[Effects of red krypton and monochromatic green argon lasers in the foveal region. A clinical and experimental study].

The destruction of senile neovascular membranes in the central avascular region of the macula using argon laser is difficult and associated with complications. Yellow pigment in this region absorbs the blue component of the conventional argon laser radiation. In this study, we compared laser of different wavelenghts: red krypton and green argon. Light and electron microscopic studies on non-human primates were performed at one hour and three weeks following laser burns. With the red krypton laser maximum damage was seen at the level of choriocapillaris and the choroïd, although the pigment epithelium was also destroyed. With the green argon laser the maximum absorption occurred at the level of the pigment epithelium. A clinical and angiographic study showed that the destruction of juxtafoveal neovascular membranes by both these lasers was possible after one or several treatment sessions. After an average follow-up period of 45 months, visual acuity was stable or improved in 10 out 17 eyes treated with the green argon laser and in 27 out of 53 eyes treated with the red krypton laser. Our results suggest that the red krypton laser offers a better alternative for the treatment of neovascular membranes located near the foveola since less unnecessary damage is induced. Outside the xanthophyllic area there is no major difference between the different wavelengths.