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Yueh-Hsun Wu, Gordon E Legge; Adapting to Blurry Text: Impact on Acuity and Reading. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1281.
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© ARVO (1962-2015); The Authors (2016-present)
Blur adaptation refers to the finding that letter acuity improves after extended exposure to blurry movies. It is not known if this improvement follows exposure to blurry text.
30 normally sighted volunteers participated. 15 were randomly assigned to the blur adaptation (B) group, and 15 to the no-blur adaptation (no-B) group. Blur was produced by diffusing goggles that reduced equivalent acuity to 0.83 logMAR. The outcome measures were letter acuity (Lighthouse Distance Visual Acuity chart), contrast sensitivity (Pelli-Robson chart) and reading performance (MNREAD chart). Both groups were measured without the goggles before and after the adaptation task, and the B group was also measured with the goggles. The critical print size (CPS) obtained from the MNREAD test was used as a reference print size in the adaptation task. During the adaptation period lasting about 60 minutes, participants read 7500 words from the first book of Harry Potter in blocks of about 50 words at five different print sizes--CPS, CPS ± 0.1 logMAR and CPS ± 0.2 logMAR . The B group read the text through the diffusing goggles and the no-B group read without blur.
The pre- and post-test outcome measures for the two groups were examined with a 2-way mixed effects model. Significant interactions between these two factors showed group differences revealing improvements in the B group for both letter acuity (F(1,28) = 8.89, p<.01) and contrast sensitivity (F(1,28)=17.59, p<.001). The average improvements after adaptation for the B group were 0.08 logMAR for acuity and 0.18 log units for contrast sensitivity. However, changes in the reading parameters—maximum reading speed, critical print size and reading acuity—did not differ significantly after adaptation for the two groups.
Similar to other studies using different methods of blur adaptation, we found improvements in letter acuity and letter contrast sensitivity following adaptation to blurry text. But, surprising to us, the improvements did not transfer to parameters of reading performance. This may indicate that important factors that limit reading, such as the size of the visual span or crowding, are not affected by adapting to blurry text.
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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