• Visual acuity and contrast threshold functions of five patients with bilateral keratoconus were measured following optimal spectacle correction. Contrast attenuation occurred before visual acuity loss, and its nature could not always be predicted by the visual acuity findings. Routine visual acuity tests do not describe well the extent of the visual disability in keratoconus.
Carney LG. Visual Loss in Keratoconus. Arch Ophthalmol. 1982;100(8):1282-1285. doi:10.1001/archopht.1982.01030040260012