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PubMed1988

Fluorescein angiography of the iris and specular microscopy of the corneal endothelium in some cases of glaucoma secondary to chronic cyclitis.

A series is presented of middle- to old-aged female patients with gray irides and mild bilateral cyclitis accompanied by severe glaucoma with advanced cupping and field loss in the late stages. The cyclitis is accompanied by edema of the corneal endothelium, with the presence of inflammatory cells on the posterior surface of the endothelium; these changes were reversible with topical corticosteroids. There also was hypoperfusion of the iris with microneovascular changes, but these changes were not reversible. The rise in intraocular pressure (IOP) was associated with changes in the endothelial cells of the posterior cornea that may be accompanied by similar changes in the endothelium of the trabecular meshwork. A large proportion of these patients had sarcoidosis, but the more florid ocular appearances of sarcoid were not present although two patients had chorioretinal scarring. The use of topical corticosteroids was important in helping to control the elevated IOP in these cases. Recognition and treatment of the condition is important, because cupping and field loss were extreme in long-standing cases.

Adrenal Cortex Hormones↗

PubMed1989

Mechanisms of intraocular pressure elevation after pars plana vitrectomy.

A prospective study of 222 consecutive patients undergoing pars plana vitrectomy was done to determine the incidence and mechanisms of postoperative intraocular pressure (IOP) elevation. Within 48 hours of surgery, postoperative IOP increased by at least 5 to 22 mmHg in 136 eyes (61.3%) and to 30 mmHg or more in 79 eyes (35.6%). Presumed mechanisms of open-angle glaucoma included intraocular gas expansion (28.4%), inflammatory trabecular meshwork obstruction (4.5%), silicone oil-related glaucoma (3.6%), and erythroclastic glaucoma (2.2%). Closed-angle mechanisms included pupillary block glaucoma (6.8%) and ciliary body edema (3.6%). Factors which were associated with postvitrectomy pressure elevation included placement of a scleral buckle, either intraoperatively (P = 0.003) or before vitrectomy (P = 0.001), intraoperative scatter endophotocoagulation (P = 0.041), intra-operative lensectomy (P = 0.024), and development of postoperative fibrin membranes (P = 0.038). Surgery was required to lower IOP or relieve pupillary block in 25 eyes (11.3%).

Adolescent↗

PubMed1992

Effect of topical mitomycin C on glaucoma filtration surgery in monkeys.

In this study, an experimental model of glaucoma filtration surgery was used to evaluate the clinical and histologic effects of a single intraoperative topical application of mitomycin C. Argon laser treatment to the trabecular meshwork produced sustained elevation of intraocular pressure in monkeys. Eight eyes of four animals were randomly assigned to receive topical mitomycin C or balanced salt solution at the time of full-thickness sclerostomy. Surgical success was substantially increased in four of five eyes that received mitomycin C when compared with three eyes that received topical balanced salt solution. Mitomycin C was also effective in prolonging surgical success in two eyes that had previously undergone surgery and failed. No significant ocular toxicity was observed in eyes treated with mitomycin C. Histologic examination of mitomycin C-treated eyes showed patent sclerostomies and hypocellular, well-formed bleb cavities. A single intraoperative application of mitomycin C has a marked effect on postoperative wound healing after filtration surgery in monkeys.

Administration, Topical↗

PubMed1993

Long-term follow-up of diode laser trabeculoplasty for primary open-angle glaucoma and ocular hypertension.

