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Biomedical subjects

W F Mieler

Publications and source records attributed to W F Mieler.

At least 55 records · Page 3Linked to original sources
PubMed1997

In vitro efficacy of carboplatin and hyperthermia in a murine retinoblastoma cell line.

PURPOSE: To determine the cell-killing activity of varying doses of carboplatin, graded hyperthermia, and the combination of carboplatin and hyperthermia in the treatment of a transgenic murine retinoblastoma cell line. METHODS: Replicate cell wells (more than six wells per dose point) from an established transgenic murine retinoblastoma cell line (Rb-6) were exposed to a single application of hyperthermia for 15, 30, 60, and 120 minutes at temperatures of 37 degrees C (control), 40 degrees C, and 43 degrees C. Carboplatin dose response treatment was studied at doses of 2000, 1000, 500, 400, 300, 200, 100, and 50 ng per well. Combined treatment studies used these carboplatin dosages with each of the graded hyperthermia exposure temperatures at each exposure time. At 24 hours, all wells were pulsed with 3H-thymidine for 24 hours, washed three times, harvested, and counted. Raw counts (3H-thymidine) were fitted to a linear regression model to calculate the lethal dose for 50% (LD50) of cells. RESULTS: The LD50 for carboplatin exposure at 37 degrees C occurred at 542 ng. The LD50 for hyperthermia at 40 degrees C occurred at 90 minutes and at 43 degrees C it occurred at 62 minutes. Combined hyperthermia and carboplatin exposure yielded a synergistic interaction with an LD50 of 327 ng at 43 degrees C for 30 minutes. Determination of a thermal enhancement ratio yielded an enhancement range of 1.1 to 25.8. CONCLUSIONS: The synergistic cytocidal interaction of heat and carboplatin in a transgenic murine retinoblastoma cell line has been established in this study. The increased thermal enhancement ratio documents the potential utility of combined treatment applications in reducing treatment levels of single-modality therapy, potentially allowing for a decrease in treatment-related morbidity.

Animals↗
PubMed1997

Concurrent versus sequential application of ferromagnetic hyperthermia and 125I brachytherapy of melanoma in an animal model.

OBJECTIVE: To determine the efficacy of concurrent versus sequential ferromagnetic hyperthermia (FMH), combined with Iodine-125 (125I) brachytherapy, in the treatment of uveal melanoma in a rabbit model. MATERIALS AND METHODS: A Greene melanoma cell line was implanted in rabbit eyes to establish a tumor model comparable to a uveal melanoma. Seventy-one tumor-containing rabbit eyes were treated with 125I brachytherapy at 20, 25, 35, 45, or 55 Gray (Gy)(38 eyes), and with either concurrent (15 eyes) or sequential (18 eyes) FMH, delivered at 48.2 degrees C for 1 hour. An additional 13 eyes were treated with FMH alone at 48.2 degrees C, either in a single heat application (5 eyes), or in a repetitive mode (8 eyes). The radiation and heat were delivered via an episcleral plaque. All tumors were followed with indirect ophthalmoscopy and echography. RESULTS: Tumors treated with 125I brachytherapy alone exhibited complete tumor regression in 50% of eyes at 42 Gy with none of the tumors responding to less than 35 Gy. FMH alone at 48.2 degrees C applied in one cycle limited tumor growth in 20% of eyes, while all eyes treated with repetitive heating exhibited complete tumor control. With concurrent application of FMH and 125I, the 50% tumor control rate occurred at 9.5 Gy, thus resulting in a thermal enhancement ratio (TER) of 4.4. With sequential treatment, the 50% tumor control rate was at 30 Gy, with a resultant TER of 1.4. No complications related to 125I brachytherapy were noted in any eyes, while transient retinal whitening was seen with the FMH. CONCLUSION: This study documents the enhanced synergistic interaction of concurrent FMH and 125I brachytherapy, compared to sequential treatment, in this rabbit melanoma model.

Animals↗
PubMed1996

Ruptured globes following radial and hexagonal keratotomy surgery.

