Aging-Related Choroidal Heterogeneity and Loss: An Investigative Global Human Choroidal Thickness Review (ARCHLIGHT Study).

PURPOSE: To synthesize current evidence on the pathophysiology, clinical relevance, and implications for age-related choroidal thinning. METHODS: A systematic literature search of relevant publications was conducted across MEDLINE, Embase, and Cochrane Library, up to and including May 2024. Identified studies reported choroidal thickness changes with aging. Data on subfoveal choroidal thickness, choroidal vascularity index, and associated factors (ethnicity, systemic disease, axial length) were analyzed (PROSPERO ID: CRD420251041101). RESULTS: Choroidal thickness declines with age, with ethnicity-specific rates ranging from -0.93 µm/year in Spanish cohorts to -4.00 µm/year in Chinese populations. Age-related choroidal thinning correlates with retinal and neurodegenerative pathologies, including glaucoma (nasal choroidal thinning >250 µm in older adult patients), myopic maculopathy (subfoveal choroidal thickness <100 µm in high myopia), and Alzheimer disease (subfoveal choroidal thickness 169 µm vs 253 µm in control patients). Enhanced depth imaging optical coherence tomography (OCT) and swept-source OCT reveal preferential vascular loss (choroidal vascularity index <30%) and stromal atrophy. Systemic risks, such as hypertension or smoking, accelerate choroidal thinning. CONCLUSIONS: Age-related choroidal thinning exists on a continuum between physiologic aging and pathology, with implications for retinal and systemic health. Future prospective studies will help determine diagnostic thresholds (subfoveal choroidal thickness <200 µm in nonmyopic adults >60 years or rapid thinning beyond ethnic normative values), management recommendations for high-risk cohorts (glaucoma, age-related macular degeneration, high myopia), and therapeutic considerations for monitoring of choroidal thickness changes from moderate- to low-certainty evidence.