Search PubMed⌕ Search

Biomedical subjects

R Ritch

Publications and source records attributed to R Ritch.

At least 127 records · Page 7Linked to original sources
PubMed1996

Trabeculectomy at the inferior limbus.

OBJECTIVE: To evaluate intraocular pressure (IOP) control and surgical complications following trabeculectomy with 5-fluorouracil (5-FU) or mitomycin at the inferior limbus. METHODS: The charts of all patients undergoing trabeculectomy at the inferior limbus from July 1984 to March 1993 were reviewed. Surgical success was defined as IOP greater than 4 mm Hg and less than 22 mm Hg and at least a 20% reduction from preoperative IOP. PATIENTS: All 101 eyes of 101 patients had undergone prior intraocular surgery at the superior limbus. Mean patient age was 57.5 +/- 2.0 (+/-SE) years; mean follow-up was 23.4+/-2.3 months; mean preoperative IOP was 32.8+/-0.9 mm Hg; and mean number of preoperative antiglaucoma medications was 2.8+/-0.1. RESULTS: Ninety-four eyes (93.1%) received postoperative 5-FU (mean total dose, 36.3+/-1.7 mg) and seven eyes (6.9%) received intraoperative mitomycin (0.5 mg/mL). Cumulative success for all eyes at 2 and 5 years was 56% and 38%, respectively. Intraocular pressure control without medications was achieved in 39% and 15% of eyes at 2 and 5 years, respectively. Complications included 5-FU epitheliopathy (34.0% of eyes receiving 5-FU), early wound leak (26.7%), choroidal effusion (25.7%), late bleb leak (12.9%), and late bleb-related endophthalmitis (11.9%). CONCLUSION: Although trabeculectomy at the inferior limbus offers the opportunity for surgical success in eyes at high risk of failure, this procedure carries an increased risk for late complications and should be reserved for cases in which the therapeutic options are extremely limited.

Adolescent↗
PubMed1996

Personal computer-based 3-dimensional ultrasound biomicroscopy of the anterior segment.

OBJECTIVE: To develop a practical, inexpensive system for 3-dimensional ultrasound biomicroscopic imaging of the anterior segment with a commercially available high-frequency ultrasound imager and a personal computer. METHODS: Sequential, high-frequency, ultrasound biomicroscopic images of the anterior segment were obtained with a motorized scanning control arm designed in our imaging laboratory. Images were acquired by a personal computer-based video capture device. Ultrasound slice data were then reconstructed as 3-dimensional volumetric images by a personal computer and commercially available software. RESULTS: Four 3-dimensional visualization formats were developed to enhance the clinical utility of high-frequency ultrasound. Rotational animation sequences were created that detailed the extent and anatomy of a filtering bleb, intraocular lens subluxation, focal angle closure from an iridociliary cyst, intraocular foreign bodies, and an iris tumor. CONCLUSIONS: Three-dimensional, high-frequency ultrasound of the anterior segment enhances our ability to visualize spatial relationships between adjacent anatomic structures. The low cost and ease of use of this system make widespread clinical application practical.

Adult↗
PubMed1996

Reduced trabecular meshwork height in juvenile primary open-angle glaucoma.

OBJECTIVE: To compare trabecular meshwork height in a series of patients with juvenile primary open-angle glaucoma (JPOAG) with that in normal control patients. METHODS: Ultrasound biomicroscopy and A-scan biometry were performed on 16 eyes with JPOAG and 24 normal eyes. A radial, perpendicular image in the horizontal temporal meridian detailing the line of Schwalbe, scleral spur, and angle anatomy was obtained for each eye by a single examiner. Trabecular meshwork height was defined as the distance from the scleral spur to the Schwalbe line. RESULTS: Mean patient age (P = .85, t test), refractive error (P = .68), sex distribution (P = .26, Fisher exact test) and axial length (P = .39) were similar between the groups. Mean +/- SE trabecular meshwork heights were 0.36 +/- 0.03 mm (range, 0.19-0.53 mm) for JPOAG and 0.58 +/- 0.02 mm (range, 0.40-0.80 mm) for controls (P < .001). Eyes with greater axial length tended to have larger trabecular meshworks in both groups (P = .012, multivariate regression). A trabecular meshwork height-axial length ratio of 0.021 or less was associated with a significantly increased risk for JPOAG being present (odds ratio, 57; 95% confidence interval, 6.0-541). CONCLUSIONS: The trabecular meshwork is smaller in eyes with JPOAG compared with that in normal eyes. This finding suggests a structural abnormality that may underlie the reduced outflow.

