Enzymatically induced posterior vitreous detachment in proliferative diabetic vitreoretinopathy

Background Complete detachment of the posterior vitreous cortex is an important aim in the treatment of proliferative diabetic vitreoretinopathy (PDVR). Today a posterior vitreous detachment (PVD) can only be achieved during vitrectomy. A randomized pilot study was started to evaluate wether intravitreally injected TPA is sufficient to induce a PVD in diabetic eyes. Patients and methods Eight weeks prior to vitrectomy because of proliferative diabetic vitreoretinopathy (non-clearing haemorrhage, fibrovascular proliferations) 20 eyes which had an attached vitreous received a cryopexy of the peripheral retina. In II eyes that had been selected at random 10 mu g of recombinant tissue plasminogen activator were injected midvitreally 24 hrs later. A newly formed PVD was assessed by means of biomicroscopy or ultrasound. Results A newly formed partial (n = 3) or complete (n=7) PVD was found in 10 of II TPA-treated eyes versus one partial detached vitreous in the control group. In 3 younger patients PVD developed exclusively after TPA-injection. We did not observe severe changes of the ERG, decrease of visual acuity, severe new vitreous haemorrhages or opacities of the lens. In 3 eyes (2 eyes of the controll group) a circumscribed retinal detachment developed during the follow-up period. Conclusions The described technique can be used in diabetics without severe side effects. It facilitates the removal of the vitreous cortex and may be avaluable adjunct to the surgical management of PDVR. Unlike other proteases TPA is available for clinical use through recombinant DNA technology which allows standardized enzymatic activities, steril and non-infectious conditions.