Association between body stature with ocular biometrics and refraction among Chinese preschoolers.

PURPOSE: To evaluate the association of body stature with ocular biometrics and refraction in preschool children. METHODS: A cross-sectional, school-based study was conducted in Shenzhen, China. Preschool children aged 3 to 6 from 10 randomly-selected kindergartens were recruited. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), corneal radius curvature (CR), axial length to corneal radius ratio (AL-to-CR ratio) and lens thickness (LT) were measured using non-contact partial-coherence laser interferometry. Cycloplegic refractions were obtained by a desktop autorefractor. Body height and weight were measured using standard procedures. The association between body stature and ocular biometrics were analyzed with univariable and multivariable regression model. RESULTS: A total of 373 preschoolers were included. AL, ACD, VCD, CR, and AL-to-CR ratio, were positively associated with height and weight (p < 0.05), whereas LT was negatively associated with height and weight (p < 0.01). No association was observed between stature and central cornea thickness and refraction. After adjusted for age and gender in a multivariable regression model, AL had positive associations with height (p < 0.01) and weight (p < 0.01). However, refraction had no significant association with stature parameters. CONCLUSION: Taller and heavier preschoolers had eyes with longer AL, deeper vitreous chamber, and flatter cornea. The significant associations between body stature and ocular biometric parameters reveal the driving influence of body development on the growth of eyeballs in preschoolers.

Long-Term Risk and Prediction of Progression in Primary Angle Closure Suspect.

Importance: Identifying primary angle closure suspect (PACS) eyes at risk of angle closure is crucial for its management. However, the risk of progression and its prediction are still understudied in long-term longitudinal studies about PACS. Objective: To explore baseline predictors and develop prediction models for the 14-year risk of progression from PACS to primary angle closure (PAC). Design, Setting, and Participants: This cohort study involved participants from the Zhongshan Angle Closure Prevention trial who had untreated eyes with PACS. Baseline examinations included tonometry, ultrasound A-scan biometry, and anterior segment optical coherence tomography (AS-OCT) under both light and dark conditions. Primary angle closure was defined as peripheral anterior synechiae in 1 or more clock hours, intraocular pressure (IOP) greater than 24 mm Hg, or acute angle closure. Based on baseline covariates, logistic regression models were built to predict the risk of progression from PACS to PAC during 14 years of follow-up. Results: The analysis included 377 eyes from 377 patients (mean [SD] patient age at baseline, 58.28 [4.71] years; 317 females [84%]). By the 14-year follow-up visit, 93 eyes (25%) had progressed from PACS to PAC. In multivariable models, higher IOP (odds ratio [OR], 1.14 [95% CI, 1.04-1.25] per 1-mm Hg increase), shallower central anterior chamber depth (ACD; OR, 0.81 [95% CI, 0.67-0.97] per 0.1-mm increase), and shallower limbal ACD (OR, 0.96 [95% CI, 0.93-0.99] per 0.01 increase in peripheral corneal thickness) at baseline were associated with an increased 14-year risk of progression from PACS to PAC. As for AS-OCT measurements, smaller light-room trabecular-iris space area (TISA) at 500 µm from the scleral spur (OR, 0.86 [95% CI, 0.77-0.96] per 0.01-mm2 increase), smaller light-room angle recess area (ARA) at 750 µm from the scleral spur (OR, 0.93 [95% CI, 0.88-0.98] per 0.01-mm2 increase), and smaller dark-room TISA at 500 µm (OR, 0.89 [95% CI, 0.80-0.98] per 0.01-mm2 increase) at baseline were identified as predictors for the 14-year risk of progression. The prediction models based on IOP and central and limbal ACDs showed moderate performance (area under the receiver operating characteristic curve, 0.69; 95% CI, 0.63-0.75) in predicting progression from PACS to PAC, and inclusion of AS-OCT metrics did not improve the model's performance. Conclusions and Relevance: This cohort study suggests that higher IOP, shallower central and limbal ACDs, and smaller TISA at 500 µm and light-room ARA at 750 µm may serve as baseline predictors for progression to PAC in PACS eyes. Evaluating these factors can aid in customizing PACS management.

