[Thermal photodisruptive laser iridotomy. A retrospective long-term study]

Abstract

Background: The combined application of the argon- and Nd:YAG-laser for iridotomies permits utilizing advantages of both lasertypes and avoiding their disadvantages. Long-term results of this thermal-photodisruptive technique have so far not been presented, however.

Patients and methods: 127 eyes of 70 patients with an average age of 67.8 years were retrospectively examined in order to obtain information on the longterm results, with special attention being given to a potential occlusion of the iris coloboma, potential cataract progression, regulation of IOP, the pigmentation of the anterior chamber angle and the formation of synechiae. The average time of follow-up was 2.8 years. Laser iridotomy had been performed because of glaucoma of the involved eye or at the fellow eye or because of a narrow angle situation.

Results: The total amount of energies applied was 1.1 J on the average for the argon laser and 172.2 mJ for the Nd:YAG-laser. Iris colobomas with an average diameter of 500 microns were performed on all eyes. Due to this large diameter none of the colobomas was found to be occluded. Progression of cataract was seen in 21/127 eyes (16.5%). In some of the cases this seemed to be attributable to a lentogene component already in starting the acute angle closure glaucoma or the narrow angle situation. IOP was within the normal range in 113/127 (89.0%) eyes not additionally treated by any other therapy. In 46/74 (62.2%) eyes was increased pigmentation of the chamber angle. Synechiae arose in 25/74 (33.8%) eyes. These, however, could be significantly reduced by giving mydriatics immediately after the procedure. There were no significant differences on comparing laser iridotomy with surgical iridectomy.

Conclusion: Thermal-photodisruptive laser iridotomy has become a successful alternative method to the application of either argon- or Nd:YAG-laser alone. Since it is a low-risk procedure, it should be regarded as the method of choice prior to surgical iridectomy.