M. Bruce Shields

Clinical and Histopathologic Observations Concerning Hypotony After Trabeculectomy with Adjunctive Mitomycin C

Prolonged hypotony-induced maculopathy is a serious complication of trabeculectomy with adjunctive mitomycin C. We performed trabeculectomies with intraoperative mitomycin C on 59 eyes of 52 consecutive patients. Exposure time to mitomycin C was five minutes in the first seven patients, two of whom had prolonged hypotony-induced maculopathy. One of these required surgical revision of the filtering procedure. Light and electron microscopic study of the excised, avascular bleb disclosed an irregular epithelium and largely acellular subepithelium of loosely arranged connective tissue. In the remaining 52 eyes, the exposure time to mitomycin C was titrated between two and five minutes according to each patients risk for failure of filtration from excessive fibrosis. Four additional cases of prolonged hypotony-induced maculopathy occurred among these 52 cases (7.7%), all of which were in the lower risk groups that received two- or three-minute exposure to mitomycin C. Four procedures failed, requiring further glaucoma surgery, and all of the patients were in the higher risk groups, receiving three- to five-minute exposures. Our titration of the exposure time to mitomycin C may have reduced, but did not eliminate, the risk fo prolonged hypotony-induced maculopathy, and further study is needed to establish the optimum protocol for the use of this drug as an adjunct to trabeculectomy.

Axenfeld-Rieger syndrome. A spectrum of developmental disorders

The clinical and histopathologic features of Axenfelds anomaly and Riegers anomaly and syndrome are reviewed, and recent findings regarding the pathogenesis of this spectrum of developmental disorders are discussed. Based on these observations, it has been suggested that a developmental arrest, in the third trimester of gestation, of tissues derived from the neural crest cells accounts for the ocular and most of the nonocular abnormalities in this group of disorders. Since previous collective terms, such as mesodermal dysgenesis and anterior chamber cleavage syndrome, are not consistent with these new observations, the alternative name, Axenfeld-Rieger syndrome, has been proposed. The differential diagnosis of the syndrome includes two additional spectra of disorders: the iridocorneal endothelial syndrome and the posterior polymorphous dystrophies. The most serious ocular problem in Axenfeld-Rieger syndrome is the associated glaucoma, which occurs in a high percentage of patients and is typically difficult to control. Recent observations regarding the mechanism of the glaucoma, as reviewed in this paper, provide guidance in the management of this aspect of Axenfeld-Rieger syndrome.

Prevalence and Mechanisms of Secondary Intraocular Pressure Elevation in Eyes with Intraocular Tumors

A survey of 2704 eyes with intraocular tumors in patients who were evaluated on the Oncology Service at Wills Eye Hospital showed that 126 of the tumor-containing eyes (5%) had tumor-induced elevated intraocular pressure (IOP) at the time of diagnosis of the tumor. Of the 2111 eyes with uveal melanomas, secondary IOP elevation was present in 55 (3%). Secondary IOP elevation was present in 7% of eyes with iris melanoma, 17% with ciliary body melanoma, and 2% with choroidal melanoma. The most common mechanism of elevated IOP was tumor invasion of the angle in the case of iris melanomas, pigment dispersion and tumor invasion of the angle in the case of ciliary body melanomas, and iris neovascularization in the case of choroidal melanomas. Of the 256 eyes with uveal metastases, secondary IOP elevation was found in 12 eyes (5%). Secondary IOP elevation was present in 64% of eyes with iris metastases, 67% with ciliary body metastases, and 1% with choroidal metastases. The most common mechanism of elevated IOP was tumor invasion of the angle in the case of iris and ciliary body metastases, and angle closure in the case of choroidal metastases. There were 303 eyes with retinoblastoma, 17% of which had elevated IOP which was secondary to iris neovascularization in 70% of cases and to an angle closure without neovascularization in 27%. Several other intraocular tumors including lymphoma, leukemia, medulloepithelioma, melanocytoma, and adenoma of the iris pigment epithelium were occasionally associated with secondary elevated IOP.

Side effects associated with prostaglandin analog therapy.

Topical prostaglandin analogs, which have become first-line therapy in the medical management of glaucoma, have an excellent safety profile with regard to systemic side effects, but are associated with several ocular side effects. Some of these are common, with no apparent serious consequences other than cosmetic, whereas others are much less common but represent potentially sight-threatening side effects. The former group includes conjunctival hyperemia, elongation and darkening of eyelashes, induced iris darkening, and periocular skin pigmentation. The latter group of side effects, which are relatively rare and lack definitive causal relationship to prostaglandin analog therapy, includes iris cysts, cystoid macular edema, anterior uveitis, and reactivation of herpes simplex keratitis. Most of the literature regarding side effects associated with prostaglandin analogs involves the use of latanoprost, probably because it was the first to be studied. There is no evidence, however, aside from less conjunctival hyperemia with latanoprost, that the commercially available prostaglandin analogs differ significantly with regard to side effects.

The non-contact tonometer. Its value and limitations.