BACKGROUND: Initial studies of laser trabeculoplasty using infrared energy (810 nm) emitted by diode semi-conductor lasers have been encouraging. A 2-year study of diode laser trabeculoplasty (DLT) in the control of primary open-angle glaucoma (POAG) and ocular hypertension has been completed. METHODS: Patients with uncontrolled POAG or ocular hypertension were treated with DLT to one half of the trabecular meshwork using a trabeculoplasty lens. Spot size was 100 microns, exposure time was 0.2 second, and mean power was 1096 mW (+/- 46.5 mW). The desired endpoint was a mild blanching of the meshwork only. RESULTS: Twenty-five eyes of 16 patients were treated. Mean intraocular pressure reduction was 9.24 mmHg (+/- 3.4 mmHg) at 6 weeks, 9.32 mmHg (+/- 3.6 mmHg) at 3 months, 9.34 mmHg (+/- 3.8 mmHg) at 6 months, 8.42 mmHg (+/- 2.62 mmHg) at 12 months, 8.14 mmHg (+/- 3.42 mmHg) at 18 months, and 7.9 mmHg (+/- 3.63 mmHg) at 24 months. No pressure peaks (> 5 mmHg) were recorded after therapy. Inflammation and discomfort were minimal after laser treatment. Of 16 eyes examined at 2 years, there were no peripheral anterior synechiae. During the course of the study, six eyes became uncontrolled, despite one session of DLT. Four eyes regained control with a further session of DLT, but two required trabeculectomy. CONCLUSION: Diode laser trabeculoplasty is an effective form of therapy in POAG and ocular hypertension. Hypotensive effects and success rates are comparable with argon laser trabeculoplasty (ALT). Reduced inflammation after laser treatment may be due to reduced absorption of infrared energy by the melanin of the anterior segment. The portable nature of these lasers may allow for laser delivery in developing countries and remote situations.

Aged↗

PubMed1996

Location of the iris insertion in pigment dispersion syndrome.

PURPOSE: To evaluate the position of the iris insertion into the ciliary body in persons with pigment dispersion syndrome (PDS) and control subjects. METHODS: Ultrasound biomicroscopy was performed on 19 eyes with PDS and on 21 eyes of control subjects. A radial, perpendicular image in the temporal meridian detailing Schwalbe line (SL), scleral spur (SS), and iris root insertion (IR) was obtained for each eye by a single examiner. The distances between these structures then was measured. RESULTS: There were no differences between the groups in refractive error (mean +/- standard error, -2.8 +/- 0.7 diopters for PDS eyes versus -2.2 +/- 0.6 for control subjects) (P=0.46), sex distribution (P=0.49), and trabecular meshwork height (SL to SS) (0.63 +/- 0.03 mm [PDS eyes] versus 0.59 +/- 0.03 [control eyes]; P = 0.24). The SS-to-IR distance was significantly greater in PDS eyes (0.04 +/- 0.04 mm) than in control eyes (0.28 +/- 0.04 mm) (P=0.01) as was the overall distance from SL to IR (0.98 +/- 0.04 mm versus +/- 0.04 mm) (P = 0.003). CONCLUSION: The insertion of the iris into the ciliary body is more posterior in PDS eyes than in control eyes. This anatomic variation places the iris pigment epithelium proximal to the zonular apparatus and may increase the likelihood of iridozonular contact and zonular pigment dispersion.

Adolescent↗

PubMed1997

Chronic use of apraclonidine decreases its moderation of post-laser intraocular pressure spikes.

OBJECTIVE: The purpose of the study is to investigate the efficacy of 1.0% apraclonidine in preventing intraocular pressure (IOP) spike after argon laser trabeculoplasty (ALT) in patients on chronic apraclonidine therapy compared with patients not on chronic apraclonidine use. DESIGN: The study design was a prospective study. PARTICIPANTS: This study consisted of 231 consecutive eyes of patients with primary open-angle glaucoma undergoing ALT: 70 eyes (30%) were started on a regimen including chronic apraclonidine 0.5% use (group A) and 161 eyes (70%) were started on a regimen without chronic apraclonidine 0.5% use (group B). INTERVENTION: Both groups received one drop of apraclonidine 1.0% 15 minutes before ALT to 180 degrees of previously untreated trabecular meshwork. Intraocular pressure was measured before the procedure and at 5 minutes, 1 hour, and 24 hours after the laser treatment. MAIN OUTCOME MEASURES: Incidences of an IOP spike and mean IOPs at 5 minutes, 1 hour, and 24 hours after the laser treatment were compared between the two groups. Multivariate logistic regression analysis also was carried out to identify the significant risk factors for post-ALT IOP spikes despite prophylactic apraclonidine 1.0% treatment. RESULTS: The incidences of IOP spikes greater than 0 mmHg, greater than 2 mmHg, and greater than 5 mmHg at 1 hour after ALT were 32.9%, 22.9%, and 12.9%, respectively, in group A versus 13.7%, 11%, and 3.1%, respectively, in group B (P = 0.0007, P = 0.009, and P = 0.004). Chronic apraclonidine 0.5% use was found to be the only significant risk factor for IOP spikes at 1 hour after ALT by multivariate logistic regression analysis. CONCLUSIONS: The incidences of IOP spikes in group A were significantly greater than in group B and approached the reported incidences of IOP spikes without perilaser apraclonidine prophylaxis. This indicates that peri-ALT apraclonidine is relatively ineffective in patients with chronic apraclonidine 0.5% use (group A) compared with patients without chronic apraclonidine use (group B), presumably because of saturation of the ocular alpha-2 receptors with apraclonidine in patients with chronic apraclonidine use. Therefore, in patients receiving chronic apraclonidine therapy, it is especially important to monitor their post-ALT IOPs and to be prepared to treat postlaser IOP spikes using agents other than apraclonidine.

