TPA-assisted vitrectomy for proliferative diabetic retinopathy: results of a double-masked, multicenter trial.

OBJECTIVE: Some complications of vitrectomy are related to adherence of the vitreous body to the retina. We studied whether these complications could be decreased by injecting a proteolytic enzyme, tissue plasminogen activator (TPA), at the beginning of surgery to aid separation of the vitreous from the retina. METHODS: Fifty-six patients receiving surgery for complications of proliferative diabetic retinopathy were divided into two groups in this prospective, randomized, double-blind study. Group I patients received 25 microg of intravitreal TPA in buffered salt solution (BSS) 15 minutes before vitrectomy. Group II received BSS alone. Postoperative follow-up lasted up to 3 months. The major criteria for comparison were the number of perioperative iatrogenic tears, the gain in visual acuity, and the reattachment rate of tractional retinal detachments. RESULTS: No difference was found between the two groups for the principal indicators or for complications. CONCLUSION: In proliferative diabetic retinopathy, the use of 25 microg of TPA by intravitreal injection 15 minutes before vitrectomy does not improve the results. No specific complications of the method were noted. The failure can be attributed to a too-short delay between TPA injection and beginning of surgery, an insufficient dose, or an insufficient quantity of plasminogen in the vitreous at the beginning of the intervention.