Decai Wang

Longitudinal Changes of Axial Length and Height Are Associated and Concomitant in Children

PURPOSE To examine the association between the longitudinal changes of axial length (AL) and height in Chinese children. METHODS The study participants were recruited from the Guangzhou Twin Registry. AL and height were measured every year from 2006 to 2008. AL was measured using partial coherence laser interferometry. Height was measured with the participants standing without shoes. Bivariate correlation coefficients and a multivariate generalized regression model were used to calculate the association between the changes of AL and height. Data from the first-born twins were selected to present the results: The right eye was arbitrarily selected to represent AL of the specific individual. RESULTS Mean annual increases of AL and height were 0.22 (SD, 0.17) mm and 3.93 (SD, 3.02) cm, respectively. Correlations between AL and height were 0.47 (95% CI, 0.40-0.52) in 2006. The correlation between AL at 2006 and height at 2008 was 0.44 (95% CI, 0.37-0.51); the correlation between AL at 2008 and height at 2006 was 0.38 (95% CI, 0.32-0.45). These cross-trait cross-time correlation coefficients remained statistically significant after adjusting for age and sex. Plotting the changes of AL and height suggested that the changes of AL and height with age were concomitant; greater changes were observed in younger children. CONCLUSIONS The association between AL and height in cross-sectional analysis and longitudinal changes may suggest common pathways for the development of eye size and body size in children.

Distribution and Heritability of Peripheral Eye Length in Chinese Children and Adolescents: The Guangzhou Twin Eye Study

PURPOSE Peripheral eye length (PEL) provides a measure of overall eye shape, which may play a role in the development of myopia. The current study explores the distribution and heritability of PEL, relative PEL (RPEL, defined as PEL minus axial eye length) and relative ratio PEL (RRPEL, defined as PEL divided by axial eye length) in Chinese children and adolescents. METHODS Subjects included both male and female youths participating in the Guangzhou Twin Eye Study. Eye length was measured by partial coherence laser interferometry axially, 40° temporally (PEL-T(40)) and 40° nasally (PEL-N(40)). Structural equation modeling (SEM) was used to estimate the relative contribution of genetic and environmental factors on PEL, RPEL, and RRPEL, adjusting for age and sex. RESULTS We examined 104 monozygotic (MZ) and 54 dizygotic (DZ) twins aged 8 to 20 years old. The intraclass correlation coefficients were 0.89 for PEL-T(40), 0.92 for PEL-N(40), 0.80 for RPEL-T(40), 0.73 for RPEL-N(40), 0.77 for RRPEL-T(40), and 0.73 for RRPEL-N(40) in MZ pairs, and 0.52, 0.50, 0.39, 0.58, 0.37, and 0.58 in DZ pairs, respectively. The best fit adjusted models estimated that additive genetic effects accounted for approximately 86.2%, 89.8%, 79.9%, 75.5%, 77.1%, and 74.5% of the variance for the above mentioned traits, respectively, while dominant genetic effects and shared environmental factors were negligible. CONCLUSIONS Additive genetic effects had a substantial influence on phenotypic variation in PEL and RPEL, suggesting genetic rather than environmental factors play a major role in determining eye shape.

Perceived difficulty of various steps of manual small incision cataract surgery among trainees in rural China.

The perceived difficulty of steps of manual small incision cataract surgery among trainees in rural China was assessed.

Methodology of the ZOC-BHVI High Myopia Cohort Study: The Onset and Progression of Myopic Pathologies and Associated Risk Factors in Highly Myopic Chinese

