Prevalence and Characteristics of Peripapillary Gamma Zone in Children With Different Refractive Status: The Hong Kong Children Eye Study.

Purpose: This study aimed to assess the prevalence and characteristics of the peripapillary gamma zone in myopic, emmetropic, and hyperopic eyes of Chinese children. Methods: Overall, 1274 children aged 6 to 8 years from the Hong Kong Children Eye Study underwent ocular examinations, including measurements of cycloplegic auto-refraction and axial length (AL). The optic disc was imaged using a Spectralis optical coherence tomography (OCT) unit and a protocol involving 24 equally spaced radial B-scans. The Bruch's membrane opening (BMO) was identified in over 48 meridians in each eye. The peripapillary gamma zone was defined as the region between the BMO and the border of the optic disc, identified by the OCT. Results: The prevalence of the peripapillary gamma zone was higher in myopic eyes (36.3%) than in emmetropic (16.1%) and hyperopic eyes (11.5%, P < 0.001). AL (per 1 mm; odds ratio [OR]) = 1.861, P < 0.001) and a more oval disc shape (OR = 3.144, P < 0.001) were associated with the presence of a peripapillary gamma zone after adjusting for demographic, systemic, and ocular variables. In the subgroup analysis, a longer AL was associated with the presence of a peripapillary gamma zone in myopic eyes (OR = 1.874, P < 0.001), but not in emmetropic (OR = 1.033, P = 0.913) or hyperopic eyes (OR = 1.044, P = 0.883). A peripapillary zone was not observed in the region nasal to the optic nerve in myopic eyes, in contrast to its presence in the same region in 1.9% of emmetropic eyes and 9.3% of hyperopic eyes; these intergroup differences were statistically significant (P < 0.001). Conclusions: Although peripapillary gamma zones were observed in the eyes of both myopic and non-myopic children, their characteristics and distribution patterns were substantially different.

Association of Maternal and Paternal Astigmatism With Child Astigmatism in the Hong Kong Children Eye Study.

Importance: Parental astigmatism is a factor associated with risk for development of child astigmatism; however, the magnitude of the association has not been determined. Objective: To determine the association between parental and child astigmatism. Design, Setting, and Participants: This population-based, cross-sectional study included participants from familial trios, each comprising a child aged 6 to 8 years and both parents, recruited from the Hong Kong Children Eye Study. No restriction criteria were set on the children in terms of refractive status. Data were analyzed from February to June 2022. Exposures: Cycloplegic autorefraction and autokeratometry were conducted on the children, whereas noncycloplegic autorefraction and autokeratometry were conducted on their parents. The children were categorized into 6 groups on the basis of the severity of astigmatism of both parents. Information on parental education, family income, and children's outdoor and near work time were obtained by questionnaires. Main Outcomes and Measures: The primary outcome was the odds of child astigmatism among the 6 categories of children. Associations of factors with child astigmatism were evaluated by logistic regression analyses. Results: A total of 17 124 participants from 5708 trios (2964 boys and 2754 girls) at a mean (SD) age of 7.32 (0.87) years, and 11 416 parents were examined. Astigmatism of 1.0 D or greater in both parents was associated with greater odds of refractive astigmatism (RA) (odds ratio [OR], 1.62; 95% CI, 1.15-2.26) and corneal astigmatism (CA) (OR, 1.94; 95% CI, 1.50-2.50) in the child. The respective ORs increased to 3.10 (95% CI, 1.34-7.21) and 4.31 (95% CI, 1.76-10.55) when both parents had astigmatism 2.0 D or greater. Higher parental astigmatism conferred higher risks for both RA and CA in children (P for trend <.001). Parental astigmatism was significantly associated with greater odds of corresponding child astigmatism (maternal RA: OR, 0.76; 95% CI, 0.68-0.84; paternal RA: OR, 0.82; 95% CI, 0.74-0.91; maternal CA: OR, 1.70; 95% CI, 1.51-1.93; paternal CA: OR, 1.33; 95% CI, 1.19-1.49). Conclusions and Relevance: The findings of this cross-sectional study suggest that parental astigmatism may confer an independent and dose-dependent association with child astigmatism. Children with parents with astigmatism should have early eye examinations for timely detection of astigmatism to facilitate age-appropriate vision correction and visual development.