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J. Naor, P. Hnik, Y. Hao, M. Wolin; Comparison of Visual Acuity Scores Obtained With an EDTRS Chart at 2 and 4 Meters . Invest. Ophthalmol. Vis. Sci. 2005;46(13):245.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare visual acuity scores obtained at 2 and 4 meters. Methods: The Visudyne in Occult (VIO) Trial is an ongoing Phase 3, multicenter, double–masked randomized trial designed to determine if photodynamic therapy with verteporfin can reduce the risk of vision loss in AMD patients with subfoveal occult with no classic CNV compared to placebo. Best–corrected visual acuity (VA) was measured with an ETDRS chart at 2 and 1 meters (referred to as 2–meter VA scores), at baseline and at each study visit (scheduled at 3–month intervals). In addition, VA assessment was supplemented, after majority of patients had been recruited to the study, with a measurement at 4 and 1 meters (referred to as 4–meter VA scores). The latter was performed at baseline, month 12 and month 24, always subsequent to the former, and with different set of charts. Results: Of the 364 patients enrolled in the VIO study, 38 and 308 had both 2– and 4–meter VA scores measured at baseline and month 12, respectively. At baseline, 30 (79%) patients had a difference of no more than 5–letters between 2– and 4– meter VA scores; 36 (95%) had a difference of no more than 10–letters between 2– and 4– meter VA scores Similarly, at 12 months, 260 (84%) patients had a difference of no more than 5–letters between 2– and 4– meter VA scores; 294 (95%) had a difference of no more than 10–letters between 2– and 4– meter VA scores. The Pearson correlation coefficients between the 2– and 4–meter VA scores were 0.91 and 0.97 at baseline and 12 months, respectively. Conclusions: This is the first clinical trial in patients with subforveal CNV secondary to AMD in which 2– and 4–meter ETDRS VA scores are prospectively collected and analyzed. A high degree of correlation between the 2– and 4–meter VA measurements was observed.
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