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Biomedical subjects

R Ritch

Publications and source records attributed to R Ritch.

At least 37 records · Page 2Linked to original sources
PubMed2001

Exfoliation (pseudoexfoliation) syndrome: toward a new understanding. Proceedings of the First International Think Tank.

Exfoliation (pseudoexfoliation; PEX) syndrome is the single most common identifiable cause of open-angle glaucoma, however, very few investigators are engaged in basic research on this disease. To stimulate the field, the First International Think Tank on Exfoliation Syndrome was held in New York in July 1999, comprising clinicians and scientists. This report is a summary of the proceedings of this meeting.

Exfoliation Syndrome↗
PubMed2001

Exfoliation syndrome.

Exfoliation syndrome (XFS) is an age-related disorder of the extracellular matrix characterized by production and progressive accumulation of small, white deposits of a fibrillar extracellular material in many ocular tissues, most commonly seen on the pupillary border and anterior lens capsule. Characteristic signs of pigment liberation and deposition throughout the anterior segment aid in the diagnosis. Exfoliation syndrome predisposes to both open-angle and angle-closure glaucoma, and to capsular rupture, zonular dehiscence, and vitreous loss during cataract extraction. Exfoliation syndrome is associated with ocular and perhaps systemic ischemia. The exact chemical composition of exfoliation material remains unknown. Medical, laser, and surgical therapy are similar to treatment of primary open-angle glaucoma.

Adrenergic alpha-Agonists↗
PubMed2001

Hepatocyte growth factor is increased in the aqueous humor of glaucomatous eyes.

PURPOSE: To assess the concentrations of hepatocyte growth factor (HGF) in the aqueous humor of eyes with glaucoma compared with control eyes with cataract only. METHODS: Concentrations of HGF were measured in aqueous humor aspirates taken during anterior segment surgery from 84 patients, of whom 72 had glaucoma (38 cases of primary open-angle glaucoma, 17 angle-closure glaucoma, and 17 exfoliative glaucoma) and 12 had cataract only, using a sandwich enzyme-linked immunosorbent assay kit. RESULTS: Hepatocyte growth factor was detected in all samples. The concentration in eyes with cataract only was 563.3 +/- 178.8 pg/mL (mean +/- standard deviation), which was significantly lower than that in eyes with glaucoma (967.1 +/- 514.7 pg/mL, P < 0.01). Eyes with exfoliative glaucoma had significantly higher HGF concentrations (1,425.5 +/- 586.7 pg/mL) than did eyes with primary open-angle glaucoma (855.0 +/- 341.5 pg/mL) and angle-closure glaucoma (759.4 +/- 511.4 pg/mL) (P < 0.01). There was no effect of age, sex, or history of medical, laser, or surgical treatment on the aqueous humor HGF concentration (P > 0.05). Aqueous humor and plasma HGF concentrations were measured and compared in 28 patients. The aqueous humor HGF concentration (908 +/- 586.2 pg/mL) was significantly higher (P < 0.01) than the plasma concentration (521.3 +/- 183.1 pg/mL). No significant correlation could be found between aqueous humor and plasma HGF concentrations. CONCLUSIONS: The relatively high concentration of HGF in human aqueous humor suggests that HGF may play an important role in ocular physiology and disease. The higher concentration in patients with glaucoma may indicate a response to injury.

Aqueous Humor↗
PubMed2001

Diode laser transscleral cyclophotocoagulation for refractory glaucoma.

