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PubMed1983

Argon laser trabeculoplasty in pigmentary dispersion syndrome with glaucoma.

Thirteen eyes in ten patients with pigmentary dispersion syndrome and glaucoma underwent argon laser trabeculoplasty. All eyes responded well initially with an average decrease in intraocular pressure of 10.6 mm Hg. The intraocular pressure in five of these eyes increased to levels higher than those before treatment after an average of nine months. This loss of control occurred in patients who were older (average age, 59 years vs 31 years) and who had had glaucoma for a longer period (10.2 years vs 2.5 years). There was no evidence of further pigment dispersion to explain failure. Trabecular sclerosis may have prevented the maintenance of an adequate trabecular "tightening effect" of argon laser trabeculoplasty. Because of its greater absorption in the deeply pigmented trabecular meshwork, the laser may actually cause further trabecular damage.

Adult↗
PubMed1997

The effect of interleukin-1alpha on outflow facility in rat eyes.

PURPOSE: The authors investigated whether regulation of the trabecular extracellular matrix turnover rate and remodeling plays an important role in decreasing outflow resistance by determining the effect of intracamerally given interleukin-1alpha, a known stimulator of the expression of trabecular matrix metalloproteinases, on outflow facility of albino rat eyes. MATERIALS AND METHODS: Forty normal albino rats (Sprague-Dawley), weighing 250 to 300 g, were studied. Rats were anesthetized by intraperitoneal pentobarbital sodium (30 mg/kg) injection. The rats were separated into four groups and given 5, 10, 25, or 50 units of interleukin-1alpha injected intracamerally in one eye. Bovine serum albumin in phosphate-buffered saline, which was used to dissolve the interleukin-1alpha, was injected in the fellow eye as a control. Outflow facility was measured by two-level constant pressure perfusion 1, 3, and 7 days after injection. RESULTS: The eyes treated with 50 units of interleukin-1alpha showed a statistically significant increase of outflow facility by 37% compared with the contralateral control eyes 3 days after injection, but returned to normal levels in 7 days. The eyes treated with 5, 10, 25, or 50 units of interleukin-1alpha showed outflow facility increases of 12%, 20%, 39%, and 37%, respectively, 3 days after injection. CONCLUSION: Interleukin-1alpha increased the outflow facility, supporting the hypothesis that regulation of trabecular meshwork extracellular matrix plays a role in trabecular outflow resistance.

Animals↗
PubMed1977

Glaucoma occurring after closed vitrectomy.

Six of 20 eyes developed postoperative glaucoma within two to ten days after closed vitrectomy for vitreous hemorrhage. Intraocular pressure was greater than 40mm Hg in all six eyes, and three developed pressure greater than 60 mm Hg. Intraocular pressure in four eyes was controlled with medical antiglaucoma therapy and two eyes required anterior chamber irrigation. Six months postoperatively three of the eyes had normal pressures, one was hypotonous, and two developed increased intraocular pressure secondary to angle neovascularization. Three of the 14 eyes that did not develop glaucoma developed a cellular accumulation in the anterior chamber. The glaucoma was caused mainly by obstruction of the trabecular meshwork by degenerated red blood cells known as ghost cells. The cells may be identified by phase-contrast examination of anterior chamber aspirates. Glaucoma can be prevented through irrigation of the vitreous cavity at the time of vitrectomy ensuring that no cells and debris are left behind to migrate into the anterior chamber and obstruct the trabecular meshwork. This type of glaucoma is caused mainly by ghost cells, whereas hemolytic glaucoma is caused mainly by macrophages and red blood cell debris.

Eye Diseases↗
PubMed2006

Viscogonioplasty: an effective procedure for lowering intraocular pressure in primary angle closure glaucoma.

PURPOSE: To evaluate the safety and intraocular pressure (IOP) lowering effect of combined phacoemulsification and viscogonioplasty (Phaco-VGP) in managing primary acute closed-angle glaucoma (ACAG) unresponsive to conventional therapy (patent PI). PATIENT AND METHODS: In all, 15 consecutive eyes of patients with refractory ACAG and greater than 270 degrees peripheral anterior synechiae (PAS) underwent VGP. The technique of VGP involved routine phacoemulsification with intraocular lens implantation (Phaco/IOL) under topical anaesthetic. Following IOL implantation a heavy viscoelastic was used to deepen the anterior chamber and then injected near the angle for 360 degrees (without touching the trabecular meshwork) to break the PAS. No surgical instrument was used to physically break the PAS. Upon completion of VGP, automated irrigation with balanced salt solution to remove the viscoelastic was performed. RESULTS: Mean IOP reduced from 52.1 to 14.1 mmHg by Phaco-VGP at 6-months review. 14/15 patients were free of glaucoma medications at 6-month review. All angles showed exposure of the trabecular meshwork over 360 degrees postoperatively without evidence of residual synechiae. No untoward complications were observed in any patient. CONCLUSION: VGP may have a role in controlling IOP effectively and safely in patients with refractory ACAG. It produces a large drop in the IOP and opening of the angle. It is a relatively simple technique to learn and we would recommend its use in the eyes of all patients who have had ACAG and are undergoing cataract extraction.

