Ocular aqueous humor dynamics after photodisruptive laser surgery procedures.

Iridotomy and capsulotomy using the Q-switched Nd:YAG laser affect ocular aqueous humor dynamics, causing intraocular pressure (IOP) temporarily to rise following these procedures. We measured aqueous outflow facility and aqueous secretion flow by oculopression tonometry in 20 eyes before and after YAG laser iridotomy, and in 19 eyes before and after YAG laser posterior capsulotomy. IOP increased after both laser procedures. Our measurements showed that this elevation must have been caused by a reduction in outflow facility, since aqueous secretion flow actually decreased. In the iridotomy patients, the preoperative outflow facility (in most of the cases, already compromised preoperatively by glaucoma), was directly related to the maximum postoperative IOP elevation. In the capsulotomy patients, postoperative outflow facility was correlated with the total laser energy used. No such correlation was observed in the iridotomy patients. Additionally, in the capsulotomy patients, the type of secondary cataract (ie, proliferative or fibrotic) may have influenced the level of reduction of outflow facility.