Abstract
Abstract: :
Purpose:We have reported that standard acuity chart (SAC) underestimate the acuity in patients with macular hole, and a newly developed chart, multiple letter acuity chart (MLAC), can estimate optimum acuity (Horiguchi et al IOVS 2000). The purpose of this study is to assess visual acuity in patients with sub-macular choroidal neovascularization (CNV) using MLAC. Methods:Visual acuity was measured using SAC and MLAC. The MLAC consists of 14 plates (45 X 45 cm), and on one plate, many Landolt rings (C's) are printed with the gaps pointing in the same direction and all of the same size. In patients with central scotoma, this chart projects C’s outside the lesion regardless of patient’s fixation and measures optimum acuity. Subject:Twenty eyes with advanced CNV were recruited. In Group A, recruited 13 eyes had visual acuity (determined by standard chart) lower than the fellow eye by 2 or more lines. Group B included the remaining 7 eyes; the acuity in recruited eye is better than fellow eye or the difference of the acuity is less than 1 line. Results:In Group A, the acuity by MLAC(0.75± 0.39, log MAR )was significantly higher than that by the standard chart (1.19± 0.41)( paired t-test (P<0.01).) In Group B, however, the visual acuity by standard chart, (0.77± 0.50) was not significantly different from that measured by MLAC(0.61± 0.51)( P=0.56). Conclusions:The results can be explained as follows. Patients in Group A have not learned eccentric fixation, because they usually use fellow eyes with better acuity, and then the 2 charts revealed significant difference. However, patients in Group B have learned it, because they use examined eyes, and then the 2 chart revealed no differences. Thus, we must be very careful about the status of eccentric fixation, when we evaluate visual acuity in patients with severe macular damage.
Keywords: choroid: neovascularization • visual acuity • macula/fovea