Retinal signs in sickle cell anaemia.
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Adult↗
Biomedical subjects
M S Roy
Publications and source records attributed to M S Roy.
Posterior vitreous fluorophotometry. I. Description of a new analysis procedure and results in normal subjects.
A new automated analysis procedure was used to evaluate the apparent blood-retinal barrier permeability (mean +/- SD = 1.31 = 0.31 X 10(-7) cm/s at 60 minutes after intravenous dye administration) and the effective diffusivity (mean +/- SD = 0.88 +/- 0.40 X 10(-5) cm2/s) for fluorescein in the vitreous of 21 normal subjects. The analysis improvements include (1) use of an individualized convolution (spread) function for each eye in comparing simulated and experimental scans, (2) separation of vitreous and chorioretinal fluorescence, and (3) precise determination of vitreous position relative to the retina. The average reproducibility in six subjects was 23% for permeability and 22% for diffusivity based on repeated determinations separated in time by at least a week. Diffusivity values, but not permeability values, significantly associated in comparisons of first and second determinations, suggesting permeability may fluctuate in time while diffusivity remains relatively constant. The fluorescence at 3 mm anterior to the retina (commonly employed as a measure of blood-retinal barrier leakiness) was strongly associated with diffusivity. In contrast, the anticipated association between permeability and 3-mm fluorescence was weak or absent.
Adult↗
Posterior vitreous fluorophotometry. II. Comparison of diabetic patients and controls with the use of a new analysis procedure.
We used a new computerized procedure to analyze posterior vitreous fluorophotometry scans, obtained with a commercial fluorophotometer (Fluorotron Master Coherent, Palo Alto, Calif), in insulin-dependent diabetic patients and controls. Diabetic patients with minimal retinopathy had significantly higher effective fluorescein vitreous diffusivity and 30-minute 3-mm vitreous fluorescence values than either controls or diabetic patients with no retinopathy. However, there was no significant difference between the groups for the apparent permeability of the blood-retinal barrier to fluorescein. These results suggest the possibility that the higher 3-mm fluorescence levels found in the diabetic patients with minimal retinopathy may result in part from enhanced movement of fluorescein through the vitreous.
Adult↗
The electroretinogram in Stargardt's disease and fundus flavimaculatus.
A retrospective study was performed comparing the ERG results of 15 patients with Stargardt's disease and fundus flavimaculatus. Patients with fundus flavimaculatus had "fish-tail" lesions with or without macular changes, while the Stargardt's group had macular atrophy without fish-tail flecks. The mean visual acuity was 20/200 for the Stargardt's patients compared with a mean of 20/80 for the fundus flavimaculatus patients. The Stargardt's photopic and scotopic amplitudes were respectively 33% and 34% of normal, while the fundus flavimaculatus values were less impaired at 58% and 64% of normal.
Adolescent↗
Loss of heparan sulphate proteoglycan and retinal microinfarcts in diabetes mellitus.
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Blood Coagulation↗
Ocular blood flow in dogs using radiolabelled microspheres.
We used radioactive microspheres of different sizes to determine the rate of blood flow through the various parts of the eye in dogs. The use of either 15 +/- 5 microns or 25 +/- 5 microns microspheres gave reproducible measurements of total ocular and uveal blood flows. Using these sphere sizes, retinal flow was found to be close to 1% of the total ocular blood flow and showed poor reproducibility due in part to the small number of spheres trapped in the retinal vessels.
Animals↗
Nutritional factors in diabetics with and without retinopathy.
We used 3-d food-record-keeping techniques to examine nutritional factors in diabetic patients with and without retinopathy. Patients without retinopathy had significantly higher daily intakes of total carbohydrate, water-soluble dietary fibers, insoluble dietary fibers, and glucose than did patients with retinopathy. Also, patients without retinopathy took a significantly lower proportion of their total daily calories as protein.
Adult↗
Use of selective vasodilation in treatment of sickle cell disease.
