Background To assess prevalence and associated factors of changes in the ophthalmoscopic optic disc size and shape.
Methods The case–control study included all highly myopic eyes (myopic refractive error ≤−6.0 diopters) and a randomly selected group of non-highly myopic eyes, examined in the population-based Beijing Eye Study 2001 and 2011.
Results The study included 89 highly myopic eyes (age:65.0±9.8 years) and 86 non-highly myopic eyes. Reduction in ophthalmoscopic disc size (prevalence, high myopia: 30 (33.7%) eyes; non-high myopia: 7 (8.1%) eyes) was associated with non-circular gamma zone enlargement (OR: 19.4; 95% CI: 6.7 to 56.6; p<0.001) and disc-fovea line elongation (OR: 2.80;95% CI: 1.12 to 6.98; p=0.03). Disc size reduction was correlated with a disc diameter shortening in direction of the widest gamma zone enlargement (correlation coefficient r=34; p=0.01). The perpendicular disc diameter remained mostly unchanged, resulting in an ovalisation of the ophthalmoscopic disc shape. Enlargement of the ophthalmoscopic disc size (prevalence, high myopia: 22 (24.7%) eyes; non-high myopia: 4 (4.7%) eyes) was associated with circular gamma zone enlargement (4.99; 95% CI: 1.95 to 12.8; p=0.001) and high myopia (OR: 4.29; 95% CI: 1.34 to 13.8; p=0.01).
Conclusions Myopic axial elongation may lead first to a Bruch’s membrane (BM) opening (BMO) shift into the foveal direction leading to BM overhanging into the nasal intrapapillary compartment, development and enlargement of gamma zone at the temporal disc side, reduction in the ophthalmoscopically visible disc area and ovalisation of the ophthalmoscopic disc shape. In a second step, an axial elongation-associated BMO enlargement may lead to a circular gamma zone increase and, due to the retraction of BM at the nasal disc border, to an enlargement of the ophthalmoscopically visible optic disc.
- optic nerve
Data availability statement
Data are available on reasonable request.
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Contributors Design: JBJ, QZ, LX, WW, RAJ and YXW; Measurements: JBJ, QZ, LX, WW, RAJ and YXW; statistical analysis: JBJ, RAJ and YXW; first manuscript draft: JBJ and RAJ; approval of final draft: JBJ, QZ, LX, WW, RAJ and YXW;
Funding National Natural Science Foundation of China (#81570835); Beijing Municipal of Health Reform and Development Project (#2019-4).
Competing interests JBJ and RAJ: European patent application 16 720 043.5 and US patent application US 2019 0085065 A1: Agents for use in the therapeutic or prophylactic treatment of myopia or hyperopia). JBJ: Advisory Board Novartis; Patent holder with Biocompatibles UK. (Farnham, Surrey, UK) (Title: Treatment of eye diseases using encapsulated cells encoding and secreting neuroprotective factor and/or anti-angiogenic factor; Patent number: 20120263794), Patent application: Agents for the use in the therapeutic or prophylactic treatment of retinal pigment epithelium-associated diseases.
Provenance and peer review Not commissioned; externally peer reviewed.
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