Biomedical subjects
Radhika Tandon
Publications and source records attributed to Radhika Tandon.
Pyruvate modulates antioxidant status of cultured human lens epithelial cells under hypergalactosemic conditions.
Lens epithelial cells are the metabolic unit of the lens and antioxidant enzymes are mainly concentrated here. The purpose of this study was to maintain human lens epithelial cells (HLEC) in culture and examine the status of antioxidant enzymes (glutathione peroxidase (GSHPx), catalase (CAT), glutathione-S-transferase (GST)), lipid peroxidation product malondialdehyde (MDA) and glutathione (GSH) levels in these cells under normal as well as hypergalactosemic (30 mM galactose) conditions. Further, effect of pyruvate, a physiological antioxidant has also been evaluated on these parameters. For conducting experiments, anterior capsule specimens obtained from fresh cadaver eyes from eye bank were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 20% fetal calf serum. Upon confluency, the cells were subcultured in three separate flasks containing DMEM alone (normal group), DMEM + 30 mM D-galactose (control group), DMEM + 30 mM D-galactose + 5 mM pyruvate (test group) and incubated for 24 or 72 h. These cells were observed under the phase contrast microscope for any morphological changes and harvested for the estimation of various antioxidant parameters. Our results show significant weakened antioxidant defense in HLEC when incubated in the presence of galactose as compared to normal. Addition of pyruvate significantly modulated levels of GSH, MDA, GSHPx, CAT and GST.
A study of the indications and changing trends of evisceration in north India.
AIM: To study the demographic pattern and indications for evisceration in north India and to evaluate the changing trends over the last decade. METHODS: In a retrospective hospital-based study, case records of all patients who underwent evisceration at Rajendra Prasad Centre for Ophthalmic Sciences from January 1990 to December 1999 were reviewed. The parameters evaluated were the age and sex distribution, the place of residence (urban/rural) and the indications for evisceration. The aetiology responsible for evisceration was determined on the basis of history, clinical examination and investigations as determined from previous records. RESULTS: One hundred and sixty-four patients had one eye eviscerated during the study period. The mean age of the patients was 51 +/- 13.84 years (range 6 months to 90 years). Panophthalmitis was the most common indication for evisceration (78.6%, n = 129), followed by irreparable globe injury (21.3%, n = 35). There was a significant decrease in the eviscerations performed due to pano-phthalmitis from 104 cases during the period 1990-1994, to 25 cases in the period 1995-1999. CONCLUSION: Panophthalmitis and severe ocular injury are the major indications of evisceration in north India. There has been a significant decrease in the number of eviscerations related to panophthalmitis over the last decade.
Case series of 12 children with progressive axial myopia following unilateral cataract extraction.
PURPOSE: We report the occurrence of unilateral progressive axial myopia ipsilaterally in a retrospective analysis of 12 children following uniocular cataract surgery. METHODS: A retrospective analysis of the case records of children who had developed progressive ipsilateral axial myopia following unilateral cataract surgery was done. Follow-up ranged from 4 years to 14 years. RESULTS: Twelve children, 7 male and 5 female, were eligible for the study. Mean age at the time of cataract surgery was 6.7 +/- 2.5 years (range, 4-11 years) and follow-up period was 7.8 +/- 3.1 years (range, 4-14 years). Ten children (83.3%) had traumatic cataracts of which 8 had undergone repair of penetrating eye injuries and 2 had suffered blunt trauma. Two patients (16.7%)had been operated for unilateral developmental cataracts. Three children had aphakia and nine had pseudophakia. Degree of myopic shift ranged from -4.75 D to -15 D (mean, -7.35 +/- 3.51 D). Axial length difference between the 2 eyes ranged from 1 mm to 3.5 mm (mean, 2.2 +/- 0.9 mm). Mean increase of axial length from preoperative recording to final follow-up was 2.53 +/- 0.90 mm (range, 1.6-4 mm). Three children had to undergo IOL explantation and 1 had posterior chamber intraocular lens exchange due to high unilateral myopia. The rest were visually rehabilitated with either spectacles or contact lenses. CONCLUSION: Following cataract surgery pediatric eyes may suffer from progressive axial myopia. Trauma or multiple ocular surgeries may be predisposing factors.
