BLUR PERCEPTION OF THE HUMAN EYE IN A CLINICAL ADULT POPULATION

Title BLUR PERCEPTION OF THE HUMAN EYE IN A CLINICAL ADULT POPULATION
Author, Co-Author George Zikos, Kenneth Ciuffreda, Arkady Selenow, Steven Ali, Stephen Pereira, L. Spencer, Melissa Lee, Sylvia Kang
Topic
Year
2007
Day
Wednesday
Program Number
075083
Room
Affiliation
Private Practitioner
Abstract PURPOSE: To determine the characteristics of blur perception of the human eye in a large sample of inexperienced adult subjects

METHODS: Three groups of visually-normal subjects ages 40- 50 years were tested under cycloplegia using 3 pupil sizes (3.0, 4.5 and 6.0mm). These included high myopes (SE-4.25D to -8.00D, n=32), low myopes (SE=-0.50 to-4.00D, n=39) and hyperopes (SE=+0.25 to +4.00D, n=28). All subjects had low astigmatism (<-0.75D). 31 were male and 68 were female. The blur perception criteria were first noticeable blur (or depth of field), bothersome blur, and non-resolvable blur. Stimuli consisted of 20/50 text words subtending 1.4x0.8 degrees in a Badal optical system. Subjects were tested monocularly with full distance single vision contact lens correction in place in order to minimize magnification effects. Wavefront measurements were taken using a COAS Shack-Harman device.

RESULTS: Mean blur thresholds (i.e. the dioptric interval between proximal and distal thresholds for each threshold) and SEMs for each pupil diameter were:



First Noticeable Blur criterion

3mm 1.20(0.05)

4.5mm 1.11(0.05)

6mm 1.05(0.05)



Bothersome Blur criterion

3mm 2.00(0.07)

4.5mm 1.80(0.06)

6mm 1.75(0.06)



Non Resolvable criterion

3mm 2.95(0.09)

4.5mm 2.61(0.08)

6mm 2.55(0.08)



The blur thresholds were:

1. Decreased with increased pupil size, and they increased from first noticeable blur to bothersome blur to non-resolvable criteria.

2. Increased in low myopes as compared to high myopes on average by 0.34D.

3. Did not correlate with measured spherical aberration value

CONCLUSIONS: First, the results are consistent with earlier literature conducted with highly experienced subjects using similar criteria and pupil sizes. Second, the increased blur thresholds in the low myopic group is consistent with the notion that they are more susceptible to the myopigenic effects of increased retinal defocus, whereas the high myopes are less susceptible because of their decreased blur thresholds.

ADDITIONAL COMMENTS: Supported by Vistakon a Division of Johnson & Johnson Vision Care, Inc.
Affiliation of Co-Authors State University of New York, Schnurmacher Institute for Vision Research, Private Practitioner, Private Practitioner, Private Practitioner, State University of New York, College of Optometry, Private Practitioner
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