OBJECTIVE: To ascertain if cases of radial keratotomy wound rupture were occurring and whether the globes ruptured through the corneal incisions. DESIGN: Cases of traumatic ruptured globe after incisional corneal refractive surgery were collected from ophthalmologists and from peer-reviewed and other ophthalmic literature. RESULTS: Twenty-eight human eyes (eight previously unreported) are known to have ruptured through refractive corneal incisions in activities of daily living (n = 12), assault (n = 7), motor vehicle accidents (n = 5), and sports (n = 4). Two patients died of their injuries. Of the remaining 26 ruptured eyes, eight (31%) recovered 20/40 or better visual acuity. Six eyes (23%) were totally blinded, six (23%) were legally blinded, and six (23%) had best corrected visual acuity of 20/40 to 20/100 despite multiple surgical procedures. CONCLUSIONS: As radial keratotomy becomes more popular the pool of patients who may experience traumatic ruptured globe will grow. Every patient who has had radial keratotomy should be aware that the surgery has weakened the eye(s).

Adult↗
PubMed1996

Management of ectopia lentis in a family with Marfan syndrome.

OBJECTIVE: To determine the effectiveness of combined pars plana vitrectomy-lensectomy and open-loop anterior chamber lens implantation for the management of ectopia lentis associated with Marfan syndrome. METHODS: Retrospective review of the medical records of 4 consecutive patients with Marfan syndrome who underwent combined pars plana lensectomy-vitrectomy and anterior chamber lens implantation at our institution between August 1994 and July 1995. RESULTS: All patients demonstrated postoperative visual acuity of 20/25 or better during an average follow-up period of 6 months (range, 4-9 months). Two patients developed pseudophakic pupillary block and required YAG laser iridotomy postoperatively. CONCLUSIONS: Pars plana lensectomy-vitrectomy and anterior chamber intraocular lens implantation appears to be an excellent technique for the management of ectopia lentis associated with Marfan syndrome. A bimanual, closed-system endosurgical technique avoids many of the complications previously associated with surgery for ectopia lentis.

Adult↗
PubMed1996

Retinal complications after aqueous shunt surgical procedures for glaucoma.

OBJECTIVES: To assess retinal complications and to identify risk factors for retinal complications following aqueous shunt procedures. MATERIALS AND METHODS: Records of 38 consecutive aqueous shunt procedures that were performed on 36 patients at the Eye Institute of the Medical College of Wisconsin, Milwaukee, from June 1993 to March 1995 (minimum follow-up, 6 months) were reviewed. The mean +/- SD follow-up was 11.4 +/- 5.2 months (median, 10.5 months). RESULTS: Twelve patients (32%) had the following retinal complications: 4 serous choroidal effusions (10%) that required drainage, 3 suprachoroidal hemorrhages (8%), 2 vitreous hemorrhages (5%), 1 rhegmatogenous retinal detachment (3%), 1 endophthalmitis (3%), and 1 scleral buckling extrusion (3%). Surgical procedures for retinal complications were required in 8 (67%) of these 12 patients. Visual acuity decreased 2 lines or more in 9 (75%) of these 12 patients. The median onset of a postoperative retinal complication was 12.5 days, with 10 patients (83%) experiencing complications within 35 days. Serous choroidal effusions developed in 10 other patients (26%), and these effusions resolved spontaneously. Visual acuity decreased 2 lines or more in 2 (20%) of these additional 10 patients. Patients who experienced serious retinal complications were significantly older, had a higher rate of hypertension, and postoperative ocular hypotony. Serious retinal complications were distributed evenly among patients with Krupin valves with discs and Molteno and Baerveldt devices. Experience with the Ahmed glaucoma valve implant was limited. CONCLUSION: Aqueous shunt procedures may be associated with significant retinal complications and subsequent visual loss.

Adult↗
PubMed1996

Vitrectomy in eyes with peripheral retinal angioma associated with traction macular detachment.

