Shoichi Sawaguchi

Experimental glaucoma model in the rat induced by laser trabecular photocoagulation after an intracameral injection of India ink.

A simple and reproducible rodent glaucoma model is required to elucidate the pathophysiology of damage to the optic nerve. We developed chronically elevated intraocular pressure (IOP) unilaterally in rats by injecting india ink into the anterior chamber of one eye using a 30-gauge needle. One week later, trapped carbon particles in the chamber angle formed a black band along the corneal limbus in the injected eyes. We performed direct laser photocoagulation without a gonio lens, and selectively burned the trabecular meshwork. Intraocular pressure was measured every week and laser photocoagulation was repeated until mean IOP in the experimental eyes rose above 25 mmHg. Unilateral IOP elevation was attained in all rats within 4 weeks. Twelve weeks after ink injection, we sacrificed the rats and excised the eyes for histologic analysis. The anterior chamber angle showed peripheral anterior synechia caused by laser photocoagulation, and carbon particles were engulfed by macrophages that infiltrated the ciliary cleft. In the optic nerve head, a remarkable decrease in the nerve fiber layer and cavernous degeneration were observed, suggesting glaucomatous optic nerve damage. This experimental rodent model should facilitate the study of the complex mechanisms involved in glaucoma.

Localization and expression of AQP5 in cornea, serous salivary glands, and pulmonary epithelial cells

Aquaporin (AQP) 5 gene was recently isolated from salivary gland and identified as a member of the AQP family. The mRNA expression and localization have been examined in several organs. The present study was focused on elucidation of AQP5 expression and localization in the eye, salivary gland, and lung in rat. RNase protection assay confirmed intense expression of AQP5 mRNA in these organs but negligible expression in other organs. To examine the mRNA expression sites in the eye, several portions were microdissected for total RNA isolation. AQP5 mRNA was enriched in cornea but not in other portions (retina, lens, iris/ciliary body, conjunctiva, or sclera). AQP5 was selectively localized on the surface of corneal epithelium in the eye by immunohistochemistry and immunoelectron microscopy using an affinity-purified anti-AQP5 antibody. AQP5 was also localized on apical membranes of acinar cells in the lacrimal gland and on the microvilli protruding into intracellular secretory canaliculi of the serous salivary gland. In the lung, apical membranes of type I pulmonary epithelial cells were also immunostained with the antibody. These findings suggest a role of AQP5 in water transport to prevent dehydration or to secrete watery products in these tissues.

Intraocular Pressure-Dependent Progression of Visual Field Loss in Advanced Primary Open-Angle Glaucoma: A 15-Year Follow-Up

We studied the relationship between intraocular pressure (IOP) and progression of visual filed loss in 83 eyes of 83 patients with advanced primary open-angle glaucoma (loss of at least one quarter of the visual field on Goldmann perimetry). During the 15-year follow-up study, 71 eyes (86%) showed progression of visual field loss. The mean IOP was significantly lower in eyes that remained stable (13.4 +/- 1.3 mm Hg) than in those that showed progression of visual field loss (19.4 +/- 2.6 mm Hg). These results suggest that it is necessary to reduce IOP to below 15 mm Hg to prevent further progression of visual filed loss in advanced glaucoma.

Extracellular matrix changes of the optic nerve lamina cribrosa in monkey eyes with experimentally chronic glaucoma

Using light microscopic immunohistochemistry, we studied the immunolocalization and immunoreactivity of the extracellular matrix, including collagen types III, IV, VI, laminin, and alpha elastin in the lamina cribrosa of monkey eyes with normal and experimentally chronic glaucoma. Our results showed: (1) abnormal linearlike immunodeposits of both collagen type IV and laminin in the margin of the lamina cribrosa with significant density in the glaucomatous eyes; (2) the immunoreactivity of collagen type III resembled that of the normal eye, but was slightly stronger at the laminar surface; (3) findings with collagen type VI resembled those of type III with an enhanced linearlike staining surrounding the nerve-fiber bundles. Furthermore, staining of alpha elastin demonstrated dramatic changes in both reactivity and localization.The lamina cribrosa of glaucomatous eyes showed a markedly reduced immunoreactivity as well as an irregular, interrupted pattern. These observations suggest that the changes might be a secondary to the long-standing elevation of intraocular pressure. The alteration of these macromolecules may modify the course of glaucomatous optic damage.

Observation of Human Corneal and Scleral Collagen Fibrils by Atomic Force Microscopy

Purpose: We attempted to analyze the three-dimensional ultrastructure of human corneal and scleral collagen fibrils with an atomic force microscope (AFM).Methods: A normal eye removed from a 66-year-old male was used in the study. Suspended corneal and scleral collagen fibrils were individually attached to glass slides by centrifugation. These collagen fibrils were air-dried and observed with a noncontact mode AFM in air.Results: AFM imaging provided information on the surface topography of both corneal and scleral collagen fibrils. The corneal collagen fibrils had a height of 11.9 +/- 1.0 (mean +/- standard deviation) nm and the scleral fibrils of 82.5 +/- 35.6 nm. A periodic banding pattern of grooves and ridges was clearly found in both types of fibrils: the D-periodicity and the groove depth were 65.7 +/- 0.8 nm and 1.46 +/- 0.50 nm in the corneal fibrils, and 67.3 +/- 1.1 nm and 6.16 +/- 1. 23 nm in the scleral fibrils.Conclusions: Surface topographic images of human corneal and scleral collagen fibrils were clearly obtained with the AFM. This technique provides quantitative information on the surface morphology of the collagen fibrils at high resolution.

