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Yi-Zhong Wang, Gina Mitzel; A New Contour Integration Macular Perimetry (CIMP) on iPad for Visual Function Evaluation in Maculopathy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5019.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with maculopathy often show early abnormalities outside fovea. Such paracentral deficits may not be detected by visual function tests for foveal vision. In this study, a new macular perimetry based on contour integration was developed on iPad, and the feasibility of using CIMP to detect paracentral vision loss in maculopathy was assessed.
Thirty normal subjects (mean age 51 years ± 22SD, mean visual acuity (VA) 0.04 logMAR ± 0.08SD) and 30 patients (mean age 62±21, mean VA 0.36±0.35) with maculopathy (12 with Stargardt disease, 7 diabetic maculopathy, and 11 age-related macular degeneration) participated in the study. CIMP stimuli were circular contour segments, and were generated on iPad screen that subtended 18x23.4 deg at a viewing distance of 18”. In each trial, 4 contour segments, each a 30 deg circular arc, were evenly placed along the center of the inner or outer ring of the ETDRS macular grid. Among 4 segments, one was distorted and others were smooth. The distortion was introduced by radial modulation. The stimulus duration was 0.25 sec. The subject’s task was to indicate by touch which one of 4 locations had distorted contour. A spatial 4-alternative, forced-choice (4AFC) staircase paradigm and a maximum likelihood fitting procedure were employed to estimate the threshold for detecting contour distortion in the inner or outer ring of the grid.
Thirty-four diseased eyes (mean VA 0.19±0.20) were able to perform the CIMP test. Their mean thresholds to detect distortion in the inner and outer rings were -0.36±0.36 and -0.54±0.35 logMAR, respectively, significantly worse than normal controls (-0.73±0.16 and -0.81±0.16, respectively, p<0.008). Furthermore, for the diseased eyes with VA 0.20 or better (n=23, mean VA 0.08±0.11, not significantly different from the normal control, p>0.16), the inner and outer ring mean thresholds were -0.36±0.39 and -0.49±0.41, respectively, also significantly worse than the normal controls (p<0.0012). Twenty-six diseased eyes (mean VA 0.58±0.39) were unable to perform CIMP due to severe damage to the macula.
These results suggest that the new CIMP test can detect paracentral loss of visual function in patients having normal visual acuity. CIMP implemented on iPad has the potential to be a new remote monitoring tool for early detection of treatable disease condition outside fovea in maculopathy.
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