Acute intraocular pressure elevation produced by argon laser trabeculoplasty in the cynomolgus monkey.

The short-term effect of argon laser trabeculoplasty (ALT) was studied in a nonhuman primate model. The ALT treatment produced a consistent intraocular pressure elevation in the treated eye for eight hours. A statistically significant indomethacin-resistant increase in aqueous humor protein concentration was also observed. Morphologic observations using light microscopy and scanning and transmission electron microscopy revealed evidence of a fibrinous material covering the trabecular openings four hours after ALT. Cells and tissue debris appeared to be trapped in this fibrinlike net and may be the cause of the acute rise in IOP. Twenty-eight hours after ALT, the fibrin net was shown to be discontinuous, with fewer cells and less debris present. These acute morphologic alterations were not seen in control eyes or the laser-treated eyes observed later.