• We compared visual acuity with visual field radius in 235 patients with typical retinitis pigmentosa and no evidence of other visual acuity-limiting problems (such as cataract or foveal cystoid edema). Results show a strong relationship between visual acuity loss and proximity to the fovea of the visual field border (shortest distance from the foveal center to the border of the V-4-e isopter) for these patients. Ninety-six percent of patients with central visual field radii greater than 30° have visual acuities of 20/40 or better; 32° of patients with central visual field radii smaller than 10° have visual acuity of 20/40 or better.
Madreperla SA, Palmer RW, Massof RW, Finkelstein D. Visual Acuity Loss in Retinitis PigmentosaRelationship to Visual Field Loss. Arch Ophthalmol. 1990;108(3):358-361. doi:10.1001/archopht.1990.01070050056030