Adrenergic alpha-Agonists↗

PubMed1997

Ultrasound biomicroscopy in infantile glaucoma.

BACKGROUND: Glaucoma in infants has many causes: Evaluation of the anatomy of the anterior segment of eyes with infantile glaucoma may help to determine the pathogenesis of an infant's disease and influence therapeutic decisions. METHODS: Eleven eyes of six infants with glaucoma were evaluated with ultrasound biomicroscopy (UBM) to evaluate the anatomic characteristics and relationships of the anterior segment structures. RESULTS: The anterior chamber angle, iris, lens, ciliary body, and posterior chamber angle could be imaged in detail. Elongated and anteriorly placed ciliary processes were noted in all eight eyes with trabeculodysgenesis. There were no apparent anomalies in the trabecular meshwork, or anterior chamber. In three eyes with dense corneal opacities, ultrasound biomicroscopy showed severe anterior segment disorganization and thin central corneas with posterior corneal excavation. CONCLUSIONS: Ultrasound biomicroscopy is a useful non-invasive method for evaluating infants with glaucoma in cases with corneal opacities. This information can help in surgical planning for glaucoma management.

Anterior Eye Segment↗

PubMed1998

Pseudoexfoliation syndrome for the comprehensive ophthalmologist. Intraocular and systemic manifestations.

BACKGROUND: Renewed interest in pseudoexfoliation syndrome (PEX) may be attributed to an increased awareness of many clinical risks not only for open-angle glaucoma and its recent recognition as a generalized disorder. This review summarizes the range of intraocular and extraocular manifestations. Involvement of all tissues of the anterior segment of the eye results in a spectrum of intraocular complications that have management implication for all practicing ophthalmologists. DESIGN: The study design was a review. METHODS: Clinical diagnosis depends on biomicroscopy, biocytology, and laser-tyndallometry. Laboratory research methods range from light and electron microscopy, to immunohistochemical and molecular biologic approaches. OBSERVATIONS: Clinical-histopathologic correlations focus on the involvement of lens (PEX-phacopathy), zonular apparatus (zonulopathy), ciliary body (cyclopathy), iris (iridopathy), trabecular meshwork (trabeculopathy), and cornea (corneal endotheliopathy) leading to the following complications: (1) open-angle glaucoma as well as angle-closure glaucoma due to pupillary and ciliary block; (2) phacodonesis, lens dislocation, and increased incidence of vitreous loss in extracapsular cataract surgery caused by alterations of the zonular apparatus and its insertion into the ciliary body and lens; (3) blood-aqueous barrier breakdown (pseudouveitis), anterior chamber hypoxia, iris stromal hemorrhage, pigment epithelial melanin dispersion, poor or asymmetric pupillary dilatation, and formation of posterior synechiae due to involvement of all cell populations of the iris; and (4) early diffuse corneal endothelial decompensation explained by a damaged and numerically reduced endothelium. CONCLUSIONS: In view of the multitude of clinical complications, PEX is of relevance to comprehensive ophthalmologists, including specialists in glaucoma, cataract, cornea, neuro-ophthalmology, and retina. Special attention to the risks associated with PEX is advised before, during, and after surgery.

Anterior Eye Segment↗

PubMed2001

Experimental glaucoma in the primate induced by latex microspheres.

The injection of sterile latex microspheres into the anterior chamber of the eye is presented as a simple and cost effective method for inducing chronic elevation of intraocular pressure (IOP) and experimental glaucoma in primates. The microspheres produce elevated IOP primarily by restricting the outflow of aqueous humor through the trabecular meshwork located in the chamber angle. Different levels and durations of elevated IOP can be obtained by altering the frequency and number of microspheres injected. In comparison with other primate models of experimental glaucoma, the approach described here has the advantages of producing chronic elevations of IOP without the need for expensive ophthalmic equipment and personnel, surgical intervention or intraocular inflammation, and without compromising visibility of the optic disc, which is necessary for clinical assessment of the onset and progression of the disease.

