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H Suzuki, Y Kojima, Y Shimada, K Hori, H Yamada, M Horiguchi; Optimum Visual Acuity in Patients with Submacular Neovascularization . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1222.
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Purpose: We reported that the standard visual acuity chart underestimates the acuity of patients with a macular hole and have developed a new chart, the multiple letter acuity chart (MLAC), to measure the optimum acuity (IOVS, 2001). In this study, we used the MLAC in patients with a sub-macular neovascularization (SNV), in which the size of central scotoma was larger than the macular hole. Methods: 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. The letter spacing was 33% of the letter size. The size of the letter was equivalent to visual acuities of 0.1, 0.15, 0.2, 0.3, 0.4 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5 and 2.0, when presented at 5 meters. The charts were presented at 1, 2.5, and 5 meters, and the plates subtended a 5 x 5, 10 x 10 and 25 x 25 degrees on the macula, respectively. The subjects were informed that all C's on the plate had the gap in the same direction and instructed to identify the direction of the gap in any C they could see. Twenty-two patients with SNV (65±8 years) were recruited. The size of the SNV varied from 2 to 20 degrees. Results: The mean acuity (log MAR) determined by the standard chart was 1.25±0.23, and that by MLAC was 0.78±0.23 (P=0.001). The patients with larger lesions required shorter measuring distance to achieve optimum acuity. Conclusion: The standard acuity chart underestimates the acuity in patients with SNV, and MLAC is very useful to measure optimum acuity in patients whose lesions are less than 20 degrees.
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