Altered visual sensitivity in axial high myopia: A local postreceptoral phenomenon?
Jaworski, Alexandra, Gentle, Alex, Zele, Andrew J., Vingrys, Algis J., & McBrien, Neville A. (2006) Altered visual sensitivity in axial high myopia: A local postreceptoral phenomenon? Investigative Ophthalmology and Visual Science, 47(8), pp. 3695-3702.
PURPOSE. The present study investigated retinal integrity in high myopia using spatial psychophysical tasks. METHODS. Ten axial high myopes (-8.5 to -11.5 D) and 10 age-matched control subjects (+/- 1.0 D) were recruited. All participants underwent clinical examination and ocular biometry and demonstrated no visible macular disease with visual acuities better than 6/12. Foveal summation thresholds were determined for white and S-cone-isolating spots of various diameters up to 5.4° and spatial contrast sensitivity to luminance sine wave gratings (0.5–9.7 cyc/deg). Data were analyzed after correction for the magnification induced by eye size and correcting lens power. RESULTS. Spatial summation for both white and S-cone-isolating spots showed a generalized loss of sensitivity at all spot sizes in myopes relative to control subjects (P < 0.01). Critical areas at maximum summation were significantly larger in myopes, for S-cone isolating spots only, after image size correction (P < 0.048). Sensitivity at maximum summation correlated negatively with vitreous chamber depth for both targets (P < 0.005). Sensitivities for S-cone and luminance spots also correlated (P < 0.001), indicating widespread dysfunction. Myopes displayed contrast sensitivity losses at high spatial frequencies (P < 0.006) with a normal peak contrast sensitivity. CONCLUSIONS. These data can be interpreted to indicate that highly myopic eyes have either (1) a reduction in the number of receptors and/or a reduction in their sensitivity or, (2) a reduction in the sensitivity of postreceptoral processes. The presence of normal contrast sensitivity at low spatial frequencies indicates dysfunction at a postreceptoral level in high myopes.
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|Item Type:||Journal Article|
|Additional Information:||Articles free to read on journal website after 6 months|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
|Copyright Owner:||Copyright 2006 Association for Research in Vision and Ophthalmology|
|Deposited On:||09 May 2007 00:00|
|Last Modified:||03 Feb 2015 00:47|
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