PURPOSE: Peripheral angiomas have been associated with epiretinal membranes and traction retinal detachment. The authors investigated the timing, results, and complications of vitreous surgery to remove the retinal traction and treat the peripheral vascular tumor. METHODS: The authors reviewed the results of ten eyes that had undergone vitrectomy for macular pucker and/or traction retinal detachment. These eyes had either preoperative or intraoperative treatment of the peripheral tumor. RESULTS: Patients were followed 4 to 95 months. Six eyes had nonfamilial peripheral acquired retinal hemangioma, three had von Hippel angiomas, and one had multiple large peripheral retinal angiomas associated with extensive retinal telangiectasis. Four eyes received cryotherapy and/or laser photocoagulation 2 to 3 months before surgery. In the remaining six eyes, initial treatment to the peripheral angioma was performed at the time of vitreous surgery. At final follow-up, all eyes were attached without retinal traction. Vision improved in all eyes; six (60%) achieved 20/50 or better visual acuity. Complications included recurrent epiretinal membrane (n=3); nonregressed angiomas (n=3); increased nuclear sclerosis (n=2); and retinal detachment (n=1). CONCLUSION: Vitreous surgery, when applied to epiretinal membranes or traction retinal detachments associated with peripheral vascular tumors, has a good chance of improving vision. Treatment of the hemangioma, before or during vitrectomy, usually results in tumor regression.

Adult↗
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

High-resolution magnetic resonance imaging evaluation of blood-retinal barrier integrity following transscleral diode laser treatment.

OBJECTIVE: To compare the effects of contact transscleral diode laser treatment and retinal cryotherapy on blood-retinal barrier integrity with the use of high-resolution magnetic resonance imaging techniques with constant infusion of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA). METHODS: Transscleral diode laser photocoagulation and retinal cryotherapy were used to treat equivalent areas of the inferior retinal periphery of pigmented rabbits. Magnetic resonance imaging time-course studies with measurement of signal enhancements due to Gd-DTPA leakage were conducted 2 and 15 days following treatment. RESULTS: Two days following treatment, cryotherapy-treated eyes exhibited a mean (+/- SD) effective Gd-DTPA permeability coefficient of 4.6 +/- 0.8 x 10(-6) cm/s; in comparison, diode laser-treated eyes exhibited 1.6 x 1.4 x 10(-6) cm/s effective permeability. Significant decreases in the effective permeability were also noted 15 days after treatment in both groups. CONCLUSIONS: Transscleral contact probe diode laser photocoagulation induces less disruption of the blood-retinal barrier than does conventional cryotherapy. In addition, the continuous infusion method of Gd-DTPA delivery is a reliable and easily interpretable alternative to the commonly used bolus injection approach.

Animals↗
PubMed1995

2 peripheral scatter photocoagulation for neovascularization associated with pars planitis.

BACKGROUND: Peripheral cryotherapy appears to be efficacious in the treatment of neovascularization of the vitreous base in patients with pars planitis, although it may be associated with the development of rhegmatogenous retinal detachments. OBJECTIVE: To evaluate the safety and efficacy of peripheral scatter photocoagulation for treatment of neovascularization of the vitreous base when used alone or combined with pars plana vitrectomy. METHODS: Six patients (10 eyes) presented with vitritis, cystoid macular edema, and neovascularization of the vitreous base, unresponsive to corticosteroid therapy. Three patients (five eyes) received scatter diode or argon photocoagulation treatment alone. The other three patients (five eyes) underwent pars plana vitrectomy coupled with argon or diode photocoagulation, placed in three rows, posterior to the area of inferior neovascularization of the vitreous base. RESULTS: Pretreatment visual acuity ranged from 20/20 to 20/200. All patients were followed up for a minimum of 6 months. After placement of photocoagulation (with or without concurrent pars plana vitrectomy), the neovascularization regressed, inflammation was stabilized, and cystoid macular edema improved in all eyes. There were no retinal detachments or other complications of treatment. Posttreatment visual acuity ranged from 20/20 to 20/100. When final visual acuity was 20/40 or less, cataract formation was generally responsible. CONCLUSIONS: Peripheral scatter photocoagulation is efficacious and appears at least equal to peripheral cryotherapy in causing regression of neovascularization of the vitreous base in patients with pars planitis.

Adult↗
PubMed1995

Golf-related ocular injuries.