Iris volume change with physiologic mydriasis to identify development of angle closure: the Zhongshan Angle Closure Prevention Trial.

AIMS: To assess dynamic change of iris area (Iarea) and volume (VOL) with physiologic pupil dilation for progression of primary angle closure suspects. METHODS: Participants underwent baseline examinations including gonioscopy and anterior segment OCT (AS-OCT) as part of the Zhongshan Angle Closure Prevention Trial. The AS-OCT images were obtained both in the dark and light. Progression was defined as development of primary angle closure or an acute angle closure attack. Static ocular biometrics and dynamic changes were compared between progressors and non-progressors and multivariable logistic regression was developed to assess risk factors for progression. RESULTS: A mean 16.8% decrease in Iarea and a mean 6.26% decrease in VOL occurred with pupil dilation, while 22.96% non-progressors and 40% progressors presented VOL increases with pupil dilation. Iarea in light and dark and VOL in light were significantly smaller in progressors. In a multivariable logistic model, older age (p=0.008), narrower horizontal angle opening distance (AOD) 250 µm from the scleral spur (AOD250, p=0.001), flatter iris curvature (IC, p=0.006) and lower loss of iris volume (ΔVOL, p=0.04) were significantly associated with progression. With receiver operating characteristic analysis, the area under the curve for ΔVOL alone was 0.621, while that for the combined index (age, AOD250, IC and ΔVOL) was 0.824. Eyes with elevated intraocular pressure had less VOL loss compared with progressors developing peripheral anterior synechiae alone (p=0.055 for ΔVOL adjusted for pupil enlargement). CONCLUSION: A smaller change in ΔVOL is an additive risk factor to identify eyes more likely to develop angle closure disease. TRIAL REGISTRATION NUMBER: ISRCTN45213099.

The Impact of Pharmacological Dilation on Intraocular Pressure in Primary Angle Closure Suspects.

PURPOSE: To assess changes in intraocular pressure (IOP) 1 hour after pharmacological dilation in eyes treated with laser peripheral iridotomy (LPI) and untreated fellow eyes of primary angle closure suspects (PACS). DESIGN: A prospective randomized, fellow-eye controlled trial. METHODS: A total of 889 participants with PACS aged 50 to 70 years with LPI in 1 randomly selected eye and a fellow untreated eye were included. All participants underwent comprehensive examinations before and at 2 weeks, 6 months, 18 months, 36 months, 54 months, and 72 months after LPI. The IOP was measured using Goldmann applanation tonometry before and 1 hour after pharmacological dilation. RESULTS: The mean predilation IOP in the untreated eyes was 14.8 ± 2.7 mm Hg, which increased to 16.4 ± 2.7 mm Hg after pharmacological dilation (P < .001). The treated and untreated eyes had similar predilation and postdilation IOP (all P > 0.05). The average postdilation IOP elevation was 1.5 mm Hg in the treated eyes and 1.6 mm Hg in the untreated eye, without significant differences (P = .802). Lower predilation IOP (P < .001), smaller AOD500 (P = 0.001), smaller ARA500 (P = .030), smaller TISA500 (P = .043), and larger Iarea (P < 0.001) were associated with postdilation IOP elevation of 5 mm Hg and greater. Three untreated eyes (1.04 per 1000 pupil dilation) and 1 treated eye (0.34 per 1000 pupil dilation) developed acute angle closure (AAC) after dilation during the 72-month follow-up. CONCLUSIONS: Postdilation IOP elevation was similar among treated and untreated eyes, and the risk of developing AAC was very low, even among patients with PACS. Routine LPI before pupil dilation for people with PACS is not recommended.

Who needs myopia control?

Myopia has become a major visual disorder among school-aged children in East Asia due to its rising prevalence over the past few decades and will continue to be a leading health issue with an annual incidence as high as 20%-30%. Although various interventions have been proposed for myopia control, consensus in treatment strategies has yet to be fully developed. Atropine and orthokeratology stand out for their effectiveness in myopia progression control, but children with rapid progression of myopia require treatment with higher concentrations of atropine that are associated with increased rates of side effects, or with orthokeratology that carries risk of significant complication. Therefore, improved risk assessment for myopia onset and progression in children is critical in clinical decision-making. Besides traditional prediction models based on genetic effects and environmental exposures within populations, individualized prediction using machine learning and data based on age-specific refraction is promising. Although emerging treatments for myopia are promising and some have been incorporated into clinical practice, identifying populations who require and benefit from intervention remains the most important initial step for clinical practice.

