Primary Open-angle Glaucoma Alters Retinal Recovery from a Thiobarbiturate: Spatial Frequency Dependence

Electrophysiological responses of the retina to a series of grating stimuli (6-768 min of arc/phase) were recorded in seven sessions using normal Beagles and in 21 sessions using Beagles afflicted with inherited glaucoma. A 15° and a 30° field, centered around the animal’s area centralis, were used to stimulate the central retina. Two recording series were completed on each animal, with both stimulus sizes presented in each recording session. The first recording took place 30 min. and the second 2 hr. after the injection of thiamylal sodium. The signals recorded from the toroidal 15° of the retina of the glaucomatous dogs during the second recording were significantly larger than those of the first recording. This difference was found only for the larger (> 48 min of arc/phase) gratings. No significant differences were found between the first and second recordings from the central 15° of glaucomatous dogs, nor at any site in the normal dogs.