Animals↗

PubMed1999

Expression pattern and in situ localization of the mouse homologue of the human MYOC (GLC1A) gene in adult brain.

The MYOC (GLC1A) gene has recently been associated with both juvenile-onset primary open angle glaucoma (JOAG) and typical late-onset primary open angle glaucoma (POAG). As a result, much scrutiny has been focused on the pathology of these diseases. In order to better understand the pathophysiology of POAG, we have been developing a mouse model of the disease. As a step in this development, we have investigated the expression pattern of Myoc transcripts in embryonic and adult mouse tissue using Northern blot and in situ hybridization analyses. Myoc transcripts were found in high levels in adult eye, heart, brain, skeletal muscle and testis and to a lesser extent in lung and kidney. They were also present, albeit in very low amounts, during mouse embryogenesis. We present new evidence using in situ hybridization analysis that Myoc transcripts were present in widespread regions of the adult brain including the ependymal lining of the third and fourth ventricles, in the choroid plexus, the zonal layer of the junction of the inferior and superior colliculi, the neurons of the habenula, the piriform cortex, the median pre-optic nucleus of the hypothalamus, the olfactory tubercle, and in the inferior olive. In a functional sense, Myoc expression in the ependyma and choroid plexus, two regions of the brain involved in cerebrospinal fluid synthesis and resorption, parallels Myoc expression in the ciliary body and trabecular meshwork of the anterior segment of the eye where aqueous humor synthesis and outflow occur.

Animals↗

PubMed2003

Aqueous humor dynamics and the iris.

Solutes concentration in the aqueous humor of the eye is highest near the ciliary processes in the posterior chamber (p.c.) and lowest near the trabecular meshwork in the anterior chamber (a.c.). The high osmotic gradient across the semipermeable iris causes it to easily move forward at this location and occasionally occlude the iridocorneal angle. Vector analysis of the forces generated by miosis helps explain on osmotic grounds why it reduces the intraocular pressure, while at the same time the analysis elucidates the reason for the higher frequency of angle closure glaucoma when the anterior chamber is shallow.

Aqueous Humor↗

PubMed1998

Short note: aqueous humour water clusters: the importance of the physical properties of the aqueous humour in primary open angle glaucoma.

The size, form and charge of the stabilized water clusters present in the aqueous humour of the mammalian eye influence the facility for aqueous flow through the pupillary ball valve and through the trabecular meshwork. The properties of the clusters can be influenced in many different ways, all of which can influence the anterior and posterior chamber intraocular pressures as well as the uveoscleral outflow.

Aqueous Humor↗

PubMed2001

Viscoelastic material as an adjunct to dissections and to treat microperforations during nonpenetrating filtering surgery.

A case is described in which viscoelastic material was used in the anterior chamber to minimize or prevent fluid flow through the area of the trabecular meshwork and Schlemm's canal during nonpenetrating filtering surgery. In cases with or without small perforations, the technique minimizes or decreases fluid flow so that the surgeon has a clearer view of these tissues and can perform more thorough and accurate stripping of deeper layers of tissue.

Anterior Chamber↗

PubMed2001

Pigment vacuum iridectomy for phakic refractive lens implantation.

I present a technique designed to ensure an atraumatic patent basal iridectomy for phakic refractive lens implantation. The technique divides the iridectomy procedure into 2 steps. First, the stromal layer is removed by surgical excision. Then, the pigment layer is removed by gentle vacuum aspiration with a 25 gauge cannula. Atraumatic, small, basal peripheral iridectomies that are functional and cosmetically pleasing have been performed in 12 eyes. There were no cases of large amounts of pigment debris deposited in the trabecular meshwork as checked by gonioscopy. Pigment vacuum iridectomy may be a reliable procedure to ensure a proper basal iridectomy in any type of anterior segment eye surgery.

Drainage↗

PubMed2001

Dilation of Schlemm's canal in viscocanalostomy: comparison of 2 viscoelastic substances.

