LONG-TERM EFFECT OF HYPERMETROPIC ANISOMETROPIA ON THE VISUAL-ACUITY OF TREATED AMBLYOPIC EYES

Aim-To evaluate the effect of the extent of hypermetropic anisometropi a on the long term visual acuity results in amblyopic eyes following t heir treatment by occlusion. Methods-The visual acuity of 86 patients, who had been treated for unilateral amblyopia by occlusion of the fel low eye and followed up at least to the age of 9 years, was examined 6 .4 years, on average, after cessation of treatment. Patients were divi ded into two groups-those with a small amount of hypermetropic anisome tropia, where the spherical equivalent difference between the eyes ran ged between 0 and +1.50 dioptres, and those with a large amount of hyp ermetropic anisometropia, where the difference was +1.75 dioptres or g reater. Results-Deterioration of visual acuity after cessation of occl usion treatment occurred in 51% of the patients in the: group with a s mall; amount of anisometropia and in 75% of the patients in the group with a large amount. At cessation of treatment, the average visual. ac uity in both groups was 20/40+. At the long term follow up examination , however, the average visual acuity was 20/40- and 20/70, respectivel y. This difference was statistically significant. Conclusions-Hypermet ropic anisometropia greater than 1.50 dioptres appears to be a risk fa ctor for deterioration of visual acuity in the long term, following tr eatment of amblyopic eyes by occlusion of the fellow eye.