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Biomedical subjects

R Ritch

Publications and source records attributed to R Ritch.

At least 253 records · Page 14Linked to original sources
PubMed1979

Continuous wave argon laser iridectomy in angle-closure glaucoma.

By using a continuous wave argon laser in a multiburn fashion, successful iridectomies were achieved in 42 out of 45 phakic eyes with either acute or chronic angle-closure glaucoma. Five of the successful procedures required multiple sittings on different days or abandonment of the primary treatment site in favor of an alternate site, or both, to attain patency. Within the immediate postoperative period, ten eyes needed retreatment to eliminate moderate pigment proliferation at the perforation site. The procedure was performed on an outpatient basis under topical anesthesia, usually required less than one-half hour for completion, and resulted in only minimal complications. Therefore, continuous wave argon laser iridectomy appears to present a viable alternative to surgical iridectomy for the definitive treatment of angle-closure glaucoma, although long-term evaluation of this modality of therapy is presently unavailable.

Adult↗
PubMed1979

Continuous wave argon laser iridectomy in angle-closure glaucoma.

Utilizing a continuous wave argon laser in a multiburn fashion, successful iridectomies were achieved in 42 of 45 phakic eyes with either acute or chronic angle-closure glaucoma. Five of the successful procedures required multiple sittings on different days or abandonment of the primary treatment site in favor of an alternate site to attain patency. Within the immediate postoperative period, ten eyes needed further treatment to eliminate moderate pigment proliferation at the perforation site. The procedure was performed on an outpatient basis under topical anesthesia, usually required less than one-half hour for completion, and resulted in only minimal complications. Therefore, CWAL iridectomy appears to present an alternative to surgical iridectomy for the definitive treatment of angle-closure glaucoma, although long-term evaluation of this modality of therapy is presently unavailable.

Adult↗
PubMed1978

Lack of association of histocompatibility antigens with primary open-angle glaucoma.

Eighty-seven patients (35 with primary open-angle glaucoma, 20 with angle-closure glaucoma, and 32 controls) underwent HLA typing of peripheral lymphocytes. Sixteen specificities were detected at the A locus, 19 at the B locus, and four at the C locus. No significant differences were found between patients with either type of glaucoma and control patients.

Ethnicity↗
PubMed1978

Retail cost of antiglaucoma drugs in two cities.

Volunteer shoppers purchased antiglaucoma medications dispensed from prescriptions written according to generic and brand-name products in Manhattan and in the St. Louis area. All drugs obtained were more expensive in Manhattan than in St. Louis. No significant cost difference was found between generic and brand-name items in either city, but only in a few instances were generic drugs actually dispensed. No difference in overall price was found between pharmacies located in better and poorer neighborhoods in Manhattan or between pharmacies located in urban, suburban, or rural areas in St. Louis. A white shopper paid significatnly lower retail prices than did a Hispanic shopper in Manhattan, particularly in better neighborhoods. The range of prices in each city for all drugs studied was greater than twofold. Pharmacies offering more patient services tended to charge higher prices, but frequently, pharmacies did not actually offer the services they advertised.

Drug Prescriptions↗
PubMed1978

A comparison of the effects of timolol and epinephrine on intraocular pressure.

We conducted a double-masked, six-week crossover study comparing bilateral twice-a-day therapy with timolol maleate (0.1%, 0.25%, and 0.5%) and epinephrine hydrochloride (0.5%, 1.0%, 2.0%) in 36 otherwise untreated patients. Increasing concentrations of each drug were administered until an arbitrary level of control was achieved before each of the six-week follow-up periods. Seventeen patients were controlled by both drugs and four patients were controlled by neither drug. Timolol, but not epinephrine, was effective in ten patients, whereas epinephrine, but not timolol, was effective in two patients. Three patients did not complete the study. The mean decrease in intraocular pressure from baseline was significantly greater with timolol than with epinephrine both before crossover and overall at both the lowest and highest concentrations of drug used. Significantly toxicity was produced in four patients during treatment with epinephrine, but in no patients during treatment with timolol.

Adult↗
PubMed1978

The effect of 1.5% timolol maleate on intraocular pressure.

