Purpose To explore the prevalence and associated factors of parapapillary scleral ridges (PSRs).

Methods Out of the cohort of the population-based Beijing Eye Study (n=3468 participants), the study included all eyes with an axial length of ≥25 mm and a randomised sample of eyes with an axial length of <25 mm. Using optical coherence tomographic (OCT) images and fundus photographs, we examined the presence and height of PSRs, defined as a ridge-like structure located on the OCT scans in the parapapillary region.

Results The study cohort consisted of 366 eyes (314 individuals; mean age: 63.7±9.7 years). PSR prevalence increased from 0% in the non-myopic group to 3.8% (95% CI 0.3%, 7.3%) in moderately myopic group and 29.2% (95% CI 15.7%, 42.5%) in the highly myopic group. All PSRs were located in the temporal parapapillary gamma zone and corresponded to an ophthalmoscopically visible demarcation line running almost parallel to the optic disc border. Higher PRS prevalence correlated with longer axial length (OR 2.98; 95% CI 1.99, 4.46; p<0.001), female sex (OR 6.48; 95% CI 1.56, 27.0; p=0.01) and older age (OR 1.09; 95% CI 1.01, 1.18; p=0.02). Axial length had the strongest influence (beta: 0.48), followed by sex (beta: 0.20) and age (beta: 0.14). If age was dropped from the multivariable model, myopic maculopathy prevalence (OR 10.0; 95% CI 1.41,70.9; p=0.02) and stage (OR 3.57; 95% CI 1.21, 10.6; p=0.02) became significantly correlated with higher PSR prevalence.

Conclusions With a PSR prevalence of >60% in eyes with an axial length of >28 mm, PSRs are a common morphological feature of high myopia, with age and female sex as additional associated factors. PSRs may be due to a biomechanical interplay between the optic nerve and the posterior ocular segment of markedly axially elongated eyes.