Biomedical subjects
Publications and source records attributed to M B Shields.
A 14-week course of timolol therapy in 38 eyes with open-angle glaucoma produced a statistically significant drop (6 mm Hg) in their mean intraocular pressure but had no effect on the mean coefficient of aqueous outflow. These data are compatible with those of Zimmerman et al. obtained after a single drop of treatment and suggest that timolol reduces intraocular pressure by inhibiting aqueous production.
Eighty-two consecutive filtering procedures (47 thermal sclerostomies and 35 posterior lip sclerectomies), performed by senior staff and residents at the Duke University Eye Center between 1972-1976, were reviewed and compared. Operative and early postoperative complications were more common with the posterior lip sclerectomies. However, late postoperative complications were equal for the two groups, with cataracts occurring in approximately 30% of both categories. A final intraocular pressure of 20 mm Hg or less, with or without medication, was achieved in 66% of the thermal sclerostomies and 85.7% of the posterior lip sclerectomies. Residents did not perform as well as the senior staff when using thermal sclerostomy (60% vs. 70%, respectively), but performed equally well when using posterior lip sclerectomy (85.7% for both groups). In comparing black and white patients, the final intraocular pressures were the same in both groups.
It has been suggested that glaucomatous field loss may progress on the basis of ischemia of the optic nerve head alone after the intraocular pressure has been controlled. Bishydroxycoumarin (Dicumarol) has been reported to be of benefit in such situations. A review of 551 consecutive glaucoma records did not support this theory. Apparent progression of field loss at intraocular pressures of 20 mm Hg or less was either due to artifacts in field testing or to a pressure that was still too high. A pilot study suggested that bishydroxycoumarin was of no benefit in these situations.
In human limbal tissue from four glaucomatous and four nonglaucomatous eyes, the average collagen fibril diameter in the inner and outer layers was 100.86 and 115.33 nm., respectively. In both layers the fibrils occupied an average of two thirds of the total area The possible implications of this observation in the trabeculectomy procedure are discussed.
An in vitro study suggests that flow through the scleral flap of a trabeculectomy procedure can significantly increase outflow. It also suggests that this flow may be through vessels in the flap or through the ground substance of the flap.
Case reports of oculodermal melanocytosis (nevus of Ota) and ipsilateral glaucoma often have other ocular disorders which could account for the glaucoma. It has not been clearly shown that the oculodermal melanocytosis alone can cause secondary glaucoma. In the present case report, optic nerve head and visual field changes, suggestive of a long-standing unilateral elevation of intraocular pressure, occurred in an eye with oculodermal melanocytosis and no other apparent ocular disorder to account for the chronic glaucoma.
Seven cases are reported, believed to be the first in the literature, in which iris nodules are verified in the complete spectrum of essential iris atrophies. This feature appears late in the course of the disease as small yellow nodules that progressively increase in number and gradually become dark brown. The differential diagnosis of multiple iris nodules includes neurofibromatosis, melanomas, inflammatory nodules, and developmental anomalies such as iridocorneal dysgenesis.
A 68-year-old white man with Paget's disease and open-angle glaucoma was treated with methazolamide, 50 to 100 mg three times daily. Ten months after the medication was initiated he developed ureteral colic and a calcium oxalate stone was surgically removed. Three months after the drug was reinstituted the patient passed three calcium phosphate stones. This suggested a casual relationship between methazolamide and stone formation, although renal calculi also complicate Paget's disease and acetazolamide had been administered briefly.
The trabecular meshwork of eyes with open-angle glaucoma has been demonstrated to have an increase in gamma globulin and plasma cells, raising the question of an immunogenic mechanism in this disorder. In the present study, however, immunofluorescence assays on the trabecular meshwork of eyes with open-angle glaucoma were negative for specific immunoglobulins and for complement components that would result specifically from an antigen-antibody reaction. The study fails to provide any evidence in support of an immunogenic mechanism in open-angle glaucoma.
Combined cyclodialysis and cataract extraction was performed on 78 eyes in a consecutive series of 26 years duration. This operation was performed on eyes with severe glaucoma, inadequately controlled on maximum medical therapy, and with a cataract needing extraction. Glaucoma types included open-angle, angle-closure with peripheral anterior synechias, combined open-angle and angle-closure, and secondary to uveitis. Seventy of the 78 eyes had follow-up of six months or more and the results in these 70 eyes were analyzed. In thirteen percent of the eyes in this study the postoperative intraocular pressure was the same or higher than the preoperative level, or reductions of intraocular pressure were not clinically significant. Eighty-seven percent (61 eyes) had a clinically significant lowering of intraocular pressure following the combined procedure. Thirty-nine percent (27 eyes) of the 70 eyes in this study had a tension of 0-14 mm Hg, and 44% (31 eyes) had a tension of 15-20 mm Hg. Intraocular pressure was improved significantly more often in patients over 60 years of age. Resulting intraocular pressures of 14 mm Hg or less were more likely when the cyclodialysis was performed in the lower quadrant. The results of the combined procedure were not significantly influenced by the type of glaucoma involved or by a history of previous glaucoma surgery. Bleeding was a frequent complication, but was not related to resulting intraocular pressure. Other complications were rare. We conclude that combining cyclodialysis with cataract extraction is safe and effective, and is a suitable procedure when there is need for surgery to relieve severe glaucoma, along with a need for cataract extraction.
