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Susan J. Leat, Cristina Yabobchuk-Stanger, Elizabeth L Irving; The Odd One Out – Differential Visual Acuity. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1083.
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© ARVO (1962-2015); The Authors (2016-present)
The intention is to develop recognition acuity tests that can be used in younger populations than currently is possible. Identifying one unique target among three others which are identical (we refer to this as differential acuity) may be an easier cognitive task than current commercially–available matching acuity tests. The purpose of this study was to determine if differential acuity is equivalent to standard measures of recognition acuity.
Sixteen adults with normal visual acuity (VA) participated. To create a range of visual acuity between the participants, vision was optically blurred in sixteen adults with normal visual acuity (VA). VA was measured monocularly with the differential acuity targets (Sloan letters) in both crowded and uncrowded format and compared with ETDRS acuity, and with letters presented singly.
The VA results for crowded and uncrowded letters were analyzed separately. Repeated measures ANOVA showed that when a crowded Sloan C had to be differentiated from three crowded Os (CvsO crowded), the results were not significantly different from ETDRS acuity or from naming one of 4 letters (Name4 crowded, p<0.05). However, differential acuity for crowded ZvsO gave rise to significantly better VA than the crowded CvsO, ETDRS or crowded Name4 (p>0.05). Similar results were found for uncrowded letters - the CvsO and Name4 gave similar visual acuity to each other, but ZvsO was significantly different. The 95% limits of agreement between the naming and CvsO differential acuity measures were between 0.17 and 0.27 logMAR.
The cognitively simpler differential visual acuity task could be applied in clinical settings for young children or patients with developmental disabilities who cannot respond by naming or matching an acuity target, and can give comparable results to the ETDRS chart. However, the choice of letters or targets used in differential acuity impacts the results.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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