Biomedical subjects

H C Boldt

Publications and source records attributed to H C Boldt.

30 records · Page 2Linked to original sources

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↗

PubMed1993

Preretinal and optic nerve head neovascularization induced by photodynamic venous thrombosis in domestic pigs.

OBJECTIVE: To develop a reliable model of ischemic preretinal and optic nerve head neovascularization in young male domestic pigs. METHODS: Using laser-induced branch retinal venous obstruction assisted by photodynamic thrombosis with rose bengal, 15 of 15 treated eyes developed neovascularization of the optic nerve head and retina. All cases of neovascularization were followed up clinically for up to 12 weeks. RESULTS: Clinical, fluorescein angiographic, and histopathologic features were consistent with neovascular proliferation into the vitreous. CONCLUSIONS: Further evaluation of the long-term natural history, role of the degree of ischemia, and the effect of interventions for various types of ischemic retinopathy (eg, panretinal photocoagulation) is warranted. This model is simple and relatively inexpensive and allows easy clinical assessment.

Animals↗

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

Ocular injuries caused by elastic cords.

Five patients with ocular trauma due to elastic cords with attached metal or plastic hooks were evaluated over a 13-month period. Injuries included hyphema, angle recession, lens subluxation, choroidal rupture, vitreous hemorrhage, retinal detachment, and scleral rupture. Two patients suffered penetrating ocular injuries, and three patients had final visual acuities of 20/200 or less. This series emphasizes the potential severity of ocular injury due to these commonly used devices and reiterates a modification in design that might decrease the likelihood of accidental trauma from elastic cords.

Adult↗

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↗

PubMed1991

Echographic evaluation of optic disc drusen.

With the improved resolution of the newer B-scan instrumentation, echography can be used to confirm rapidly and accurately the diagnosis of optic disc drusen. Over a 4-year period, we retrospectively identified 48 patients with the echographic diagnosis of optic disc drusen. Ages ranged from 6 to 78 years. Drusen were echographically bilateral in 69% of these patients. In 30 eyes, drusen were not visible clinically but were detected echographically. Standardized A-scan echography also helped to confirm the diagnosis of pseudotumor cerebri (2 patients) and optic neuritis (2 patients), emphasizing the need for performing a thorough evaluation before attributing clinical findings of an ophthalmoscopically abnormal optic nerve head to optic disc drusen. Six of 48 patients had vascular occlusions at the level of the optic nerve head. In 5 of these 6 patients, unilateral deep optic disc drusen were detected on the side of the occlusion. This finding lends support to the theory of potential mechanical compression of vascular structures by optic disc drusen.

Adolescent↗

PubMed1990

Slow leakage from the retinal pigment epithelium (ooze) in age-related macular degeneration.

The authors describe a condition called retinal pigment epithelial (RPE) ooze in patients with age-related macular degeneration. Patients with ooze have a neurosensory retinal detachment, a slowly progressive indiscrete leakage of fluorescein dye from the level of the retinal pigment epithelium, and no other signs of choroidal neovascularization. Sixteen patients with RPE ooze were followed for a mean of 4.5 years without treatment. Nine patients had a single round or oval area of leakage. In seven of these patients, choroidal neovascular membranes developed, with moderate to poor visual outcomes. The other seven patients had multiple smaller areas of leakage from the level of the RPE. None of these patients had a choroidal neovascular membrane, and all had resolution of the subretinal fluid with good final visual acuities. Patients with discrete round or oval RPE oozes appear to be at a high risk for the development of more definite choroidal neovascular membranes and vision loss.

Aged↗

PubMed1990

Prophylactic treatment to the fellow eye of patients with phakic lattice retinal detachment: analysis of failures and risks of treatment.

The authors performed a retrospective analysis on 296 phakic patients who had bilateral lattice degeneration and a retinal detachment in one eye. The analysis was done to determine the complications of full prophylactic treatment to lattice and breaks in the fellow eye and to explain the reasons that this treatment sometimes did not prevent new retinal breaks or detachments. The patients were followed for a mean +/- SD of 7.415 +/- 5.422 years after their first detachment. Twenty-four new tears occurred in the fellow eyes during this time, seven (29.2%) of which were away from areas of visible lattice. Prophylactic treatment did not appear to cause new tears or increase the risk of detachment if a new tear occurred. It also did not compromise the surgical repair in those patients who had eyes in which new breaks or detachments developed. The risk of visual loss was similar in those patients receiving prophylactic treatment compared with those not receiving treatment.

Cryosurgery↗

PubMed1989

Rural endophthalmitis.

