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R. Moosavi, G. M. Verdon-Roe, M. C. Westcott, D. P. Crabb, A. C. Viswanathan, F. W. Fitzke, D. F. Garway-Heath; Assessment of the Learning Effect for Healthy Subjects Using Motion Displacement Perimetry. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1624.
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The Moorfields Motion Displacement Test (MDT) is a novel multi-location visual field test for the early detection of glaucoma using moving line stimuli, which are scaled by retinal ganglion cell density according to age and eccentricity, presented on a computer screen. The purpose of this study was to establish the effect of learning in healthy subjects with varying levels of psychophysical experience.
Fifty subjects were recruited (18 male, 32 female; mean age: 38, range 22 to 82 years; mean refraction: -1.02, range -5.75 to +3.00 DSph), and divided into 4 groups by level of previous perimetry experience, as follows: no previous experience: 9 subjects; optometrists’ visual field tests: 16 subjects; Standard Automated Perimetry (SAP): 15 subjects; MDT: 10 subjects. Subjects were tested with the Heidelberg Retina Tomograph II and SAP (Humphrey 24-2 SITA), to establish healthy optic nerves and perimetric reliability. One randomly selected eye of each subject was tested on four 5-minute MDTs. The tests were presented at a distance of 30cm, on either a 20-inch flat-screen monitor or a laptop computer (15.4-inch screen), of equivalent contrast (85%). A baseline MDT, test a), was performed on the 20-inch monitor, with near refractive correction and head-rest. Subsequent tests were randomised as follows: b) repeat baseline c) laptop, unaided, with head-rest d) laptop, unaided, without head-rest.
A paired t-test suggests there is no significant difference between the average threshold values of baseline MDT and any subsequent test. Though these values show greater variance for the group with no experience, a one-way ANOVA test shows no significant differences in average learning between the 4 groups.
In subjects with a previous reliable SAP test, there is no evidence for an average learning effect with repeated performance of the MDT, but responses tend to be more consistent in subjects with more psychophysical experience.
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