Acute Disease↗
PubMed1999

Patterned expression of BDNF and NT-3 in the retina and anterior segment of the developing mammalian eye.

PURPOSE: The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are hypothesized to play an important role in vertebrate eye development because of their patterned expression in the developing and adult neuroretina, their regulated response to retinal and optic nerve injury, and the effects of altered neurotrophin signaling on retinal development. To further characterize the role of these neurotrophins in mammalian eye development and maintenance, the pattern of expression of BDNF and NT-3 was analyzed in the developing and mature mouse eye. METHODS: Using mouse strains in which the reporter gene lacZ, encoding the enzyme beta-galactosidase, was targeted to either the BDNF or NT-3 locus, the expression of BDNF and NT-3 in the eyes of mice heterozygous for these mutations was analyzed by enzyme histochemistry during embryogenesis, postnatal development, and adulthood. RESULTS: BDNF and NT-3 expression were first observed in the inner and outer segments of the developing optic cup at embryonic days 10.5 to 11.5. As the retina matured, BDNF expression was restricted to retinal ganglion cells and a subset of cells in the inner nuclear layer (INL), whereas NT-3 expression was confined to a small subset of cells in the INL and ganglion cell layer. Both neurotrophins were expressed within the developing retinal pigment epithelium. In the anterior segment, BDNF and NT-3 were expressed at high levels in the developing and mature ciliary epithelium. In the lens and cornea, however, these neurotrophins displayed distinct patterns of expression during development and adulthood. BDNF expression was found in the lens epithelium, immature trabecular meshwork, corneal endothelium, and corneal epithelium, whereas NT-3 expression was confined to the corneal epithelium. CONCLUSIONS: BDNF and NT-3 exhibit different, yet overlapping, patterns of expression during the development and differentiation of the mouse eye. In addition to the neuroretina, the spatiotemporal expression of BDNF and NT-3 may play an important role in the development and maintenance of the lens, ciliary body, trabecular meshwork, and cornea.

Animals↗
PubMed2000

[Unilateral or asymmetric PEX syndrome? An electron microscopy study].

BACKGROUND: The pseudoexfoliation (PEX) syndrome which is characterized by the accumulation of an abnormal extracellular material in intra- and extraocular tissues, clinically strictly manifests both unilateral and bilateral. However, the generalized nature of this matrix process does not support unilateral ocular manifestation. The aim of this study, therefore, was a detailed histopathological analysis of the apparently not involved fellow eyes in so-called "unilateral" PEX syndrome. MATERIAL AND METHODS: For transmission electron microscopy, 5 pairs of donor eyes with slitlamp-microscopic, macroscopic and light microscopic evidence of unilateral PEX syndrome and 6 normal control eyes were studied. For immunohistochemistry, light and electron microscopic antibodies against LTBP-1 and HNK-1, two well-known markers for PEX deposits, were used. RESULTS: All apparently not involved contralateral eyes showed ultrastructural changes in the iris, in the ciliary body and in the trabecular meshwork. These changes include deposits of typical PEX fibrils on iris and ciliary epithelia as well as in the iris dilator muscle, microfibrillar precursors in the periphery of iris vessels, degenerative changes of the iris pigment epithelium and of the dilator muscle and an increased accumulation of extracellular matrix components around iris vessels, in the dilator muscle and in the juxta-canalicular connective tissue of the trabecular meshwork. In all contralateral and PEX eyes, but not in the control eyes, LTBP-1 and HNK-1 positive deposits could be identified in the periphery of iris vessels and in the dilator by light- and electron microscopic immunolabeling. CONCLUSIONS: The observed alterations in contralateral eyes in so-called "unilateral" PEX syndrome support the concept that the PEX syndrome is a generalized, basically bilateral disease which may present in a clinically asymmetric manifestation. This should be considered in the clinical management of these patients.