Adolescent↗
PubMed1996

A 90-day study of the efficacy and side effects of 0.25% and 0.5% apraclonidine vs 0.5% timolol. Apraclonidine Primary Therapy Study Group.

OBJECTIVE: To compare long-term intraocular pressure (IOP)-lowering efficacy of 0.25% and 0.5% apraclonidine hydrochloride with 0.5% timolol maleate. DESIGN: Multicenter, randomized, double-masked trial. Adult patients of either sex diagnosed as having open-angle glaucoma or ocular hypertension were enrolled following appropriate washout from all ocular hypotensive medications. Morning IOPs of 22 to 35 mm Hg were required for entry. Patients received 0.25% or 0.5% apraclonidine 3 times a day or 0.5% timolol twice a day for 90 days. Intraocular pressure was measured at 8 AM (before morning dosing) and at 4 PM (8 hours after dosing) on days 1, 30, and 90, and only at 8 AM on day 14. RESULTS: All 3 medications significantly reduced IOP from baseline at all observation times (P < .001): 0.5% apraclonidine reduced IOP more than 0.25% apraclonidine; no significant difference was observed between 0.5% apraclonidine and 0.5% timolol 8 hours after dosing on days 1, 30, and 90; and a significant difference (P < .05) in favour of 0.5% timolol over 0.25% apraclonidine was observed 8 hours after dosing on day 30. At all morning visits following evening dosing, 0.5% timolol significantly reduced IOP more than both concentrations of apraclonidine. CONCLUSIONS: Both 0.25% and 0.5% apraclonidine significantly reduce IOP when used as primary ocular hypotensive medication. Although 0.25% and 0.5% apraclonidine reduce IOP to a similar degree as 0.5% timolol 8 hours after morning dosing, neither concentration is as effective for reducing morning IOP after evening dosing.

Administration, Topical↗
PubMed1996

Repair of Descemet's membrane detachment with the assistance of intraoperative ultrasound biomicroscopy.

PURPOSE: To evaluate the ability of ultrasound biomicroscopy to monitor the repair of large Descemet's membrane detachments. METHODS: Intraoperative ultrasound biomicroscopy was performed in two patients who had undergone previous unsuccessful surgical repair of large Descemet's membrane detachments. RESULTS: Ultrasound biomicroscopy visualized and located Descemet's membrane detachment and verified proper suture placement and membrane repositioning. CONCLUSIONS: Ultrasound biomicroscopy is a useful tool to guide surgical repair of Descemet's membrane detachments, particularly when hazy media prevent satisfactory visualization.

Aged↗
PubMed1996

Increase in iris-lens contact after laser iridotomy for pupillary block angle closure.

PURPOSE: To quantitate changes in anterior ocular segment anatomy after laser iridotomy for pupillary block angle closure. METHODS: We prospectively performed ultrasound biomicroscopy and A-scan biometry in 13 eyes of 13 consecutive untreated patients with relative pupillary block and appositional angle closure, without peripheral anterior synechiae on indentation gonioscopy. A radial, perpendicular image in the horizontal temporal meridian was obtained with ultrasound biomicroscopy before and one week after laser iridotomy in each eye. RESULTS: Mean age of the 13 patients was 69.3 +/- 1.8 (S.E.) years, mean refractive error was +1.37 +/- 0.39 diopters, and mean axial length was 22.54 +/- 0.20 mm. In 13 eyes, before and after laser iridotomy measurements of angle-opening distance (0.11 +/- 0.02 vs. 0.18 +/- 0.02 mm) (P = .0004; paired t test), angle aperture (8.3 +/- 1.3 vs 18.6 +/- 2.8 degrees) (P = .0003) and iris-lens contact distance (0.58 +/- 0.06 vs 1.18 +/- 0.14 mm) (P = .0003) were greater postoperatively, but anterior chamber depth was unchanged (P = .7). CONCLUSIONS: Flattening of the iris after laser iridotomy for pupillary block causes an increase in iris-lens contact. The change in angle configuration after iridotomy results more from an alteration in aqueous pressure gradients across the iris rather than from posterior lens movement.

Aged↗
PubMed1996

Optic coherence tomography of optic disk pit maculopathy.

