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Carina Kelbsch, Jakob Lange, Helmut Wilhelm, Barbara Wilhelm, Tobias Peters, Melanie Kempf, Laura Kuehlewein, Krunoslav Stingl; Objective Measurement of Functional Defects in Age-related Macular Degeneration by Pupil Campimetry. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2295.
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© ARVO (1962-2015); The Authors (2016-present)
Age-related macular degeneration (AMD) is a disease with a high prevalence in the elderly population and is one of the major causes of visual impairment in this age-group. There is a high challenge in functional testing due to the age of the patients and fixation related problems. In recent years, novel objective tests have been suggested that can be suitable for this population. We tested the applicability of gaze-controlled pupil campimetry with two different protocols to measure functional defects in AMD patients.
Gaze-controlled pupil campimetry evaluates local retinal function by measuring the pupil response to light stimuli. 19 AMD patients (age=75±4; M=8; F=11) and 11 age-matched controls (age=72±6; M=3; F=8) were examined with two campimetry protocols covering 30 degrees of the central visual field at 41 positions: one protocol with 1 degree white stimuli (400 cd/m2, 1 sec, targeting all photoreceptors), the other protocol with 3 degrees red L-cone specific stimuli (60 cd/m2, 1 sec, 620nm±30 nm, 1.7x10-5 Watt). The total test duration was about 20 minutes, with 6 minutes per protocol. Relative pupil constriction at each stimulus position was used as the read-out parameter. For each stimulus position, a two-tailed t-test was used to evaluate statistical differences.
The analysis of both protocols revealed a statistically significant difference in pupil responses in the macular region with the largest difference in the fovea between the patient and the control group. In the peripheral areas outside the macula, there was no difference between the two groups. The comparison between monochromatic (red) and white stimuli showed that monochromatic stimulation had larger relative differences (of about 25%) when compared with white stimulation (Fig.1).
Pupil campimetry can track functional changes in AMD. This can be better achieved with a cone-specific protocol. In combination with short-duration, objectiveness of the measurement and gaze-correction for fixation problems, this method presents a suitable alternative to the currently used clinical functional tests of the macula.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Fig.1: Topographical map of the difference of pupil responses between the groups (AMD, age-matched controls) in the L-cone-specific protocol. The scattered area represents the area of statistically significant difference (p<0.05).
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