Grating Visual Acuity Following Hemorrhagic Foveal Lesions

Grating visual acuity was measured in three cases of experimentally produced foveal, hemorrhagic vitreous lesions in rhesus monkeys. A dual-Purkinje-image DPI eye-tracker and a modified laser photocoagulator were used to target the laser exposure while the subject was engaged in an operantly trained grating detection task. Each subject received one exposure in the right eye from a Q-switched Ndglass laser. The resulting vitreous hemorrhage emanated from a disk-shaped area of edema and disrupted tissue the blood was largely confined to a single, inferiorly directed column, with only slight, diffuse mixing with the vitreous. Grating acuity in the injured eye declined immediately after the laser exposure. During the ensuing 37-day assessment period, acuity returned to the pre-exposure range within 5 to 14 days. The size of the area of retinal injury also decreased over the assessment period, but complications of vitreous clouding and strial traction lines were noted.