Disclosing disease mechanisms with a spatio-temporal summation paradigm
Zele, Andrew J., O'Loughlin, Rebecca K., Guymer, Robyn H., & Vingrys, Algis J. (2006) Disclosing disease mechanisms with a spatio-temporal summation paradigm. Graefe's Archive for Clinical and Experimental Ophthalmology, 244(4), pp. 425-432.
Background: We develop the logic for a stimulus that can evaluate cone-dependent spatial summation and detail the modelling and interpretation of thresholds obtained with this stimulus. Methods: Fifteen observers participated, including two young normals tested extensively in control experiments, and a clinical trial based on four observers with age related macular degeneration (AMD), four age-similar controls and five young observers. Monocular spatial summation functions were measured with contrast-modulated Gabor targets that approximated the optimal visual contrast detector. Thresholds were returned from a yes/no adaptive psychophysical algorithm. By fine titration along the size domain it was demonstrated that the spatial summation of normal observers can be adequately described by a two-component model. A reduced set of variables are proposed for clinical applications and the model was applied to data derived using these variables in persons with AMD and age-similar controls. Results: We do not find a significant age-related loss of contrast sensitivity in our normal group. On the other hand, persons with early AMD exhibited a 0.41 log unit loss of sensitivity (P=0.04) from age-similar controls, without any change in their maximum summation area (Amax).
Conclusions: The nature of the spatial summation is consistent with the interpretation that early AMD produces a decrease in cone input to post-receptoral mechanisms in the absence of neural remodelling.
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|Item Type:||Journal Article|
|Additional Information:||For more information or for a copy of this article please contact the author at firstname.lastname@example.org|
|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 Springer 2006|
|Copyright Statement:||The original publication is available at SpringerLink http://www.springerlink.com|
|Deposited On:||08 May 2007 00:00|
|Last Modified:||12 Nov 2012 23:09|
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