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Biomedical subjects

T G Murray

Publications and source records attributed to T G Murray.

At least 73 records · Page 4Linked to original sources
PubMed1996

Intraoperative echographic localization of iodine 125 episcleral radioactive plaques for posterior uveal melanoma.

PURPOSE: Plaque radiotherapy has been reported to have a higher relapse rate than charged-particle radiotherapy for posteriorly located uveal melanomas, which also are more technically difficult to localize accurately. The authors used intraoperative echography in patients with posterior uveal melanoma to determine the rate of inaccurate localization of iodine 125(125I) episcleral plaques using standard localization techniques. METHODS: The authors reviewed the records of 29 consecutive patients with medium-sized posterior uveal melanomas who underwent 125I episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement. RESULTS: After careful plaque placement using standard localization techniques, 4 of 29 plaques (14%) did not cover at least one tumor margin. All four of these plaques were associated with posterior tumors with at least one margin posterior to the temporal arcades. Two (7%) additional juxtapapillary plaques were displaced away from the sclera by the optic nerve. In all six cases, it was possible to immediately reposition the plaque to achieve coverage of all tumor margins. CONCLUSIONS: Placement of 125I episcleral radioactive plaques for posteriorly located uveal melanomas using standard localization techniques occasionally results in suboptimal plaque positioning. Intraoperative echography can identify plaques that are localized poorly and allows immediate adjustment to achieve optimal plaque positioning.

Brachytherapy↗
PubMed1996

Local carboplatin therapy in transgenic murine retinoblastoma.

PURPOSE: To determine the efficacy and toxicity associated with intraocular delivery of carboplatin in the treatment of murine transgenic hereditary retinoblastoma. METHODS: Forty-eight transgenic BLH-SV40 Tag retinoblastoma mice were administered five intravitreal injections of carboplatin in one eye. After 12 weeks, the eyes were examined histopathologically to evaluate tumor burden. Twelve rabbits were administered intravitreal injections of carboplatin in one eye, after which they underwent serial electroretinography. All experimental and control eyes were obtained for histopathology and electron microscopy. RESULTS: A dose-dependent inhibition of intraocular tumor growth by carboplatin was observed in transgenic retinoblastoma mice. Tumor development was inhibited in 50% of the mouse eyes at doses of 1.4 micrograms. In rabbits, retinal toxicity resulted when intravitreal injections of carboplatin were administered at doses of 10 micrograms or higher. CONCLUSIONS: Local delivery of carboplatin in serial doses effectively inhibits intraocular tumor growth in a dose-dependent manner in transgenic murine retinoblastoma.

Animals↗
PubMed1995

Thermoradiotherapy of intraocular tumors in an animal model: concurrent vs. sequential brachytherapy and ferromagnetic hyperthermia.

PURPOSE: To compare concurrent vs. sequential ferromagnetic thermoradiotherapy in vivo. METHODS AND MATERIALS: Greene melanomas were implanted subretinally in rabbits and observed until they were 3-5 mm in diameter. Episcleral plaques were assembled with 125I seeds for radiation therapy, or with ferromagnetic (FM) thermoseeds and nonradioactive I seeds for hyperthermia. Rabbits were implanted by centering a plaque over the intraocular melanoma. After a given dose of radiation had been delivered, the plaque was removed and a nonradioactive plaque containing FM thermoseeds was inserted into the same extrascleral space. One hour later, hyperthermia (46-47 degrees C at the plaque-scleral interface) was initiated and continued for a period of 1 h by placing the rabbits in a magnetic induction coil powered to 1200 W. Tumor size was determined at 1- to 2-week intervals by indirect ophthalmoscopy and by ultrasound. RESULTS: Dose-response analysis of 27 treated eye melanomas showed 50% local tumor control at 43 Gy for 125I alone and 29.4 Gy for 125I followed by FM hyperthermia. The thermal enhancement ratio was 1.4. CONCLUSION: Comparison with a previously published thermal enhancement ratio of 4.4 (for concurrent 125I and FM hyperthermia) leads us to conclude that thermal enhancement of 125I brachytherapy is more efficient in this tumor model system when hyperthermia is delivered during, rather than after, the irradiation process.

Animals↗
PubMed1995

Pars plana vitrectomy for chronic pseudophakic cystoid macular edema.

