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Biomedical subjects

M B Shields

Publications and source records attributed to M B Shields.

At least 127 records · Page 7Linked to original sources
PubMed1983

Combined timolol and epinephrine therapy for open angle glaucoma.

A survey of the literature concerning the interaction of timolol and epinephrine in lowering intraocular pressure, and a study comparing the efficacy of timolol and dipivefrin (a prodrug of epinephrine) to that of timolol and pilocarpine are presented. These observations suggest that timolol-epinephrine therapy is less effective than timolol-pilocarpine treatment, although the former combination has clinical value in some patients, and it is possible that this can be enhanced when special schedules for drug administration are used.

Drug Therapy, Combination↗
PubMed1983

Axenfeld-Rieger syndrome: a theory of mechanism and distinctions from the iridocorneal endothelial syndrome.

Twenty-four patients with the diagnosis of Axenfeld's anomaly or Rieger's anomaly or syndrome were the subjects of a clinical study, which included specular microscopy of the corneal endothelium in 16 cases and fluorescein angiography of the iris in 5. Histopathologic material was obtained from ten eyes of eight of these patients (one enucleated eye and nine trabeculectomy specimens) and was studied by light and electron microscopy. The overlapping of ocular and nonocular defects in these patients prevented subclassification according to traditional criteria. Any attempted subdivision appears to have minimal clinical value, and a single classification for the disease spectrum is believed to be more practical. The collective term Axenfeld-Rieger (A-R) syndrome is proposed. A theory of mechanism for the ocular features of the A-R syndrome is postulated which involves a developmental arrest, late in gestation, of tissues derived from neural crest cells. This leads to retention of primordial endothelial tissue on the iris and across the anterior chamber angle, which produces the iridic changes and the peripheral tissue strands. Continued contraction of these membranes after birth explains the progressive changes noted in some patients. This primordial endothelium also produces excessive and atypical basement membrane, especially near the corneolimbal junction, which accounts for the prominent Schwalbe's line. The secondary glaucoma results from arrested development of the anterior chamber angle structures, characterized by incomplete maturation of the trabecular meshwork and Schlemm's canal and a high insertion of the iris. The ICE syndrome may be confused with the A-R syndrome on the basis of certain clinical and histopathologic similarities. Based on available evidence, however, it is postulated that the two entities are distinctly separate, in that the fundamental defect in the ICE syndrome is believed to be an abnormality of the corneal endothelium with secondary proliferation of a tissue layer over the anterior chamber angle and iris, while the A-R syndrome is thought to represent a developmental arrest with retention of a primordial membrane and other developmental defects.

Abnormalities, Multiple↗
PubMed1982

Crowding of the peripheral nasal isopters in glaucoma.

We studied 300 visual fields of 153 consecutive patients who had glaucoma or increased intraocular pressures. All the visual fields were plotted with the same technique on a Goldmann perimeter. Crowding of the peripheral nasal isopters was said to be present when the nasal isopter, outlined with the peripheral threshold target, was less than 55 degrees from fixation and within 5 degrees of the nasal isopter plotted with the V4e (largest, most intense) target. This finding was detected in 65 visual fields; in 12 of these it was the only abnormality. Crowding of the peripheral nasal isopters is important in the early detection of glaucoma; the V4e target, or equivalent, is useful in examining the nasal periphery in screening protocols for glaucoma.

Adolescent↗
PubMed1982

Combined cataract extraction and glaucoma surgery.

An approach to the surgical management of eyes with concomitant cataract and glaucoma is outlined, and the author's experience in 73 consecutive cases is described. Cataract extraction alone is recommended when glaucomatous damage is minimal, and the intraocular pressure is controlled with a low-dose, well-tolerated medical regimen. When the glaucoma is uncontrolled on maximum tolerable medical therapy and poses an immediate threat to vision, a two-stage procedure of filtering surgery with subsequent cataract extraction is preferred. Between these two extremes of glaucoma control are those cases for which a combined operation is felt to be indicated, especially when cataract surgery is planned in an eye with borderline glaucoma control and/or moderate to advanced glaucomatous damage. The preferred combined approach is cataract extraction with a guarded filtering procedure, and a simplified technique to accomplish this is described.

Cataract↗
PubMed1981

Effect of synthetic cannabinoids on elevated intraocular pressure.

Two chemical derivatives of delta-1-tetrahydrocannabinol were evaluated in a randomized, double-masked study, administered as a single oral dose to a group of ocular hypertensive patients. One of the compounds (BW146Y) was found to have a significant intraocular pressure lowering effect that was independent of orthostatic blood pressure changes, although such changes did occur in some patients. The other compound (BW29Y) was ineffective in lowering intraocular pressure at the doses tested. Psychological and performance parameters were measured, and except for a time production test among the BW29Y group, these parameters were not significantly affected by the test drugs. Patients receiving both drugs experienced mild subjective side effects.

