The practical near acuity chart (PNAC) and prediction of visual ability atnear

Objective: To improve on present reading chart designs, providing a quick a nd accurate method to measure the near acuity threshold, of particular impo rtance with low vision patients. Design: The Practical Near Acuity Chart (P NAC) uses a single paragraph with 3 simple related words on each line (12 l ower case letters). The line print size decreases in a logMAR progression ( N80-N5). Methods: The time taken to measure near acuity of 53 subjects aged 9-91 yea rs with the PNAC and Bailey-Lovie near chart was recorded and compared to t heir distance acuity (Bailey-lovie chart), contrast sensitivity (Melbourne Edge Test) and ability to read extracts of newsprint. Results: There was no difference in near acuity threshold using related or un-related words. There was a high correlation (r = 0.97) between near acui ty measured with the PNAC and Bailey-Lovie charts. However, the time taken to measure near acuity was significantly faster with the PNAC (32 +/- 2 s v s 76 +/- 4 s, p<0.001). Near acuity measured with either chart was highly c orrelated (p < 0.001) to distance acuity (r = 0.74), contrast sensitivity ( r = 0.62) and ability to read newsprint (r = 0.87). The PNAC was shown to h ave high test-reliable (r = 0.99). Conclusions: The PNAC offers a quick but accurate way to measure near acuit y and shows a high degree of correlation with distance acuity, contrast sen sitivity and the ability to read newsprint. (C) 2000 The College of Optomet rists. Published by Elsevier Science Ltd. All rights reserved.