PURPOSE: To define the structure of optic disk pit maculopathy. METHODS: A patient was examined with optic coherence tomography before and after an intravitreal gas tamponade. RESULTS: Before intravitreal gas injection, optic coherence tomography defined a separation between the inner and outer layers of the retina that connected with the optic disk pit. An outer retinal layer detachment that centered on the fovea was also present. After pneumatic displacement of the intraretinal and subretinal fluid, optic coherence tomography disclosed that the two layers were opposed and in contact with the retinal pigment epithelium. CONCLUSIONS: Optic coherence tomography confirmed the two-layer structure of optic disk pit maculopathy and demonstrated the positive effect of pneumatic displacement.

Humans↗
PubMed1996

Clear corneal graft overlying the seton tube to facilitate laser suture lysis.

PURPOSE: To reduce hypotony and shallowing of the anterior chamber after seton implantation. METHODS: The silicone tube is ligated with an 8-0 nylon suture and a clear corneal graft placed over the tube to facilitate postoperative laser suture lysis. RESULTS: Laser suture lysis has been performed in 34 cases to date with a follow-up period of up to 26 months. No severe complications occurred after laser suture lysis. CONCLUSIONS: This technique provides another option to increase drainage postoperatively without the risk of releasable sutures or instrumentation within the eye.

Corneal Transplantation↗
PubMed1996

Risk factors for ciliochoroidal effusion after panretinal photocoagulation.

PURPOSE: To determine the incidence, duration, and risk factors for ciliochoroidal effusion after panretinal photocoagulation. METHODS: Thirty-nine consecutive patients with diabetic retinopathy underwent ultrasound biomicroscopy of both eyes to image the ciliochoroidal space immediately before and 1 day after unilateral argon-green panretinal photocoagulation. Imaging was repeated on days 3, 7, and 14 in patients in whom ciliochoroidal effusion developed. RESULTS: Low-lying ciliochoroidal effusions were imaged in 23 (59%) of 39 eyes. Of 23 eyes, effusions resolved in 6 (26%), 12 (52%), and 5 (22%) eyes by 3, 7, and 14 days respectively. The number of laser applications (P = 0.02), shorter axial length (P = 0.01), and percentage of retinal surface area treated (P = 0.02) were associated with systemic hypertension, location of treatment, previous panretinal photocoagulation of cataract surgery, retinal surface area treated, and mean blood pressure before photocoagulation were not associated with effusion. All fellow, untreated eyes remained effusion-free. CONCLUSION: Ciliochoroidal effusion develops commonly after panretinal photocoagulation. Limiting the number of laser applications and the percentage of retinal surface area treated reduces the likelihood of this complication. Eyes with shorter axial lengths are at higher risk

Adult↗
PubMed1996

Location of the iris insertion in pigment dispersion syndrome.

PURPOSE: To evaluate the position of the iris insertion into the ciliary body in persons with pigment dispersion syndrome (PDS) and control subjects. METHODS: Ultrasound biomicroscopy was performed on 19 eyes with PDS and on 21 eyes of control subjects. A radial, perpendicular image in the temporal meridian detailing Schwalbe line (SL), scleral spur (SS), and iris root insertion (IR) was obtained for each eye by a single examiner. The distances between these structures then was measured. RESULTS: There were no differences between the groups in refractive error (mean +/- standard error, -2.8 +/- 0.7 diopters for PDS eyes versus -2.2 +/- 0.6 for control subjects) (P=0.46), sex distribution (P=0.49), and trabecular meshwork height (SL to SS) (0.63 +/- 0.03 mm [PDS eyes] versus 0.59 +/- 0.03 [control eyes]; P = 0.24). The SS-to-IR distance was significantly greater in PDS eyes (0.04 +/- 0.04 mm) than in control eyes (0.28 +/- 0.04 mm) (P=0.01) as was the overall distance from SL to IR (0.98 +/- 0.04 mm versus +/- 0.04 mm) (P = 0.003). CONCLUSION: The insertion of the iris into the ciliary body is more posterior in PDS eyes than in control eyes. This anatomic variation places the iris pigment epithelium proximal to the zonular apparatus and may increase the likelihood of iridozonular contact and zonular pigment dispersion.

Adolescent↗
PubMed1996

Ciliary body enlargement and cyst formation in uveitis.