Aged↗
PubMed1991

Autoradiographic mapping of the glucose transporter with cytochalasin B in the mammalian eye.

The anatomic localization of the glucose transport protein in the eyes of rats, rabbits, baboons, marmosets, and humans with [3H]cytochalasin B using in vitro autoradiography showed high densities of glucose carrier densities. These densities were seen in the ciliary body, especially ciliary processes, iris, retina, and in some species, the trabecular meshwork and lens. In the lens, specific [3H]cytochalasin B-binding sites were mainly concentrated in the lens nucleus. Lower concentrations were found in the cortex. During aging, glucose transporter concentration increases up to the age of 8 yr in the marmoset lens nucleus, but decreases in the cortex and retina. Moderate amounts of carrier are located in the corneal endothelium and epithelium. The enrichment of glucose carrier protein in the trabecular meshwork suggests a high metabolic activity and a possible relationship in the regulation of intraocular pressure.

Aging↗
PubMed1997

Cell-mediated immune response and stability of intraocular transgene expression after adenovirus-mediated delivery.

PURPOSE: To evaluate the role of cell-mediated immunity in the stability of ocular adenovirus-mediated transgene expression. METHODS: Adenovirus (4 x 10(6) pfu) containing lacZ (Ad.CMVlacZ) was injected intravitreally or subretinally into one or both eyes of immunocompetent (+/+) and immunocompromised (nu/nu) CD-1 mice. Control eyes received injections of saline. Additional +/+ mice received subretinal injections of Ad.CMVlacZ with coadministration of 200 microg of human immunoglobulin (Ig) G or CTLA4Ig by intraperitoneal, intravitreal, or subretinal injection. The mice were killed at various times after injection, and their eyes were examined histologically and immunohistochemically. RESULTS: LacZ expression was extended from 1 week to more than 5 weeks in the corneal endothelium, iris, and trabecular meshwork of nu/nu mice compared with time of expression in +/+ mice when adenovirus was administered intravitreally. In contrast, subretinal injection resulted in only a minimal increase in transgene stability in nu/nu mice compared with that in +/+ mice. Neither systemic nor intraocular administration of IgG or CTLA4Ig affected the stability of lacZ expression in the retina or retinal pigment epithelium after subretinal injection in +/+ mice. Immunoglobulin G and CTLA4Ig enhanced the stability of transgene expression in the trabecular meshwork. CONCLUSIONS: A T-cell-mediated immune response appears to play a role in the loss of adenovirus-mediated lacZ expression after intravitreal but not after subretinal injection. This result implies that the subretinal space is an immune-privileged site and a favorable site for gene transfer.

Abatacept↗
PubMed2002

Identification of the mouse uveoscleral outflow pathway using fluorescent dextran.

PURPOSE: This study was undertaken to assess directly whether there is uveoscleral outflow in the mouse eye by monitoring the movement of intracamerally injected fluorescent dextran. METHODS: After anesthesia, NIH Swiss mice received intracameral injection of 1.5 microL of 0.2 pg/microL 70-kDa dextran conjugated to tetramethyl-rhodamine and to lysine. After survival times of 10, 20, 60, and 120 minutes, the experiments were terminated by transcardial perfusion with 2% paraformaldehyde. The eyes were enucleated and embedded in paraffin, and sections were prepared. These sections were then analyzed by fluorescence microscopy. RESULTS: Fluorescent tracer in the eyes of animals that survived for 10 minutes was prominent in the iris root and ciliary processes and was of moderate intensity in the adjacent sclera. Moderate intensity fluorescence also was observed in the trabecular meshwork and adjacent cornea. At 20 minutes, intense fluorescence was observed in the ciliary processes and the ciliary muscle. This fluorescence in the ciliary muscle extended from the posterior edge of the ciliary muscle's tail into the anterior choroid. At 60 minutes, the fluorescence in the choroid extended to the equator and adjacent sclera. The intensity of the fluorescence within the ciliary processes of these eyes was substantially reduced when compared with the 20-minute-survival eyes. At 120 minutes, label was observed only within trabecular meshwork and Schlemm's canal. CONCLUSIONS: These results indicate that at least a portion of aqueous outflow in the mouse eye is through the uveoscleral outflow pathway.

Animals↗
PubMed2002

[A clinical study on laser peripheral iridoplasty for primary angle-closure glaucoma with positive provocative tests after iridectomy].

