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Arvind Iyer, Edward Chu, Billy Pan, Bosco Tjan, Alfredo Sadun, Kenneth Lu, Firdaus Udwadia; Subjective Influences on Visual Acuity Testing Performance: A Prospective Study with Non-accommodating Intra-ocular Lenses. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5321.
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© ARVO (1962-2015); The Authors (2016-present)
Multifocal and accommodating intraocular lenses (IOLs) have been purported to provide much better near vision than what is optically predicted. In this study, we perform multiple measurements of visual acuity (VA) in IOL users to investigate if different verbal interactions induce improvement in visual performance.
Distance and near VA measurements were obtained from each of 19 patients with non-accommodating IOLs, in four sessions during the same visit interspersed with two reading conditions : (i) before and after reading a page of typed text on an extraneous topic, handed by a non-expert, and (ii) before and after reading a page of text that emphasized the favorable aspects of these IOLs, handed by the attending physician who also briefly presented the advantages of IOL to patients. There was a break (without any reading) between these two pairs of sessions. All patients had distance vision of 20/40 or better. In each session, near VA measurements retained for analysis were from the better-performing eye. All near VA measurements were converted to logMAR (log minimum angle of resolution).
The accompanying figure shows the mean near VA across subjects for each of the four sessions. Near VA varied significantly across sessions [F(3,54)=6.66, p=0.007] and better acuity was observed in Session 4 than in Session 1 [t(18)=3.72, one-tail p<0.001]. No interaction between reading (measuring VA before vs. after reading) and reading type (extraneous vs. IOL-related) was observed [F(1,18)=0.29, p=0.6]. Furthermore, there was also no significant difference between VA changes due to reading versus that due to the non-reading break [F(1,18)=1.24, p=0.28].
Our preliminary results show short-term improvement in near-VA testing performance over sessions. There is no evidence that prior reading contributes to this improvement, which suggests that test-retest practice effects contribute to the apparent improvement in measured acuity.
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