PURPOSE: We determined the efficacy of pars plana vitrectomy in a series of patients with chronic pseudophakic cystoid macular edema. METHODS: Clinical records were reviewed on 24 consecutive patients who underwent pars plana vitrectomy in one eye for chronic pseudophakic cystoid macular edema. All 24 patients had failed to improve on medical therapy and had preoperative evidence of either vitreous adhesions to anterior segment structures (23 eyes) or iris capture of the intraocular lens (one eye). RESULTS: The mean, best-corrected Snellen visual acuity was 20/190 preoperatively (median, 20/200; range, 20/50 to 3/200) and 20/52 postoperatively (median, 20/40; range, 20/20 to 20/400 [P < .0001]). Visual acuity improved postoperatively in all 24 eyes, with a mean improvement of 4.7 Snellen lines (range, one to eight lines). There was no highly significant difference in preoperative visual acuity (P = .41) or postoperative visual improvement (P = .17) between patients with anterior as opposed to posterior chamber intraocular lenses. Longer time interval from cataract surgery to vitrectomy did not correlate with less postoperative visual improvement. CONCLUSIONS: In pseudophakic eyes with chronic cystoid macular edema, vitreous adhesions to anterior segment structures, and visual loss that is unresponsive to medical therapy, pars plana vitrectomy with removal of these vitreous adhesions may lead to improved visual acuity.

Aged↗
PubMed1995

Reversible loss of light perception after vitreoretinal surgery.

PURPOSE: We studied reversible loss of light perception after vitreoretinal surgery to show that functional vision can return in some patients. METHODS: We reviewed the medical records of seven patients who had postoperative reversible loss of light perception in the eye that underwent vitreoretinal surgery. Differences in the postoperative courses and interventions were studied. RESULTS: Five of the seven patients had diabetes mellitus but none had hypertension. The indications for vitreoretinal surgery were severe proliferative diabetic retinopathy in five patients and retinal detachment with advanced proliferative vitreoretinopathy in two patients. Seven patients had reversible loss of light perception within the first three postoperative days. Six of the seven patients had an intraocular pressure greater than 26 mm Hg at the time the eye had no light perception. Decreasing the intraocular pressure was associated with return of light perception in five of seven patients. Return of useful vision was gradual. Four of seven patients had a visual acuity of 20/400 or better one month after surgery, and all seven had a visual acuity of 20/400 or better three months after surgery. Visual acuity in four eyes improved further to 20/70 or better at six months or more after surgery. CONCLUSION: Reversible loss of light perception after vitreoretinal surgery does occur in some patients. Monitoring vision and intraocular pressure is important because prompt treatment may assist in the recovery of functional vision.

Adult↗
PubMed1995

Open-angle glaucoma after pars plicata lensectomy and vitrectomy for congenital cataracts.

PURPOSE/METHODS: We examined an infant with familial cataracts in whom bilateral open-angle glaucoma developed shortly after pars plicata lensectomy with anterior vitrectomy. RESULTS/CONCLUSIONS: Some eyes with congenital nuclear cataracts have a predisposition to develop glaucoma after removal of the cataract, which is irrespective of the method chosen to remove the cataract. Careful monitoring of the intraocular pressure is indicated.

Cataract↗
PubMed1995

Endophthalmitis after pars plana vitrectomy. The Postvitrectomy Endophthalmitis Study Group.

PURPOSE: To describe the clinical course and incidence of culture-proven postvitrectomy endophthalmitis in 18 patients from five academic centers and three private practices. METHODS: Patients undergoing pars plana vitrectomy for recent trauma or endophthalmitis were excluded. The average age was 58 years (range, 21-85 year). Sixty-one percent of the patients (11/18) had diabetes mellitus. The indication for initial vitrectomy was vitreous hemorrhage (n = 10), macular epiretinal membrane (n = 3), recurrent retinal detachment with proliferative vitreoretinopathy (n = 2), retinal detachment with retinoschisis (n = 1), proliferative diabetic retinopathy with tractional retinal detachment (n = 1), and dislocated intraocular lens (n = 1). None of these eyes received prophylactic intraocular antibiotics during the vitrectomy. RESULTS: All eyes were treated with intraocular antibiotics after the diagnosis of postvitrectomy endophthalmitis was made. Final visual acuity ranged from 20/20 to no light perception and included five eyes with 20/50 or better visual acuity and 11 eyes with less than 5/200 visual acuity. Nine eyes had a final visual acuity of no light perception. Of the 16 eyes infected with a single organism, 71% (5/7) of eyes infected with coagulase-negative staphylococci retained 20/50 or better final visual acuity compared with no eyes (0/9) infected with other organisms (P = 0.005). Two eyes infected with both coagulase-negative Staphylococcus and Streptococcus had a final visual acuity of 20/400. Three eyes with a total hypopyon later had enucleation or evisceration. Based on the data from four medical centers, the incidence of endophthalmitis after pars plana vitrectomy performed over the last 10 years was 9/12,216 (0.07%). CONCLUSION: Endophthalmitis after vitrectomy is rare. Postvitrectomy bacterial endophthalmitis caused by organisms other than coagulase-negative staphylococci has a poor visual prognosis.