OBJECTIVE: To evaluate the therapeutic effects of laser peripheral iridoplasty for primary angle closure glaucoma with positive dark room and prone test after laser peripheral iridectomy. METHODS: A long-term prospective study of 56 eyes (34 cases) with primary angle-closure glaucoma was carried out. The patients presented with positive dark room and prone provocative test after laser peripheral iridectomy, and laser peripheral iridoplasty by Double-Frequency Nd:YAG laser was performed on them. Their extent of goniosynechia was less than 1/2 circumference of the anterior chamber angle. Forty-nine eyes (27 cases) of all those studied were acute angle-closure glaucoma and the other 7 eyes (7 cases) were chronic angle-closure glaucoma. The inferior peripheral anterior chamber depth, anterior chamber angle, the configuration of peripheral iris and intraocular pressure were observed carefully, and the dark room, prone and mydriatic provocative tests were performed. The postoperative follow-up ranged from 1 year to 4 years. RESULTS: The results showed that in all these cases, the peripheral anterior chamber depth was increased, the anterior chamber angle was widened on goniscope and the trabecular meshwork could be visualized widely in static state. All patients did not have ocular hypertension and damage of visual field in the follow up. Mydriatic, dark room and prone provocative tests following laser peripheral iridoplasty were negative. CONCLUSIONS: In some acute angle-closure glaucoma and chronic angle-closure glaucoma patients, the pupillary block is relieved by laser peripheral iridectomy, but provocative tests can also be positive because of the abnormal configuration of the peripheral iris. Pupillary dilation results in peripheral iris bunching, and the surface of the trabecular meshwork can be blocked, hypertension then occurs. But the laser peripheral iridoplasty can improve the shape of the peripheral iris effectively and it can prevent the disease from deteriorating. The goniscopic examination and provocative tests following laser peripheral iridectomy are very important and also effective in detecting this kind of glaucoma.

Adult↗
PubMed2001

[Does the dissection depth and thickness of the deep scleral flap affect intraocular pressure after viscocanalostomy? A clinico-pathologic correlation].

BACKGROUND: Non-perforating glaucoma surgery preserves the integrity of the trabecular meshwork in order to avoid postoperative hypotony. The purpose of our study was to investigate whether the morphologic variability of the excised deep scleral flap influences the postoperative intraocular pressure (IOP) after viscocanalostomy. METHODS: Light-microscopy of the deep scleral flap was performed in 17 patients who had undergone viscocanalstomy. Morphologic parameters (thickness and dissection level of the deep scleral flap) were correlated with the postoperative IOP. RESULTS: The mean thickness of the deep scleral flap was 309 +/- 95 microns; the dissection level was too deep in 5 cases (trabecular tissue excised) and too high in 6 cases (no signs of Schlemm's canal). The max. preop. IOP was 36.2 +/- 8.5 mmHg and came down to 10.6 +/- 5.7 mmHg at day 1 postop. and 12.4 +/- 4.9 mmHg at day 3/4 postop. At a median follow-up of 6 months IOP was 21.7 +/- 5.5 mmHg. A significant correlation between postop. IOP and the morphology of the deep scleral flap could not be demonstrated. CONCLUSIONS: Variations of the thickness and depth of the deep scleral flap showed little influence on the initial IOP level following viscocanalostomy. Other factors, f.e. the suturing of the external flap or invisible microruptures of the trabecular meshwork, could be of importance for the early postoperative IOP.

Adult↗
PubMed1995

Role of cameral mucous gel in primary narrow angle and closed angle glaucoma: a pathogenic clue.

The cameral mucous gel (CMG) has been described as a layer of glycoprotein-enriched hyaluronic acid lining the anterior surface of the iris, covering the trabecular meshwork, and spreading over the posterior surface of the cornea. The CMG is thought to exert a colloid-osmotic effect on the hydrostatic forces involved in the circulation of the aqueous humour which may help our understanding of the pathophysiology of open angle and angle closure glaucomas. The CMG was precipitated in two normal human eyes, one with an artificially shortened anterior chamber and the other with an open chamber. In the eye with a narrow angle, the CMG was seen to fill the iridocorneal gap completely, blocking access to the trabecular meshwork from the central anterior chamber. The CMG may be implicated in the pathogeny of narrow angle and closed angle glaucoma. The two types of glaucoma may share a common mechanism depending on the thickness of the layer of CMG that precedes the exit pathways. Pretrabecular CMG thickness is a decisive determinant of the colloid-osmotic resistance of the gel to aqueous outflow, and this thickness is governed by, among other factors, the position of the iris relative to the posterior surface of the cornea. The formation of a thick layer of CMG in the narrow chamber angle prevents the normal anterior chamber pressure from exerting a backward displacement effect on the peripheral iris. Unopposed posterior chamber pressure may therefore force the peripheral iris forward, making angle closure likely.

