title: Enzyme-assisted vitrectomy in enucleated pig eyes: a comparison of hyaluronidase, chondroitinase, and plasmin.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Ophthalmology, Albert-Ludwigs-University, 79106 Freiburg, Germany. staubach@aug.ukl.uni-freiburg.de
authors.forename: Flemming
authors.initials: F
authors.lastname: Staubach
authors.forename: Veronika
authors.initials: V
authors.lastname: Nober
authors.forename: Peter
authors.initials: P
authors.lastname: Janknecht
mesh_terms: D000818:Animals; D002810:Chondroitinases and Chondroitin Lyases / Q000627:therapeutic use*; D015353:Eye Enucleation; D005341:Fibrinolysin / Q000627:therapeutic use*; D006821:Hyaluronoglucosaminidase / Q000627:therapeutic use*; D013552:Swine; D013997:Time Factors; D014821:Vitrectomy / Q000379:methods*; D014822:Vitreous Body / Q000187:drug effects / Q000601:surgery*
chemical_list: D006821:Hyaluronoglucosaminidase; D005341:Fibrinolysin; D002810:Chondroitinases and Chondroitin Lyases