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The Effect of Optical Blur on Central and Peripheral Word Visual Acuity

Khuu, Sieu K.*; Chou, Philip Hi; Ormsby, Jacob; Kalloniatis, Michael

doi: 10.1097/OPX.0000000000000077
Original Articles

Purpose: We investigated how dioptric blur affected word acuity thresholds for targets presented at different retinal eccentricities.

Methods: Word thresholds were measured at 0, 5, and 10 degrees and for different Weber contrast levels of 4, 10, 45, and 90%.

Results: We find that increasing optical blur increased word acuity thresholds, but the extent of change was dependent on retinal eccentricity and stimulus contrast. In particular, the resolution reduction per diopter of blur (as indicated by the slope of lines fitted to data) was significantly less at peripheral locations (0 degrees vs. 5 and 10 degrees) and for low-contrast targets.

Conclusions: These findings provide useful guidelines to predict how patients with contrast loss and/or those that rely upon an eccentric retinal location for reading respond to the introduction of optical blur in a clinical setting.



BSc(Optom), PhD

The School of Optometry and Vision Science (SKK, MK), The University of New South Wales, Kensington, New South Wales, Australia; Department of Optometry and Vision Science (PHC, JO, MK), University of Auckland, Auckland New Zealand; and Centre for Eye Health (MK), The University of New South Wales, Kensington, New South Wales, Australia.

Michael Kalloniatis Centre for Eye Health University of New South Wales Sydney 2052, NSW Australia e-mail:

© 2013 American Academy of Optometry