Axial length defines distinct clinical phenotypes of primary rhegmatogenous retinal detachment: a study of 2645 eyes

Background To examine associations between fellow-eye axial length (AL) and clinical features at presentation in surgically treated primary rhegmatogenous retinal detachment (RRD). Methods This single-centre retrospective cohort study used routinely collected electronic medical record data from a tertiary ophthalmic referral centre in Guangzhou, China. It included 2645 surgically treated eyes with primary RRD and a recorded duration of visual loss of ≤31 days. Eyes were grouped into prespecified, pragmatic fellow-eye AL strata (<26 mm, 26–28 mm inclusive and >28 mm). Among 633 patients with macula-on RRD and bilateral measurements, fellow-eye and affected-eye AL were strongly correlated (r=0.872), with 95.1% of paired measurements differing by ≤0.70 mm. Adjusted associations were estimated using multivariable logistic regression. Results Each 1 mm increase in fellow-eye AL was associated with higher odds of total retinal detachment at presentation (OR 1.41), multiple retinal breaks (OR 1.13) and round-hole morphology (OR 1.20). In a model conditional on total retinal detachment, AL was also associated with choroidal detachment (OR 1.43). Giant retinal tear proportions were similar across AL strata, while retinal dialysis was uncommon (16 eyes) and showed no monotonic pattern. Conclusion Longer fellow-eye AL was associated with differences in detachment extent, retinal break characteristics and selected complications. Fellow-eye AL may, therefore, serve as a descriptive stratification variable for characterising clinical heterogeneity in primary RRD.