Purpose: Facilitation of vitrectomy by vitreolytic enzymes may be of great value in complicated or office-procedure vitreo-retinal surgery. In this study, we quantified and compared the effect of hyaluronidase, chondroitinase, and plasmin pre-incubation on vitrectomy rate and explored potential retinal damage.
Methods: Freshly enucleated pigs eyes were incubated (1 or 3 hours) with an intravitreally injected enzyme or control solution. Enzyme doses were 100 and 1000 U for hyaluronidase, 1 and 2 U for chondroitinase, 3 and 30 U for plasmin. The eyes were weighed before and after 10 minutes of one-port vitrectomy, the difference representing the amount of removed vitreous. Light microscopy was used to assess potential damage to the retina.
Results: All enzymes significantly increased the amount of removed vitreous at all doses and incubation periods. The highest increase was found with hyaluronidase 1000 U, 3 hours, the lowest with chondroitinase 1 U, 1 hour. Damage occasionally occurred to the internal limiting membrane and very rarely to the nerve fiber layer. No damage at all was seen in the 100 and 1000 U hyaluronidase (1-hour incubation) groups.
Conclusions: Hyaluronidase, chondroitinase, and plasmin are good candidates for enzyme-assisted vitrectomy. Although retinal structural damage was very rarely seen, safety concerns will have to be investigated further.