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Robert Rosen, Jennifer Jayaraj, Shrikant R Bharadwaj, Henk A Weeber, Marrie Van der Mooren, Patricia A Piers; Contrast sensitivity in patients with macular degeneration. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2224.
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Age-related macular degeneration (AMD) is a common cause of visual impairment and blindness. It is of great interest to measure contrast sensitivity in patients with AMD, as it has been shown to correlate with e.g. risk of falling independently of acuity. We investigated the use of a quick method to measure the contrast sensitivity function (CSF) in both a group of patients with AMD as well as a control group. In the group with AMD, other clinical measurements were also taken
The study included 12 patients with AMD (acuity 0.5±0.4 logMAR) and 11 healthy volunteers of similar age (0±0.05 logMAR) from Hyderabad, India. The CSF was measured for both groups. The patients with AMD used their preferred retinal locus in the periphery. We used a quick Bayesian method that gave the full CSF curve in less than five minutes, which has earlier been tested for peripheral vision on healthy experienced volunteers. None of the subjects in this study had previous experience with psychophysical tests. Besides the CSF, we also measured visual acuity, visual field, fixation stability, and acquired autoflorescence images of the AMD lesion
The CSF could be measured on at least one eye of 10 of the subjects with AMD and all of the healthy volunteers. Two of the subjects with AMD could not see enough of the screen to get meaningful results. The average ± standard deviation of the CSF can be seen in Fig 1. The area under the logarithm of the CSF was significantly smaller for the patients with AMD than for the healthy volunteers (p<0.05, 1.05±0.72 vs 2.1±0.51), with an average individual standard deviation of 0.08 and 0.13 area units respectively. The CSF of the healthy volunteers was similar to that of other healthy subjects. For the patients with AMD, the loss of contrast sensitivity was most pronounced in the lower spatial frequency range. The mean peak of the curve was only 21, whereas it was 89 for the healthy volunteers. Looking at individual spatial frequencies, the difference was significant (p<0.05) at 15 cycles/deg and lower.
It is possible to quickly measure the CSF of inexperienced elderly patients with AMD. Their total area under the CSF and peak contrast sensitivity at lower spatial frequencies is significantly lower than that of healthy volunteers.
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