Internal sclerostomy with argon contact laser--animal experiment using 5-fluorouracil

A full-thickness sclerostomy was carried out with an ab interno approach, using an argon endolaser, in 9 eyes of 7 rhesus monkeys. After the injection of sodium hyaluronate into the subconjunctival space and the anterior chamber, a 300 micron fiber optic probe coupled with a water-cooled argon laser was inserted into the anterior chamber through the corneal incision made by a 23-gauge needle and positioned on the trabecular meshwork opposite to the corneal incision. A patent sclerostomy was obtained in all 9 eyes by 1 to 3 laser pulses with an energy of 4 W and a pulse duration of 0.5 seconds. After the surgery, 0.1 ml of 5-fluorouracil was injected subconjunctivally every day for one week. Intraocular pressure (IOP) was determined by pneumatic tonometer for one month at appropriate intervals. Mean preoperative IOP was 22 mmHg in both operated and nonoperated eyes. After one month IOP was 4.6 +/- 0.4 mmHg lower in the operated eyes than in the nonoperated eyes. Histologic study revealed that the sclerostomies from the anterior chamber opening to the subconjunctival space with the diameter of 200-300 microns still remained patent one month after surgery. Ab interno sclerostomy with an argon endolaser would be useful as a new filtering procedure which can easily be performed with minimum conjunctival damage.