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Biomedical subjects

R Varma

Publications and source records attributed to R Varma.

At least 37 records · Page 2Linked to original sources
PubMed1988

Variability in digital analysis of optic disc topography.

We determined the magnitude of variability in optic disc topographical parameters on digital analysis of the optic disc using the IS 2000. The variability introduced by the system, the observer, the observer and patient, and by clinically different types of discs was assessed in the measurement of the vertical cup-to-disc ratio, horizontal cup-to-disc ratio, cup area-to-disc area, cup volume, neuroretinal rim area, and neuroretinal rim area-to-disc area. The system itself accounted for no variability. The variability introduced by one observer for the parameters ranged from 1% to 7%, and by one observer and patient from 1% to 28%. The variation among five observers ranged from 1% to 55%. Direct image acquisition (using video cameras) gave results that were no different from those obtained by digitizing the slides. Contrast-enhancement techniques did not decrease observer variability. A change in the flash intensity level at which optic disc images were acquired from 94.5 to 15.0 Watt-seconds introduced a variability of 3% to 21%. These results are less variable than those obtained on clinical observation and comparable to those of the Rodenstock image analyzer in evaluating these aspects of optic disc topography.

Adult↗
PubMed1988

Surgical therapy of chronic glaucoma in aphakia and pseudophakia.

Most glaucoma surgical procedures are less successful in aphakic or pseudophakic eyes. The authors reviewed 91 consecutive initial glaucoma procedures in aphakic patients from 1979 to 1986 to determine successful outcomes and complications. Success was defined as an intraocular pressure (IOP) of at least 30% below the preoperative value and less than 21 mmHg, less than 2 lines of Snellen acuity loss, and no further surgical intervention. At 9 months, success rates were: trabeculectomy, 4 of 15 patients; cyclodialysis, 3 of 20 patients; neodymium:YAG (Nd:YAG) cyclophotocoagulation, 1 of 8 patients; cyclocryotherapy, 9 of 22 patients; anterior chamber tube shunt (Schocket procedure), 3 of 6 patients; and argon laser trabeculoplasty, 2 of 20 patients. Severe complications included phthisis bulbi in 11% of cyclocryotherapy and severe visual loss in 20% with cyclodialysis and 14% with cyclocryotherapy. Results confirm the difficulty of surgical therapy in these patients.

Aged↗
PubMed1988

The PAR IS 2000: a new system for retinal digital image analysis.

We describe the PAR IS 2000, a new system of digital image analysis of the optic disc. The system uses a simultaneous stereoscopic camera and a video camera to acquire images directly from the optic disc and from optic disc photographs, respectively. The image data are stored on an optical laser disk capable of handling large amounts of data (4000 monochrome images/disk). These images can be analyzed using a modified digital interactive mapping program to generate stereometric parameters, contour maps, section profiles, pallor maps, depth maps, and three-dimensional topographic plots of the retina. A skeletonizing program permits determination and measurement of shifts in the position of retinal vessels. The system's wide range of capabilities may be helpful in improving patient care and ophthalmic research.

Computers↗
PubMed1987

Positional changes in the vasculature of the optic disk in glaucoma.

We analyzed 34 sets of optic disk photographs from 19 patients with glaucoma who had been followed up for ten years to evaluate changes in the position of the vasculature of the optic disks over time. Each photograph was analyzed by an image analyzer's edge-defining program for optic disk analysis and by three experienced clinicians. Image analysis of the blood vessels in 16 optic disks showed positional centrifugal shifts. The clinicians consistently noted changes in the appearance of seven optic disks. The difference between the results obtained using the image analyzer and those obtained by clinical observation was significant (P less than .05).

Adult↗
PubMed1986

Vitamin C in the human aqueous humor and cataracts.

Blood, aqueous humor and cataracts obtained from an Indian population were analyzed for ascorbic acid content. While the concentrations of ascorbic acid in the blood and cataracts were similar in patients with cortical and nuclear cataracts, the level of this nutrient was lower in the aqueous humor of patients with cortical cataracts. This suggests a sluggish transport of ascorbate from the blood to the aqueous humor in the latter group. It is possible that this lower level of ascorbate might be one of the factors participating in cataractogenesis. The lower aqueous ascorbate in the group with the cortical cataracts could not be accounted for by any dietary deficiency of this nutrient. Hence, it appears metabolically related.

Age Factors↗
PubMed1979

Simple gas-chromatographic measurement of valproic acid in psychiatric patients: effect on levels of other simultaneously administered anticonvulsants.

A simple, rapid and precise gas-chromatographic procedure which involves one-step extraction and on-column methylation for routine clinical monitoring of plasma valproic acid levels is described. Six other commonly, simultaneously administered anticonvulsants can also be determined by substituting methylene chloride for chloroform for extraction and changing the column temperature. Also, described is the effect of valproic acid on blood levels of other simultaneously administered anticonvulsants.

Adult↗
PubMed1979

Serum and mucopolysaccharide (glycosaminoglycans) levels in psychiatric patients.

Serum acid glycosaminoglycans (GAG) levels were measured in 50 normals and 177 samples from different types of psychiatric patients. Mean levels were significantly higher in paranoid type schizophrenia, organic brain syndrome associated psychosis and manic type manic-depressive psychosis. The levels returned to slightly above the normal range upon partial remission in paranoid schizophrenics. In catatonic and hebephrenic schizophrenias the values were in the upper part of normal range. The levels were either in upper normal range or slightly higher in non-psychotic organic brain syndrome. In depressed type manic depressive psychosis levels were either lower than normal or in the lower part of normal range.

Adolescent↗