Long-term effect of YAG laser iridotomy on corneal endothelium in primary angle closure suspects: a 72-month randomised controlled study.

PURPOSES: To evaluate the effect of YAG laser peripheral iridotomy (LPI) on corneal endothelial cell density (ECD) and morphology in primary angle closure suspects (PACS) over 72 months. METHODS: The Zhongshan Angle Closure Prevention Trial is a single-centre randomised controlled trial. Subjects with bilateral PACS received YAG LPI prophylactic treatment in one eye randomly, while the fellow eye served as control. Central corneal ECD and morphology were assessed using non-contact specular microscopy (SP-2000P, Topcon) at baseline, 6, 18, 36, 54 and 72 months postoperatively. Mixed model analysis was conducted to compare the difference between treated and fellow eyes. RESULTS: A total of 875 participants were included, with a mean age of 59.3±5.0 years and 83.5% female. The ECD declined significantly (p<0.001) over time in both treated and fellow eyes, but the treated eyes showed more progressive cell loss with increasing time (p<0.001). The difference in ECD loss between LPI-treated and fellow eyes was not significant at each follow-up until 72 months (4.9% in LPI eyes vs 4.2% in non-LPI eyes, p=0.003). Mean cell areas increased significantly over time in both treated and fellow eyes (p<0.001), but no longitudinal change was observed for hexagonality. In LPI-treated eyes, no significant correlation was found between age, gender, ocular biometrics, intraocular pressure and laser settings with endothelium change, except for time effect (p<0.01). CONCLUSION: ECD decreases over time primarily due to ageing effect. YAG LPI does not appear to cause clinically significant corneal endothelial damage over 72 months after treatment. TRIAL REGISTRATION NUMBER: ISRCTN45213099.

Visual impairment in highly myopic eyes: The ZOC-BHVI High Myopia Cohort Study.

IMPORTANCE: Understanding visual impairment (VI) under different definitions and potential risk factors in high myopic is important for future myopia control. BACKGROUND: Limited studies exists investigating the VI among high myopic and with varying VI definitions. DESIGN: Registry cohort study. PARTICIPANTS: Eight hundred and eighty-four participants were from ZOC-BHVI study. METHODS: Subjects aged 7 to 70 years with high myopia were enrolled. Uncorrected visual acuity and best-corrected visual acuity (UCVA and BCVA), cycloplegic refraction, axial length (AL), corneal curvatures, anterior chamber depth and lens thickness were measured. Axial length/corneal radius of curvature ratio (AL/CR ratio) was calculated. Fundus lesions were graded into five categories. VI and blindness were defined based on the better-seeing eye according to the World Health Organization (WHO) criteria and US criteria. Multiple logistic regression analysis was used to assess risk factors for VI. MAIN OUTCOME MEASURES: Rates of VI and blindness. RESULTS: A total of 884 participants were included, with mean (SD) age 18.5 (12.4) years and 46.4% male. Rate of UCVI/blindness were 72.6%/27.3% and 17.9%/82.1% based on WHO and US criteria. With respect to BCVA, 4.1%/5.9% of participants had BCVI using two definitions, whereas the rate for blindness was 0.2% and 0.6%. After adjusting confounders, multiple logistic regression showed that more severe fundus lesions, greater AL/CR ratio were at a higher risk of being VI, both in two definitions (P < .005). CONCLUSIONS AND RELEVANCE: The rate of VI and blindness in highly myopic patients varies significantly using different definition. Severe fundus lesions and greater AL/CR ratios were associated with a higher risk of VI.

Effects of corneal crosslinking on corneal shape stabilization after orthokeratology.

