AVRC: Clinical and Physiological Optics research group

Loss of chromatic and achromatic sensitivity in glaucoma

Summary:

Primary Open Angle Glaucoma (POAG) is a disease which affects around 250 000 of the over forties in the UK, with a possible 250 000 remaining undetected. Current tests for the disease include tonometry, visual fields and assessment of the optic disc, but all have fairly low sensitivity and specificity.

Loss of both chromatic and achromatic sensitivity in POAG glaucoma has been demonstrated in numerous studies. We do not, however, know which of these systems is affected most in POAG. The purpose of this investigation is to develop visual tests that are truly selective for colour and achromatic sensitivity and to investigate their relative loss in glaucoma.

The tests are based on studies of chromatic and achromatic sensitivity in normal subjects using static and dynamic luminance contrast (LC) noise. These studies have demonstrated the existence of a motion channel that receives only achromatic, transient inputs. Other related experiments have shown that the use of colour-defined motion stimuli buried in dynamic luminance contrast noise isolates the activity of chromatic mechanisms. The aim of the project is to assess the relative loss of chromatic and achromatic sensitivity first, as a function of age and second, in patients with POAG.

References:

Pacheco-Cutillas, M., Sahraie, A., and Edgar, D.F. (1999) Acquired colour vision defects in glaucoma - their detection and clinical significance. British Journal of Ophthalmology, 83, 1396-1402.

Pacheco-Cutillas M, Sahraie A, Edgar DF, Barbur JL, Bentley CR. (1998). Assessment of chromatic discrimination loss in glaucoma: preliminary findings. Ophthalmic & Physiological Optics. Ophthal. Physiol. Opt. 18, 381.

Barbur, J. L., Cole, V. A., and Plant, G. T. (1997). Chromatic discrimination in subjects with both congenital and acquired colour vision deficiencies. (28), 211-223. 1997. Dordrecht, Kluver Academic Publishers. Colour Vision Deficiencies XIII. Ed. Cavonius C.R.

Sahraie A, Edgar DF, Barbur JL. (1996). Theoretical predictions and experimental findings of visual defects in glaucoma. Ophthalmic & Physiological Optics, 16: p251.

Sahraie, A., Barbur, J. L., Edgar, D. F. and Weiskrantz, L. (1996) Motion Displacement thresholds: comparison of normal subjects and patients with glaucoma. Graefe's Arch. Clin. Exp. Ophthalmol., 234, 553-560.

Supported by:

John Barbur | David Edgar Applied Vision Research Centre | Clinical and Physiological Optics

This page was last updated on 12th March 2001.