Ou Xiao

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.

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.

Prevalence of age-related macular degeneration in rural southern China: the Yangxi Eye Study

Purpose To describe the prevalence of age-related macular degeneration (AMD) among older adults in rural southern mainland China. Methods Eligible persons aged 50 years or over were identified by geographically defined cluster sampling from Yangxi County, Guangdong Province, China. Participants underwent a standardised interview and comprehensive eye examinations from August to November in 2014. Digital retinal photographs were graded for AMD lesions using the Clinical Classification of Age-Related Macular Degeneration developed by the Beckman Initiative for Macular Research Classification Committee. Age-standardised prevalence of AMD and AMD lesions was calculated using the 2010 world population data and compared with those of other populations. Results Of 5825 subjects who participated (90.7% response rate), 4881 (83.8%) had fundus photographs gradable for AMD. Early, intermediate and late AMD were present in 2003 (41.0%), 879 (18.0%) and 42 (0.86%) participants. The age-standardised prevalence of early, intermediate and late AMD was 40.4% (95% CI 39.6% to 41.2%), 17.6% (95% CI 17.0% to 18.2%) and 0.79% (95% CI 0.65% to 0.95%), respectively. Total AMD was more prevalent in men than in women (62.8% vs 57.1%). Conclusions AMD is an important public health concern for rural southern China, and the prevalence of AMD was higher in men than in women.

Wide-Field En Face Swept-Source Optical Coherence Tomography Features of Extrafoveal Retinoschisis in Highly Myopic Eyes

Purpose To evaluate the features of extrafoveal retinoschisis (EFRS) in highly myopic eyes detected by swept-source optical coherence tomography (SS-OCT). Methods In this retrospective case series, 89 eyes of 65 patients with high myopia and coexisting EFRS were included. The participants underwent a comprehensive ophthalmologic examination, including visual acuity, ocular biometry, refraction, and perimetry. Three-dimensional wide-field scans were obtained with SS-OCT, and en face images were reconstructed with custom software. En face OCT features of EFRS were determined by two ophthalmologists masked to clinical characteristics. The associations of EFRS subtypes with ocular biometry and other OCT changes were evaluated as well. Results In wide-field SS-OCT scans, EFRS was classified into three different types, the inner limiting membrane (ILM) detachment and inner and outer EFRS, according to the specific layer of the splitting. All these three types were most frequently distributed in the inferotemporal quadrant (71.2% for ILM detachment, 59.5% for inner EFRS, and 75.0% for outer EFRS). Inner limiting membrane detachment and inner EFRS were often adjacent to peripapillary atrophy. Outer EFRS tends to coexist with inner EFRS, as we did not observe any case with standalone outer EFRS or with coexisting with ILM detachment. Eyes with all three types combined had the longest axial length (29.1 ± 1.26 mm, P = 0.003) and the greatest refractive error (-13.0 ± 2.86 diopters [D], P = 0.014). The incidence of retinal microfolds and breaks among subgroups was significantly different (P = 0.012 and 0.003, respectively). Staphyloma was associated with outer EFRS (30.6% with versus 7.6% without outer EFRS). Conclusions Wide-field SS-OCT reveals the spatial distribution of retinoschisis outside the fovea, and associations with retinal vessels and other retinal landmark structures. Further observations on the longitudinal changes and functional damage would help lead to a better understanding of its mechanism and prognosis.

Qualitative and quantitative assessment of posterior segment optical coherence tomography images using standard photos: the Liwan Eye Study.

Background/aims To develop a standardised grading scheme, using standard photos, for spectral-domain ocular coherence tomography (SD-OCT) images of the posterior eye and evaluate the interobserver agreement among trained ophthalmologists in identifying pathological changes. Methods Subjects were recruited from Liwan District, Guangzhou, with SD-OCT data collection from June 2013 to November 2013 as part of 10-year follow-up visits from the Liwan Eye Study. All subjects underwent SD-OCT imaging of the macula with scanning lines analysed by two ophthalmologists to assess for the presence of 12 different posterior segment lesions. Per cent agreement for each lesion between the graders and quantitative measures of dome-shaped macula (DSM) height and choroidal thickness were calculated. Results A total of 679 SD-OCT images from 679 subjects were independently evaluated by the two graders. Each of the 12 lesions was successfully graded as present or absent in over 96% of images. For all lesions, per cent agreement between observers was over 90%, ranging from 90.7% for epiretinal membranes and retinal pigment epithelium thickenings to 99.7% for full thickness macular holes and retinal detachments. Quantitative measurements of DSM height and choroidal thickness at three locations of the eye all exhibited intraclass correlation scores between the two graders of greater than 0.9. Conclusion Our study demonstrates high concordance between graders in characterising posterior segment lesions using SD-OCT images, validating the continued use of this imaging modality in the diagnosis of posterior eye disease.