OBJECTIVE: To review golf-related ocular injuries, which account for 1.5% to 5.6% of all sports injuries. METHODS: During 8 years (1986 to 1994), a retrospective review of sports-related trauma was performed at the Medical College of Wisconsin, Milwaukee. Eight blunt ocular injuries (four ruptured globes and four globes without rupture) caused by golf-related activities were identified. The four ruptured globes caused by golf-related trauma accounted for 1.2% of all penetrating injuries and/or ruptured globes and 11.7% of sports-related injuries. RESULTS: A golf ball projectile was the mechanism of injury in six patients, while two patients were struck with a gold club. The four patients with ruptured globes had an initial visual acuity of light perception or worse, and three globes were subsequently enucleated, while one was prephthisic. In the four trauma cases without rupture, surgical intervention was required to achieve anatomic stability, with final visual acuities ranging from 20/25 to 20/40. CONCLUSIONS: The incidence of ocular injuries caused by golf-related trauma is low compared with that for other sports-related injuries. Although the prognosis for ruptured globes occurring in this setting remains extremely guarded, blunt trauma without rupture caused by a golf-related injury is associated with a more favorable visual and anatomic outcome.

Adolescent↗
PubMed1995

Echographic pseudoextension of uveal melanomas.

BACKGROUND: Standardized echography is routinely utilized to assess uveal melanomas. Echographic pseudoextension is defined as normal structures mimicking intrascleral or extrascleral extension of tumor on echography. METHODS: The records of 151 consecutive uveal melanoma patients evaluated with standardized echography over a 6-year period (1986-1991) were reviewed to identify those in which pseudoextension or true extension was diagnosed. RESULTS: Fourteen (9%) cases of pseudoextension were noted, with causes including juxtapapillary tumor location (seven cases), extraocular muscle insertion (five cases), vortex ampullae (one case), and post-brachytherapy changes (one case). Clinical, echographic, and/or histopathologic follow-up confirmed absence of true extension. Six (4%) cases of true extrascleral extension were identified and confirmed histopathologically. CONCLUSION: Differentiating extraocular tumor extension from pseudoextension is critical, and use of standardized A-scan and contact B-scan echography is integral in this assessment.

Adult↗
PubMed1995

Vitrectomy for proliferative diabetic retinopathy with severe equatorial fibrovascular proliferation.

PURPOSE: We studied the surgical treatment and visual outcome in a consecutive series of eyes with an unusual syndrome of diabetic retinopathy and severe peripheral fibrovascular proliferation involving the equatorial and pre-equatorial fundus. METHODS: In a retrospective study of 276 eyes (245 patients) that underwent pars plana vitrectomy for diabetic retinopathy between November 1988 and February 1993, nine eyes of eight patients (3.3% of eyes and 3.3% of patients) had severe equatorial fibrovascular proliferation. The condition occurred primarily in previously unoperated-on eyes (except for panretinal photocoagulation) and resulted in peripheral traction or traction-rhegmatogenous retinal detachment (six eyes), severe vitreous hemorrhage (two eyes), and severe hypotony (one eye). Relief of traction from peripheral fibrovascular membranes was obtained with an encircling scleral buckle (nine eyes) and limited delamination and segmentation (five eyes) or relaxing retinectomy (two eyes). Lensectomy was required for adequate membrane dissection in three eyes. RESULTS: After follow-up of six to 52 months (mean, 20.4 months), the visual acuity was 20/200 or better in seven of nine eyes, with complete retinal attachment in seven of nine eyes and postequatorial attachment in all eyes (100%). Poor outcome resulted from a persistent response resembling Coats' disease in one eye and preexistent long-standing retinal detachment in one eye. CONCLUSIONS: Vitrectomy for severe equatorial fibrovascular proliferation differs from conventional approaches to diabetic retinopathy in that relief of retinal traction must be attained by scleral buckling and adequate dissection of peripheral fibrovascular tissue. In advanced cases, lensectomy and relaxing retinotomy may be required.

Adult↗
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

Early vitrectomy and endolaser photocoagulation in patients with type I diabetes with severe vitreous hemorrhage.

