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The practical near acuity chart (PNAC) and prediction of visual ability at near 1
Author(s) -
Wolffsohn James S.,
Cochrane Anthea L.
Publication year - 2000
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.2000.00479.x
Subject(s) - visual acuity , chart , contrast (vision) , optometry , ophthalmology , medicine , mathematics , optics , artificial intelligence , computer science , statistics , physics
Summary Objective : To improve on present reading chart designs, providing a quick and accurate method to measure the near acuity threshold, of particular importance with low vision patients. Design : The Practical Near Acuity Chart (PNAC) uses a single paragraph with 3 simple related words on each line (12 lower 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 years with the PNAC and Bailey–Lovie near chart was recorded and compared to their 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 acuity 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 vs 76±4 s, p <0.001). Near acuity measured with either chart was highly correlated ( 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 have high test‐reliable ( r =0.99). Conclusions : The PNAC offers a quick but accurate way to measure near acuity and shows a high degree of correlation with distance acuity, contrast sensitivity and the ability to read newsprint.