Levodopa-carbidopa with occlusion in older children with amblyopia.
PURPOSE: To study the role of levodopa-carbidopa in supplementing occlusion therapy in older children with strabismic or anisometropic amblyopia. METHODS: A clinical study was performed on 40 amblyopic children (19 strabismic and 21 anisometropic), 6 to 18 years old (mean age, 10.9 years). They received an average dose of 1.86 mg/kg/day (1.33-2.36 mg/kg/day) of levodopa and carbidopa (4:1 ratio) or a placebo in 3 divided doses over a 4-week period, combined with full-time occlusion. The occlusion was continued for the study duration of 3 months. Early Treatment Diabetic Retinopathy Study visual acuity charts and Cambridge low-contrast gratings for contrast sensitivity (CS) were used to assess visual functions. Tolerance and compliance with occlusion and capsule consumption were assessed. RESULTS: Visual acuity of the nonamblyopic eye did not deteriorate during the study in either group. CS decreased by 22 units in the levodopa group and increased in the placebo group by 53 units at the first month. The CS in the levodopa group recovered later by the third month of follow-up. Both the levodopa and the placebo groups showed significant improvement in visual function in the amblyopic eye (P <.001). Overall changes in logarithm of minimum angle of resolution values and CS in the amblyopic eyes were similar in both groups (P >.05). Strabismic and anisometropic amblyopes did not behave differently. Drug tolerance, occlusion compliance, and capsule ingestion compliance were similar between the groups, with no significant side effects. CONCLUSIONS: Clinically, levodopa supplementation does not offer any advantage over occlusion alone. Moreover, the risk of occlusion amblyopia could increase with the use of drugs like levodopa that might affect the plasticity of the visual cortex.
Tectonic grafts for corneal thinning and perforations.
PURPOSE: To evaluate the success of tectonic grafts in cases of corneal thinning and perforations. METHODS: We performed 42 tectonic grafts in 41 eyes of 40 patients. Three types of tectonic grafts were used in our treatment protocol. These were (a) full-thickness grafts, (b) mushroom grafts, and (c) lamellar grafts. The parameters evaluated were indications, visual acuity, location, size and type of graft, postoperative outcome, and complications, if any. RESULTS: The most common indication for tectonic grafts was corneal thinning and perforation subsequent to infection (12 eyes) followed by those due to immunologic causes (six eyes) and trauma (six eyes). Twenty-four full-thickness tectonic grafts, nine mushroom grafts, and nine lamellar patch grafts were performed. Anatomical success was achieved in 35 of 41 (85.4%) eyes. Visual acuity of 6/24 or better was obtained in 29 of 41 (70.73%) eyes. The mean of best-corrected visual acuity (expressed in decimal) improved from 0.2 +/- 0.26 to 0.34 +/- 0.26 at an average follow-up of 10.83 +/- 6.27 months. The major complications were peripheral anterior synechiae in four eyes (9.76%) and graft melting in five eyes (12.2%). CONCLUSIONS: Tectonic graft is a useful therapeutic option in selected cases of corneal thinning and perforations because it effectively restores the integrity of the eye and allows acceptable visual rehabilitation.
Laser in-situ keratomileusis after penetrating keratoplasty.
