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Biomedical subjects

R Ritch

Publications and source records attributed to R Ritch.

At least 19 recordsLinked to original sources
PubMed1992

Lattice degeneration of the retina and the pigment dispersion syndrome.

Retinal detachment occurs more frequently in patients with pigment dispersion syndrome. We evaluated the incidence of peripheral retinal abnormalities known to predispose to rhegmatogenous retinal detachment in a consecutive series of 60 patients with pigment dispersion syndrome with or without glaucoma. Lattice degeneration was present in at least one eye of 12 patients (20%). Seven patients had bilateral lesions. Full-thickness retinal breaks were found in seven patients (11.7%) and two patients (3.3%) had asymptomatic rhegmatogenous retinal detachments that required scleral buckle procedures. The incidence of lattice degeneration and full-thickness retinal breaks appears to be increased in this group of patients, and may be responsible for the increased risk of rhegmatogenous detachment.

Adult↗
PubMed1992

Asymmetric pigmentary glaucoma resulting from cataract formation.

Pigment dispersion syndrome usually manifests bilaterally, and asymmetric involvement is unusual. When asymmetry is present, the eye with greater involvement may have an additional exacerbating condition or the eye with less involvement may be protected. Analysis of such cases should further elucidate the mechanism of the disorder and its development and regression. We examined four patients in whom unilateral cataract formation or extraction was associated with reduced clinical signs of pigment dispersion syndrome in the affected eye. Cataract formation, by inducing relative pupillary block, appears to decrease or prevent the manifestation of pigment liberation.

Adult↗
PubMed1992

Ultrasound biomicroscopy in plateau iris syndrome.

Ultrasound biomicroscopy is a new technique that uses high-frequency ultrasound (50 to 100 MHz) to produce images of the entire anterior segment at high resolution (20 to 50 microns). The iridocorneal angle, iris, ciliary body, and posterior chamber can be imaged in detail and the dimensions and anatomic relationships of these structures determined. Plateau iris syndrome is a condition in which the angle remains appositionally closed or occludable after iridectomy for angle-closure glaucoma. How the iris remains in a position that allows it to occlude the angle has been uncertain. We performed ultrasound biomicroscopy eye examinations on eight patients with clinically diagnosed plateau iris syndrome. In all the patients, ciliary processes were situated anteriorly compared to the position in normal subjects and in patients with angle closure caused by pupillary block. The ciliary processes provide structural support beneath the peripheral iris, preventing the iris root from falling away from the trabecular meshwork after iridectomy.

Anterior Eye Segment↗
PubMed1992

Ophthalmology in Laos.

Laos, a small, landlocked nation of 4 million persons, has only recently begun modernization of its medical services, now a national priority. Five ophthalmologists and 11 cataract surgeons are responsible for the entire country. Tertiary care is available only at two centers; the first eye hospital opened in 1990. Several voluntary organizations have recently become involved in assisting with the development of services.

Blindness↗
PubMed1992

Initial 5-fluorouracil trabeculectomy in young patients.

The effectiveness of initial trabeculectomy with adjunctive 5-fluorouracil (5-FU) for uncomplicated glaucoma in patients age 40 years or younger at the time of surgery was evaluated retrospectively in a consecutive series of 20 eyes of 20 patients. Fifteen patients had juvenile primary open-angle glaucoma, 4 had pigmentary glaucoma, and 1 had glaucoma associated with angle recession. Mean patient age was 26.8 +/- 9.7 years (range, 13 to 40 years) at the time of surgery. The mean total 5-FU dose administered was 27.8 +/- 8.8 mg (range, 15 to 45 mg). The intraocular pressure (IOP) decreased from 34.4 +/- 11.5 mmHg preoperatively to 10.5 +/- 4.0 mmHg postoperatively after a mean follow-up of 31.1 +/- 17.3 months (range, 11.5 to 70 months). Nineteen eyes (95%) had a postoperative IOP of 20 mmHg or less without pressure-lowering medications. One patient required additional medical therapy to control the IOP. Complications included bleb-related endophthalmitis (2 eyes) and hypotony maculopathy (1 eye).

Adolescent↗
PubMed1992

Age-related decline of disc rim area in visually normal subjects.

Optic disc parameters and axial lengths were measured in 81 visually normal young and elderly white adults (young [n = 41]: 27.2 +/- 5.7 years versus elderly [n = 40]: 68.8 +/- 8.4 years) using Rodenstock Optic Disc Analyzer and A-scan sonography. Axial lengths correlated positively with optic disc parameters (Spearman correlation analysis: rim area: P = 0.042, disc area: P = 0.052, and cup volume: P = 0.010). Older subjects had a shorter axial length (23.09 +/- 1.02 mm) and smaller disc rim area (1.171 +/- 0.338 mm2) than younger subjects (23.60 +/- 1.15 mm and 1.325 +/- 0.314 mm2; Mann-Whitney U test: P = 0.011 and P = 0.013, respectively). While both axial length and disc rim area declined with age (0.011 mm and 0.003 mm2 per year; Spearman correlation analysis: P = 0.032 and P = 0.020, respectively), the cup-to-disc and rim area-to-disc area ratios appeared to remain relatively constant throughout adult life. The age-related decline of disc rim area is consistent with histologic evidence of age-related decline of ganglion cell axons. The rim area-to-disc area ratio seems less affected by age, and is thus a better parameter to isolate age-related change from disease-related change of optic nerve in a longitudinal follow-up of diseases involving the optic nerve head.

