Purchase this article with an account.
M. Mei, S.J. Leat; Supra–Threshold Contrast Matching With Macular Disorders . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5828.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To examine supra–threshold contrast perception in macular disorders.
Two groups of control subjects (14 aged 20–49 and 15 aged 50+) and three groups of subjects with macular disorders (13 dry ARMD, 14 wet ARMD, and 8 macular dystrophy) participated. Contrast sensitivity (CS) up to 8 cycles per degree and supra–threshold contrast matching at 3.6% and 28% contrast were measured. Measurements were taken up to the highest spatial frequency that each subject could detect. CS was measured with a temporal 2AFC staircase procedure. A method of adjustment was used for contrast matching. A 0.5 cycle per degree sine–wave grating was the standard grating for contrast matching, the subject being asked to match the contrast of gratings of different spatial frequencies.
For both threshold and supra–threshold contrast matching there was no effect of diagnosis (repeated measures ANOVA, 3 x groups x 5 spatial frequency x 3 levels, p > 0.05). There was an effect of spatial frequency (p < 0.001) at all contrast levels. Although contrast matching for those with macular disorders was often outside the 95% of the normal range at the lower contrast (3.6%), at the higher contrast of 28% contrast matches were accurate and within the normal range. Contrast matching functions at 28% contrast are flatter compared with the threshold and the 3.6% matching functions.
Patients with macular disorders performed similarly and all three groups showed evidence of contrast constancy. Supra–threshold contrast perception is less impaired than contrast thresholds in ARMD and macular dystrophy.
This PDF is available to Subscribers Only