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C. G. De Moraes, S. Demirel, S. K. Gardiner, J. M. Liebmann, G. A. Cioffi, R. Ritch, M. O. Gordon, M. A. Kass, Ocular Hypertension Treatment Study; Effect of Treatment on Rates of Visual Field Change in the Ocular Hypertension Treatment Study. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2049.
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To assess the effect of treatment on rates of global [Mean Deviation (MD)] and local visual field change in the OHTS.
MD and pointwise thresholds from OHTS subjects originally randomized to observation were examined before and after initiation of topical ocular hypotensive medication. The analysis dataset included eyes with ≥5 reliable visual fields covering ≥5 years both pre and post treatment. 677 eyes of 392 participants met these criteria. The rate of change of MD over time [MDR (dB/yr)] was calculated (linear regression) separately for the period before and the period after starting treatment. This exercise was repeated using a subset of eyes that reached a POAG endpoint (n=239) but the minimum follow-up before and after starting treatment was relaxed to 2.5 years. Pointwise Linear Regression (PLR) was also performed separately pre and post treatment. A difference in MDR and in the number of eyes deemed progressing by PLR (≥1 location changing at least -1.0 dB/yr with p<0.01) across the treatment boundary was sought.
Average MDR before treatment was -0.07 ± 0.26 and after initiation of treatment was -0.07±0.30 dB/yr. Among POAG endpoint eyes the pre and post treatment values were -0.21±0.54 and -0.24±0.50 dB/yr. None of these pre and post treatment differences in MDR was significant (p=0.9 whole group; p=0.6 POAG subgroup). Applying PLR to the subset of POAG endpoint eyes, 98 eyes progressed before and 95 eyes progressed after treatment (p=0.8).
These results suggest that any benefit of treatment on the velocity of visual field change in ocular hypertensive and early POAG eyes was not evident when examining MD, perhaps because very few locations are deteriorating. They also suggest that a commonly used PLR criterion may be too strict to capture the effect of treatment on local rates of visual field change in ocular hypertensive or early POAG eyes.
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