This video presents dark adaptometry as a non-invasive functional test that assesses the retina’s ability to recover sensitivity in low-light conditions following photobleaching. This video explores the physiological mechanisms underlying dark adaptation (DA), including photopigment regeneration and the critical role of the retinal pigment epithelium in the visual cycle. This video details clinical protocols for dark adaptometry using modern instruments such as the AdaptDx, highlighting methodological advances that improve testing efficiency and reproducibility. The clinical utility of dark adaptometry is examined in this video across a range of inherited and acquired retinal disorders, including age-related macular degeneration (AMD), retinitis pigmentosa (RP), Stargardt disease, diabetic retinopathy (DR), cone–rod dystrophy (CRD), vitamin A deficiency, and congenital stationary night blindness (CSNB). This video shows that dark adaptometry has emerged as a sensitive biomarker capable of detecting functional deficits before structural changes are evident, making it a valuable tool for early diagnosis and monitoring disease progression. However, this video also notes that limitations such as age-related variability, patient compliance, and lack of standardization remain challenges to broader clinical adoption. This video concludes that continued refinement of dark adaptometry protocols and instrumentation is essential to maximize its diagnostic potential in ophthalmic practice.