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Denis Pelli, Shuang Song, Dennis Levi; Crowding accounts for the limits of amblyopic reading. Journal of Vision 2007;7(9):519. doi: 10.1167/7.9.519.
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© 2015 Association for Research in Vision and Ophthalmology.
Might the impairment of reading in amblyopia be a consequence of increased crowding (i.e. larger critical spacing)? We measured the reading rate of amblyopes as a function of letter spacing in central and peripheral vision. From these results, we estimate the “critical spacing for reading” (similar to critical print size). We find that the amblyopic reading deficit is large but very specific. Peripheral reading is unaffected. Central reading has greatly increased critical spacing, but normal maximum reading rate. We compared the critical spacing for reading with the observers' letter acuity and the critical spacing for identifying a letter among flankers, which is the classic measure of crowding (Bouma, 1970). For both normals and amblyopes, in both central and peripheral vision, we find that the critical spacing for reading equals the critical spacing for crowding.
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