Adult↗
PubMed1994

Treatment of massive subretinal hemorrhage from complications of scleral buckling procedures.

Vitrectomy techniques permit removal of subretinal hemorrhage, but the prognosis varies and depends principally on the cause of the hemorrhage. Nine consecutive patients undergoing pars plana vitrectomy with internal drainage of massive subretinal hemorrhage from complications of scleral buckling procedures were studied, to evaluate the long-term results. In all eyes, the final visual acuity was improved, compared with preoperative visual acuity, and was 20/80 or better in seven of nine cases. Recurrent retinal detachment secondary to proliferative vitreoretinopathy developed in two patients, but complete retinal reattachment was achieved after further procedures were performed. Patients with massive subretinal hemorrhage from complications of scleral buckling procedures comprise a subgroup of patients with subretinal hemorrhage in which internal drainage via pars plana vitrectomy is an acceptable alternative to observation only and may result in improved visual acuity outcomes.

Adult↗
PubMed1994

Retained lens fragments after phacoemulsification.

PURPOSE: The authors present the clinical features of patients with retained lens fragments after phacoemulsification and their outcome after pars plana vitrectomy. METHODS: The authors performed a retrospective chart review of 62 patients who had surgical management of posteriorly dislocated lens fragments after phacoemulsification during the 3-year period from January 1990 to December 1992. RESULTS: Eight of the 62 patients underwent vitrectomy on the same day as the cataract surgery. Of the remaining 54 patients examined in the outpatient clinic, initial clinical features included marked intraocular inflammation (87%), elevated intraocular pressure of 30 mmHg or higher (46%), and corneal edema (46%). Retinal detachment was present before vitrectomy in one patient and occurred after vitrectomy in two others. Initial visual acuity was 20/200 or worse in 68% of patients. After vitrectomy, final visual acuity was 20/40 or better in 68% of patients. Using the percentage of patients with 20/40 or better final visual acuity, there was no statistically significant difference in surgery performed within 7 days (70%), between 1 and 4 weeks (60%), and after 4 weeks (70%). Twenty (80%) of 25 patients with initial posterior chamber intraocular lenses (PC IOLs) and 16 (62%) of 26 patients with initial anterior chamber IOLs (AC IOLs) achieved 20/40 or better visual acuity. A visual acuity outcome of 20/200 or worse occurred in all three patients with retinal detachment. Six of the eight patients who underwent vitrectomy on the same day as the cataract surgery achieved 20/30 or better visual acuity. CONCLUSIONS: The timing of vitrectomy did not influence visual acuity outcomes. Intraocular lenses inserted at the primary operation did not adversely affect the visual outcome. However, vitrectomy on the same day as cataract surgery generally yielded favorable visual acuity outcomes and eliminated the need for a second operation at a later date. In most patients with retained lens fragments, management with vitrectomy allowed good visual acuity outcomes.

Aged↗
PubMed1994

Evaluation of anterior segment tolerance to short-term intravitreal perfluoron.

PURPOSE: A study was performed to evaluate corneal and anterior segment toxicity from short-term (24-hour) intravitreal use of perfluoro-n-octane. METHODS: Forty aphakic, vitrectomized eyes of pigmented rabbits underwent intravitreal injection of either 0.5 ml of perfluoro-n-octane (Perfluoron; Infinitech, St. Louis, MO; treated) or 0.5 ml balanced saline solution (control). Perfluoron was allowed to remain in the vitreous cavity for 24 hours. Serial measurements of corneal pachymetry and pneumotonometry were performed at 1, 4, 12, and 24 hours after injection. After 24 hours, endothelial cell morphology and barrier function were evaluated. RESULTS: No significant differences in corneal thickness or intraocular pressure were noted between the two groups at any of the time points studied, and no differences in endothelial cell density/hexagonality or endothelial cell barrier function were observed 24 hours after injection. CONCLUSIONS: In the absence of sustained corneal contact, no evidence of significant acute corneal or anterior segment toxicity was observed in response to short-term intravitreal perfluoro-n-octane in aphakic, vitrectomized rabbit eyes.

Animals↗
PubMed1994

Postoperative fibrin formation and visual outcome after pars plana vitrectomy.