Orthokeratology (Ortho-K) works to reshape cornea and is the only non-surgical way to enable vision without corrective aids. However, its effect is only temporary, and successful stabilization requires ongoing Ortho-K wear to maintain the reshaping effect. Corneal crosslinking (CXL) is a commonly-used technique in clinical practice to stabilize corneal shape in keratoconic eyes. However, whether or not CXL can stabilize corneal shape after Ortho-K in normal cornea has not been reported. Therefore, this proof-of-concept study using 2 rhesus monkeys aimed to determine the efficacy of the combined procedure. One monkey wore Ortho-K bilaterally for 24 hours, and the other from 6 pm to 8 am for 7 days. The left eyes of both monkeys underwent CXL after Ortho-K while the contralateral eye served as control. Results showed a gradual regression of corneal shape in all eyes with or without CXL. However, eyes underwent CXL regressed more slowly than the control eyes. The control eyes and the CXL treatment eye in the 7-day Ortho-K monkey regressed completely at last, while the CXL treatment eye in the 24 h Ortho-K monkey maintained a corneal flattening of -1.48 D 27 days after procedure. These findings suggest CXL can slow the regression of Ortho-K for a short duration, but cannot sustain its effect according to the current protocol.

Visual span and cognitive factors affect Chinese reading speed.

Visual span, which is the number of recognizable letters seen without moving the eyes, has been proven to impose a sensory limitation for alphabetic reading speed (Chung, 2011; Chung, Legge, & Cheung, 2004; Lee, Kwon, Legge, & Gefroh, 2010; Legge, Ahn, Klitz, & Luebker, 1997; Legge, Hooven, Klitz, Stephen Mansfield, & Tjan, 2002; D. Yu, Cheung, Legge, & Chung, 2010). However, little is known about the effects of visual span on Chinese reading performance. Of note, Chinese text differs greatly from that of the alphabetic writing system. There are no spaces between words, and readers are forced to utilize their lexical knowledge to segment Chinese characters into meaningful words, thus increasing the relative importance of cognitive/linguistic factors in reading performance. Therefore, the aim of the present study is to explore whether visual span and cognitive/linguistic factors have independent effects on Chinese reading speed. Visual span profiles, cognitive/linguistic factors indicated by word frequency, and Chinese sentence-reading performance were collected from 28 native Chinese-speaking subjects. We found that the visual-span size and cognitive/linguistic factors independently contributed to Chinese sentence-reading speed (all ps < 0.05). We concluded that both the visual-span size and cognitive/linguistic factors represented bottlenecks for Chinese sentence-reading speed.

Role of Parental Refractive Status in Myopia Progression: 12-Year Annual Observation From the Guangzhou Twin Eye Study.

Purpose: We investigate the impact of parental myopia on spherical equivalent (SE) progression and axial length (AL) elongation. Methods: Children and their parents were invited for annual examinations from 2006 (baseline). Cycloplegic autorefraction and AL were measured at each visit. Parental refractive status was determined using refraction data from their baseline visit. Children were classified into five groups: no myopic parents (non-non), only one moderately myopic parent (non-moderate), only one highly myopic parent (non-high), two moderately myopic parents (moderate-moderate), and one moderately myopic or more severe and one highly myopic parent (moderate-high/high-high). The relationship between progression of SE and AL with parental refractive status was estimated by linear mixed-effects models. Data from 2006 to 2017 were analyzed in the current study. Results: A total of 1831 children were enrolled (mean age, 11 ± 2.7 years; mean standard error, -0.49 ± 2.16 diopters [D] at baseline. Myopia progressed faster for children with parental myopia (non-non group as reference, all P < 0.05), while AL elongation mirrored the change in SE (all P < 0.001 except for non-mod group P = 0.12). As for the age-specific change in SE and AL, children in the mod-high/high-high group presented with the fastest progression. Children with highly myopic parents were at higher risks of being highly myopic during adulthood (odds ratio = 13.98 and 25.71 for non-high and mod-high/high-high groups; both P < 0.001). Conclusions: SE progresses and AL elongates at a faster rate at an earlier age in children with parental myopia. Children with highly-myopic parents have higher risks of being highly myopic during adulthood.