Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/18617
Title: Validity of the University of Waterloo's near visual acuity charts
Authors: Cheng, D
Woo, GC
Issue Date: 2001
Source: Practical optometry, 2001, v. 12, no. 2, p. 54-61 How to cite?
Journal: Practical Optometry 
Abstract: Purpose: We investigated the validity of the University of Waterloo's (UW) near visual acuity (VA) test card that consists of seven charts: the paragraph (PAR), illiterate (ILL) tumbling E, high contrast vertical (HCV), high contrast horizontal (HCH), low contrast vertical (LCV), and low contrast horizontal (LCH) charts, and the LEA chart that consists of a series of four optotypes - a circle, square, house, and heart. Methods: The VA of the right eyes of 31 patients, aged 15 to 30 years, with near VA of 6/30 or better, were determined using the seven charts. The charts were presented at 0.4 meters (with a luminance level of 95 to 115 cd/m2). Performance was scored using Kitchin and Bailey's per letter scoring method. Results: There was a positive agreement between the HCV and HCH charts. A ceiling effect was found with the PAR chart - the highest resolution, where the logarithm of the minimum angle of resolution (log MAR) is 0.0 units, was inadequate to measure the limit of near acuity. The ILL and LEA charts, for children and patients who are illiterate, were found to be valid only when the VA was close to 0.0 log MAR units. For patients with poor, uncorrected near acuity, both the ILL and LEA charts slightly overestimated VA. No statistically significant difference between the vertical and horizontal line charts was found. The difference in acuity between LCV and HCV, and between LCH and HCH, was constant over the entire measured acuity range. Conclusion: The seven near VA charts generally rendered valid measurements of near VA, in spite of some limitations.
URI: http://hdl.handle.net/10397/18617
ISSN: 1181-6058
Appears in Collections:Journal/Magazine Article

Access
View full-text via PolyU eLinks SFX Query
Show full item record

SCOPUSTM   
Citations

2
Last Week
0
Last month
0
Citations as of Feb 26, 2017

Page view(s)

34
Last Week
1
Last month
Checked on Jun 25, 2017

Google ScholarTM

Check



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.