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Biomedical subjects

T Sharma

Publications and source records attributed to T Sharma.

At least 73 records · Page 4Linked to original sources
PubMed1999

Vitreoschisis in Eales' disease: pathogenic role and significance in surgery.

PURPOSE: To report the surgical anatomy of vitreoretinal adhesions as observed intraoperatively in patients undergoing vitreous surgery for complications of Eales' disease. METHODS: Eighteen consecutive male patients (18 eyes) undergoing vitrectomy for Eales' disease were studied prospectively. Intraoperative diagnosis was vitreous hemorrhage (VH) in nine cases, traction retinal detachment (TRD) in four, VH and TRD in three, and combined traction-rhegmatogenous retinal detachment in two. Epiretinal membranes (ERMs) obtained during surgery were studied using light microscopy and immunohistochemistry. RESULTS: An incomplete posterior vitreous detachment was observed in all eyes. Multifocal vitreoretinal adhesions were evident in 83.3% of eyes. The proliferation was fibrovascular in 10 eyes and fibrous in eight. A radial traction fold extending from optic disk to periphery was observed in three eyes. A double-layered membrane, probably the result of vitreoschisis, caused tangential traction. ERMs consisted principally of type II collagen and the cellular element was predominantly composed of lymphocytes, glial cells, and macrophage-like cells (probably hyalocytes). CONCLUSIONS: Fibrous and fibrovascular proliferations have multiple areas of adhesions to the posterior vitreous cortex. The presence of type II collagen in the ERM indicates a possible vitreous collagen component to the double-layered membranes (vitreoschisis). Recognition of the double-layered membranes aids in relief of traction during surgery by delamination.

Adult↗
PubMed1999

Normalization of information processing deficits in schizophrenia with clozapine.

OBJECTIVE: The authors tested the hypothesis that the use of an atypical drug, clozapine, for patients with schizophrenia is related to less impairment in information processing deficits (assessed by prepulse inhibition of the startle response) than is the use of typical antipsychotics. METHOD: Two groups of schizophrenic patients--receiving either clozapine or a range of typical antipsychotics--were tested for prepulse inhibition (a reduction in response to a starting stimulus, if preceded briefly by a weak, nonstartling stimulus; measured at prepulse-to-pulse intervals of 30 msec, 60 msec, and 120 msec) of the acoustic startle response and compared with a group of healthy volunteers. RESULTS: Patients receiving typical antipsychotics showed less prepulse inhibition with 30-msec and 60-msec prepulse trials than did comparison subjects. Clozapine-treated patients showed normal levels of prepulse inhibition. CONCLUSIONS: Clozapine is superior to typical antipsychotics in normalizing prepulse inhibition, presumably because of its pharmacological effects on prefrontal regions of the brain or its effects on a broader range of neuroreceptors.

Acoustic Stimulation↗
PubMed1999

No evidence for left superior temporal dysfunction in asymptomatic schizophrenia and bipolar disorder. PET study of verbal fluency.

BACKGROUND: Positron emission tomography (PET) studies have revealed functional left superior temporal gyrus (STG) abnormalities in symptomatic schizophrenia during word generation. AIMS: To discover if this dysfunction is present in asymptomatic schizophrenia. To determine whether, without concurrent symptomatology, schizophrenia and bipolar affective disorder (BPD) are distinguishable by differing regional cerebral blood flow (rCBF) patterns during word generation. METHOD: A PET verbal fluency protocol was applied to six patients with BPD in remission and six patients with asymptomatic schizophrenia. Analysis included 10 control subjects from a contemporaneous study. RESULTS: All groups showed relative reduction of rCBF in both superior temporal cortices. There were no quantitative differences in any group comparison. All groups exhibited negative covariation between rCBF in left prefrontal and right (but not left) temporal regions. CONCLUSIONS: Abnormal patterns of left STG function cannot be regarded as a trait marker for schizophrenia. Functional abnormalities may reflect aspects of mental state.

Adult↗
PubMed1999

A rural population based case-control study of senile cataract in India.