PURPOSE: To evaluate the efficacy of contact diode laser transscleral cyclophotocoagulation using different treatment parameters. METHODS: All eyes undergoing contact diode laser transscleral cyclophotocoagulation between April 1991 and September 1997 at our two institutions were enrolled. Success was defined as an intraocular pressure less than or equal to 22 mm Hg or absence of pain for poorly sighted and blind eyes. RESULTS: Two hundred six eyes of 204 patients (Salzburg, 117 eyes; New York, 89 eyes) were enrolled. Mean patient age was 65.8 +/- 18.7 years (range, 4-96 years). Mean follow-up was 9.2 +/- 11.2 months (range, 3-56 months). Mean preoperative and postoperative IOPs were 42.1 +/- 11.0 mm Hg (range, 24-76 mm Hg) and 17.3 +/- 10.9 mm Hg (P < 0.001) and 20.3 +/- 13.2 mm Hg (P < 0.001) at 12 and 24 months, respectively. The number of laser applications (mean, 18.6 +/- 4.2; range, 10-40) and maximal laser power (mean, 2,352 +/- 408.5 mW; range, 1,500-3,000) were not associated with a lower postoperative IOP. An IOP less than or equal to 22 mm Hg was achieved in 72.7% of eyes at the mean follow-up of 9 months. Thirty-three (16.0%) eyes required at least one retreatment. Phthisis occurred in four (1.9%) eyes. CONCLUSION: Contact diode laser transscleral cyclophotocoagulation is useful in eyes with refractory glaucoma in which the risks of outflow surgery are deemed unacceptable.

Adolescent↗
PubMed2000

Iris and ciliary body melanomas: ultrasound biomicroscopy with histopathologic correlation.

OBJECTIVE: To correlate ultrasound biomicroscopic images of iris and ciliary body melanomas with their histopathologic features. METHODS: Ultrasound biomicroscopy was performed in 3 cases of iris melanoma and in 3 cases of ciliary body melanoma. Cross-sectional ultrasound biomicroscopic images were compared with findings from clinical examination and light microscopy to evaluate associations between their histopathologic, surface, and internal ultrasound characteristics. Unique images of intrastomal and obscured posterior tumor margins were visualized by ultrasound biomicroscopy. RESULTS: Results of this study revealed that ultrasound biomicroscopy offers an accurate method to evaluate tumor shape, reflectivity, and local invasion. Neoplastic tissue had only medium echogenicity. Enlarged vessels were correlated to echolucent spaces in the iris stroma. Anterior tumor margins were found within the iris stroma, within the anterior chamber angle, and on the endothelial surface of the cornea. Posterior tumor extension was noted to encroach onto the lens, into the sclera, and serous peripheral retinal detachments were associated with ciliary body tumors. CONCLUSION: Ultrasound biomicroscopic images correlated well with histopathologic features of anterior uveal melanomas including shape, reflectivity, and local extension. Arch Ophthalmol. 2000;118:1515-1521

Aged↗
PubMed2000

Iridocorneal endothelial syndrome in Thai patients: clinical variations.

OBJECTIVE: To evaluate the spectrum of iridocorneal endothelial syndrome, to our knowledge, never studied previously in Orientals. METHODS: From 1986 to 1998, we examined 60 consecutive patients (20 men, 40 women) with characteristic signs of iridocorneal endothelial syndrome and compared the clinical manifestations to those reported in white patients. RESULTS: Cogan-Reese syndrome (CRS) was most common (38 patients), while 14 patients had Chandler syndrome (CS), and 8 had progressive iris atrophy. Three patients initially classified as having CS and 1 as having progressive iris atrophy progressed to CRS. Glaucoma occurred in 46 patients (76.7%), most commonly in patients with progressive iris atrophy or CRS. Ten patients had slow progression of disease during the follow-up period of up to 12 years. Three patients (2 with CRS, 1 with CS) had asymptomatic localized islands of "hammered-silver" appearance and 11 (8 with CRS, 2 with CS, and 1 with progressive iris atrophy) had subclinical abnormal endothelium in the contralateral eyes. A translucent membrane was commonly seen on the brown iris surface. Total endothelial involvement was present in 49 patients, while 6 (4 with CRS, 2 with CS) had focal endothelial abnormalities with sharp demarcation from adjacent normal endothelium. CONCLUSIONS: Iridocorneal endothelial syndrome occurs in Orientals. Cogan-Reese syndrome is the most common form and is strongly associated with glaucoma. Although several clinical manifestations were similar between whites and Orientals (mean age of onset, sex predilection, iris changes, peripheral anterior synechiae formation, or corneal edema), CRS was most prevalent; a translucent membrane were more noticeable in Orientals.

