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R. Moosavi, G. M. Verdon-Roe, M. C. Westcott, D. P. Crabb, A. C. Viswanathan, F. P. Fitzke, D. F. Garway-Heath; Comparison of the Effect on Moorfields Motion Displacement Test (MDT) Thresholds of Stimulus Scaling for Retinal Eccentricity and Age. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1083.
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© ARVO (1962-2015); The Authors (2016-present)
The Moorfields Motion Displacement Test (MDT) is a novel 32 location visual field test for the early detection of glaucoma. The purpose of this study was to compare the effect on MDT thresholds of stimulus scaling for retinal eccentricity and age.
MDT uses moving line stimuli scaled in size according to literature-based anatomical estimates of ganglion cell density distribution by retinal eccentricity (except at central locations) and age, to produce 1 strategy for each of three 20-year agebands. MDT thresholds were measured on a 20-inch LCD monitor using a head rest at 30 cm test distance. 118 control subjects (normal HRT by Moorfields regression analysis; IOP <22; reliable standard automated perimetry; age mean 62, range 21 to 82 years) underwent baseline MDT on one eye followed by a repeat MDT. Only repeat MDT tests were used for analysis.
‘All seen’ responses (all displacements at a location seen), were recoded to a value of one half of that of the smallest displacement presented at that location. Unseen displacements (no displacements at a location seen), were recoded to a value 5 minutes or arc above that of the largest displacement for that location. For 5 selected locations of varying eccentricity (-27,3; -21,3; -15,3; -9,3; -3,3 degrees from fixation), linear regression of threshold versus age gave r2 values of 0.004, 0.002, 0, 0.011, and 0.09, slopes (minutes of arc per decade) of 0.12, 0.08, 0.02, 0.12, and 0.49, with p values of 0.49, 0.61, 0.89, 0.04, and 0.01 respectively. There is significant threshold elevation with eccentricity (p<0.01) with r2 values of 0.24, 0.21 and 0.13, slopes (minutes of arc per degree of visual angle) of 0.48, 0.40 and 0.35, for agebands 1, 2 and 3 respectively.
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