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Biomedical subjects

R D Stone

Publications and source records attributed to R D Stone.

At least 19 recordsLinked to original sources
PubMed1992

Extramacular disciform lesions simulating uveal tumors.

PURPOSE: The purpose of this study is to identify clinical, ultrasonographic, and fluorescein angiographic features of extramacular disciform lesions that allow differentiation from uveal tumors. METHODS: This was a retrospective study of 19 patients referred to our ocular oncology unit with a possible malignancy who had a diagnosis of an extramacular disciform lesion made after complete evaluation. RESULTS: The level of accuracy for each diagnostic technique alone was as follows: clinical (79%), ultrasonography (83%), and angiography (83%). Fluorescein angiography had limited utility because of severe media opacities in seven cases. No tumor developed an intraocular malignancy during the follow-up period. CONCLUSION: A combination of the above, noninvasive techniques can be used to correctly diagnose extramacular disciform lesions.

Adult↗
PubMed1990

Five-year follow-up of helium ion therapy for uveal melanoma.

One hundred sixty-four patients with uveal melanoma were treated with helium ion irradiation prior to May 1984, and the data were analyzed in June 1989. Most uveal melanomas were large, with a mean tumor thickness of 6.5 mm; approximately 60% of the patients had tumors that extended anterior to the equator. A complete follow-up was obtained for all patients. One hundred twelve patients were alive at the time of this report; 18% of the patients developed clinical and laboratory evidence of metastases and eventually died of widespread tumor. Eighty-four percent of eyes were retained. Data were analyzed with a number of parametric and nonparametric techniques. Larger tumors and those located in close proximity to the optic nerve and fovea had a higher incidence of most complications, especially visual loss.

Adult↗
PubMed1990

Ultrasonographic measurement of uveal melanoma thickness: interobserver variability.

We retrospectively reviewed ultrasonographic data on 32 uveal melanomas that had been studied both at a referral institution and at our centre within a six-week period. Generally there were good correlations between ultrasonographic measurements of tumour thickness. The mean absolute difference in ultrasound measurements of tumour thickness was 0.64 mm (range 0-2.2 mm); the mean tumour thickness was 5.2 mm (range 3.5-10.2 mm). Tumour diameter, location, the relative ultrasonographic experience with uveal melanoma, type of equipment, and tumour thickness all affected the interobserver variation of measurement.

Humans↗
PubMed1989

Effect of various doses of radiation for uveal melanoma on regression, visual acuity, complications, and survival.

We reviewed 284 choroidal and ciliary body melanomas treated with 50, 60, 70, or 80 gray equivalents (GyE) of helium ion radiation. Multivariate methods of data analysis were used to adjust for differences between dose groups with respect to the characteristics of patients (and their tumors). Radiation dose level did not affect survival, complications, visual outcome, or tumor regression in this model. The minimum radiation dose necessary to achieve tumor control with charged particles may be less than 50 GyE.

Dose-Response Relationship, Radiation↗
PubMed1989

Uveal melanoma radiation. 125I brachytherapy versus helium ion irradiation.

The optimum radiation therapy for uveal melanoma is uncertain. Both helium ion irradiation and 125I brachytherapy have been used to treat this neoplasm. This investigation analyzed the control and complication rates of uveal melanomas treated with helium ions of 125I plaques. In both a retrospective and a prospective dynamically balanced study, the control rates appeared to be similar. There were more posterior segment complications after 125I plaques and more anterior segment complications, including neovascular glaucoma, after helium ion irradiation. The follow-up period is too short to draw definitive conclusions on the radiation complications. Overall, approximately 89% of eyes were retained and less than 4% of treated eyes were removed because of failure to control the tumor.

Adult↗
PubMed1988

Increased left ventricular diastolic stiffness in the early phase of hereditary cardiomyopathy.

Isolated hearts from normal and cardiomyopathic hamsters (160 to 180 days of age) were perfused through the aorta and assessed by echocardiographic and 31P-NMR (nuclear magnetic resonance) techniques. A decreased left ventricular systolic pressure in cardiomyopathic hamsters was associated with diminished cardiac size and left ventricular wall thickness. However, the ratio of inner/outer cross-sectional area and estimated left ventricular volume at any given left ventricular weight was significantly higher, indicating relative left ventricular chamber enlargement in cardiomyopathic hamsters. Left ventricular volumes were increased with an intraventricular balloon. Gradual inflation of the balloon resulted in increments of left ventricular systolic and developed stress that rose to the same values in both groups. At this point, the normalized stress-strain relationship was approximately two times steeper for cardiomyopathic hamsters, while at lower strain values the diastolic stress in cardiomyopathic hamsters was less than in controls, possibly due to cardiac dilatation. Almost the same degree of dilatation was induced in control hearts by the acute addition of 1% alcohol, but it was not followed by increased diastolic stiffness. Examination of hearts by 31P-NMR techniques revealed a decreased phosphocreatine/inorganic phosphate (PCr/Pi) ratio in the cardiomyopathic hamsters that progressed further with balloon inflation and was associated with a relative fall in PCr and adenosine triphosphate (ATP) content. Results suggest increased diastolic stiffness in cardiomyopathic hamsters, which was not seen in acute cardiac depression with alcohol. Diastolic volume overload with increased wall stress is probably the major factor contributing to increased diastolic stiffness early in the cardiomyopathy.