Adolescent↗
PubMed1992

Sub-Tenon's anesthesia for trabeculectomy.

Sub-Tenon's anesthesia for anterior segment surgery avoids the risks associated with retrobulbar and peribulbar injections. Localized injections over the appropriate rectus muscles ensure patient comfort as well as optimal exposure of the surgical field in eyes undergoing trabeculectomy. We have used this technique without significant complications in approximately 400 procedures.

Anesthesia, Local↗
PubMed1992

Isolation and cultivation of human iris pigment epithelium.

There have been very few attempts to isolate and culture human iris pigment epithelium (IPE). Earlier efforts that used whole iris explant methods did not achieve pure cultures of IPE. We have developed methods for separating the IPE from the iris stroma of post-mortem eyes that avoid contamination by other cell types. Three different isolation methods were studied: direct dissection, enzyme digestion, and enzyme-assisted microdissection. The latter method yielded the best results. After treatment with enzyme solution, the IPE was easily separated from the stroma under the stereomicroscope and subsequently cultured with supplemented F12 medium. With this method, approximately 2.3 x 10(5) cells were isolated from each iris with an average viability of 90.2%. IPE cells isolated from 19 of 24 eyes grew to confluence in primary culture. The IPE could be maintained in pure culture for many generations over several months with up to 20 population doublings. Cultured IPE demonstrated cytokeratin and S-100 protein by immunocytochemistry. Some of these cells also displayed desmin, indicating origin from the anterior IPE. Cultured IPE cells retained most of the characteristics of IPE in vivo, such as apical/basal polarization, microvilli, and many cell junctions. Gradual dilution of pigment occurred in the dividing IPE cells, suggesting an inability to produce melanin in vitro. A subpopulation of the IPE cells contained myofilaments by electron microscopy, also indicating a anterior IPE origin. This method provides a source for large numbers of human IPE cells and could be useful in studies of the biology of IPE and the role of IPE in pathogenesis of several eye diseases, most notably exfoliation syndrome and its associated glaucomas.

Adult↗
PubMed1991

Optic nerve head and nerve fiber layer in Alzheimer's disease.

We compared (1) the differences in the retinal nerve fiber layer between 26 patients with Alzheimer's disease and 30 age- and race-matched normal controls with use of blue-light high-resolution photography, (2) the differences in disc pallor between 30 patients with Alzheimer's disease and 32 controls with use of a boundary-tracking program and fundus photographs, and (3) the topographic disc variables between 26 patients with Alzheimer's disease and 36 controls with use of an optic nerve head analyzer. A higher proportion of patients with Alzheimer's disease had detectable nerve fiber damage as seen by red-free photography compared with controls. Although the pallor area-to-disc area ratio was not significantly different between patients with Alzheimer's disease and controls, the patients with higher pallor area-to-disc area ratios had higher Alzheimer's Disease Assessment Scale (ADAS) scores and longer durations of disease. Patients had an increased cup-to-disc ratio and cup volume and decreased disc rim area compared with controls. These variables also correlated significantly with ADAS scores and the duration of disease. The correlation among the optic nerve head changes and the ADAS scores in patients with Alzheimer's disease suggests a potential role for optic nerve head analysis in monitoring the progression of Alzheimer's disease and in assessing the effectiveness of any treatments developed.

Aged↗
PubMed1991

Posterior polymorphous dystrophy and Alport syndrome.

Seventeen Thai patients from nine families with Alport syndrome underwent complete ocular examination and specular microscopy. Fourteen (82.3%) patients had ocular changes. Eleven (64.7%) had endothelial vesicles compatible with posterior polymorphous dystrophy. Four of these also had subepithelial opacities, a previously undescribed phenomenon. Other ocular changes included lenticonus and macular and midperipheral retinal flecks. A second group of 18 consecutive patients from 14 families with posterior polymorphous dystrophy detected during routine ocular examination underwent renal evaluation. Five had hematuria, four of whom had sensorineural hearing loss. Two of the four patients also had characteristic renal biopsy findings. Another had sensorineural hearing loss without hematuria, and renal biopsy showed a thin glomerular basement membrane. Posterior polymorphous dystrophy is a common but frequently overlooked finding in Alport syndrome. The frequent association of these two hereditary conditions suggests a common defect in basement membrane formation. Patients with posterior polymorphous dystrophy should be examined for renal abnormalities and hearing loss.

Adolescent↗
PubMed1991

Late bleb-related endophthalmitis after trabeculectomy with adjunctive 5-fluorouracil.