Benzopyrans↗
PubMed1981

Combined trabeculotomy-trabeculectomy for the management of glaucoma associated wih Sturge-Weber syndrome.

Experience in managing five eyes with glaucoma associated with the Sturge-Weber syndrome is presented. All cases were treated with a combined trabeculotomy-trabeculectomy as the primary surgical procedure. A review of the proposed mechanisms involved in the glaucoma of this syndrome is given to provide the reasoning behind the selection of this operation. Although the results of this small series do not prove superiority of this surgical approach over techniques reported by others, we feel that a combined operation of this type offers the most reasonable hope for success, until a more precise understanding of the glaucoma mechanism in this condition is established.

Adolescent↗
PubMed1980

Gray crescent in the optic nerve head.

Twenty-nine patients had a slate-gray crescent within the peripheral tissue of the optic nerve head. Twenty-five of the patients were black; an examination of 100 consecutive black patients revealed the gray crescent in 12 cases. The gray crescents were usually bilateral and were most often located along the temporal or inferotemporal disk margin. Failure to recognize the anatomic location of the gray crescent may lead to misdiagnosis of disk cupping.

Adolescent↗
PubMed1980

Specular microscopy of iridocorneal endothelia syndrome.

Clinical specular microscopic examination of 17 patients with features common to the iridocorneal endothelial syndrome (including Chandler's syndrome, iris nevus syndrome, and essential iris atrophy) showed pathognomonic endothelial changes and no areas of normal endothelial mosaic. Even in those patients with minimal anterior synechiae, gross central endothelial changes could be found, suggesting that the endothelial changes are primary and not secondary to the iris-corneal adhesions. Specular microscopy of the clinically uninvolved contralateral eye in these patients revealed frequent endothelial cell pleomorphism incommensurate with the patient's age. This study also confirmed the value of the specular microscope for qualitative endothelial observations.

Adolescent↗
PubMed1980

Anterior uveal melanomas and intraocular pressure.

A study of 11 consecutive patients with anterior uveal melanomas from one institution demonstrated the wide variation in the clinical and histopathologic manifestations of the tumors. The intraocular pressure in the involved eye compared with the fellow eye was elevated in five cases, equal in four, and reduced in two. Histologic studies suggest that the anterior uveal melanomas influence intraocular pressure through their effect on the balance between aqueous production and outflow. Three of the four patients with ciliary body melanomas and glaucoma died of metastatic disease within 3 years of enucleation.

Adult↗
PubMed1980

Trabeculectomy vs full-thickness filtering operation for control of glaucoma.

A survey of the literature and a comparison of 26 trabeculectomies and 23 posterior lip sclerectomies performed by the author suggest that glaucoma control is comparable between trabeculectomy and full-thickness filtering procedures, although trabeculectomy offers a reduction in some postoperative complications. At the present time, however, there does not appear to be sufficient evidence to claim superiority for one filtering procedure in all situations.

Adolescent↗
PubMed1979

Corneal edema in essential iris atrophy.

In a clinical study of the essential iris atrophies, corneal edema occurred in 49 of 90 patients, and a characteristic hammered-silver appearance of the posterior cornea was visible in 54 cases. Intraocular pressure in the eyes with corneal edema ranged from normal to extreme elevation with glaucomatous damage, and lowering the pressure relieved the corneal edema in many cases with penetrating keratoplasty being effective when other measures failed. Electron microscopy of two keratoplasty specimens revealed extremely few, distinctly abnormal cells lining a collagenous layer posterior to Descemet's membrane.

Adolescent↗
PubMed1978

The corneal endothelium and the spectrum of essential iris atrophy.

We found that the spectrum of essential iris atrophy (progressive essential iris atrophy, Chandler's syndrome, and the Cogan-Reese syndrome) began as a corneal endothelial degeneration, which, with ectopic endothelial membrane overgrowth over an open angle, followed by contraction of this membrane and further growth onto the iris, accounted for all aspects of the syndrome. The contractile membrane caused the synechiae, the glaucoma, the corectopia, the ectropion uveae, the occasional iris nodules, and the iris atrophy. Thus we found this disease to be primarily of the cornea, and only secondarily of the iris. The results of this study led us to propose a new designation for this spectrum: primary proliferative endothelial degeneration.

Adult↗
PubMed1978

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.

Adolescent↗