A review of the literature and a comparative study against Goldmann applanation tonometers suggest that the non-contact tonometer is reliable for measuring intraocular pressures within the normal range. In addition, the non-contact tonometer eliminates the need for corneal contact and topical anesthesia, thereby avoiding the potential problems of corneal abrasion, spread of infection, and drug reactions. The instrument can be used reliably by paramedical personnel and has particular value in mass screening and possibly in studies of topical antiglaucoma drugs. The non-contact tonometer is less reliable in patients with elevated intraocular pressure, since comparative studies against the Goldmann applanation tonometers have shown poorer correlations in the higher pressure ranges. The instrument is also limited by an abnormal cornea or poor fixation, which may interfere with accurate pressure measurements. Furthermore, the non-contact tonometer is less portable than many tonometers and more expensive than most.

Risk Factors for the Development and Severity of Glaucoma in the Pigment Dispersion Syndrome

The medical records of 93 patients with pigmentary glaucoma and 18 patients with pigment dispersion syndrome were studied with regard to factors associated with the presence and severity of secondary glaucoma within this population. Male gender, black race, severe myopia, and Krükenberg spindles were identified as possible risk factors. Men were predominant in this population 75 (67.6%); the diagnosis was made in men at an earlier age; they had a higher proportion in the glaucoma group; and they required more aggressive glaucoma therapy. There were only four black patients, but all required surgery. Patients in the glaucoma group had significantly more severe myopia and a higher incidence of Krükenberg spindles. These risk factors may help to identify which patients with the pigment dispersion syndrome require closer follow-up or the possible initiation of prophylactic therapy.

The essential iris atrophies.

We studied 82 cases of essential iris atrophy. The findings support some traditional concepts of this complex spectrum of disorders, but conflict with others. Corneal abnormality appeared early and may be the primary disorder. A corneal endothelial disturbance was present in 55% of cases and corneal edema was present in 50%. Peripheral anterior synechiae occurred in all but one of the cases studied by gonioscopy. The pupil was distorted in 71% of the cases and was usually pulled in the direction of the most prominent synechia. The iris was stretched with stromal atrophy in 71%. Iris holes occurred in 33%. The degree of corneal and iris changes occurred as a spectrum of disorders. The prognosis for most patients with essential iris atrophy is slow progression with eventual involvement of vision because of corneal edema, secondary glaucoma, or both. Treatment of increased IOP was required in 77% of our cases, and 44% required surgical intervention.

Management of anterior chamber depth after trabeculectomy.

We followed up 36 eyes of 34 patients for the first three months after trabeculectomy, paying special attention to the depth of the anterior chamber. A significant difference in postoperative course was noted between those eyes with central cornea-lens touch and those with cornea-iris touch but not contact between cornea and lens. The former group (four eyes) had a high rate of complications, including corneal edema, cataract, and bleb failure, despite early efforts to reform the anterior chamber. The latter group (18 eyes), in which the anterior chambers were all allowed to reform spontaneously, had a favorable course, similar to those eyes that maintained formed anterior chambers throughout the study.

Current concepts in pigmentary glaucoma

Since its initial description over 50 years ago as a rare clinical entity, pigmentary glaucoma has become recognized as one of the most common forms of secondary open-angle glaucoma. Pigmentary glaucoma affects a much younger patient population than most other forms of open-angle glaucoma, and has a predilection for Caucasian males with myopia. Hallmarks of this disease include midperipheral iris transillumination defects, Krukenberg spindles and a heavily pigmented trabecular meshwork. The mechanism of pigment dispersion appears to be a rubbing between iris pigment epithelium and packets of lens zonules, possibly associated with an inherent abnormality of the pigment epithelium, and the mechanism of aqueous outflow obstruction is believed to involve accumulation of the pigment granules in the trabecular meshwork, followed by denudation, collapse, and sclerosis of the trabecular beams. Current management includes standard antiglaucoma drugs, laser trabeculoplasty, and filtering surgery, although research suggests the possibility of earlier intervention with medication or surgery to arrest the pigment dispersion and reverse or prevent the secondary glaucoma.

A comparison of dorzolamide–timolol combination versus the concomitant drugs☆

PURPOSE To compare the intraocular pressure (IOP) lowering effect of fixed combination dorzolamide 2% and timolol 0.5% therapy to that of concomitant administration of a topical beta-blocker and dorzolamide. METHODS Seventy-four consecutive glaucoma patients were changed from a regimen including a topical beta-blocker and dorzolamide to the fixed combination dorzolamide-timolol in 1 eye, with the other eye used as the control. The average IOP readings before and 1 month after the change were compared. RESULTS The mean baseline IOP in the entire study population was 19.4 +/- 4.2 mm Hg in the study eyes and 16.9 +/- 4.2 mm Hg in the control eyes. Four weeks after the medication change, the mean IOP was 17.3 +/- 3.9 mm Hg in the study eyes (P <.001) and 16.1 +/- 4.1 mm Hg in the control eyes (P =.02). The difference between the mean IOP change of 2.1 mm Hg in the study eyes and 0.8 mm Hg in the control eyes was found to be statistically significant (P =.01). CONCLUSION These findings suggest that the fixed combination dorzolamide-timolol therapy achieves additional lowering of the intraocular pressure compared with the concomitant administration of a beta-blocker and dorzolamide.