Snellen chart
Snellen chart: history of visual acuity testing from Hooke to ETDRS, with key milestones, optotype design, and contributions from Snellen, Donders, Sloan
Tag ETDRS chart
Louise Sloan
Louise L. Sloan (1898–1982) developed Sloan optotypes (LogMAR), pioneering colour vision screening, perimetry, and low-vision rehabilitation