[Bruch's membrane and its significance for retinopexy following laser irradiation]

Retinopexy may be produced by either of two mechanisms following transpupillary irradiation of the retina with the Nd:YAG laser. Which of these mechanisms is operative will depend on the degree of disruption produced within the elastic component of Bruch's membrane. Small defects in the elastic component of Bruch's membrane are soon completely bridged by regenerated retinal pigment epithelium (RPE) cells. However, there is a risk of subretinal neovascularization in such defects. Large defects in the elastic component of Bruch's membrane are not completely bridged by regenerating RPE cells before proliferating Müller cells invade this region and spread from it, mushroom-like, within the choroid. In this case subretinal neovascularization does not occur. In the former instance (small defects) retinopexy is achieved by a process of interdigitation between the microvilli of Müller and RPE cells; and in the latter (large defects) via a press-stud-like anchorage of Müller cells within the choroid. It has not yet been established whether these two retinopexy phenomena, observed after irradiation of rabbit retinas, occur in the same way in man.