PURPOSE: To determine whether postvitrectomy fibrin formation was associated with visual outcome, a prospective study of patients undergoing pars plana vitrectomy was performed. METHODS: In 121 patients undergoing vitrectomy at the Medical College of Wisconsin between July 1986 and April 1989, the association of fibrin formation and other perioperative factors with visual outcome was evaluated by univariate and multivariate regression analysis. Poor visual outcome was defined as visual acuity worse than 5/200. RESULTS: After a median follow-up period of 23 months (range 6 to 51 months), patients with severe fibrin formation experienced a higher rate of poor visual outcome (19 of 26 patients, 73%) than patients with little or no fibrin formation (23 of 95 patients, 24%; P < 0.0001, univariate analysis). After adjusting for a variety of factors with multivariate regression analysis, fibrin formation was not significantly predictive of final visual outcome. CONCLUSIONS: Factors associated with postvitrectomy fibrin formation may affect visual outcome more than fibrin formation itself.

Adolescent↗
PubMed1992

Retained lens fragments after phacoemulsification manifesting as marked intraocular inflammation with hypopyon.

We reviewed the medical records of four patients with marked intraocular inflammation and hypopyon as the initial manifestation of retained lens fragments after phacoemulsification. The severe inflammatory reaction occurred between one month and one year after the cataract extraction. All four patients underwent pars plana vitrectomy to remove the lens fragments. The vitreous specimens were cultured to rule out infectious endophthalmitis. In all patients, no organisms were isolated from the vitrectomy specimens placed on both aerobic and anaerobic media. All patients had improved vision and resolution of the marked intraocular inflammation after vitrectomy. Echography was useful in establishing the diagnosis in these uncommon cases.

Aged↗
PubMed1992

The lowest effective dose of tissue plasminogen activator for fibrinolysis of postvitrectomy fibrin.

Tissue plasminogen activator (tPA) has been shown to be effective at a dose of 25 micrograms in the treatment of severe postvitrectomy fibrin. However, a recent report based on an animal model indicates that retinal toxicity may occur at doses as low as 25 micrograms. This study uses a low dose (1.5 micrograms to 3 micrograms) of tPA for 34 injections in 26 eyes, and determines the lowest effective dose to be between 1.5 and 3 micrograms. Complete fibrinolysis was achieved in all 28 eyes in which 3 micrograms of tPA was administered within 10 days of vitrectomy, whereas partial fibrinolysis was achieved in eyes treated with 3 micrograms of tPA 27 days and 82 days after vitrectomy. Complete fibrinolysis occurred in only 1 of 4 eyes that receive 1.5 micrograms of tPA. A dose of 3 micrograms of tPA is recommended for treatment of severe fibrin after vitrectomy, as it has a wider margin of safety than do higher doses.

Adolescent↗
PubMed1991

Methanol poisoning. A rodent model with structural and functional evidence for retinal involvement.

Methanol ingestion can lead to visual impairment, central nervous system dysfunction, or death. The extent of ocular involvement has been difficult to determine because the toxicity is restricted to humans and nonhuman primates due to species differences in methanol metabolism. A rodent model of methanol toxicity recently developed by us was used to evaluate retinal dysfunction in methanol poisoning. Formic acidemia and visual toxic reactions developed in methanol-intoxicated rats. Electroretinographic analysis indicated a significant early deficit in b-wave amplitude followed by a temporally delayed, lesser reduction in a-wave amplitude. Histologic evaluation of the eyes 60 hours after methanol administration revealed generalized retinal edema and vacuolation in the photoreceptors and retinal pigment epithelium. Ultrastructural examination showed swelling and disruption of the mitochondria in photoreceptor inner segments, optic nerve, and the retinal pigment epithelium. These studies document direct retinal involvement in this nonprimate model of methanol toxicity.

Animals↗
PubMed1991

A technique for facilitated visualization and dissection of the vitreous base, pars plana, and pars plicata.

We describe a technique to facilitate visualization of the vitreous base, pars plana, and pars plicata during vitreous surgery. This technique takes advantage of an externally applied fiberoptic light source coupled with scleral depression to enable direct viewing of the ciliary processes and anterior vitreous base. No special instrumentation or alteration in pars plana vitrectomy techniques is required. We have used this technique to enhance anterior dissection during vitrectomy surgery in the aphakic and pseudophakic eye associated with proliferative vitreoretinopathy, diabetic retinopathy, epithelial down-growth syndromes, and postvitrectomy fibrin formation.

Eye Diseases↗