A controlled trial was instituted to compare the effect on intraocular pressure of topical administration of timolol maleate with epinephrine hydrochloride. A bottling error by the manufacturer resulted in the placebo bottles containing 1.5% timolol maleate. This drug given twice a day for two weeks significantly reduced intraocular pressure and produced no side effects.

Administration, Topical↗
PubMed1977

Inadvertent substitution of acetohexamide for acetozolamide.

In three cases acetohexamide (Dymelor), an oral hypoglycemic agent, was mistakenly given to patients instead of acetazolamide (Diamox), which had been prescribed for their glaucoma. A number of similarities, including the fact that both medications are 250-mg white tablets, with similar generic and brand names which are generically repackaged medications juxtaposed on the pharmacist's shelf, predispose to the inadvertent substitution of one medication for the other. In one instance a systemic hypoglycemic reaction resulting in head trauma and confusion ended in an emegency hospital admission following the substitution of acetohexamide for acetazolamide.

Acetohexamide↗
PubMedDate not supplied

Epinephrine as the initial therapy in selected cases of ocular hypertension.

The authors believe that the epinephrines should be employed as the initial therapy in both primary open angle glaucoma and, when treated, ocular hypertension. Unlike pilocarpine, epinephrine does not produce miosis and accommodative spasm. Because of longer experience with epinephrine than with costly timolol, its longterm effectiveness and side effects are better known. Although the side effects of epinephrine are usually not serious, they may be intolerable to the patient. However, allergic blepharoconjunctivitis may be ameliorated by concomitant hydroxymesterone therapy. The availability of dipivalyl epinephrine (DPE) may decidedly shift the balance of the treatment of ocular hypertension, when indicated, to an epinephrine compound.

Costs and Cost Analysis↗
PubMedDate not supplied

Ultrasound biomicroscopy dark room provocative testing: a quantitative method for estimating anterior chamber angle width.

PURPOSE: To describe a quantitative method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). METHODS: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 microm anterior to the scleral spur to the iris surface. ARA, and acceleration and gamma-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b, the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. RESULTS: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 +/- 0.04 vs. 0.15 +/- 0.05 mm2, P < .0001, Student t-test), acceleration a (0.22 +/- 0.15 vs. 0.26 +/- 0.17, P = .068), and y-intercept b (66 +/- 46 vs. 92 +/- 47 microm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions (P = .1, paired t-test), while acceleration a did (P < .0001). In the eyes that were occluded, both decreased significantly under dark conditions (P < .0001). CONCLUSIONS The ARA linear regression formula provides useful quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.

Adult↗
PubMedDate not supplied

Angle recess area decreases with age in normal Japanese.

PURPOSE: To investigate prospectively the relationships between anterior chamber angle configuration and refractive error, axial length, age, and body height in the Japanese. METHODS: We studied 65 eyes of 65 subjects (30 men, 35 women) who were either patients at the Ophthalmology Department of Mie University or volunteers. The 65 subjects underwent a complete eye examination, A-scan biometry, and ultrasound biomicroscopy. Images were exported to an IBM-compatible personal computer in PCX format. The angle recess area (ARA) was measured using a software program of our own design. RESULTS: The ARA decreased with age in all quadrants of all eyes. In older individuals, the angle in the superior quadrant was significantly narrower than in the other quadrants. The ARA correlated directly with anterior chamber depth (P < .001), axial length (P < .001), and body height (P = .003), and inversely with age (P < .001) and refractive error (P = .003) in pairwise analysis. Multivariate analysis revealed a significant association between ARA and anterior chamber depth (P < .001), axial length (P = .016), and younger age (P = .043). CONCLUSIONS: The anterior chamber area narrows with age, especially in the superior quadrant. Narrowing of the angle in Japanese is associated with older age, shorter axial length, and shallower anterior chamber depth. We hypothesize that because of the increasing prevalence of axial myopia in younger Japanese, angle-closure glaucoma could become less common in Japan in the future.

Adult↗
PubMedDate not supplied

Exfoliation syndrome.

