Automated perimetry in amblyopia: A generalized depression

(PURPOSE)-P-.: To quantitate the visual field abnormalities associated with amblyopia. (METHODS)-M-.: In a prospective study, 37 amblyopic patients (11 anisometro pic, 13 strabismic, 9 combination, 4 deprivation) performed automated perim etry in each eye using the Humphrey 30-2 program. Primary outcome measures were foveal threshold, mean deviation, and average threshold. (RESULTS)-R-.: When the probability plots were examined, 21 visual fields i n amblyopic eyes were normal, 8 had central scotomas, and 7 had diffuse dep ressions. No focal defects other than mild central scotomas were seen. Howe ver, the foveal threshold of amblyopic eyes was decreased by an average of 7.2 +/- 8.0 dB (P <.0001) compared with fellow eyes; intereye differences i n mean deviation (3.2 +/- 5.4 dB; P <.001) and average threshold (2.9 +/- 5 .3 dB; P <.005) were also seen. This decrease in sensitivity for the amblyo pic eye occurred for all types of amblyopia, The depression in threshold wa s greatest at the fovea but was detectable and significant at all eccentric ities of the 30-degree field. The average threshold in the amblyopic eye wa s highly correlated with visual acuity (r =.839; P <.001). (CONCLUSIONS)-C-.: Although automated visual fields in amblyopic eyes typic ally appear normal, all four types of amblyopia are associated with a gener alized depression of light sensitivity, which is proportionately greatest a t the fovea and highly correlated with visual acuity loss. In general, ambl yopia is not associated with any area of focal loss of threshold light sens itivity. If a focal defect is present in the visual field of the amblyopic eye, organic causes of visual loss should be suspected. The Humphrey visual field analyzer STATPAC program (Allergan-Humphrey, Inc, San Leandro, Calif ornia) may artifactually transform small and generalized full-field depress ions in a manner that makes them appear to be isolated central defects, (C) 1999 by Elsevier Science Inc. All rights reserved.