No abstract

Vascular and glial changes of the retrolaminar optic nerve were studied in monkey eyes with increased intraocular pressure (IOP) from 1 to 4 years and with different stages of optic nerve atrophy. In histological cross-sections of retrolaminar optic nerves of 11 rhesus and 6 cynomolgus monkeys the entire area, number of axons and vessels and area of pial septa were quantitated and three different kinds of nerve degeneration classified. Ultrathin sections of these different stages were performed and the number of open and occluded vessels was determined. In addition, in cynomolgus monkey optic nerves immunohistochemical staining for αB-crystallin, glial fibrillary acidic protein (GFAP) and vimentin was performed. Even in animals with the same duration of glaucoma and comparable mean IOP values the axon degeneration varied considerably. Independently of axon loss the number of capillaries in the rhesus monkeys remained constant, whereas there was a slight decrease in the cynomolgus monkeys. Some of the vessels, especially in the most severely damaged regions, were occluded. The density of glial cells increased whereas the total number remained nearly constant. In control sections all astrocytes stained for GFAP and αB-crystallin. In the glaucomatous optic nerves the density of αB-crystallin- and GFAP-positive cells was significantly increased. The vascular reaction in the retrolaminar glaucomatous optic nerves differs from that described in the prelaminar region. We assume that in the postlaminar region in areas with diminished nutritional needs vessels occlude and finally degenerate.

Clinical features of capsular glaucoma during a recent 15-year period were compared with those of primary open-angle glaucoma (POAG). Out of 1623 new glaucoma patients, 263 patients (16.2%) were capsular glaucoma and 268 (16.5%) were POAG. The patients with capsular glaucoma were older than the patients with POAG. The former had higher intraocular pressure, lower visual acuity, more advanced visual field change and heavier trabecular pigmentation than POAG patients at the time of initial examination. These findings suggest that capsular glaucoma is more difficult to manage than POAG and that the prognosis is poorer than for POAG. Pseudoexfoliative material was found on the pupillary border in 98.3%, on the central lens surface in 46.1%, and on the peripheral lens surface in 72.3%. Though 190 of 263 patients with capsular glaucoma (73.9%) were unilateral cases, 38.9% of the fellow eyes had some abnormalities related to glaucoma. Phakodonesis was found in 10% of patients with capsular glaucoma. This finding suggests that the presence of capsular glaucoma might be a risk factor in cataract surgery.

The choroid of primates possesses an elaborate nitrergic nerve fiber plexus containing a great number of ganglion cells. Postganglionic nerve fibers innervate mainly the choroidal vasculature. In addition, the choroid contains an elastic muscular system closely associated to the vasculature. The goal of the present investigation was to analyze how sustained IOP elevation would affect the choroidal vasculature with its specialized innervation and the adjacent retina. For this purpose the posterior eye segment of 15 rhesus monkeys which after laser coagulation of the trabecular meshwork developed elevated IOP up to 4 years were studied using immunohistochemical and histochemical methods, and scanning electron microscopy of corrosion casts. The most striking finding was a significant reduction of choroidal thickness and loss of choroidal ganglion cells and nerve fibers, especially in the central portion of the choroid. Corrosion casts of the choroidal vasculature showed a slight decrease in capillary density and a decrease in length of the arterioles in glaucomatous eyes. Whole mount preparations of the retina stained for NADPH diaphorase revealed a significant reduction in positively stained amacrine cells, reduction in diameter of arterioles and changes in the staining pattern of the retinal vasculature, particularly in the perimacular region.

Trabeculectomy specimens from 11 patients with juvenile glaucoma were studied by electron microscopy and quantitatively evaluated. In all cases, large amounts of extracellular material arranged in a fingerprint-like pattern, resembling basement-membrane-like material (FBM) was found, similar to that described in steroid-induced glaucoma. This material was found mainly within the inner cribriform and outer corneoscleral regions of the trabecular meshwork, and caused the cribriform layer to be greatly thickened. FBM was also intimately associated with trabecular cells, which frequently appeared activated. In 3 cases, there was also an increase in fine fÍbrillar material which resembled that found in eyes with steroid-induced glaucoma. The amount of sheath-derived plaque material, which is increased in primary open angle glaucoma, was greatly increased in the subendothelial layer adjacent to Schlemm’s canal.