PURPOSE: Senile cataract contributes to 75% of blindness in India and there is a growing backlog of cataract cases needing surgery. The present study seeks clues to the etiology of senile cataract, so that strategies to prevent or even delay cataract formation could be planned. METHODS: Using a community based case-control design, 258 cases & 308 controls from one centre and 301 cases & 591 controls from another were studied. The subjects were from rural areas and were aged 40-60 years. Logistic regression analysis technique was employed to study the associations between senile cataract and various variables. RESULTS: Systolic blood pressure, duration of exposure to sunlight per day were associated with senile cataract in both the centres (OR = 1.4 & 1.5 for systolic BP and 1.6 & 1.4 for exposure to sunlight). Utilization of rice gruel (OR = 0.5), duration of exposure to fire & dust per day (OR = 1.8), family history of cataract (OR = 5.0), use of cheap cooking fuels (OR = 1.8), increased height (OR = 0.7) and increased number of hours of work per day (OR = 0.7) were other variables that showed significant association in either of the centres. CONCLUSION: Senile cataract appears to have a multi factorial etiology. Though the study provided some clues to the etiology of senile cataract, further studies are needed to know the specific role of these factors in the causation of cataract, so that any preventive or control measures could be initiated in the community. Till such time, we have to fall back on the available surgical approach in control of senile cataract.

Adult↗
PubMed1999

Functional MR imaging of confounded hypofrontality.

Comparatively reduced blood flow to frontal brain regions in patients with schizophrenia (hypofrontality) has been frequently observed in the last 25 years. However, there is an inconstant quality to hypofrontality, suggesting either confounded observation of a static (trait-like) abnormality, or that it is a genuinely dynamic (state-like) phenomenon. Possible confounds in functional magnetic resonance imaging (fMRI) studies of hypofrontality are classified. Methods for assessment and correction of stimulus correlated motion (an extracerebral confound) are reviewed in the context of fMRI data acquired from five schizophrenic patients and five comparison subjects during performance of a verbal fluency task. Factorial analysis of these and other data, acquired from the same subjects during a semantic decision task, is used to exclude a number of possible intracerebral confounds. By analogy to the historical controversy concerning the appearance of the planet Saturn viewed through early telescopes, understanding the inconstancy of hypofrontality in schizophrenia is likely to progress more by theoretically driven experiments that exploit the repeatability of fMRI than by further technological development alone.

Analysis of Variance↗
PubMed1999

pH-adjusted periocular anaesthesia for primary vitreoretinal surgery.

PURPOSE: To evaluate the efficacy of pH-adjusted bupivacaine in conjunction with medial orbital periconal block (periocular anaesthesia). METHODS: Sixty consecutive patients undergoing primary vitreoretinal surgery were enrolled prospectively. RESULTS: Adequate anaesthesia and akinesia with no intraoperative supplementation was achieved in 53 eyes (88.3%). Factors influencing intraoperative supplementation were combined vitrectomy with scleral buckling (p = 0.005) and duration of surgery of more than 2 hours (p = 0.001). No ocular or systemic complication resulted. CONCLUSION: pH-adjusted periocular anaesthesia is safe and effective in patients undergoing primary vitreoretinal surgery.

Adult↗
PubMed1999

Methods for diagnosis and treatment of stimulus-correlated motion in generic brain activation studies using fMRI.

Movement-related effects in realigned fMRI timeseries can be corrected by regression on linear functions of estimated positional displacements of an individual subject's head during image acquisition. However, this entails biased (under)estimation of the experimental effect whenever subject motion is not independent of the experimental input function. Methods for diagnosing such stimulus-correlated motion (SCM) are illustrated by application to fMRI data acquired from 5 schizophrenics and 5 normal controls during periodic performance of a verbal fluency task. The schizophrenic group data were more severely affected by SCM than the control group data. Analysis of covariance (ANCOVA) was used, with a voxelwise measure of SCM as a covariate, to estimate between-group differences in power of periodic signal change while controlling for variability in SCM across groups. Failure to control for SCM in this way substantially exaggerated the number of voxels, apparently demonstrating a between-group difference in task response.

Adult↗
PubMed1998

Primary vitrectomy for rhegmatogenous retinal detachment associated with choroidal detachment.

