Six African green monkeys (six eyes) underwent vitrectomy and vitreous replacement with Vitreon (perfluorophenanthrene) or Vitreon plus silicone. A seventh animal served as a control. Vitreon alone and in combination remained optically clear and allowed fundus examination up to 162 days. No toxic effects to the retina were detectable. Vitreon exhibited some degree of emulsification and formed some globules at 45 days postoperatively. Interestingly, Vitreon emulsification occurred at a later time (80 days) in one of the silicone plus Vitreon eyes. The combination of silicone plus Vitreon may offer the advantage of tamponading the inferior and superior retina in phakic eyes.