Adult↗
PubMed2000

Risk factors for glaucoma filtering bleb infections.

OBJECTIVE: To determine risk factors for bleb-related ocular infection after glaucoma filtering surgery. METHODS: A case-control study comparing all consecutive cases of glaucoma filtering bleb-related infections (55 eyes of 55 patients) with matched control eyes between January 1, 1990, and June 30, 1998, was performed. Bleb-related infection was classified as blebitis when a mucopurulent infiltrate was identified within the bleb and associated with mild to moderate anterior segment inflammation. Eyes with endophthalmitis had hypopyon, cells in the anterior vitreous cavity, or a positive vitreous biopsy sampling result. A control was selected for each case based on matching of the surgeon, date and type of glaucoma surgery, and type of antifibrotic agent used. Multivariate, matched, case-control logistic regression analysis was performed using age, race, sex, diagnosis, number of previous incisional operations, filtering bleb location, and presence of bleb leak to determine which variables were associated with bleb-related infection. RESULTS: The odds of an eye with a bleb-related infection being seen with a concomitant late-onset bleb leak are 25.8 times the odds of a noninfected eye having a late-onset bleb leak at any time in the postoperative period (P<.001; 95% confidence interval, 2.3-294.1). Other risk factors for bleb-related infection included younger age (P = .05), black race (P = .03), diagnosis of primary open-angle glaucoma (P = .03), and inferior location of the filtering bleb (P = .04). CONCLUSIONS: Late-onset bleb leakage is a significant risk factor for bleb-related infection. The risk of infection may warrant closure of late-onset bleb leaks in selected eyes.

Aged↗
PubMed2000

Assessment of retinal nerve fiber layer internal reflectivity in eyes with and without glaucoma using optical coherence tomography.

OBJECTIVE: To assess the internal reflectivity of the retinal nerve fiber layer in normal, ocular hypertensive, and glaucomatous eyes using optical coherence tomography. METHODS: All patients underwent complete ophthalmic examination and achromatic automated perimetry. Intraocular pressure was 21 mm Hg or less for low-tension glaucoma and normal eyes and at least 25 mm Hg on 2 separate occasions in ocular hypertensive and high-tension glaucoma eyes. All glaucomatous eyes had characteristic glaucomatous optic neuropathy and associated achromatic automated perimetry defect. Relative retinal nerve fiber layer internal reflectivity was measured on optical coherence tomography images using a software program of our own design. RESULTS: We enrolled 98 eyes (19 normal, 34 ocular hypertensive, 17 high-tension glaucoma, and 28 low-tension glaucoma). Relative internal reflectivity was less in eyes with glaucoma than in normal (P<.001, t test) and ocular hypertensive eyes (P<.001, t test). There was no difference in relative internal reflectivity between normal and ocular hypertensive eyes (P =.32) and between eyes with high-tension glaucoma and low-tension glaucoma (P =.43). Internal reflectivity correlated with mean deviation on achromated automatic perimetry (r(2) = 0.49, P<.001, quadratic regression analysis). CONCLUSION: Relative retinal nerve fiber layer internal reflectivity may provide useful information about the extent of retinal nerve fiber layer injury in glaucoma. Arch Ophthalmol. 2000;118:1044-1047

Adult↗
PubMed2000

Increased growth factor activity in the aqueous humour of patients with exfoliation syndrome.

BACKGROUND: To investigate the growth factor activity in the aqueous humour of patients with exfoliation syndrome (XFS). METHODS: We collected 154 aqueous humour samples (69 from patients with XFS and 85 from age-matched controls) prior to routine extracapsular cataract surgery. Growth factor activity was investigated using a [3H]thymidine incorporation assay on McCoy cells that assesses DNA synthesis. Albumin concentration was measured by a radio-immunoassay as an index of blood aqueous barrier integrity. N-Acetylglucosaminidase (NAG) activity, a marker of cellular breakdown, was ascertained by a fluorometric method. RESULTS: XFS aqueous samples exhibited significantly higher growth factor activity than to the control samples (P<0.001). Albumin concentration was also higher in the XFS group. NAG activity was similar in the two groups. No relationship between growth factor activity and the other parameters investigated was found. CONCLUSIONS: Increased growth factor activity was detected in the aqueous humour of patients with XFS. This finding may be related to the pathogenesis of XFS.