Anterior Chamber↗
PubMed1990

[Quantitative autoradiography of the glucose transport protein with (3H)cytochalasin-B in the mammalian eye].

In vitro autoradiography with [3H]cytochalasin for the anatomic localization of the glucose transport protein in eyes of rats, rabbits, baboons, marmosets and humans reveals high glucose carrier densities in the ciliary body, especially ciliary processes, iris, retina and, in some species, in the trabecular meshwork and lens. In the lens, specific [3H]cytochalasin B binding sites are mainly concentrated in the lens nucleus. Lower concentrations are found in the cortex. During again, the glucose transporter concentration increases up to the age of 8 years in the marmoset lens nucleus, but decreases in the cortex and retina. Moderate amounts of carrier are located in the corneal endo- and epithelium. These findings suggest a possible involvement of glucose transporter-related mechanisms in cataractogenesis, e.g. in that resulting from glycosylation of lens proteins. The enrichment of glucose carrier protein in the trabecular meshwork suggests a high metabolic activity and a possible involvement in the regulation of intraocular pressure. The relationship between glucose transport and utilization is also briefly discussed.

Animals↗
PubMed2006

Kinin modulation of conventional outflow facility in the bovine eye.

The aim of this study was to investigate the effects of bradykinin on conventional outflow facility in relation to kinin effects on matrix metalloproteinase (MMP) secretion. Conventional outflow facility was measured in isolated bovine segments perfused at a constant pressure of 10 mmHg. Experiments were also performed in primary cultures of bovine trabecular meshwork cells to assess bradykinin effects on the secretion of MMP-9 assessed by western blot. Administration of bradykinin (10(-7) M) to perfused anterior segments produced a 50% increase in outflow facility above basal levels. The effect was slow to develop, requiring 100 min for a significant increase in facility and 4 h for the peak response to be observed. Pretreatment of anterior segments with the B(2) kinin receptor antagonist, HOE-140 (10(-6) M), or with the nonselective MMP inhibitor, GM6001 (10(-5) M) blocked the response to bradykinin (10(-7) M). Treatment of cultured trabecular meshwork cells with bradykinin (10(-7) M) for 120 min stimulated secretion of MMP-9 into the extracellular media, and this response was inhibited by HOE-140 (10(-6) M). These results demonstrate that bradykinin activates B(2) kinin receptors to increase conventional outflow in the perfused bovine eye and provide evidence that secretion and activation of MMPs within the conventional pathway may mediate the effect.

Animals↗
PubMed2005

[Selective laser trabeculoplasty treatment for medication-refractory open angle glaucoma].

BACKGROUND: Selective laser trabeculoplasty (SLT) is a new method to reduce intraocular pressure in eyes with primary open angle glaucoma. The laser parameters are set to selectively target pigmented trabecular meshwork (TM) cells without damage to the adjacent non-pigmented tissue. PURPOSE: A clinical retrospective study was conducted to evaluate the 12 months results of SLT in the treatment of medically uncontrolled open angle glaucoma. PATIENTS AND METHODS: During the period March to September 2004, the authors performed a SLT in 50 patients (50 eyes) with open angle glaucoma uncontrolled on maximally tolerated medical therapy. Treatment was carried out with a frequency-doubled, Q-switched Nd:YAG laser 532 nm.(Selectra 7000 Laser Coherent, Inc., Palo Alto,CA). Approximately 85 to 90 non-overlapping laser spots were placed over 180 degrees of the trabecular meshwork at energy levels ranging from 0.6 to 1.4 mJ per pulse. In patients who required additional SLT therapy, the untreated 180 degrees was treated. During the follow-up period, patients were treated with antiglaucoma medications as required. The success rates were defined as decreases in intraocular pressure (IOP) of 3 mmHg or more with no additional medications, laser, or glaucoma surgery. RESULTS: The mean IOP reduction from baseline 6 months after treatment was 21% and 20% after 12 months. The success rates were 66% after 6 months and 55% after 12 months. Four eyes (8%) did not respond to SLT. One hour after SLT, an increase in IOP of more than 5 mm Hg was detected in 5 eyes (10%). Seven patients (14%) required additional SLT. CONCLUSIONS: SLT is efficient in lowering IOP in medication-refractory open angle glaucoma. It should be considered in such patients when surgery is contraindicated or refused.

