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TR Friberg, D MuschPTAMD Study Group; Prophylactic Treatment of Age-Related Macular Degneration (PTAMD): Update on the Clinical Trial . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2904.
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Purpose: The PTAMD trial was organized to determine whether a single treatment placing a grid of 48 spots of 810 nm subthreshold laser is effective in decreasing the rate of choroidal neovascularization (CNV) and/or visual loss in patients whose eyes harbor multiple large drusen (more than 5 drusen ≷63 microns in diameter). Methods: Patients with good visual acuity (20/63 or better) and multiple drusen in both eyes (bilateral group), or with good visual acuity and multiple drusen in one eye and advanced AMD in the fellow eye (unilateral group) were randomized to treatment (bilateral group: right or left eye treated; unilateral group: eligible eye randomized to treatment or observation). Patients were followed at multiple intervals after entry into the study with fluorescein angiography and best corrected visual acuity (ETDRS). Results: 242 patients in the unilateral arm and over 600 patients in the bilateral arm were enrolled and followed for up to 5 years thus far. Enrollment in the unilateral arm closed on 4/1/00, based on a difference between treated and observed eyes; as of the most recent follow-up (8/01), 21.0% (26 of 124) of treated eyes and 14.4% (17 of 118) of observed eyes developed CNV (P<0.02, Wilcoxon test). Early post-randomization visual acuities also differed, with treated eyes showing higher rates of moderate loss (≥ 3 lines) at six months (11.4%) than observed eyes (4.0%). Follow-up of the unilateral group continues. Enrollment in the bilateral arm was closed as of 12/1/01, based on advice from the monitoring committee that the enrollment was sufficient to evaluate clinically important differences in outcomes with further follow-up. Conclusion: Prophylactic diode laser treatment of an eye of a patient whose fellow eye already had an AMD event shows no beneficial effect in preventing CNV, and may promote CNV events and visual loss at least in the short term. Patients who only have bilateral drusen and no CNV may or may not benefit from prophylactic subthreshold laser treatment; follow-up in the bilateral study arm is also ongoing and no safety issues have been raised.
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