BACKGROUND: Acute anterior uveitis has diverse causes and systemic associations. Inflammation is predominantly localised to the iris and pars plicata. Little is known about the in vivo effects of uveitis on ciliary body anatomy. METHODS: Bilateral, high frequency, high resolution, ultrasound biomicroscopy was performed on consecutive patients with unilateral anterior uveitis to evaluate ciliary body anatomy. Imaging was repeated when possible during the clinical course. The cross sectional area of the anterior ciliary body was measured using image processing and analysis software. Measurements from the uveitic eyes were compared with the fellow eyes and the effect of treatment was evaluated. RESULTS: Fourteen patients were enrolled. Ultrasound biomicroscopy demonstrated a larger ciliary body cross sectional area in the uveitic eyes compared with the fellow, clinically uninvolved eyes (2.45 (SD 0.48) mm2 versus 1.55 (SD 0.15) mm2, (p = 0.0000; paired t test)). A ciliochoroidal effusion was present in one uveitic eye. Epithelial cysts were imaged bilaterally in four uveitic patients (29%) and unilaterally in unaffected eyes of two uveitic patients. Ciliary body cross sectional area decreased following steroid therapy (p = 0.0001; paired t test). New cysts were noted in three uveitic eyes during the follow up period and in none of the fellow, unaffected eyes. CONCLUSION: Ultrasound biomicroscopy offers a new approach to the evaluation of anterior uveitis. The response to treatment can be evaluated objectively and therapeutic efficacy can be more easily assessed. It has the potential to help elucidate the pathophysiology and anatomical changes of this heterogeneous group of disorders.

Adolescent↗
PubMed1996

In vivo increase of the human lens equatorial diameter during accommodation.

The movement of the human lens equator during accommodation was examined in vivo. High-resolution ultrasound images of the lens equator were obtained from young human subjects whose amplitude of accommodation was controlled with 1% tropicamide and 2% pilocarpine. To avoid errors that otherwise arise from eye rotation or other movement, the cornea and sclera were used as positional references in comparative studies of the video images obtained from the unaccommodated and accommodated states. During accommodation, the movement at the lens equator involved small displacement; i.e., < 100 microns, and the equator did not move anteriorly or posteriorly but peripherally toward the sclera. These results indicate that the lens equator is under increased zonular tension during accommodation, in contradiction to Helmholtz's widely accepted theory of accommodation.

Accommodation, Ocular↗
PubMed1996

Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy.

BACKGROUND AND OBJECTIVE: To evaluate the ability of high-frequency ultrasound biomicroscopy to diagnose traumatic cyclodialyses not evident on clinical examination. PATIENTS AND METHODS: Six eyes to six patients with posttraumatic hypotony and/or shallow anterior chamber and suspected cyclodialysis clefts were examined with slit-lamp biomicroscopy, gonioscopy, B-scan ultrasonography, and ultrasound biomicroscopy. Ultrasound biomicroscopy provided high resolution of cross-sectional images of the anterior chamber angle, posterior chamber, and anterior uveal tissue. RESULTS: Ultrasound biomicroscopy confirmed the disinsertion of the ciliary body from the scleral spur and associated ciliary body detachment in all eyes. Gonioscopy failed to demonstrate a cyclodialysis cleft in five eyes because of hyphema (two eyes) and abnormal iris architecture (related to trauma) precluding visualization of the angle recess (three eyes). Using information from ultrasound biomicroscopy imagining, one patient underwent a ciliary body reattachment procedure and repair of the cyclodialysis cleft. CONCLUSION: Ultrasound biomicroscopy is a noninvasive method that can accurately diagnose the presence of traumatic cyclodialyses and can aid in surgical management. It is particularly useful in the presence of hazy media, hypotony, and/or abnormal anterior segment anatomy.

Adolescent↗
PubMed1996

Ultrasound biomicroscopic features of iris retraction syndrome.

BACKGROUND AND OBJECTIVES: To examine anatomic relationships of anterior and posterior chamber structures in iris retraction syndrome using ultrasound biomicroscopy. PATIENTS AND METHODS: Four eyes of four patients with iris retraction syndrome were imaged using high-frequency, high-resolution, anterior segment ultrasound biomicroscopy. In two patients, scans were obtained before and after medical therapy. RESULTS: Three patients presented with iris retraction configuration and one with iris bombe. In the latter case, iris bombe converted to iris retraction and back to iris bombe with the administration and later withdrawal of aqueous suppressants. Ciliochoroidal effusion was present in all eyes. CONCLUSIONS: Ciliochoroidal effusion is a constant feature of iris retraction syndrome. The hypotony associated with this disorder may result in part from aqueous hyposecretion related to ciliary body detachment. Ultrasound biomicroscopy is a useful aid in the diagnosis and follow-up of eyes with iris retraction syndrome.

Adult↗