Q-Switched Neodymium-Yag Laser Trabeculopuncture in Monkeys

Shlomo Melamed, Jean Pei, Carmen A. Puliafito, David L. Epstein

Research output: Contribution to journalArticlepeer-review


In nine cynomolgus monkeys, trabeculopuncture was performed with a Q-switched neodymium-YAG laser, using a pulse energy of 5 to 7 millijoules and an exposure time of 14 nanoseconds. A penetration into Schlemm's canal was successfully achieved with two to four pulses; this penetration was accompanied by intraocular pressure (IOP) reduction and blood reflux into the anterior chamber. However, after eight days, IOP returned to baseline level, while white tissue was observed gonioscopically to fill in the puncture sites. Histologically, one hour after laser treatment, a blasting effect on the trabecular meshwork was observed with no signs of necrosis. Ater eight days, a hypertrophic scar formed, with the corneal endothelium extending over the scarred surface. At eight weeks and at six months after laser treatment, further shrinkage of the scar and the formation of a membrane over it was evident. Attempts to control scar formation by preventing blood reflux or injecting fluorouracil subconjunctivally for two weeks were unsuccessful. Scar formation at the trabecular puncture site severely limits the applicability of this potentially simple glaucoma treatment.

Original languageEnglish
Pages (from-to)129-133
Number of pages5
JournalArchives of Ophthalmology
Issue number1
StatePublished - Jan 1985
Externally publishedYes


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