Effect of blur adaptation on blur sensitivity and discrimination in emmetropes and myopes.

PURPOSE To determine whether blur adaptation influences blur sensitivity and blur discrimination thresholds in young adult myopes and emmetropes. In addition, to determine whether there is a differential effect of blur adaptation on blur sensitivity and discrimination between refractive error groups. METHODS Proximal and distal blur sensitivity thresholds and blur discrimination thresholds were measured under cycloplegia with a Badal optometer in 24 young adult subjects (8 emmetropes [EMM], 8 early-onset myopes [EOM], and 8 late-onset myopes [LOM]). Adaptation to 1 D of myopic refractive blur was then undertaken for 30 minutes. Blur sensitivity and discrimination thresholds were then remeasured. RESULTS After blur adaptation, blur sensitivity, and blur discrimination thresholds were found to be elevated. Blur adaptation had a significant effect on distal blur sensitivity threshold, with the largest effect being observed in the EOMs. Mean changes in distal blur sensitivity thresholds were EMMs +0.03 +/- 0.14 D, EOMs +0.30 +/- 0.21 D, and LOMs +0.08 +/- 0.13 D. CONCLUSIONS Adaptation to a degraded stimulus modifies the blur detection mechanisms of the visual system in young adults. Depth of focus is expanded by prolonged exposure to defocus. EOMs are more susceptible to this phenomenon than are LOMs and EMMs.

[1]  W. N. Charman,et al.  Visual sensitivity to temporal change in focus and its relevance to the accommodation response , 1988, Vision Research.

[2]  M Rosenfield,et al.  Blur sensitivity in myopes. , 1999, Optometry and vision science : official publication of the American Academy of Optometry.

[3]  S. Cousens,et al.  The effect of optical defocus on the test-retest variability of visual acuity measurements. , 2004, Investigative ophthalmology & visual science.

[4]  Bin Wang,et al.  Foveal blur discrimination of the human eye , 2005, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[5]  M. Rosenfield,et al.  EFFECT OF INTERVENING PERIODS OF CLEAR VISION ON BLUR ADAPTATION.: 11:00 - 11:15 , 2002 .

[6]  D A Atchison,et al.  Useful Variations of the Badal Optometer , 1995, Optometry and vision science : official publication of the American Academy of Optometry.

[7]  Martin S. Banks,et al.  Depth of focus, eye size and visual acuity , 1980, Vision Research.

[8]  S. Pardhan,et al.  Unequal Reduction in Visual Acuity with Positive and Negative Defocusing Lenses in Myopes , 2004, Optometry and vision science : official publication of the American Academy of Optometry.

[9]  Blur detection thresholds in childhood myopia: single and dual target presentation , 2002, Vision Research.

[10]  Michael A. Webster,et al.  Neural adjustments to image blur , 2002, Nature Neuroscience.

[11]  Jonathan Winawer,et al.  In a matter of minutes, the eye can know which way to grow. , 2005, Investigative ophthalmology & visual science.

[12]  M. Rosenfield,et al.  Blur Adaptation and Myopia , 2004, Optometry and vision science : official publication of the American Academy of Optometry.

[13]  F. Thorn,et al.  Myopia Adults See Through Defocus Better Than Emmetropes , 1998 .

[14]  M. Bullimore,et al.  Steady-state accommodation and ocular biometry in late-onset myopia , 2004, Documenta Ophthalmologica.

[15]  P. Miles.  Depth of focus and amplitude of accommodation through trifocal glasses. , 1953, A.M.A. archives of ophthalmology.

[16]  Wa James Tam,et al.  Zero horizontal disparity in binocular depth mixture stimuli , 1987, Vision Research.

[17]  James R Tresilian,et al.  Improving vision: neural compensation for optical defocus , 1998, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[18]  M. Georgeson,et al.  Contrast constancy: deblurring in human vision by spatial frequency channels. , 1975, The Journal of physiology.

[19]  D A Atchison,et al.  Subjective Depth-of-Focus of the Eye , 1997, Optometry and vision science : official publication of the American Academy of Optometry.

[20]  S. E. Morse,et al.  Oculomotor functions and late‐onset myopia , 1999, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[21]  Leslie Hyman,et al.  Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children. , 2004, Investigative ophthalmology & visual science.

[22]  D. B. E. P. M. Faao.  Clinical Procedures in Primary Eye Care , 2003 .

[23]  D. O'leary,et al.  Undercorrection of myopia enhances rather than inhibits myopia progression , 2002, Vision Research.

[24]  Andrew Carkeet,et al.  The Slope of the Psychometric Function for Bailey-Lovie Letter Charts: Defocus Effects and Implications for Modeling Letter-By-Letter Scores , 2001, Optometry and Vision Science.

[25]  B. Jiang.  Integration of a sensory component into the accommodation model reveals differences between emmetropia and late-onset myopia. , 1997, Investigative ophthalmology & visual science.

[26]  N. Strang,et al.  Refractive group differences in accommodation microfluctuations with changing accommodation stimulus , 2006, Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians.

[27]  Bin Wang,et al.  Effect of blur adaptation on blur sensitivity in myopes , 2006, Vision Research.

[28]  Earl L. Smith,et al.  Compensation for experimentally induced hyperopic anisometropia in adolescent monkeys. , 2004, Investigative ophthalmology & visual science.

[29]  G Smith,et al.  Effect of Defocus on Blur Thresholds and on Thresholds of Perceived Change in Blur: Comparison of Source and Observer Methods , 1989, Optometry and vision science : official publication of the American Academy of Optometry.

[30]  F. Campbell,et al.  A method for measuring the depth of field of the human eye. , 1957, The Journal of physiology.

[31]  Bin Wang,et al.  Depth-of-focus of the human eye in the near retinal periphery , 2003, Vision Research.

[32]  Richard Held,et al.  Increased accommodation following adaptation to image blur in myopes. , 2004, Journal of Vision.