Axial length-stratified cataract phenotypes revealed by automated lens density quantification from IOL Master 700

Background: To evaluate automated lens average density from IOL Master 700 as a quantitative supplementary measure for cataract assessment, and whether cataract phenotypes and risk profiles differ by axial length (AL). Methods: This retrospective cross-sectional study enrolled 2000 participants; 1906 eyes were analyzed after excluding poor images and ocular pathologies. A Python-OpenCV pipeline automatically extracted lens luminance parameters. Diagnostic performance, repeatability, and biometric associations were assessed using receiver operating characteristic, intraclass correlation coefficient (ICC), and regression analyses. Results: Lens average density showed excellent diagnostic performance (area under the curve = 0.975, 95% confidence interval: 0.969–0.981; cutoff = 68.66; sensitivity 88.5%, specificity 94.4%), correlating well with Lens Opacities Classification System III nuclear opalescence ( ρ = 0.804). It had excellent repeatability (inter-technician ICC = 0.935, coefficient of variation [CV] = 1.85%; inter-time ICC = 0.928, CV = 1.99%). Among cataract patients, nuclear cataract was significantly more frequent in AL ≥26 mm eyes (83.21% vs. 39.83%, P < 0.001). Multivariable logistic regression identified age (odds ratio [OR] = 1.104/year), AL (OR = 1.360/mm), anterior aqueous depth (AQD) (OR = 0.275/mm), and lens thickness (LT) (OR = 2.013/mm) as independent predictors (all P < 0.001). Critically, risk factor profiles diverged by AL: in the non-high myopia group (AL <26 mm), AQD and LT were core predictors, whereas in the high myopia group (AL ≥26 mm), AL and white-to-white (WTW) distance emerged as principal indicators, with LT conferring seven-fold increased odds (OR = 7.012). Conclusions: Automated lens average density provides a reliable, objective biomarker, which enables AL-stratified cataract risk management—prioritize AQD and LT in the non-high myopia group, and AL and WTW distance in the high myopia group, for earlier nuclear cataract detection before vision loss.