PURPOSE: To determine if adjunctive endolaser photocoagulation has further improved the outcome of early vitrectomy for severe vitreous hemorrhage in young patients with type I insulin-dependent diabetes. METHOD: The authors reviewed clinical records and fundus photographs of all primary diabetic vitrectomies performed at the Yale Eye Center between July 1986 and June 1993. Only young patients with type I diabetes who underwent vitrectomy within 6 months of vitreous hemorrhage were included. RESULTS: Of 197 vitrectomies for diabetic retinopathy, 12 eyes of ten patients met the Diabetic Retinopathy Vitrectomy Study Group criteria. Patients ranged in age from 24 to 29 years (mean, 27.3 years) and had 11 to 21 years (mean, 17.2 years) of history of diabetes. Preoperative visual acuity was 5/200 in seven eyes, 2/200 in three eyes, hand motions in one eye, and light perception in one eye. The duration of vitreous hemorrhage was approximately 1 month in two eyes, 1 to 3 months in five eyes, and 3 to 6 months in five eyes. Neovascularization was documented in 12/12 eyes. Preoperatively, all patients had received panretinal photocoagulation with 1937 to 5328 burns (mean, 4126). Postoperative follow-up ranged from 12 to 38 months (mean, 24.6 months). Best-corrected postoperative visual acuity was 20/40 or better in 7 eyes (58.33%) and 20/70 or better in 11 eyes (91.66%). Neovascularization involuted in 11/12 eyes and remained so till the last follow-up. CONCLUSION: Patients with type I diabetes with severe vitreous hemorrhage benefit from early endolaser photocoagulation combined with current vitrectomy techniques. The authors' findings are consistent with those of the Diabetic Retinopathy Vitrectomy Study Group, and patients can expect both improved visual acuity and anatomic success.

Adult↗
PubMed1995

Idiopathic retinal vasculitis, aneurysms, and neuro-retinitis. Retinal Vasculitis Study.

PURPOSE: The authors describe the clinical feature of ten patients with a new syndrome characterized by the presence of retinal vasculitis, multiple macroaneurysms, neuro-retinitis, and peripheral capillary nonperfusion. METHODS: The authors evaluated ten patients identified to have clinical features compatible with the syndrome of idiopathic retinal vasculitis, aneurysms and neuroretinits (IRVAN). Clinical examination findings, sequential funds photographs (when available), fluorescein angiograms, systemic investigations, response to therapy, and visual outcomes were reviewed. RESULTS: Seven eyes of four patients sustained a marked decrease in visual acuity of 20/200 or worse. Visual loss was due to a combination of an exudative maculopathy and sequelae of retinal ischemia. Capillary nonperfusion was seen in all ten patients and was severe enough to warrant panretinal laser photocoagulation in six patients. Systemic investigations were uniformly noncontributory. Oral prednisone appears to have little beneficial effects on patients with this disorder. CONCLUSIONS: Patients with IRVAN have characteristic retinal features that readily identify this syndrome. An increased awareness of this rare syndrome may help to identify sight-threatening complications at an earlier stage. The authors caution against extensive medical investigations.

Adult↗
PubMed1995

Combined pars plana vitrectomy-lensectomy and open-loop anterior chamber lens implantation.

PURPOSE: To investigate the effectiveness of open-loop, one-piece, flexible, Kelman-style, all-polymethylmethacrylate (PMMA) anterior chamber intraocular lenses (AC IOLs) in patients undergoing pars plana vitrectomy surgery for a variety of vitreoretinal disorders. METHODS: Fifteen patients (6 women and 9 men) underwent combined pars plana vitrectomy with insertion of an open-loop AC IOL. Postoperative results were evaluated. RESULTS: The average preoperative visual acuity of 20/360 (logMAR scale, 1.25 +/- 0.80) improved to 20/52 (logMAR scale, 0.42 +/- 0.35) after an average follow-up of 10.2 months (range, 1-41 months). Of 15 eyes, 7 (47%) achieved a visual acuity of better than 20/40. There was no evidence of glaucoma exacerbation or corneal decompensation. Visual acuity was limited primarily by chronic cystoid macular edema in 4 (27%) of 15 eyes. CONCLUSION: In this preliminary series of patients, open-loop, flexible, all-PMMA, Kelman-style AC IOLs appear to be well tolerated and represent a viable, simple alternative to transscleral fixation of a posterior chamber IOL or surgical aphakia in patients undergoing vitrectomy surgery.

Adult↗