Laser in situ keratomileusis (LASIK) after penetrating keratoplasty has been used more commonly for the correction of myopia or myopic astigmatism and less so for hypermetropia or hyperopic astigmatism. The primary goal after LASIK in such cases is resolution of sufficient myopia and astigmatism to allow spectacle correction of the residual refractive error and decrease anisometropia. All sutures should be removed prior to LASIK and the interval between penetrating keratoplasty and LASIK should be a minimum of 1 year. Preoperative evaluation includes refraction, slit-lamp biomicroscopy, corneal topography, and specular microscopy. The technique of LASIK surgery after penetrating keratoplasty is similar to the standard procedure. However, many variations have been described. These include maneuvers during surgery such as augmentation with arcuate cuts on the stromal bed and topographically guided LASIK. Other variations are relaxing incisions followed by LASIK surgery and sequential treatment by LASIK, that is, raising of the flap as a first stage procedure followed by ablation if required, 4 to 6 weeks later after relifting the flap in the second stage. Improvement in both uncorrected visual acuity and spectacle-corrected visual acuity, as well as a decrease in spherical equivalent, cylinder, and anisometropia, has been reported in various studies. All grafts were clear and no occurrence of wound dehiscence has been reported. Intraoperative complications include hemorrhage, microkeratome failure, flap buttonhole, dislocation, and perforation. Postoperative complications include undercorrection, decentered ablation, and regression. Re-enhancements after LASIK following keratoplasty are possible with acceptable visual outcome.
The osteo-odonto-keratoprosthesis (OOKP).
The osteo-odonto-keratoprosthesis (OOKP), although described over 40 years ago, remains the keratoprosthesis of choice for end-stage corneal blindness not amenable to penetrating keratoplasty. It is particularly resilient to a hostile environment such as the dry keratinized eye resulting from severe Stevens-Johnson syndrome, ocular cicatricial pemphigoid, trachoma, and chemical injury. Its rigid optical cylinder gives excellent image resolution and quality. The desirable properties of the theoretical ideal keratoprosthesis is described. The indications, contraindications, and patient assessment (eye, tooth, buccal mucosa, psychology) for OOKP surgery are described. The surgical and anaesthetic techniques are described. Follow-up is life-long in order to detect and treat complications, which include oral, oculoplastic, glaucoma, vitreo-retinal complications and extrusion of the device. Resorption of the osteo-odonto-lamina is responsible for extrusion, and this is more pronounced in tooth allografts. Regular imaging with spiral-CT or electron beam tomography can help detect bone and dentine loss. The optical cylinder design is discussed. Preliminary work towards the development of a synthetic OOKP analogue is described. Finally, we describe how to set up an OOKP national referral center.
Pyruvate inhibits galactosemic changes in cultured cat lens epithelial cells.
An attempt was made to maintain cat lens epithelial cells (CLEC) in culture and study the morphology, growth and survival of these cells in vitro. The influence of incorporation of galactose (30 mM) into the culture medium on the morphology and biochemistry of CLEC in the primary culture was then investigated. To establish the effect of galactose on CLEC, various biochemical parameters associated with galactosemic cataract such as aldose reductase (AR), Na+K+ATPase, glutathione, polyol and soluble/insoluble proteins were estimated after 24 h of incubation. The effect of pyruvate (5 mM), a 'physiological antioxidant', on the changes induced by galactose in CLEC was studied. CLEC in culture showed regular hexagonal cells with prominent nuclei. The CLEC culture attained confluency in 11 days during primary culture and semiconfluency in 14 days in two subsequent passages. Vacuolization and significantly raised AR activity, polyol levels and insoluble protein contents were observed; they had no effect on Na+K+ATPase and soluble protein after 24 h of incubation in the culture medium with galactose. Supplementation of pyruvate (5 mM) resulted in a lesser number of vacuoles together with a positive modulation of these parameters.
Subclinically dry eyes in urban Delhi: an impact of air pollution?
