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Vision Res. 2005 Jul;45(15):1967-74.

Noticeable, troublesome and objectionable limits of blur.

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  • 1School of Optometry, Queensland University of Technology, Victoria Park Road, Kelvin Grove, QLD 4059, Australia.


We investigated limits at which induced blur becomes noticeable, troublesome and objectionable. We used 15 cyclopleged subjects, a Badal optometer with lines of three high contrast letters as targets, 3-6 mm artificial pupils, and 0.0-0.7 logMAR letter sizes. For 0.0 logMAR size, mean "noticeable" blur limits were +/-0.33D, +/-0.30D and +/-0.28D at 3 mm, 4 mm and 6 mm, respectively, but increased by about 70% for 0.7 logMAR letters. All limits reduced by about 17% as pupil size increased from 3 mm to 6 mm. Letter size had a significant influence on all blur limits (1.6-2.1 times), but blur direction had no significant effect. Magnitudes of "troublesome" and 'objectionable" limits were 1.6-1.8 times and 2.1-2.5 times relative to "noticeable" limits, respectively. Our results suggest criteria for troublesome and objectionable blur are relatively unaffected by letter size.

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