Exfoliation syndrome (XFS) is an age-related disease in which abnormal fibrillar extracellular material is produced and accumulates in many ocular tissues. Its ocular manifestations involve all of the structures of the anterior segment, as well as conjunctiva and orbital structures. Glaucoma occurs more commonly in eyes with XFS than in those without it; in fact, XFS has recently been recognized as the most common identifiable cause of glaucoma. Patients with XFS are also predisposed to develop angle-closure glaucoma, and glaucoma in XFS has a more serious clinical course and worse prognosis than primary open-angle glaucoma. There is increasing evidence for an etiological association of XFS with cataract formation, and possibly with retinal vein occlusion. XFS is now suspected to be a systemic disorder and has been associated preliminarily with transient ischemic attacks, stroke, systemic hypertension, and myocardial infarction. Further ramifications await discovery. Deposits of white material on the anterior lens surface are the most consistent and important diagnostic feature of XFS. The classic pattern consists of three distinct zones that become visible when the pupil is fully dilated. Whereas the classic picture of manifest XFS has been often described, the early stages of beginning exfoliation have not been well defined. Next to the lens, exfoliation material is most prominent at the pupillary border. Pigment loss from the iris sphincter region and its deposition on anterior chamber structures is a hallmark of XFS. Despite extensive research, the exact chemical composition of exfoliation material (XFM) remains unknown. An overproduction and abnormal metabolism of glycosaminoglycans have been suggested as one of the key changes in XFS. The protein components of XFM include both noncollagenous basement membrane components and epitopes of the elastic fiber system such as fibrillium. Regardless of etiology, typical exfoliation fibers have been demonstrated electron microscopically in close association with the pre-equatorial lens epithelium, the nonpigmented ciliary epithelium, the iris pigment epithelium, the corneal endothelium, the trabecular endothelium, and with almost all cell types of the iris stroma, such as fibrocytes, melanocytes, vascular endothelial cells, pericytes, and smooth muscle cells. The presence of XFS should alert the physician to the increased risks of intraocular surgery, most commonly zonular dehiscence, capsular rupture, and vitreous loss during cataract extraction. Heightened awareness of this condition and its associated clinical signs are important in the detection and management of glaucoma, and preoperative determination of those patients at increased risk for surgical complications.

Cataract↗
PubMedDate not supplied

Ocular parasitic infection in Thailand.

Parasitic infestation is a major health problem in tropical countries. Increasing tourism and the influx of refugees from Southeast Asia demand a greater awareness of ocular parasitology. In Thailand, cysticercosis, gnathostomiasis, and angiostrongyliasis are the three commonest ocular parasitic diseases. No antiparasitic drugs are yet available to treat ocular involvement, and therapeutic success depends upon early and complete surgical removal. Because the eye is the only site at which direct visualization and surgical removal are possible, ocular examination is crucial to diagnosis and treatment.

Angiostrongylus↗
PubMedDate not supplied

Ultrasound biomicroscopy of intrastromal photorefractive keratectomy with the Nd:YLF picosecond laser.

PURPOSE: To evaluate corneal morphology in vivo following intrastromal photorefractive keratectomy (IPRK) with the Nd:YLF picosecond laser, using the ultrasound biomicroscope. MATERIALS AND METHODS: Myopic intrastromal PRK was performed in the anterior stroma of cat corneas with the neodymium:yttrium lithium fluoride (Nd:YLF) picosecond laser. Periodic examination of the treated corneas up to 6 months postoperative was performed with high resolution ultrasound biomicroscopy. Corneal thickness, depth of the laser patterns from the corneal surface, alignment of the laser treatment, extent of stromal opacification until resolution, and contour of the corneal surface were measured with the ultrasound biomicroscope throughout follow up. RESULTS: The treated corneas were thickened on ultrasonic biomicroscopy measurement immediately after intrastromal PRK and revealed a densely echogenic shadow parallel to the corneal surface at the treatment site. There was increased stromal echogenicity denoting mild edema. The echoes decreased over time and appeared thinner at 2 months compared to the preoperative and immediate postoperative measurements. At 6-month follow up, the treated corneas were echolucent on ultrasonic biomicroscopy. CONCLUSION: The ultrasound biomicroscope might become a helpful tool in assessing accuracy of treatment parameters of intrastromal PRK as well as in monitoring the response of the cornea to treatment.

Animals↗