functional and structural changes.

Time Spent Outdoors Partly Accounts for the Effect of Education on Myopia.

The purpose of this study was to investigate if education contributes to the risk of myopia because educational activities typically occur indoors or because of other factors, such as prolonged near viewing. This was a two-sample Mendelian randomization study. Participants were from the UK Biobank, Avon Longitudinal Study of Parents and Children, and Generation R. Genetic variants associated with years spent in education or time spent outdoors were used as instrumental variables. The main outcome measures were: (1) spherical equivalent refractive error attained by adulthood, and (2) risk of an early age-of-onset of spectacle wear (EAOSW), defined as an age-of-onset of 15 years or below. Time spent outdoors was found to have a small genetic component (heritability 9.8%) that tracked from childhood to adulthood. A polygenic score for time outdoors was associated with children's time outdoors; a polygenic score for years spent in education was inversely associated with children's time outdoors. Accounting for the relationship between time spent outdoors and myopia in a multivariable Mendelian randomization analysis reduced the size of the causal effect of more years in education on myopia to -0.17 diopters (D) per additional year of formal education (95% confidence interval [CI] = -0.32 to -0.01) compared with the estimate from a univariable Mendelian randomization analysis of -0.27 D per year (95% CI = -0.41 to -0.13). Comparable results were obtained for the outcome EAOSW. Accounting for the effects of time outdoors reduced the estimated causal effect of education on myopia by 40%. These results suggest about half of the relationship between education and myopia may be mediated by children not being outdoors during schooling.

How Do Most Young Moderate Hyperopes Avoid Strabismus?

Uncorrected hyperopic children must overcome an apparent conflict between accommodation and vergence demands to focus and align their retinal images. This study tested hypotheses about simultaneous accommodation and vergence performance of young hyperopes to gain insight into ocular motor strategies used to maintain eye alignment. Simultaneous eccentric photorefraction and Purkinje image tracking were used to assess accommodative and vergence responses of 26 adult emmetropes (AE) and 94 children (0-13 years) viewing cartoons. Children were habitually uncorrected (CU) (spherical equivalent refractive error [SE] -0.5 to +4 D), corrected and aligned (CCA), or corrected with a history of refractive esotropia (CCS). Accommodative and vergence accuracy, dissociated heterophoria, and vergence/accommodation ratios in the absence of retinal disparity cues were measured for 33- and 80-cm viewing distances. In binocular viewing, median accommodative lags for 33 cm were 1.0 D (AE), 1.33 D (CU), 1.25 D (CCA), and 1.0 D (CCS). Median exophorias at 80 and 33 cm were 1.2 and 4.5 pd (AE), 0.8 and 2.5 pd (CU), and 0 and 1.2 pd (CCA), respectively. Without disparity cues, most response vergence/accommodation ratios were between 1 and 2 meter angle/D (∼5-10 pd/D) (69% of AE, 44% of CU, 60% of CCA, and 50% of CCS). Despite apparent conflict in motor coupling, uncorrected hyperopes were typically exophoric and achieved adultlike accuracy of both vergence and accommodation simultaneously, indicating ability to compensate for conflicting demands rather than bias to accurate vergence while tolerating inaccurate accommodation. Large lags and esophoria are therefore atypical. This analysis provides normative guidelines for clinicians and a deeper mechanistic understanding of how hyperopes avoid strabismus.