OBJECTIVE: This study aimed to report the success rate of primary vitrectomy, scleral buckling, and oral steroids in eyes with combined rhegmatogenous retinal detachment (RRD) and choroidal detachment (CD) and to compare these results with those reported in the literature for similar cases managed by scleral buckling alone. DESIGN: Consecutive case series. PARTICIPANTS: Twenty-one eyes of 21 consecutive patients with primary RRD associated with CD were examined. INTERVENTION: All patients were treated with systemic corticosteroids before surgery. Pars plana vitrectomy with scleral buckling or encircling or both were performed. MAIN OUTCOME MEASURES: Retinal reattachment rate and resolution of choroidal detachment were measured. RESULTS: At mean follow-up of 11.4 months, retinal reattachment was attained in 19 eyes (90.5%) compared to less than 53% reported in the literature for scleral buckling alone. With preoperative oral steroids, choroidal detachment regressed completely in 13 eyes (61.9%). In the remaining eyes with persistent choroidal detachment, suprachoroidal fluid was drained during vitrectomy. CONCLUSION: Aggressive treatment with oral steroids followed by pars plana vitrectomy and scleral buckling or encircling is recommended instead of scleral buckling alone in the management of combined primary rhegmatogenous retinal detachment and choroidal detachment.

Administration, Oral↗
PubMed1998

Surgical management of retinal detachments related to coloboma of the choroid.

OBJECTIVE: This study aimed to develop a rationale for the management of retinal detachments related to choroidal coloboma and to study the outcome of their management. DESIGN: The study design was a retrospective study. PARTICIPANTS: A total of 85 eyes of 81 patients with retinal detachments related to coloboma of the choroid participated. INTERVENTION: All eyes underwent pars plana vitrectomy with internal tamponade using silicone oil (80 eyes) or perfluropropane gas (5 eyes). Behavior of the retina on fluid-air exchange was used to guide the further steps of surgery. Endolaser was performed along the coloboma border. Silicone oil was removed in 80% of eyes. The main outcome measures were retinal reattachment and visual recovery. RESULTS: Recurrent retinal detachment occurred in 16.3% of silicone oil-filled eyes and 60% of gas-filled eyes. After silicone oil removal, 15.6% of eyes had recurrent retinal detachment. After a mean follow-up of 13.4 months, 81.2% of eyes had attached retina and 69.4% recovered equal to or better than 10/200 visual acuity. CONCLUSION: Retinal detachment secondary to coloboma of choroid is treated best by pars plana vitrectomy along with silicone oil tamponade. Gas tamponade has limited indications. Clinical evaluation of the extent of retinal detachment within the colobomatous area and the behavior of the retina on fluid-air exchange help the authors understand the pathogenesis of the retinal detachment and plan a rational therapy.

Adolescent↗
PubMed1998

Long term visual results of vitrectomy for Eales disease complications.

BACKGROUND AND OBJECTIVES: Complications of Eales disease can cause visual loss. Long term visual prognosis following vitrectomy for Eales disease complications has been studied. PATIENTS AND METHODS: Retrospective analysis of 64 eyes of 57 patients who underwent vitrectomy for Eales disease complications with a minimum follow-up of 60 months. RESULTS: 62.4% eyes at 2 months and 71.8% at 60 months had 6/60 or better visual acuity. Visual acuities for individual cases were quite stable at the 60 month follow up with 50 eyes (78.5%) either maintaining or improving upon their 2 month post operative visual acuity. CONCLUSION: Visual acuity improves after vitrectomy in majority of patients with Eales disease complications and remains stable on long term follow-up.

Adolescent↗
PubMed1998

Intraoperative mitomycin C and the corneal endothelium.

PURPOSE: Mitomycin-C (MMC) is a useful adjunct to high risk glaucoma surgery. No clinical data regarding the deleterious effect of mitomycin-C on the corneal endothelial cells are available. METHODS: Thirty eyes of 28 adult patients with high risk glaucomas were randomized to three groups. Group-I underwent a trabeculectomy alone, Group II, trabeculectomy with intraoperative 0.2mg/ml MMC and Group III, trabeculectomy with intraoperative 0.4mg/ml MMC. Preoperative and 3-month postoperative corneal endothelial cell counts were analysed. RESULTS: The percentage cell loss in Group I was 3.73+/-2.73%, in Group II 13.90+/-4.69% and in Group III 14.52+/-7.8%. Statistical analysis revealed a significant difference in cell loss between Group I and Group II and Group I and Group III, but not between Group II and Group III. CONCLUSION: There is a significant loss of corneal endothelial cells three months after trabeculectomy with adjunctive MMC.

