Recovery of phorias following monocular occlusion.
Fourteen nonstrabismic volunteers were monocularly patched for 2 and 24 hours in separate experiments. Horizontal and vertical phorias were measured at 6 m and 30 cm, at 30-second intervals, for at least 30 minutes, following removal of the patch. After 24 hours of monocular occlusion, the initial change from baseline at 6 m ranged from 9.5 prism diopters exo to 7 delta eso and 6.5 delta hyper to 3 delta hypo. At 30 cm, the initial change ranged from 7.5 delta exo to 4 delta eso and 1 delta hyper to 1 delta hypo. In all but three subjects, phorias returned to within 2 delta of baseline by 3 minutes, and in all subjects by 25 minutes. After 2 hours of monocular occlusion, the range of initial change from baseline was similar to 24 hours of occlusion, but all phorias returned to within 2 delta of baseline by 2.5 minutes. Therefore, we suggest that ocular alignment should not be routinely measured within 3 minutes of removing a patch. If patched for 24 hours, a few individuals will require up to 25 minutes for stabilization of their deviation. Further studies might address these effects in patients with subnormal fusion and stereopsis.
Department of Ophthalmology, Loyola University Chicago, Maywood, Ill 60153.
J M
JM
Holmes
K M
KM
Kaz
D000328:Adult; D006801:Humans; D012683:Sensory Deprivation; D013285:Strabismus / Q000503:physiopathology*; D013997:Time Factors; D015349:Vision, Monocular / Q000502:physiology*