PURPOSE: To study the effects of air pollution on the eyes of persons staying in the metropolis of New Delhi. MATERIALS AND METHODS: 400 healthy volunteers from within and outside the metropolis of Delhi were investigated for the presence of tear film abnormalities. All persons underwent slitlamp examination to rule out any ocular surface disorder. The tear break-up time (BUT) was assessed along with a Schirmer test and the tear lysozyme activity and the tear pH were determined. RESULTS: Of the 210 persons staying in the metropolis, 50 (24%) had an abnormal BUT, 14 (6.6%) had an abnormal Schirmer test, and the tear lysozyme activity was found to be low in 12 (5%). In contrast, of those 190 persons living outside the metropolis, only 10 (5.2%) had an abnormal BUT, 4 (2%) had an abnormal Schirmer test, and none had a low lysozyme activity (p < 0.05). None of the persons in either group had significant eye symptoms. CONCLUSIONS: Tear film abnormalities are present in a large number of people staying within the metropolis of New Delhi who have apparently normal eyes. Air pollution over a long period of time could possibly be associated with their causation.
Study of the psychosocial aspects of strabismus.
PURPOSE: To systematically evaluate the perception of psychosocial difficulties due to strabismus and the impact of corrective surgery in adolescents and young adults in India. METHODS: Patients 15 to 25 years of age with childhood onset (< or = 5 years of age) of constant concomitant squint (> or = 30 prism diopters of deviation for distance) were included in the study. After a detailed orthoptic evaluation, demographic data of the patients and their parents were recorded. Postgraduate Institute Health Questionnaire N-2 (standardized in India) was administered to rule out neuroticism in the patients. Psychosocial problems faced by the patients were evaluated with a semistructured interview schedule. Patients were evaluated 3 months after surgery using a similar interview schedule to assess the psychological impact of surgery. RESULTS: Eighty percent of both male and female patients had problems in their social life; 85% of the males and 75% of the females had personal problems due to squint. After surgery, a positive change in appearance was noticed by 97.5% and 95% noticed a change in self-esteem and self-confidence. CONCLUSION: These patients had difficulties with self-image and interpersonal relationships, faced ridicule at school and work, and generally avoided activities that brought attention to their defect. Substantial changes were noticed in them after corrective surgery, and the differences in their scores before and after surgery were statistically significant.
Unilateral versus bilateral patching: management of a post-keratoplasty epithelial defect in a case of congenital hereditary endothelial dystrophy with manifest latent nystagmus.
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Outcomes after laser in situ keratomileusis retreatment in high myopes.
PURPOSE: To evaluate the refractive and visual performance after laser in situ keratomileusis (LASIK) retreatment. METHODS: A retrospective study was performed on 33 eyes of 23 patients who underwent LASIK (Bausch & Lomb Technolas 217C) retreatment for residual myopia with or without astigmatism. Parameters evaluated were uncorrected and best spectacle-corrected visual acuity, spherical equivalent refraction, contrast sensitivity, glare acuity, and pachymetry, preoperatively and at 1, 3, and 6 months postoperatively. RESULTS: The mean spherical equivalent refraction before primary LASIK was -9.89 +/- 4.00 D and before retreatment was -2.85 +/- 2.17 D. Although contrast sensitivity and glare acuity decreased significantly after primary LASIK (P<.05), no significant change in these parameters was observed after retreatment. Smaller ablation zones were associated with decreased contrast sensitivity and glare acuity after primary LASIK as well as following retreatment. Contrast sensitivity and glare acuity following primary LASIK were significantly better in eyes with ablation zones > or = 5 mm than those with < 5 mm (P<.05). Eyes in which the ablation zone was the same as that for primary LASIK had significantly better contrast sensitivity than those with different ablation zones (increased or decreased) during retreatment. Attempted refractive correction during primary LASIK and retreatment had a significant negative correlation with contrast sensitivity and glare acuity following primary LASIK as well as retreatment. CONCLUSION: The ablation zones following primary LASIK and retreatment should be > or = 5.00 mm and remain unchanged to improve visual performance.
Central corneal thickness in Indian patients undergoing LASIK for myopia.
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