The incidence of late-onset bleb-related endophthalmitis was evaluated retrospectively in 229 consecutive trabeculectomies performed with adjunctive 5-fluorouracil (5-FU) therapy. Mean follow-up was 23.7 +/- 16.3 months (range, 3 to 60 months). Thirteen eyes (5.7%) of 11 patients developed bleb-related endophthalmitis an average of 25.9 +/- 17.4 months (range, 5 to 58 months) after surgery. Infection occurred in 9 of 96 (9.4%) procedures performed from below and in 4 of 133 (3.0%) procedures performed superiorly (P = 0.05, Fisher's exact test). The relative risk of bleb-related endophthalmitis in trabeculectomy from below versus above is 4.0 after adjustment for age and sex (95% confidence interval = 1.1, 14.8). Trabeculectomy with adjunctive 5-FU performed from below carries an increased risk of late bleb-related infection. The incidence of late bleb-related endophthalmitis after 5-FU trabeculectomy appears to be higher than that for trabeculectomy without adjunctive 5-FU injections.

Adolescent↗
PubMed1991

Initial 5-fluorouracil trabeculectomy in uncomplicated glaucoma.

The effectiveness of trabeculectomy with adjunctive low-dose 5-fluorouracil (5-FU) as the initial surgical procedure in uncomplicated glaucoma was evaluated retrospectively in a consecutive series of 52 patients (mean follow-up, 18.6 +/- 11.7 mos) and 74 control subjects. The cumulative 2-year success (intraocular pressure [IOP] less than 21 mmHg) was 100% in the 5-FU group and 78.9% in the control group (P = 0.01, Wilcoxon test). The 5-FU group had a mean postoperative IOP of 12.5 +/- 4.6 mmHg versus 17.4 +/- 5.7 mmHg in the control group at 2-year follow-up (P = 0.015, t test). Antiglaucoma medications were required in 5.8% of patients in the 5-FU group and in 41.9% of controls within 2 years (P less than 0.0001, Fisher's exact test). These results suggest that low-dose 5-FU at the time of initial trabeculectomy leads to a higher success rate, lower IOP, and less need for antiglaucoma medications postoperatively.

Adolescent↗
PubMed1991

Tears of the retinal pigment epithelium: occurrence in association with choroidal effusion.

Two patients developed large tears of the retinal pigment epithelium associated with choroidal effusion. One tear occurred after combined cataract/filtration surgery complicated by postoperative choroidal detachment; the second developed in a patient with idiopathic uveal effusion syndrome. Weakness of the junctions of the pigment epithelial cells secondary to the accumulation of fluid in the subretinal or suprachoroidal space may result in tearing of the retinal pigment epithelium as it is stretched.

Aged↗
PubMed1991

5 alpha-dihydrocortisol in human aqueous humor and metabolism of cortisol by human lenses in vitro.

Glucocorticoids have long been implicated in the etiology of primary open-angle glaucoma (POAG) and cataract. Cortisol metabolites have biologic activity and may affect aqueous humor dynamics. This study was done to determine whether these metabolites are found in human aqueous humor and can be produced by ocular tissues. Radioimmunoassays (RIA) were developed for 5 alpha-dihydrocortisol (5 alpha-DHF) and 5 beta-dihydrocortisol (5 beta-DHF). These assays, as well as a cortisol RIA, were used to quantify these three steroids in 20 surgically derived aqueous humor specimens from patients with and without POAG. The mean concentrations of cortisol and 5 alpha-DHF were 2.5 and 1.3 ng/ml, respectively. In the small group studied, there was no statistically significant difference between the aqueous humor steroid levels in patients with and without POAG. The amount of 5 beta-DHF was at the lower limits of detection of the assay system and could not be uniquivocally shown. Human lenses metabolized cortisol in vitro to 5 alpha-DHF and 3 alpha,5 alpha-tetrahydrocortisol (3 alpha,5 alpha-THF). There was no 5 beta-DHF or cortisone formed. The 5 alpha-DHF and 3 alpha,5 alpha-THF were identified by their positions on thin-layer chromatography, their retention times on high-performance liquid chromatography, and recrystallization with authentic standards to constant specific activity. The data suggest that the lens is the source of 5 alpha-DHF in aqueous humor.

Aged↗
PubMed1990

Combined exfoliation and pigment dispersion syndrome.

Both exfoliation syndrome and pigmentary dispersion syndrome can lead to secondary glaucoma. We treated five patients who had pigmentary dispersion and who subsequently developed exfoliation. In one patient who had bilateral pigment dispersion syndrome, the presence of exfoliation increased the difficulty of controlling intraocular pressure in the affected eye. In a monocular patient, exfoliation and pigmentary dispersion were concurrently present with characteristic defects of both pigmentary dispersion and exfoliation as seen by transillumination defects of the iris. A third patient had bilateral pigmentary dispersion and uncontrollable intraocular pressure in an eye with exfoliation. Despite argon laser trabeculoplasty, the pressure remained uncontrolled. Another patient had a filtering operation in the left eye, with gradually increasing intraocular pressure in the right eye. Exfoliation material complicated the pressure control in the unoperated on eye. Another patient had an eight-year history of glaucoma in the left eye for which filtering surgery was performed. Exfoliation was present in both eyes with controlled pressure in the filtered eye but uncontrolled pressure in the nonfiltered eye.

Anterior Eye Segment↗