Article Text

Download PDFPDF

Psychophysical characterisation of early functional loss in glaucoma and ocular hypertension
  1. E A Ansari1,
  2. J E Morgan1,
  3. R J Snowden2
  1. 1Department of Ophthalmology, University of Wales College of Medicine, Cardiff, UK
  2. 2Department of Psychology, Cardiff University, Cardiff, UK
  1. Correspondence to: James E Morgan, Department of Ophthalmology, University Hospital of Wales, Heath Park, Cardiff CF4 4XN, UK; morganje3{at}cardiff.ac.uk

Abstract

Aim: The psychophysical evaluation of selective cell loss in early glaucoma and ocular hypertension.

Methods: Contrast sensitivity was measured for the detection of luminance modulated gratings at a range of spatial (0.5, 2, 8 c/deg) and temporal (0, 16 Hz) frequency combinations in three groups of age matched patients (primary open angle glaucoma, ocular hypertension, normal controls; n=16). Stimuli of 5° were presented foveally and at 15° along the nasal horizontal meridian under photopic conditions.

Results: Fovea: Compared to the normal group, the thresholds for the glaucoma patients were significantly elevated at all spatial and temporal frequencies (p<0.0001), but this reduction was not significantly different at any particular spatial or temporal frequency (p>0.1). There was no difference in contrast sensitivity between the normals and OHTs (p>0.10). Periphery: The thresholds of the glaucoma patients were elevated compared to the normal controls (p<0.01). The loss of sensitivity was slightly greater at the higher spatial frequencies for both stationary and flickering patterns but this did not reach significance (p=0.09). The contrast sensitivity in normal and OHT groups was not significantly different (p>0.10).

Conclusions: In early glaucoma, the reduction in contrast sensitivity to stimuli which isolate the magnocellular pathway (0.5 c/deg, 16 Hz) was not significantly different compared with the reduction in contrast sensitivity to stimuli that isolate the parvocellular pathway. These findings are not consistent with the hypothesis that the magnocellular pathway is selectively damaged in early glaucoma.

  • glaucoma
  • psychophysics
  • magnocellular
  • parvocellular
  • cell shrinkage
View Full Text

Statistics from Altmetric.com

Footnotes

    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

    Linked Articles