Aged↗
PubMed2001

The morphology of the iridocorneal angle in the eye of buffaloes (Bos bubalis): a light and scanning electron microscopic study.

The morphology of the iridocorneal angle in the eye of the buffalo (Bos bubalis) was studied in eighteen eyes using light and scanning electron microscope (SEM). The buffalo iridocorneal angle included the pectinate ligament, the ciliary cleft, the trabecular meshwork (uveal and corneoscleral) and the angular aqueous plexus. The pectinate ligament was prominent anteriorly and appeared as strong, thick compact structure. The strands of the pectinate ligament were short and had narrow spaces between them as observed by SEM. The ciliary cleft appeared quadrilateral and contained large amount of trabecular tissue that could be divided into two parts, the uveal part and the corneoscleral part. The uveal meshwork was the internal part of the trabecular meshwork. It occupied wide area in the anterior region and narrow area in the posterior one. It composed of thick-pigmented trabeculae in the anterior part, which became thin and loose in the posterior part. Their intertrabecular spaces were large and wide anteriorly. The corneoscleral meshwork was the external part of the trabecular meshwork. It was narrow anteriorly and widened posteriorly. Their trabeculae were non-pigmented and closely arranged and the intertrabecular spaces were small. The angular aqueous plexus consisted of four to five veins. They were located between the outer border of the corneoscleral meshwork and the inner border of the sclera. These results of the iridocorneal angle suggest important implications for understanding the glaucoma disease in buffaloes.

Animals↗
PubMed1991

Tissue distribution of type VIII collagen in human adult and fetal eyes.

The type VIII collagen tissue distribution in human adult (32-78 yr of age) and fetal (16-27 weeks of gestation) eyes was studied immunohistochemically using a monoclonal antibody to type VIII collagen. Type VIII collagen was distributed in a linear or fibrous fashion in adult eyes in Descemet's membrane of the cornea, the trabecular meshwork, the walls of Schlemm's canal, Bruch's membrane, the choroidal stroma, the sclera, the cribriform plates of the optic nerve, and the intima of the central retinal artery. The staining in the central retinal artery was similar to that of type IV collagen. No distinct positive staining was seen in other blood vessels. When fetal eyes were examined, significant differences in positive staining were found between adults and fetuses in the sclera. In fetal eyes, the posterior sclera was strongly stained; however, the positive staining gradually decreased, and in the equatorial area it disappeared. The cribriform plates of the lamina cribrosa and the presumptive Bruch's membrane in fetal eyes did not react with the antibody. The trabecular meshwork and Descemet's membrane, but no other part of anterior section of fetal eyes, reacted with the antibody.

Adult↗
PubMed1997

Experimental glaucoma: perimetric field defects and intraocular pressure.

PURPOSE: To investigate the relationship between intraocular pressure (IOP) and the progression of visual field defects caused by experimental glaucoma in Macaca mulatta monkeys. METHODS: Perimetric fields were measured by behavioral methods in 18 rhesus monkeys during the course of unilateral glaucoma produced by argon laser treatment of the trabecular meshwork. The monkeys' IOPs were measured by applanation tonometry. Visual field defects were quantified by the mean deviation perimetric index from Humphrey Field Analyzer C24-2, model 630 (Humphrey Allergan, San Leandro, CA, U.S.A.), full-threshold data. RESULTS: The monkeys' eyes demonstrated considerable variability in their susceptibility to pressure-induced neural damage. For 10 of the monkeys, significant field defects were correlated with the increases in their IOPs and the defects progressed monotonically to end-state glaucoma. For the other monkeys, the mean deviation index was not well correlated with IOP; some eyes withstood pressures in excess of 35 mm Hg for several months before significant reduction in visual sensitivity. However, once they began, the rate of progression of field defects was similar across subjects. CONCLUSIONS: Laser ablation of the trabecular meshwork in monkeys provides a model for investigations of the effects of IOP that are not confounded by other ocular or visual disorders. Behavioral perimetry showed the same intersubject variability in the effects of elevated IOP on visual field sensitivities of monkeys that are common with high-tension glaucoma or ocular hypertension in patients. Thus, these investigations provide additional support for the use of the model for a wide variety of clinical investigations on glaucoma.

Animals↗