Congential ptosis associated with aniridia was found in 3 patients from 2 pedigrees. Nonsurgical aphakia, a condition not previously reported in association with aniridia, was also found in one case. The association of aniridia and congenital ptosis is suggested as evidence for the common mesodermal etiology of both anomalies.
Progressive essential iris atrophy, Chandler's syndrome, and the iris nevus (Cogan-Reese) syndrome are considered to be variations of a single disease process, which is characterized by abnormalities of the cornea, anterior chamber angle, and iris. In each variation, the typical patient is a white woman with unilateral disease, negative family history, and an onset of symptoms in early to middle adulthood. Since the membrane theory of Campbell suggests that the disease is a fundamental abnormality of the corneal endothelium, rather than the iris, the term "iridocorneal endothelial syndrome," as proposed by Yanoff, may be an appropriate inclusive term for the spectrum of disease, although further study of the pathogenesis is needed. For each variation of the disease, corneal edema and secondary glucoma are both treated primarily by medical or surgical reduction of the intraocular pressure, although penetrating keratoplasty is occasionally required for cases with advanced corneal edema.
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.
The clinical and histopathologic features of Axenfeld's anomaly and Rieger's 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.
With the advent of automated static perimetry has come the common practice of measuring only the central 30 degrees of vision in the diagnosis and management of glaucoma. While most glaucomatous field defects appear first in this portion of the visual field, the question remains as to how much useful information is being missed by ignoring the peripheral field, i.e., outside the central 30 degrees. Studies with both static and kinetic automated perimetry have revealed the same peripheral glaucomatous field defects previously recognized with manual perimetry, including generalized contraction, nasal steps, temporal sector defects, and hemianopic offsets. Of these, however, only measurement of the nasal periphery may add sufficient information to that obtained with static testing in the central 30 degrees to justify the added examination time; however, there are special situations in which peripheral field testing in other or all quadrants may be useful. Further study is required to establish optimum techniques for automated measurement of the peripheral visual field and to determine the significance of the results in the management of 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.
PURPOSE: To evaluate the success of contact transscleral cyclophotocoagulation (TDC) in patients with refractory pediatric glaucomas. METHODS: Twenty-six eyes of 20 patients with therapy-resistant pediatric glaucomas were included in this retrospective study. Subgroup analysis was performed for patients 10 or younger and patients older than 10 at time of first TDC procedure. Diode laser cyclophotocoagulation was applied using a fiber optic G-probe. Follow up until time of failure or for a minimum of 6 months was obtained for all procedures in all eyes. Failure was defined as intraocular pressure (IOP) greater than 21 mm Hg, repeat of TDC due to clinically inadequate IOP control, progression to another procedure, or serious complication. RESULTS: Baseline mean pretreatment IOP was 34.2 +/- 10.4 mm Hg (range, 15 to 62 mm Hg). Ten of 26 eyes (38%) were successful 6 months after initial TDC. A mean decrease in IOP of 10.3 +/- 14.7 mm Hg was noted after the first procedure (P < 0.05). Eighteen eyes (70%) were retreated at least once. The mean decrease in IOP for all patients after all procedures was 12.9 +/- 13.4 mm Hg (P < 0.001). This represents a mean percent decrease in IOP of 33.2 +/- 6.9%. The overall success rate was 50%, including retreated patients. The younger and older subgroups did not differ with regard to overall success, time to failure, or retreatment rats. One patient suffered a retinal detachment. Visual loss was noted in 4 of 22 eyes with reliable visual acuity measurements. CONCLUSION: TDC is an effective means of decreasing IOP in some patients with refractory pediatric glaucomas. Although the retreatment rate is high, the procedure generally is well tolerated with few complications.
BACKGROUND AND OBJECTIVES: To evaluate the benefit of measuring the intraocular pressure (IOP) on the first postoperative day after argon laser trabeculoplasty (ALT). PATIENTS AND METHODS: We retrospectively reviewed 407 ALT procedures with perioperative apraclonidine performed on 226 patients between January 1991 and December 1993. Data analyzed included type of glaucoma, extent of treatment, whether the procedure was initial or repeat, laser parameters, and IOP preoperatively and at 1 hour, 1 day, and 1 month postoperatively. RESULTS: The percentage of patients with an IOP rise of greater than 3 mm Hg at 1 hour, 1 day, and 1 month following ALT was 11.3%, 4.2%, and 5.2% respectively. The incidence of IOP elevations greater than 10 mm Hg was 2.2%, 1.0%, and 1.5% at 1 hour, 1 day and 1 month, respectively. Of 17 cases with an IOP elevation greater than 3 mm Hg at 1 day, four eventually required a trabeculectomy. However, there were no consistent factors that distinguished which cases with elevated IOP at 1 day ultimately needed further therapy, nor did the 1-day postoperative examination predict which patients would have IOP elevation at 1 month. CONCLUSION: IOP 1 day after ALT is rarely elevated and does not correlate with IOP elevation at 1 month. Therefore, an IOP check at 1 day is not felt to be necessary for most patients.