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Biomedical subjects

B R Straatsma

Publications and source records attributed to B R Straatsma.

At least 37 records · Page 2Linked to original sources
PubMed1991

Lens capsule and epithelium in age-related cataract.

On the basis of preoperative assessment of patient characteristics, intraoperative obtainment of a lens-capsule and epithelium specimen, histopathologic investigation of lens capsule and epithelium, and biochemical analysis of glutathione reductase in lens epithelium, age-related cataract was studied in 50 adult patients who underwent consecutive extracapsular cataract-posterior chamber lens implant surgery. Patients (25 men and 25 women; age range, 41 to 91 years; mean age, 75 years) had a wide range of systemic and ocular disease; 17 of 50 (34%) patients had a history of severe vision-impairing cataract in a first-degree relative. Anterior lens-capsule thickness ranged from 10 to 22 microns, with a mean of 17 microns. Statistical analysis of lens-epithelium ultrastructure in 41 of 50 specimens documented mixing of normal and abnormal cells, verified a gradation in the degree of abnormal ultrastructural features, and demonstrated a statistically significant decrease in epithelial cytologic activity with advancing age (P = .038). Biochemical analysis documented a severe glutathione reductase deficiency in nine of 39 (23%) lens-epithelium specimens, possibly reflecting a dietary deficiency of riboflavin.

Adult↗
PubMed1991

Tissue plasminogen activator treatment of experimental subretinal hemorrhage.

To determine if tissue plasminogen activator, a clot-specific fibrinolytic agent, could eventually be used to assist in the clearance or removal of subretinal hemorrhage, we studied the effect of subretinal injections of tissue plasminogen activator, autologous blood, balanced salt solution, and the combination of either tissue plasminogen activator or balanced salt solution after subretinal injection of autologous blood on retinal morphologic characteristics and clearance of subretinal hemorrhage in the albino rabbit. No morphologic evidence of tissue plasminogen activator toxicity was found in the rabbit retina at a dose of 25 to 50 micrograms/0.1 ml. Subretinal hemorrhage cleared faster after subretinal injection of tissue plasminogen activator when compared to balanced salt solution (P = .0005) but did not completely prevent overlying retinal degeneration. Both tissue plasminogen activator and balanced salt solution were found to decrease the toxic effects of subretinal blood on the morphologic characteristics of the rabbit retina, and this effect can be explained at least partly by dilution of the subretinal blood.

Animals↗
PubMed1990

Posterior vitreous cyst.

We observed two patients who had unilateral posterior vitreous cysts; one patient had been observed for 17 years. Both patients were young females who reported transient, infrequent obscurations of vision that were not disabling. One involved eye was emmetropic, and the other was highly myopic. No other ocular abnormalities were present. In the patient observed for 17 years, the physical characteristics of the posterior vitreous cyst remained unchanged. With this stable clinical course, posterior vitreous cyst that does not visually disable the patient may be managed by periodic observation.

Adolescent↗
PubMed1988

Enucleation versus plaque irradiation for choroidal melanoma.

The Collaborative Ocular Melanoma Study (COMS) is an international, multicenter-controlled study. The organization includes an Executive Committee, Steering Committee, 6 Central Units, 32 Clinical Centers, and a Data and Safety Monitoring Committee. Scientifically, the COMS consists of (1) a randomized trial of patients with medium choroidal melanoma treated with enucleation versus iodine-125 plaque irradiation, (2) a randomized trial of patients with large choroidal melanoma treated with enucleation versus preenucleation external beam irradiation and enucleation, and (3) a prospective observational study of patients with small choroidal melanoma to determine whether a randomized trial of treatment is appropriate. In design and conduct of the COMS, special consideration is given to biostatistics and sample size considerations, iodine-125 plaque irradiation of choroidal melanoma, and coordinated ocular melanoma research. Recruitment is in progress. However, the pool of eligible patients is limited and the COMS needs the continued support and cooperation of ophthalmologists throughout the United States and Canada.

Brachytherapy↗
PubMed1988

Detection and quantification of S-100 protein in ocular tissues and fluids from patients with intraocular melanoma.

S-100 protein is a 21,000 dalton acidic calcium-binding protein present in ocular melanomas and some normal ocular tissues. Ocular fluids and extracts of ocular tumours were examined by a sensitive radioimmunoassay that could detect less than 5 ng of S-100 protein in minute volumes of fluid. Three ocular melanoma biopsy specimens had S-100 protein at levels between 25 and 1300 ng/ml, comparable to that found in a cutaneous melanoma biopsy specimen (1000 ng/ml). (SI conversion: ng/ml = microgram/l.) Six melanoma culture lines had 1000 to 125,000 ng/ml. Four lymphoblastoid cultures had less than 2 ng/ml, and three colon carcinoma cultures had 180 ng/ml. Subretinal fluid from 23 melanoma-containing eyes had 10 to 76,800 ng/ml. Lesser amounts were found in eyes with small, anteriorly located, lightly pigmented tumours. Vitreous from 3 melanoma-containing eyes had 10,000 to 11,000 ng/ml. Vitreous obtained from three eyes during tractional retinal detachment repair had 500 to 1600 ng/ml, and vitreous obtained at necropsy from six normal eyes had 2 to 120 ng/ml. Aqueous from six melanoma-containing eyes had 10 to 30 ng/ml, levels not significantly different from those observed in three normal eyes (80-120 ng/ml). This approach provides new insight into the interaction of ocular tumours and adjacent ocular fluids and may, with more specific tumour markers, have diagnostic applications.

Aqueous Humor↗
PubMed1988

The potential usefulness to research of retina obtained by biopsy.

