Eyecharts are essential diagnostic tools used in ophthalmology to assess visual acuity and screen for refractive errors, amblyopia, and other vision impairments. The classic Snellen chart features 11 rows of progressively smaller block letters (optotypes like E, F, or N), tested at 6 meters (20 feet), where 6/6 denotes normal vision. Variants include LogMAR for precise research measurements, Jaeger for near vision, Tumbling E for children or non-readers, and Lea Symbols with shapes like houses or circles for pediatric use. Wall-mounted, digital, or illuminated versions ensure standardized lighting and randomization to prevent memorization. These charts guide prescriptions, monitor treatment efficacy, and support early detection in clinics worldwide.