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

James S. Wolffsohn, Anthea L. Cochrane

Research output: Contribution to journalArticlepeer-review


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 ± 2s vs 76 ± 4s, 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.
Original languageEnglish
Pages (from-to)90-97
Number of pages8
JournalOphthalmic and Physiological Optics
Issue number2
Publication statusPublished - 1 Mar 2000

Bibliographical note

Funding: This research was funded by a collaborative grant between the Victorian College of Optometry and the Vision Australia Foundation.


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