Retinal biopsy has been performed on normal rabbits and dogs. It was shown that retinal samples could be obtained by internal and external routes in rabbits, but in dogs inability to achieve adequate vitrectomy precluded useful retinal biopsy by the internal route. A single external biopsy specimen of 3 mm diameter was more than adequate to undertake standard histopathological examination, immunocytochemical experiments and determination of cyclic nucleotide levels. The quality of the micrographs, immunocytochemical labelling of rhodopsin and phosphodiesterase, and cyclic nucleotide analyses were similar to those obtained with retinas from freshly enucleated eyes. The surgical exercise was well tolerated by most eyes and does not preclude serial biopsies being undertaken. It is concluded that retinal biopsy provides material of sufficient quantity and quality to satisfy many laboratory needs in retinal research.

Animals↗
PubMed1987

Incidence, risk factors, and morphology in operating microscope light retinopathy.

A review of 135 consecutive cataract operations identified ten cases (7.4%) of operating microscope light retinopathy. Ophthalmoscopically, these light retinopathy lesions appeared as a focal pigment epithelial change with varying degrees of pigment clumping in the center. Fluorescein angiography accentuated the lesion by demonstrating a sharply demarcated transmission defect, occasionally with multiple satellite lesions. The shape of the lesion matched the shape of the illuminating source of the particular operating microscope used during the surgery. The most significant risk factor associated with the production of these light retinopathy lesions was prolonged operating time. Mean total operating time for the ten patients with light retinopathy was 51 minutes longer than for those without (P less than .0001). Other significant associated factors were the presence of diabetes mellitus (P less than .03), younger age (P less than .05), and the use of hydrochlorothiazide (P less than .04).

Cataract Extraction↗
PubMed1987

A prospective study of cystoid macular edema after neodymium: YAG laser posterior capsulotomy.

To establish the clinical and angiographic incidence of cystoid macular edema (CME) after neodymium:YAG (Nd:YAG) laser capsulotomy, the authors have prospectively studied 136 patients who underwent Nd:YAG laser discission for secondary opacification of the posterior capsule after extracapsular cataract extraction. In all patients, fluorescein angiography was obtained before the laser discission. Of the 136 patients, 78 (57%) were followed for at least 6 months, and fluorescein angiography was repeated 4 to 8 weeks after the procedure. CME did not develop in any of the patients in this series.

Adult↗
PubMed1987

Glutathione reductase in human lens epithelium: FAD-induced in vitro activation.

Glutathione reductase (GR) activity was measured with and without the addition of flavin adenine dinucleotide (FAD) in freshly excised human lens epithelium following cataract surgery, and in control eye bank lens epithelium. Large individual variations in activity were found in both groups. Out of 32 epithelia obtained from cataractous lenses, 14 showed no measurable GR activity. Activity in eight of these 14 epithelia was restored after FAD was added, implying that the apo-enzyme in these 8 epithelia was functional but FAD was not available. Another group of 8 active epithelia showed a significant increase in GR activity upon the addition of FAD, suggesting a mixed population of active enzyme and available fraction of apo-enzyme which was reactivated by the addition of FAD. Unusually high GR activities were observed in epithelia of several patients. This correlated principally with daily intake of thyroxine which is known to have a direct effect on the metabolism of riboflavin. The fact that in a significant number of cataract patients epithelial GR was not active, and the observation that activity could be restored by adding in vitro FAD, demands that more attention should be given to riboflavin nutritional status and FAD synthesis in the eye.

Cataract↗
PubMed1986

Chorioretinal juncture. Multiple extramacular drusen.

A clinicopathologic study of multiple extramacular drusen (MED) was performed on 784 eyes of 412 consecutive autopsies and on 100 eyes of 50 consecutive patients with MED. The clinical and histopathologic characteristics of MED and its correlation with reticular degeneration of the pigment epithelium (RDPE) and with macular degenerative abnormalities are presented. Multiple extramacular drusen was associated with macular degenerative abnormalities in 88% of autopsy cases, in contrast to 2% of cases in a control population without MED or RDPE. Multiple extramacular drusen and macular degenerative abnormalities are associated findings and apparently have similar pathogenetic mechanisms.

Adolescent↗
PubMed1986

Cataract surgery after expulsive choroidal hemorrhage in the fellow eye.

Expulsive choroidal hemorrhage (ECH) is a dramatic and serious complication of cataract surgery that occurred in four of 8,285 consecutive cataract operations performed at the Jules Stein Eye Institute from 1970 to 1983, an incidence of 0.05%. This report reviews six patients who had uncomplicated cataract surgery after an expulsive choroidal hemorrhage occurred during cataract operation in the fellow eye. Factors predisposing to ECH are considered, and recommendations to minimize the risk of this complication during preoperative, operative, and postoperative periods are presented.

Adult↗
PubMed1985

Fluorescein angiography in reticular degeneration of the pigment epithelium.

We studied reticular degeneration of the pigment epithelium by fluorescein angiography in 32 eyes of 50 consecutive patients who had ophthalmoscopic indications of this aging-related entity. In this type of degeneration, fluorescein angiography delineated extensive abnormalities of the retinal pigment epithelium and demonstrated normal-appearing retinal vessels and choriocapillaries in the affected areas.

Aged↗
PubMed1985

Methyl bromide optic atrophy.

A 32-year-old fumigation assistant developed systemic and neuro-ophthalmic manifestations of methyl bromide poisoning, including increased serum bromide level (6.6 mg/100 ml), paresthesias and burning dysesthesia on his hands and feet, and visual impairment. Ocular examination showed mild bilateral decrease in vision, temporal optic nerve head pallor, severely attenuated visual-evoked response amplitudes and normal latencies, a normal electroretinogram, an abnormal electrooculogram, and a severe deuteranomalous (green) defect on Farnsworth-Munsell 100-hue testing. His vision had not improved 12 months after the initial exposure.

Adult↗