The antibiotic regimens recommended for empiric use in posttraumatic endophthalmitis are based on data collected from medical centers in large metropolitan areas. In rural areas, trauma resulting in endophthalmitis frequently involves injuries with perforating objects that are contaminated with organic matter. These rural cases therefore may not be comparable with endophthalmitis occurring after nonrural injuries. A 10-year retrospective analysis was performed to investigate the incidence of rural endophthalmitis as well as determine the type of causative organisms. Endophthalmitis developed in 24 (30%) of 80 patients with rural penetrating trauma, compared with 23 (11%) of 204 patients with nonrural penetrating trauma. Of 24 patients, Bacillus spp were isolated in 11 (46%), followed by gram-negative rods in 7, Staphylococcus epidermidis in 6, and streptococcal species in 5. In 10 (42%) of these 24 patients with rural trauma, more than one organism was isolated. Bacillus spp were involved in six (60%) of ten of these mixed infections. Based on these findings, the authors suggest an intravitreal regimen of gentamicin along with either vancomycin or clindamycin for the empiric therapy of rural endophthalmitis.

Adolescent↗

PubMed1988

Orbital metastases from prostate carcinoma.

Prostate carcinoma was previously thought to be a rare source of orbital metastasis. We studied a clinical series of eight cases of orbital metastases from prostate carcinoma. Presenting symptoms included proptosis, pain, diplopia, eyelid swelling, decreased vision, ptosis, and red eye. The mean age at onset was 72.1 years. In three of the eight patients, evaluation of the orbital masses led to the diagnosis of prostate carcinoma. Of the six patients in whom computed tomography was performed, four had predominantly osteoblastic lesions. In our experience, the rapid development of an osteoblastic orbital lesion in an elderly man is highly suggestive of metastatic prostate carcinoma.

Adenocarcinoma↗

PubMedDate not supplied

Concurrent ferromagnetic hyperthermia and 125I brachytherapy in a rabbit choroidal melanoma model.

Ferromagnetic (FM) thermoseeds and radioactive (125I) seeds were combined in an episcleral plaque to give concurrent hyperthermia and irradiation for enhanced tumour destruction. A Greene melanoma cell line was utilized to study the interaction between these treatment modalities. We attached five FM thermoseeds (with an operating temperature of 48 degrees C) in parallel with alternating rows of 125I seeds onto the inner surface of each 14 mm Silastic plaque. Plaques were centred over a 3-6 mm (diameter) intraocular melanoma in each rabbit. Some rabbits were then placed within a heating coil, and their eye tumours were warmed rapidly to therapeutic temperatures (43.6 degrees C across the tumour base) while the temperature of normal conjunctiva across the globe did not exceed 38.5 degrees C. Analysis of 49 treated eye melanomas showed 50% local tumour control at 41.7 Gy for 125I alone, whereas only 9.5 Gy were needed to give the same local control rate after 125I with concurrent FM hyperthermia. Thus, a thermal enhancement ratio of 4.4 was obtained. Hyperthermia alone gave a 20% tumour response rate, but responses were only temporary. We conclude that FM thermoseeds can be used to deliver biologically effective hyperthermia concurrently with radiation, thereby reducing the dose of radiation needed for tumour control.

Animals↗

PubMedDate not supplied

Ferromagnetic hyperthermia: functional and histopathologic effects on normal rabbit ocular tissue.

Ferromagnetic (FM) hyperthermia has previously been evaluated in a rabbit tumour model of ocular melanoma. To study the effect of focal heating in normal rabbit eyes, FM seeds were implanted into a 14-mm episcleral plaque an heated to operating temperatures of 48 or 58 degrees C. Thermal induction was performed by placing rabbits in a uniform, oscillating (11 kHz) magnetic field operating at 1200 W and as H-field strength of 265 A/m. Eyes were heated for 60 min with continuous scleral temperature monitoring. Hyperthermic effects were monitored by direct opthalmic examination, fundus photography, serial electroretinography and histopathology. Intraocular temperatures were mapped with direct fiberoptic thermometry. All treatment effects were confined to the area covered by the episcleral plaque. Direct ophthalmoscopic examination revealed early retinal whitening during heat induction followed by localized exudative retinal detachments, limited to the area of the retinal surface overlying the plaque, that resolved spontaneously. Serial electroretinography was virtually indistinguishable between the 48 and 54 degrees C temperature groups. We noted a minimal alteration in a- and b-wave amplitudes with no changes in implicit times. Histopathology at 3 weeks post-treatment documented chorioretinal scarring overlying the thermal plaque treatment zone. No evidence of heamorrhage infection, cataract or scleral thinning was noted. This study documents the apparent focal containment of thermal effects with FM heating utilizing operating temperatures ad high as 54 degrees C for 60 min, and discloses no evidence of diffuse ocular toxicity.

Animals↗