Increased drift in amblyopic eyes.

Abstract

Reports are conflicting on the presence of increased drift in amblyopic eyes. Furthermore, the individual effects of either amblyopia or strabismus alone on ocular drift have not been systematically investigated. We therefore used a photoelectric method to record horizontal eye position during monocular and binocular fixation in patients having amblyopia without strabismus, intermittent strabismus, or constant strabismus amblyopia. Our principal finding was increased drift amplitude (up to 3 5 degrees) and velocity (up to 3 0 degrees per second) in amblyopic eyes during monocular fixation. While increased drift was found 75 % of the time in amblyopia without strabismus and 50% of the time in constant strabismus amblyopia, it was found only 20% of the time in intermittent strabismus. Amblyopic drift could be either error-producing or error-correcting in nature. Increased drift was not present during monocular fixation with the dominant eye or during binocular fixation in any of our 16 patients. We therefore conclude that amblyopia and not strabismus is a necessary condition for the presence of markedly increased fixational drift. Increased drift amplitude but not velocity may adversely affect visual acuity in the amblyopic eye.

Monocular activation of V1 and V2 in amblyopic adults measured with functional magnetic resonance imaging

“…Vertical gaze position was also measured, but was less variable between subjects, consistent with the known pattern of fixational eye movements in amblyopes. 55,56 Mean gaze position variance was calculated from the raw eye position data after filtering for blinks. The means did not significantly differ between amblyopic and control better eyes (CTL ϭ 1.3°, STRAB ϭ 2.2°, ANISO ϭ 2.0°), although more variability existed between subjects in the amblyopic groups than in the control group ( Figure 2A).…”

Long- and short-term monocular deprivation in the rhesus monkey: effects on visual fields and optokinetic nystagmus

“…Oculomotor deficits also occur. Saccades to visual targets viewed through the amblyopic eye are hypometric and variable in amplitude (Ciuffreda et al, 1978;Schor, 1975). Deficits in the stability of fixation (Ciufieda et al, 1980;Flom et al, 1980;Schor, 1975;Schor and Hallmark, 1978;von Noorden and Burian, 1958) and in the response to pursuit (Ciuffreda et al, 1979;Schor, 1975), vergence (Kenyon et al, 1981), and optokinetic (Schor and Levi, 1980b) stimuli have been reported.…”

Evaluating reading acuity and speed in children with microstrabismic amblyopia using a standardized reading chart system

“…The more experienced the reader is, the less reading saccades per line are performed, and the more regular they become. In case of strabismic amblyopia, the eyes show unsteady movements while reading, resulting in abnormal saccadic substitution and increased saccadic latencies so that acuity levels are reduced [5,6,28,34]. Consequently, measurements of reading performance can be significantly influenced by the crowding effect.…”