Individuals with sickle cell disease and its genetic variants demonstrate a modest to severe hemolytic anemia. They are also prone to both acute and chronic vaso-occlusive phenomena, which may lead to irreversible tissue damage, organ failure, and premature death. To better understand these vaso-occlusive phenomena, it would be useful to determine the extent to which arteriolar microvascular obstruction might contribute to the pathogenesis of sickle cell disease. We studied the hematologic and ocular effects of orally administered nifedipine in several steady-state patients and compared these with a case-control group of patients not receiving nifedipine. In the nifedipine-treated patients, a striking reversal in ischemic retinal and conjunctival changes was observed, as well as a significant improvement in color vision performance. In addition, the treated subjects showed a slight but significant decline in the levels of both indirect serum bilirubin and plasma hemoglobin, suggesting a concurrent amelioration in the rate of hemolysis. These observations are consistent with the hypothesis that inappropriate vaso-constriction, or frank vasospasm, perhaps in response to the altered rheology of red cells containing polymerized hemoglobin S, may play an important role in the pathophysiology of sickle cell disease. Furthermore, selective vasodilation may prove to be a useful adjunctive approach to the treatment of the manifestations of the sickle syndromes.
Adult↗
Plasma fibrinopeptide A, beta-thromboglobulin, and platelet factor 4 in diabetic retinopathy.
We examined plasma levels of fibrinopeptide A, beta-thromboglobulin, and platelet factor 4 in diabetic patients. Among diabetic patients (n = 33) plasma levels of fibrinopeptide A, beta-thromboglobulin and platelet factor 4 were significantly higher than in controls (n = 41). In the subgroups of diabetic patients with (1) minimal (n = 13), and (2) moderate-severe (n = 14) retinopathy only plasma fibrinopeptide A levels were significantly higher than in controls. Among the total group of diabetic patients plasma levels of fibrinopeptide A increased significantly with increasing severity of retinopathy. These results suggest that diabetic retinopathy is associated with in vivo activation of blood coagulation factors and that this activation increases with advancing retinopathy.
Blood Platelets↗
Is there a role for selective vasodilation in the management of sickle cell disease?
To test the hypothesis that microvascular obstruction to blood flow at the level of the arteriole may be significant in individuals with sickle cell anemia, the ophthalmologic effects of orally administered nifedipine were monitored in 11 steady-state patients. Three patients with evidence of acute peripheral retinal arteriolar occlusion displayed a prompt reperfusion of the involved segment. Two other patients showed fading of retroequatorial red retinal lesions. Color vision performance was improved in six of the nine patients tested. The majority of patients also demonstrated a significant decrease in the amount of blanching of the conjunctiva which reflects improved blood flow to this frequently involved area. Such improvements were not observable in a control group of untreated stable sickle cell subjects. These findings support the hypothesis that inappropriate vasoconstriction or frank vasospasm may be a significant factor in the pathogenesis of the microvascular lesions of sickle cell disease and, further, that selective microvascular entrapment inhibition may offer an additional strategy to the management of this disorder. We believe a larger, placebo-controlled study with nifedipine and similar agents is warranted.
Adult↗
Color vision defects in sickle cell anemia.
The Farnsworth-Munsell 100-hue test was used to compare color vision in patients with sickle cell anemia, 20/20 visual acuity, and mild to severe peripheral retinopathy, but without posterior retinal vessel involvement, with matched normal controls. Patients with sickle cell anemia had significantly more blue-yellow and mixed color vision defects and significantly higher Farnsworth-Munsell 100-hue scores than did controls. There were no significant associations between color vision defects and the severity of peripheral retinal findings or the diameter of the foveal avascular zone. These results suggest that color vision defects may exist in patients with sickle cell anemia in the absence of ophthalmoscopic retinal changes in the posterior fundus.
Adult↗
Posterior vitreous fluorophotometry in diabetic patients with minimal or no retinopathy.
Vitreous fluorophotometry (VFP) using the Fluorotron Master was performed in 25 insulin-dependent diabetic patients with either minimal or no retinopathy and 22 controls. At 30 minutes, baseline corrected vitreous fluorescence values 3 mm from the retina were significantly greater in diabetic patients with minimal retinopathy than in either controls or patients with no retinopathy but were similar in patients with no retinopathy and controls. At 1 hour, vitreous fluorescence values and fluorescein permeability indexes were similar in all three groups. The absence of increased posterior vitreous fluorescein leakage in the diabetic patients with no retinopathy suggests that the alteration in permeability of the blood retinal barrier, as assessed by current VFP measures, does not precede the development of clinical diabetic retinopathy. However, the significantly increased 30-minute 3-mm fluorescence values suggest that posterior fluorescein leakage is increased in minimal background diabetic retinopathy.
