Complications of hydrogel intracorneal lenses in monkeys

We performed 32 hydrogel keratophakia procedures in rhesus monkey corneas. Surgery was technically successful in 20 eyes. Toxic stromal keratitis occurred in five eyes because of impurities on the lenticules. Fibrosis appeared around the implant in five eyes. Two eyes showed aseptic necrosis of the inferior cornea with extrusion of the implant, attributed to exposure keratitis. Complications during surgery included faulty microkeratome incisions (three eyes) and epithelial implantation in the lamellar bed (one eye). Three lenticules decentered, one extruding through the wound, probably because the monkeys rubbed their eyes excessively. Nine of the 11 eyes with postoperative refraction data showed overcorrection or undercorrection of more than 1.00 diopter. Most of these complications could have been prevented by better technique, design, and manufacture of the lenticule or cooperation of the subjects.