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From the glaucoma specialist’s standpoint, the cornea has generated a great deal of interest since the Ocular Hypertension Treatment Study (OHTS) highlighted the importance of central corneal thickness as a risk factor for glaucoma development. The cornea has always been important though, because a compact and transparent cornea is necessary for a clear view of the optic nerve, for good visual acuity to perform visual fields, and for accurate measurements of intraocular pressure. The effects of glaucoma and glaucoma treatment on the corneal endothelium are of particular concern, as a compromised endothelium poses a great risk for corneal decompensation.

There are two main considerations for using laser trabeculoplasty (LTP) vs. medications as a first line or replace­ment treatment. The first is disease related and the second is economic. Disease related issues are efficacy, compliance, diurnal IOP control, and side effects/risks. Economic issues are divided into personal financial impact for the individual patient and medical costs for society in general.

Examination of the iridocorneal angle is an essential part of a complete ophthalmic examination, but a busy practitioner will not put a goniolens on every new patient. So, which patients should be examined? Glaucoma-related reasons to do gonioscopy include: identification of eyes at risk for angle-closure; evaluation of the extent of known angle-closure evaluation of the angle of any eye at risk for a secondary glaucoma: pseudoexfoliation, pigmentary dispersion, uveitis, past history of contusion, retinal vein occlusion, diabetes, etc.; treatment of the angle by laser: trabeculoplasty, iridoplasty, goniopuncture; verification of patency of a trabeculectomy, and, last but not least, learning the anatomy of the normal angle. Gonioscopy should be done routinely in cooperative patients when time permits to learn the variations in normal angles (Figs. 14.1 and 14.2). If a lens is only put on eyes with narrow angles it will be more difficult to distinguish normal from the pathologic.

Primary angle-closure glaucoma (PACG) is the most common form of glaucoma in East Asia. The racial difference is well known, as prevalence is especially high among populations of Eskimos, Mongolians, and Chinese. The specific features of PACG in these populations include a high proportion of chronic-type PACG. In addition, in these populations, both acute and chronic PACG tend to show gradual progression even after elimination of the pupillary block mechanism by iridectomy. This type of glaucoma was called post-iridectomy glaucoma by Forbes and Becker in 1964 [1 2], residual glaucoma by Chandler and Grant in 1965 [3], and late chronic glaucoma in 1973 by Lowe [1 4]. The mechanisms of intraocular-pressure (IOP) elevation include diffuse peripheral anterior synechia, trabecular functional damage, or iris angle crowding from plateau iris-like mechanisms, lenticular factors or ciliary-block mechanisms. Such residual post-iridectomy glaucoma is important because of its insidious progression to severe visual impairment via optic-nerve atrophy. Argon-laser gonioplasty or trabeculoplasty can be used for short-term relief; however, after failure of laser therapy, medical treatment remains as an essential therapeutic approach prior to a surgical procedure.

Several different kinds of lasers are widely employed for the treatment of glaucomas. They comprise iridotomy, trabeculoplasty, goniophotocoagulation, sclerostomy ab interno or externo. Except for sclerostomy, all the procedures share the potentially serious complication, that is the acute elevation of intraocular pressure (IOP) which occurs immediately after the treatment.

The morphological effect of trabeculoplasty upon the monkey eye was studied by electron microscopy. Irradiations were performed using the argon-ion and the free-running Nd: YAG lasers. Morphological analysis up to thirteen weeks after irradiation shows the following: 1. A thermal coagulation of the inner trabecular sheets occurs during irradiation. 2. A monolayer of corneal-like endothelial cells covers the inner trabecular meshwork in the impact zone four weeks after irradiation. 3. Degeneration of trabecular endothelial cells is observed predominantly in the juxtacanalicular tissue. The process continues throughout the period of observation. 4. Cells with long processes are found to phagocytose and digest fragments of collagen fibrils. These cells are located close to the posterior border of Schlemm’s canal and are most prominent during the later stages of observation. 5. Alongside the degeneration process a limited collagen synthesis is apparent, this being indicated by the presence of a small number of fibroblasts.