Preprint · Jul 8, 2026
Cataract Surgery and Cognitive Trajectories: A Multi-Cohort International Study
By Liu H
## Purpose Cataract surgery is the most commonly performed surgical procedure worldwide. Lee et al. (JAMA Internal Medicine, 2022) reported that cataract surgery was associated with a 29% lower risk of dementia (HR = 0.71). However, subsequent studies using alternative causal methods have yielded conflicting results (Joo et al., JAGS, 2025). This study provides the most rigorous test to date of whether cataract surgery alters cognitive trajectories, using: 1. Piecewise linear mixed-effects models (within-person design) 2. Staggered-adoption difference-in-differences (independent validation) 3. Negative control exposures (glaucoma surgery, hearing aid adoption) 4. Comprehensive sensitivity analyses (competing risk of death, E-values, practice effects) 5. Multi-cohort replication (HRS → ELSA → SHARE) ## Primary Hypothesis Cataract surgery is not associated with slower cognitive decline when proper control for age, practice effects, and within-person confounding is applied. ## Cohorts - HRS (US, 1992-2022, ~26,500 adults aged 50+) - ELSA (UK, 2002-2024, ~21,700 adults aged 50+) - SHARE (Europe, pending data access) ## Statistical Analysis Plan The full SAP (v3.1) and pre-registration document are attached. Primary estimand is the post-surgery cognitive slope (γ₂₀) from piecewise linear mixed-effects models, pooled across cohorts via random-effects meta-analysis.