We would like to comment on a case reported in the February 1996 issue of the Archives.1
The report by Motuz Leen et al is very important and interesting. We have been using the Ahmed glaucoma valve (model S2, New World Medical, Rancho Cucamonga, Calif) for 4 years, and our recommendation is to implant the plate 7 mm from the limbus and not 10 mm, as recommended for other implants. The design of the Ahmed implant is such that the valve itself lies 3 to 4 mm posterior to the edge of the plate. Thus, the distance from the limbus to the plate may be shortened, as the actual distance for aqueous flow is maintained (about 10 mm, despite suturing the plate 7 mm from the limbus). The recommendation of Motuz Leen et al to avoid placement of the Ahmed valve in the superonasal quadrant is well taken. However,