Extracapsular surgery in lens implantation (Binkhorst lecture). Part iv. Some anatomical and pathophysiological implications.

Extracapsular surgery is an ideal type of cataract surgery in combination with lens implantation in that stability and fixation of the lens is greatly enhanced. However, a number of complications can be expected. The main problem of extracapsular surgery is posterior capsule opacification. This is due to regeneration of germinal lens fibres. To prevent this a complete removal of cortical lens matter is advisable, even in lens implantation. This however requires special lenses which have additional iris fixation. The author's technique for extracapsular surgery is described. The clinically protective effect of extracapsular surgery for the macula has led to the discovery of a new antomical structure in front of the macula, the bursa premacularis. The bursa premacularis is a well-defined fluid-filled space inside the vitreous body in front of the macula. It is postulated to have a protective function for the macula in a hydrodynamic and biochemical sense. A number of pathological conditions could be explained as primarily determined by toxic substances in the premacular bursa or defective detachment of the premacular bursa in the course of posterior vitreous detachment. If this latter condition exists, intracapsular surgery will cause cystoid macular edema, as aqueous can enter the perimacular retina. Cystoid macular edema therefore is postulated to be anatomically predetermined.