Ischemic optic neuropathy in a female carrier with Fabry's disease.

We report ocular findings of a patient with anterior ischemic optic neuropathy (AION) and cilioretinal artery occlusion in a female carrier of Fabrys disease. Fluorescein angiography revealed delayed filling of the upper and temporal part of peripapillary choroidal vessels and capillaries of the right optic disk and late filling of the cilioretinal artery. CT scanning was performed several times in early stages and demonstrated thickening of the intraorbital optic nerve due to ischemic edema. About 5 months later, the fellow eye showed optic disk edema, an early sign of AION, and was treated by systemic corticosteroid and urokinase whereby AION did not progress.

Distribution and Expression of Transforming Growth Factor-β and Platelet-derived Growth Factor in the Normal and Glaucomatous Monkey Optic Nerve Heads ☆

PURPOSE Remodeling of the extracellular matrix occurs in the lamina cribrosa in progressed glaucomatous optic nerve damage including disc cupping. We examined immunohistochemical changes in the transforming growth factor (TGF)-beta and platelet-derived growth factor (PDGF) in the optic nerve head in an experimentally induced glaucoma model. METHODS We used 3 cynomolgus and 2 Japanese monkey eyes. Glaucoma was induced by repeated argon laser photocoagulation of the chamber angle. Eyes were enucleated after disc cupping had formed 3 to 5 months after photocoagulation. The optic nerve head was examined for expression of TGF-beta1, -beta2 and -beta3 and PDGF-A and -B in frozen sections and by the biotin ExtraAvidin-alkali phosphatase method. RESULTS Normal monkey eyes showed TGF-beta1, -beta2 and -beta3, and PDGF-A and -B in the optic nerve head including the nerve fibers, glial cells, and vascular cells. Glaucomatous eyes showed stronger expression of TGF-beta1 and -beta2 in the glial cells around the lamina cribrosa. The staining intensities for TGF-beta3, PDGF-A and -B were the same as in normal eyes. CONCLUSIONS Eyes with experimental glaucoma showed higher expression of TGF-beta1 and -beta2 around the lamina cribrosa. These findings may show upregulation of extracellular matrix production as related to remodeling of the lamina cribrosa in glaucoma.

Age-related changes of sulfated proteoglycans in the human lamina cribrosa

Sulfated proteoglycans in the lamina cribrosa of the optic nerve head from individuals aged 2 months, 18 months, and 23, 35, 44, 55, 67, 74, and 88 years were studied by electron microscopy after cuprolinic blue dye binding. Within the cores of the laminar plates, cuprolinic blue-positive chondroitin/dermatan sulfate proteoglycan filaments of different sizes were found associated with collagen fibers. In addition, small punctate and filamentous structures that represented heparan sulfate proteoglycan molecules were associated with the basal laminae of astrocytes and blood vessels. In the eyes of older individuals, the chondroitin/dermatan sulfate and heparan sulfate proteoglycan filaments were found to be shorter than those in younger persons. A mild decline with aging in the diameter of the filaments was also noted. Our findings illustrate the age-related changes in the proteoglycans in the human lamina cribrosa, which may help explain why the optic nerve head is more susceptible to damage with aging.

Nd:YAG laser trabeculopuncture (YLT) for glaucoma with traumatic angle recession

Traumatic angle recession caused by blunt trauma often induces uncontrollable glaucoma despite the maximum medical therapy tolerated, such as argon laser trabeculoplasty (ALT), with no or little benefit. Therefore, instead of ALT, we tried Nd:YAG laser trabeculopuncture (YLT) on 11 patients with this type of glaucoma. The intraocular pressure of these patients was followed up for 15 ± 7 months (average ± SD). In 6 of 7 eyes treated initially with YLT, the IOP was significantly reduced, so medication was discontinued. Four other cases with uncontrollable IOP after failed ALT were treated with YLT. The IOP of 3 cases was successfully controlled by medication after YLT. These YLT results were then compared with those of ALT in 11 glaucoma patients with traumatic angle recession. Seven of 11 cases treated initially with ALT failed in less than 3 months, and surgical intervention or additional laser treatments were required. The probability of success from the time-series analysis at 12 months after each laser application was 0.909 in YLT, 0.273 in ALT. YLT offers significant advantages over ALT for the treatment of glaucoma with traumatic angle recession after blunt trauma and thus merits further study.

Cell adhesion glycoproteins in the human lamina cribrosa.

PURPOSE The distribution of the cell adhesion glycoproteins, laminin, fibronectin, tenascin, vitronectin, thrombospondin, and entactin/nidogen, was examined in the human lamina cribrosa. METHODS Frozen sections of the optic nerve head from 7 normal human elderly donors were stained by immunohistochemistry. RESULTS All six glycoproteins were detected in this tissue. While laminin and entactin/nidogen were observed linearly, reflecting the localization of basement membranes, fibronectin was identified diffusely. Marked tenascin immunoreactivity was apparent in the lamina cribrosa, but little or no tenascin staining was detected in the sclera. Vitronectin showed a fine fibrillar staining pattern in the lamina cribrosa, and, to a lesser extent, in the sclera and pial septa. Thrombospondin staining was apparent only in the sclera and the lamina cribrosa, which traversed the optic nerve. CONCLUSIONS These results indicate that extracellular matrix components in the lamina cribrosa differ from those in the sclera or pial septa. This study is the first report that the human lamina cribrosa includes vitronectin and thrombospondin.