Adult↗
Spontaneous resolution of idiopathic foveal subretinal neovascularization with preservation of vision.
A 40-year-old women with a 17-year-history of glaucomatocyclitic crises in 1 eye developed idiopathic foveal subretinal neovascularization in the other eye. The subretinal neovascular membrane spontaneously regressed over a 2-month period, and useful reading vision was subsequently maintained for more than 6 years. This favorable outcome is discussed in relation to the previously reported cases of idiopathic macular subretinal neovascularization.
Adult↗
Retroequatorial red retinal lesions in sickle cell anemia.
We report 2 patients with sickle cell anemia who showed retroequatorial localized red retinal lesions. In 1 patient these lesions were associated with closure of the retinal precapillary arteriole and capillary bed. In both patients these lesions receded during the course of therapy with a selective arteriolar vasodilator, nifedipine. These observations are discussed in relation to the possible pathogenesis of the retinopathy seen in patients with sickle cell anemia.
Adult↗
Color vision defects in early diabetic retinopathy.
Four color vision tests were used to assess color vision in 51 insulin-dependent diabetic patients and 41 normal controls. Right and left eyes of diabetic patients, selected because they had minimal retinopathy, had significantly more color vision defects than controls on Lanthony desaturated D-15, Farnsworth-Munsell 100-Hue, and chromagraph tests. The 100-Hue scores were significantly higher in both right and left eyes of diabetic patients than in controls. There were no significant associations between presence or absence of a color vision defect and age, sex, age at onset, duration of diabetes, or its metabolic control.
Adult↗
Temporary loss of foveal contrast sensitivity associated with panretinal photocoagulation.
Snellen visual acuity and spatial contrast sensitivity measurements were used to monitor changes in foveal vision in two patients undergoing argon laser panretinal photocoagulation (PRP) in both eyes for proliferative diabetic retinopathy. Foveal edema developed in one of the four eyes. The remaining three eyes showed no signs of foveal edema, but developed temporary losses in high spatial frequency contrast sensitivity during the closely spaced PRP treatments. Since Snellen visual acuity remained stable at the prelaser level, these results indicate the need for more sensitive measures of visual resolution to monitor foveal integrity in patients undergoing PRP.
Adult↗
Posterior vitreous fluorophotometry in normal subjects.
We performed vitreous fluorophotometry using the Fluorotron Master and intravenous fluorescein injection of 14 mg/kg of body weight in 22 normal subjects. Various methods of analysis were used to evaluate vitreous fluorescein concentration at 3 mm from the retina as well as averaged over the posterior 6 mm. The various methods of calculation yielded mean (+/- SD) postinjection values ranging from 1.7 +/- 1.4 to 4.3 +/- 2.3 ng/mL at 30 minutes and from 7.1 +/- 2.4 to 10.8 +/- 2.7 ng/mL at 60 minutes. The permeability index determined 60 minutes after injection ranged from 0.92 +/- 0.40 X 10(-7) to 1.19 +/- 0.30 X 10(-7) cm/s, according to the protocol used. Replicate pairs of measurements in six subjects demonstrated that the procedure was reproducible to within 17% to 49%, depending on the analysis. The results suggest that if the current methods of data analysis are used, fluorescein leakage might be considered abnormally high if at 60 minutes the 3-mm posterior vitreous fluorescein concentration corrected for background fluorescence exceeds 14.3 ng/mL and/or the permeability index exceeds 2 X 10(-7) cm/s.
Adult↗
Measurement of color thresholds.
It is generally believed that some degree of defective color vision is frequently acquired along with certain ocular and systemic disorders. Precise definition of the nature and extent of the color defects has not been possible because of the limitations inherent in the tests currently available for clinical use. We undertook to define the defects in terms of thresholds of discrimination to each color, plotted on a color circle similar to Munsell's uniform chromaticity scale diagram. Furthermore, we were able to construct a symmetrical-type of colorimeter which plots thresholds directly on a printed circle without having to read and interpret scales or dials. Good correlation of subtle defects with certain disorders was confirmed, and may eventually be helpful in diagnosing and following some types. This system of threshold measurement was found to provide more information about color vision than any one of the conventional tests, or all of them combined.
Adult↗