ABSTRACT Purpose: The increasing prevalence of high myopia and its associated pathologies has raised challenges to ophthalmic services. This project aims to explore the onset and progression of myopic pathologies in highly myopic eyes through a prospective research cohort established in South China. Methods: Patients with high myopia (sphere ≤ −6.00 D) visiting the optometric clinic of Zhongshan Ophthalmic Center (ZOC) were invited to participate in the baseline examinations and follow-up visit over a 10-year period. People having secondary myopia, history of any refractive surgery, significant ocular media opacity, or other severe health problems were excluded. The measurements included visual acuity, ocular biometry, visual function, cycloplegic refraction, fundus imaging, ocular shape by MRI, blood tests and questionnaires. Results: A total of 890 participants completed the baseline examinations, with a mean age at baseline of 22.7 ± 12.4 years. The mean spherical equivalent at baseline was 10.13 ± 3.65 D, and the mean axial length (AL) was 27.52 ± 1.63 mm. The older subjects tended to have more severe myopia and longer ALs. Conclusion: The study will provide new knowledge on the relationship between high myopia and pathological changes such as myopic macular degeneration and staphyloma.

Desktop auxiliary apparatus for A-scan ultrasound: Repeatability and validity

PURPOSE: To evaluate the intraobserver repeatability and validity of biometric measurements with a newly developed auxiliary A‐scan ultrasound apparatus at a rural clinic. SETTING: Rural county hospital in China. DESIGN: Evaluation of diagnostic technology. METHODS: Patients awaiting surgery for age‐related cataract were consecutively enrolled for preoperative A‐scan biometric measurements. The applanation A‐scan was performed by 2 experienced nurses, with 1 using the conventional handheld method and the other using the new method with the auxiliary desktop apparatus. Two consecutive measurements were performed with each method. The 95% limits of agreement (LoA) and Bland‐Altman plot were used to assess and compare the intersession measurement repeatability between the 2 methods. RESULTS: Data for 75 eyes of 75 consecutive patients were available for analysis. The mean age of the patients was 74.3 years ± 7.4 (SD); 40.0% were men. The desktop method had a smaller standard deviation and coefficient of variance than the conventional handheld method for both measurement sessions. For intersession repeatability, the desktop method had a narrower 95% LoA range than the handheld method for all the biometry parameters. The axial length (AL) obtained with the desktop method was significantly longer than that with the handheld method (23.32 mm versus 23.14 mm; P<.01). CONCLUSION: The newly developed auxiliary device had better intraobserver repeatability and more accurate AL measurements than the conventional handheld method, making it a better option for preoperative biometric measurement of cataract patients. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Distribution and Severity of Myopic Maculopathy Among Highly Myopic Eyes

Purpose The purpose of this study was to document the distribution of the severity of myopic maculopathy in a cohort of highly myopic patients and to explore the associated risk factors. Methods A total of 890 Chinese highly myopes aged between 7 and 70 years (median age 19 years) and with spherical refraction -6.00 diopter (D) or worse in both eyes were investigated. All participants underwent detailed ophthalmic examination. Myopic maculopathy was graded into 5 categories according to the International Photographic Classification and Grading System using color fundus photographs: category 0, no myopic retinal lesions, category 1, tessellated fundus only; category 2, diffuse chorioretinal atrophy; category 3, patchy chorioretinal atrophy; category 4, macular atrophy. Category 2 or greater were further classified as clinically significant myopic maculopathy (CSMM). Results Data from 884 of 890 right eyes were available for analysis. The proportions of category 1, category 2, category 3, and category 4 were 20.0% (177 eyes), 20.2% (178 eyes), 2.6% (23 eyes), and 0.2% (2 eyes), respectively. The proportion of CSMM increased with more myopic refraction (odds ratio 1.57; 95% confidence interval: 1.46-1.68), longer axial length (odds ratio 2.97; 95% confidence interval: 2.50-3.53), and older age (40-70 years compared to 12-18 years, odds ratio 6.77; 95% confidence interval: 3.61-12.70). However, there was a higher proportion of CSMM in children aged 7 to 11 years than those aged 12 to 18 years (20.9% vs. 11.0%, P = 0.008). Conclusions Older age, more myopic refraction, and longer axial length were associated with more severe myopic maculopathy. Although CSMM was uncommon among younger participants, children with early-onset high myopia have a disproportionately increased risk.

Novel system for distant assessment of cataract surgical quality in rural China

This study aims to assess the quality of various steps of manual small incision cataract surgery and predictors of quality, using video recordings.