Axial length versus spherical equivalent for early fundus tessellation in myopic eyes: across-sectional analysis of biometric indicators under axial length–spherical equivalentdiscordance

Tessellated fundus is a characteristic early lesion of myopic maculopathy. It remains unclear whether spherical equivalent (SE) or axial length (AL) plays a more important role in risk evaluation, particularly among eyes with AL–SE discordance. This cross-sectional study aimed to compare the independent effects of SE and AL on early fundus tessellation and explore informative biometric markers for early lesions in discordant subgroups. This cross-sectional observational study recruited 426 myopic patients (821 eyes). Participants were stratified into four subgroups using predefined cut-off values for SE (−6.00 D) and AL (26 mm). Two outcome definitions were applied for fundus tessellation: any tessellation (grade 0 vs grades 1–3) and moderate-to-severe tessellation (grades 0–1 vs grades 2–3). Generalized estimating equation (GEE) models were applied to account for inter-eye correlation. Three separate GEE models were constructed for AL, SE, and the AL-to-corneal radius ratio（AL/R）, respectively, with age and sex as covariates Multiplicative and additive interaction analyses were conducted to assess the interaction effect between AL and SE. Rates of any fundus tessellation and moderate-to-severe tessellation rose progressively from group 1 to group 4. AL, SE, and AL/R were independent risk factors for both endpoints (all P < 0.001). The odds ratios（OR） for AL and AL/R were marginally lower in analyses of moderate-to-severe lesions relative to models predicting any tessellation. We detected no statistically significant multiplicative or additive interaction between AL and SE. Subsequent stratified analyses showed that greater myopia severity was consistently linked to higher risks of tessellation across all AL subgroups. AL, SE, and AL/R are independently associated with macular fundus tessellation. No statistically significant multiplicative or additive interaction was detected between AL and SE in the current study sample. In eyes with mismatched AL and refraction, AL ≥ 26 mm and SE ≤ –6.00 D conferred comparable risk of tessellation, with no statistically significant difference between the two biometric risk markers.