Contrast Sensitivity for Flickering and Static Letters and Visual Acuity at Isoluminance in Glaucoma
| Autor: | Stephen M. Drance, Michael G. Fendick, Nicholas V. Swindale, Stuart L. Graham, Peter Hnik |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Visual acuity genetic structures media_common.quotation_subject Population Glaucoma chemistry.chemical_compound Parvocellular cell Ophthalmology medicine Contrast (vision) education media_common education.field_of_study Retina business.industry Vernier acuity Retinal medicine.disease eye diseases medicine.anatomical_structure chemistry sense organs medicine.symptom business |
| Zdroj: | Journal of Glaucoma. 5:156 |
| ISSN: | 1057-0829 |
| DOI: | 10.1097/00061198-199606000-00003 |
| Popis: | PURPOSE Psychophysical testing was used to assess the effects of early glaucomatous damage on visual functions mediated by the magnocellular and parvocellular pathways. METHODS We studied 57 eyes with early glaucoma, 92 eyes suspect for glaucoma, and 88 normal eyes. Tests were designed to target the functions of the magnocellular (M) or the parvocellular (P) pathways, and included measurements of contrast sensitivity for letter recognition, using both static presentation, and counterphase modulation at 25 Hz. We assumed that ability to perform the latter task would depend on the integrity of the M-cell pathway. To evaluate P-cell function we measured spatial acuity for a green letter presented against an isoluminant white background. Tests were carried out in the fovea, and at 3 degrees nasal, superior, temporal and inferior to the fovea. RESULTS Glaucomatous eyes showed, on average, defects in almost all of the functions tested. Threshold elevations for static and isoluminant presentations were generally as large as those for flickering stimuli. The inferior paracentral part of the retina was generally more severely affected than the other locations tested. The defects observed in the suspect population were similar to, although smaller in magnitude than, those found in eyes with glaucoma. A discriminant analysis identified a subset of five tests, including P as well as M pathway tests, which was able to correctly classify 89% of normal and 79% of glaucomatous eyes. CONCLUSIONS Putative M- and P-cell functions are both impaired at a relatively early stage of glaucoma. Deficits for both types of test are most severe in the inferior paracentral area of the retina (superior visual fields). Psychophysically based detection of the condition can benefit if results from different tests, done at different retinal locations, are combined. |
| Databáze: | OpenAIRE |
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