Adenosine Triphosphate↗
PubMed1988

N-3-pyridylmethyl-N'-p-nitrophenylurea ocular toxicity in man and rabbits.

Ingestion of the rat poison N-3-pyridylmethyl-N'-p-nitrophenylurea (PNU) produced ocular toxicity in three humans and in an animal model, the Dutch Belted rabbit. The electroretinogram b wave was especially susceptible to the effects of the rodenticide, and the target tissue appeared to be the retinal pigment epithelium. Injection of PNU itself did not produce ocular toxicity. The poison had to be administered orally. Gentamicin administered orally with PNU prevented the ocular toxicity. Presumably this antibiotic killed those gastrointestinal bacteria responsible for PNU's metabolism into an ocular toxin. L-tryptophan, a known antidote for the lethal effects of PNU, was an antidote for the ocular toxicity when administered orally but not when administered parenterally.

Adolescent↗
PubMed1988

Uveal melanoma with opaque media: absence of definitive diagnosis before enucleation.

It is often difficult to make a correct diagnosis of a uveal melanoma in an eye with opaque media. A patient with a blind, painful eye and opaque media was evaluated clinically and with computed axial tomography and ultrasonography. We were unable to establish the definitive diagnosis of a uveal melanoma until the eye was examined histologically. Necrotic melanomas usually present with inflammatory signs, may produce opaque media and can be difficult to diagnose with clinical and imaging studies.

Aged↗
PubMed1987

Effects of altered coronary perfusion pressure on function and metabolism of normal and cardiomyopathic hamster hearts.

The effects of a sudden decrease in coronary perfusion pressure from 140 to 0 cmH2O for a 10-second interval were analyzed in normal and cardiomyopathic hamster hearts to determine whether cardiomyopathy would affect the relationship between altered coronary perfusion pressure and left ventricular geometry, wall thickness, myocardial hydrodynamics, and hemodynamics. In normal hamsters, an acute reduction in coronary perfusion pressure resulted in a decrease in left ventricular short axis epicardial cross-sectional area, base to apex length, diastolic wall thickness, myocardial water content and developed pressure. In cardiomyopathic hamsters all results induced by lowering the hydrostatic pressure of the perfusing medium were the same except that diastolic wall thickness failed to decline, indicating a decrease in intramyocardial elasticity in dilated cardiomyopathy. In parallel studies, hearts were freeze clamped at end-diastole and high energy phosphates and energy metabolites analyzed. In both normal and cardiomyopathic hamsters no significant changes were observed in ATP, PCr, or Pi levels at 10 s following the decrease in perfusion pressure. However, during the abrupt decrease in coronary perfusion pressure adenosine increased and cAMP decreased in both groups of animals. The erectile effect of altered coronary perfusion pressure is partially attenuated in the cardiomyopathic hamster in which no change in diastolic wall thickness occurs during an abrupt change in the hydrodynamics of the heart.

Animals↗
PubMed1986

Uveal melanoma necrosis after helium ion therapy.

A 71-year-old man underwent enucleation because of intractable pain ten months after receiving helium ion therapy for a uveal melanoma. There was no clinical or ultrasonographic evidence of tumor regression but histologically the tumor appeared almost entirely necrotic.

Aged↗
PubMed1986

Neovascular glaucoma after helium ion irradiation for uveal melanoma.

Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments.

Anterior Eye Segment↗
PubMed1979

Pupillary membrane excision and anterior vitrectomy in eyes after uveitis.

Three patients with uveitis and dense pupillary membranes, total synechial closure of the angle, and low or normal pressure, underwent membranectomy and anterior vitrectomy via a limbal approach using scissors and a vitrectomy instrument. Postoperatively all regained useful vision that has been maintained for over two years despite the persistence of angle closure in all cases and severe hypotony in two.

Adult↗
PubMed1977

An ultrasonographic study of the persistence of buckle height three years after segmental sponge explants.

We studied a consecutive series of rhegmatogenous retinal detachments treated with segmental silicone sponge explants and cryotherapy, with or without drainage, approximately three years postoperatively by ultrasonography to determine the degree and persistence of the height of the buckle measuring 1.5 to 3 mm remained in all patienst examined clinically and ultrasonographically at three years or later. Five of these patients reexamined one year later demonstrated no loss of buckle height between the third and fourth postoperative years. By comparison, in a small group of patients examined early in their postoperative course (2.5 to 4 months), the buckles were only slightly higher than in the group studied at three years. Buckle height thus appeared to stabilize relatively quickly postoperatively and to persist at least three years. We believe encapsulation of the sponge by scar tissue must contribute to the long-term maintenance of buckle height.

Cryosurgery↗
PubMed1977

Vitrectomy.

Explore the source record for details and available documents.

Humans↗
PubMed1976

Glaucomatous cupping of the optic disk by ultrasonography.

B-scan ultrasonography was used to evaluate advance glaucomatous cupping of the optic disk (0.7 cup/disk ratio or greater) in one normal subject and six patients with glaucoma. The normal eye emitted a continuous echo from the posterior pole, which conformed to its mild degree of concavity. The glaucomatous eyes emitted echos from the posterior pole, demonstrating the more extreme concavity of the optic cup. Ultrasonographic evaluation of an acrylic plate containing holes of known diameter demonstrated the limits of resolution and artifacts that resulted from this examination.

Glaucoma↗