Adult↗
PubMed1998

The cognitive efficacy of atypical antipsychotics in schizophrenia.

Cognitive dysfunction, a symptom of schizophrenia, has been recently identified as an important measure of outcome in the treatment of this disorder. Drug-mediated symptom improvement, the traditional measure of treatment success for schizophrenia, typically fails to associate with modifications of cognitive dysfunction, resulting in a failure of the patient to reintegrate into society. A paradigm shift is now required in the conceptualization of treatment success away from symptom decrement and towards treatments that improve cognitive function. Clozapine treatment has been shown to provide a significantly greater improvement in several domains of cognitive function, especially attention and verbal fluency, compared with conventional neuroleptics, whereas risperidone appears to have a beneficial effect on working memory. These results may be because of the normalization of dopamine function by clozapine and antagonism of 5HT2 receptors.

Antipsychotic Agents↗
PubMed1998

Subretinal fibrosis and nonrhegmatogenous retinal detachment associated with multifocal central serous chorioretinopathy.

PURPOSE: To report the rare occurrence of subretinal fibrosis in patients with multifocal central serous chorioretinopathy and evaluate the role of systemic corticosteroids and the effects of laser photocoagulation on multifocal leaks. METHODS: A total of 29 patients (mean age, 37.7 years; 89.7% male) treated for subretinal fibrosis and multifocal central serous chorioretinopathy from 1983-1995 were reviewed retrospectively. Mean follow up was 26 months (range, 6.8-81 months). RESULTS: Retinal detachment involved the macula in 72.4% cases. Fluorescein angiography showed a mean of 6.7 (range, 2-22) central serous chorioretinopathy leaks and a mean of 1.8 (range, 1-5) retinal pigment epithelial detachments. The fundus pictures of 23 patients who were taking systemic corticosteroids showed no improvement. Following laser treatment, however, retinal reattachment was obtained in all eyes, and improvement in visual acuity of > 2 Snellen lines was noted in 68.9% of patients. CONCLUSIONS: The presence of subretinal fibrosis with secondary retinal detachment in otherwise healthy young patients, particularly in men, should alert the physician to look for multifocal central serous retinopathy leaks. Systemic corticosteroids did not prove effective in treating these patients, although laser treatment is recommended for each leak identified on an angiogram.

Adult↗
PubMed1998

Management of glass intraocular foreign bodies.

PURPOSE: To describe the results of management of glass intraocular foreign bodies (IOFBs). METHODS: A total of 51 eyes of 43 patients that sustained penetrating injury with glass IOFB were studied retrospectively. A total of 23.5% had IOFB only in the anterior segment; the rest had IOFB in the posterior segment alone or in both the anterior and posterior segments. Six eyes were followed conservatively despite IOFB in a functional eye. Removal of IOFB was combined with repair of retinal detachment (where present) using internal tamponade with gas or silicone oil or buckle. RESULTS: After a mean follow-up of 16.8 months, 66.7% of eyes recovered better than 6/60 (20/200) vision and 75.6% had attached retina. On univariate analysis, scleral entry wound, posterior segment IOFB, larger size of IOFB, and retinal damage were found to be associated with poor anatomic outcome. Lower presenting visual acuity, hyphema, retinal damage, subretinal hemorrhage, detached retina, and larger IOFB were associated with a poor functional result. Multivariate analysis identified retinal damage caused by the foreign body as the only factor significantly associated with poor anatomic as well as functional outcome. CONCLUSIONS: Glass IOFBs are caused in a majority of cases by blast injury. Bilaterality is not uncommon. Presence of retinal damage is predictive of poor functional and anatomic results. Overall results are modest with modern vitreoretinal surgical techniques.

Adult↗