Dr Yannuzzi's critique1 of the Macular Photocoagulation Study (MPS) Group guidelines2 for laser photocoagulation of subfoveal choroidal neovascularization in the April 1994 issue of the Archives is balanced and informative and comes at a time when ophthalmologists are considering the management of agerelated macular degeneration with renewed interest. Omitted, however, was a consideration of the methods employed by the MPS Group in the subfoveal trials. I am concerned that the visual results from those studies could have been influenced by placebo response.
Initial perusal of the MPS subfoveal photocoagulation reports does not suggest that a placebo effect, as described in the classic article by Beecher,3 could have influenced the test results. After all, treated patients lost, on average, 3 lines of Snellen acuity immediately following the laser barrage. On reflection, however, such an effect could have become operative later on because the clinically significant visual results were
Hawkins WR. Laser Photocoagulation of Subfoveal Choroidal Neovascularization Secondary to Age-Related Macular Degeneration. Arch Ophthalmol. 1995;113(5):554. doi:10.1001/archopht.1995.01100050016007