Comparison of threshold and standard Amsler grid testing in patients with established antimalarial retinopathy

To evaluate the sensitivity of threshold Amsler grid testing in the detection of established antimalarial retinopathy, 30 eyes of 15 patients with bilateral, irreversible field defects were examined with the standard Amsler grid and the threshold Amsler grid. Four eyes (13%) showed significant enlargement of large relative scotomas on testing with the threshold Amsler grid. Although only a small proportion of the eyes demonstrated an increase in the size of the scotoma, the patients had established field defects of varying depth, in some cases absolute scotomas. A prospective study in patients with early disease (i.e., with small, shallow scotomas) may be worth while.