To the Editor.
—The recent article by Madreperla et al1 shows that the visual acuity in retinitis pigmentosa (RP) falls in rough association with the degree of visual field loss. However, I question the implication that the degree of visual field loss is directly related to, or determines, the risk of visual acuity loss. This article really only tells us that advanced disease is advanced.The term RP refers to a group of hereditary diseases that differ in severity, but all progress slowly over time. Every visual parameter that changes with age or with duration of disease will be "related" to every other such visual parameter, but this does not signify any direct pathophysiologic correlation. Both visual field loss and visual acuity in RP are known, on a statistical basis, to worsen with age (duration of disease), but also to be better preserved in the milder (eg, type II
Marmor MF. Visual Acuity and Field Loss in Retinitis Pigmentosa. Arch Ophthalmol. 1991;109(1):13. doi:10.1001/archopht.1991.01080010015006