PURPOSE: To study the injection of viscoelastic material into Schlemm's canal adjacent to and 6.0 mm from the scleral flap during viscocanalostomy in an autopsy eye model. SETTING: Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Viscocanalostomy was performed in 8 postmortem human globes. Sodium hyaluronate (Healon GV or Healon5) was injected into 1 side of Schlemm's canal, with the other side serving as a control in some eyes. The eyes were prepared for light microscopic analysis, and serial pathologic sections were taken adjacent to the flap and 6.0 mm circumferentially from the flap. The area of Schlemm's canal was calculated and compared using t tests. RESULTS: Injecting viscoelastic material enlarged the area of Schlemm's canal adjacent to and 6.0 mm from the flap significantly more than not injecting viscoelastic material. While there was no difference between the viscoelastic materials in dilating Schlemm's canal at the flap, with Healon5 there was a small but statistically significantly greater dilation 6.0 mm from the flap. No full-thickness breaks in the trabecular meshwork were noted adjacent to or 6.0 mm from the flap. CONCLUSION: Injecting viscoelastic material significantly increased the cross-sectional area of Schlemm's canal and may play a role in the success of viscocanalostomy. Further study is needed to elucidate the mechanism of this procedure.

Anterior Eye Segment↗

PubMed1994

Phacoemulsification with aspirated or retained Viscoat.

Endothelial cell counts, morphology, and 24-hour postoperative intraocular pressure (IOP) changes were measured in 55 consecutive patients (60 eyes) who had uncomplicated phacoemulsification and posterior chamber lens implantation with either aspirated (30 eyes) or retained (30 eyes) Viscoat (sodium chondroitin sulfate-sodium hyaluronate). The surgical technique was standardized in all cases. Endothelial cell loss was almost identical in the aspirated and in the retained groups (8.8% and 8.7%). Postoperative pleomorphism was significantly less in the retained Viscoat group than in the aspirated group, suggesting a possible protective effect of the retained viscoelastic. Corneal thickness increased significantly in the retained Viscoat group, but this was not significant clinically. The retained Viscoat group had more patients with a postoperative IOP greater than 30 mm Hg and a greater mean increase in postoperative IOP, although the difference between the groups was not significant. The IOP changes may have been caused by blockage of the trabecular meshwork by the retained Viscoat. The results suggest that Viscoat can be retained after cataract surgery if the surgeon is prepared for a greater 24-hour postoperative increase in IOP.

Aged↗

PubMed1992

Aqueous humor analysis after Nd:YAG laser capsulotomy with the laser flare-cell meter.

Using the laser flare-cell meter (Kowa FC-1000), we conducted a prospective study analyzing the effect of Nd:YAG posterior capsulotomy on the quantity of aqueous particles, aqueous flare, and intraocular pressure in 65 eyes (58 patients). Aqueous particles increased at six hours, followed by flare rise which was significant at 18 hours after capsulotomy. Only 22 eyes (34%) had a significant flare rise over prelaser values. Anti-inflammatory therapy was necessary in only one patient. The mean intraocular pressure value did not rise significantly after capsulotomy. Acute intraocular hypertension (AIOHT) (> 7 mm Hg increase) occurred between three and six hours after laser therapy in 12 patients (19%), was related in time to particle rise, and always responded to a single dose of acetazolamide. Acute intraocular hypertension was strongly correlated with elevated aqueous particles (P < .0001) and somewhat correlated with flare rise (P < .036), but was not correlated with the intraocular lens position (bag or sulcus fixation). Our findings strongly suggest that trabecular meshwork clogging by debris generated by the capsulotomy is the mechanism at the origin of AIOHT.

Adult↗

PubMed1995

Nonpenetrating trabeculectomy with placement of a collagen drainage device.

Since the advent of trabeculectomy with antimetabolite therapy, there have been few changes in the surgical management of glaucoma. This is the first report of a new technique, nonpenetrating trabeculectomy with placement of a collagen drainage device. The procedure facilitates aqueous drainage without entering the human eye. Meticulous surgical dissection of the trabecular meshwork is required with creation of an external filtration tract and subscleral positioning of a collagen device to facilitate aqueous drainage. With this procedure, the surgeon can avoid common complications of glaucoma surgery such as synechias, overfiltration, hypotony, intraocular infection, uveal prolapse, and failed surgical blebs. The procedure and device have been used extensively in Russia.

Aged↗