Acetylglucosaminidase↗
PubMed2000

Optical coherence tomography and scanning laser polarimetry in normal, ocular hypertensive, and glaucomatous eyes.

PURPOSE: To evaluate the relationship between visual function and retinal nerve fiber layer measurements obtained with scanning laser polarimetry and optical coherence tomography in a masked, prospective trial. METHODS: Consecutive normal, ocular hypertensive, and glaucomatous subjects who met inclusion and exclusion criteria were evaluated. Complete ophthalmologic examination, disk photography, scanning laser polarimetry, optical coherence tomography, and automated achromatic perimetry were performed. RESULTS: Seventy-eight eyes of 78 patients (17 normal, 23 ocular hypertensive, and 38 glaucomatous) were enrolled (mean age, 56.8+/-11.5 years; range, 26 to 75 years). Eyes with glaucoma had significantly greater neural network scores on scanning laser polarimetry and lower maximum modulation, ellipse modulation, and mean retinal nerve fiber layer thickness measured with optical coherence tomography compared with normal and ocular hypertensive eyes, respectively (all P<.005). Significant associations were observed between neural network number (r = -.51, r = .03), maximum modulation (r = .39, r = -.32), ellipse modulation (r = .36, r = -.28), and optical coherence tomography-generated retinal nerve fiber layer thickness (r = .68, r = -.59) and visual field mean deviation and corrected pattern standard deviation, respectively. All scanning laser polarimetry parameters were significantly associated with optical coherence tomography-generated retinal nerve fiber layer thickness. CONCLUSION: Optical coherence tomography and scanning laser polarimetry were capable of differentiating glaucomatous from nonglaucomatous populations in this cohort; however considerable measurement overlap was observed among normal, ocular hypertensive, and glaucomatous eyes. Retinal nerve fiber layer structural measurements demonstrated good correlation with visual function, and retinal nerve fiber layer thickness by optical coherence tomography correlated with retardation measurements by scanning laser polarimetry.

Adult↗
PubMed2000

Scanning laser polarimetry measurements after laser-assisted in situ keratomileusis.

PURPOSE: To evaluate the effect of laser-assisted in situ keratomileusis on retinal nerve fiber layer thickness measurements obtained with scanning laser polarimetry. METHODS: Thirteen consecutive eyes (13 patients) undergoing laser-assisted in situ keratomileusis were enrolled in this prospective study. Scanning laser polarimetry (NFA-GDx; Laser Diagnostic Technologies, Inc, San Diego, California) examination was performed 1 week before and 1 to 8 weeks after laser-assisted in situ keratomileusis surgery. Intraocular pressure was normal at all preoperative and postoperative examinations. Total mean, and superior, temporal, inferior, and nasal mean retinal nerve fiber layer thickness values before and after laser-assisted in situ keratomileusis were compared by Student paired t test. RESULTS: Mean +/- SD patient age was 34.6 +/- 10.9 years (range, 20 to 56 years). Mean +/- SD preoperative spherical equivalent refractive error was -6.6 +/- 3.1 diopters (range, -3.25 to -13.25 diopters) and mean +/- SD spherical equivalent refractive surgical correction was -6.2 +/- 3.0 diopters (range, -2.9 to -12.25 diopters). Total mean retinal nerve fiber layer and superior, inferior, temporal, and nasal mean retinal nerve fiber layer thicknesses were thinner after laser-assisted in situ keratomileusis (P =.01, for all comparisons, paired t test). CONCLUSIONS: Measurements of the retinal nerve fiber layer with scanning laser polarimetry depend on a corneal compensator inherent in the device. Keratorefractive surgery may affect scanning laser polarimetry measurements.

Adult↗