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G K Vemuganti

Publications and source records attributed to G K Vemuganti.

At least 19 recordsLinked to original sources
PubMed2006

A comparative study of epiretinal membranes associated with Eales' disease: a clinicopathologic evaluation.

AIM: To study the histopathologic features and clinical correlation of epiretinal membranes (ERM) obtained from patients of Eales' disease and compare with other vasoproliferative disorders. METHODS: Retrospective analysis of epiretinal membranes submitted for histological evaluation between January 1995 and June 2001, from the patients of diabetic retinopathy and vascular occlusions (Group 1; vaso-occlusive disorders) and of Eales' disease (Group 2; vasoinflammatory disorders). Demographics, pre and postoperative visual acuity, and anatomic and histologic characteristics of membranes were studied. Histopathologic features and clinical outcomes were correlated between the groups. The results were analysed statistically by Student's t-test, Fisher's exact test and Kruskal-Wallis test. RESULTS: This study consisted of 42 patients, 24 in Group 1 and 18 in Group 2. Patients in Group 2 (33.0+/-9.2 years) were significantly younger than the patients in Group 1 (49.9+/-7.6 years) (P< or =0.0001). Final visual acuity of >20/400 was attained in 79.2% (19/24) patients in Group 1 and 83.3% (15/18) in Group 2 (P=1.0). Inflammatory membranes were significantly associated with presumed Eales' disease (94.4 vs 0%) (P< or =0.0001) and fibrovascular membranes with Group 1 (70.8% vs 33.3%) (P=0.028). Mast cells and eosinophils were observed as special features in epiretinal membranes of patients with Eales' disease. CONCLUSIONS: Histological features of ERM in Eales' disease are comparable to other vasoproliferative disorders except for features of inflammation. Presence of mast cells and eosinophils in epiretinal membranes of Eales' disease needs further investigation.

Adult↗
PubMed2006

Primary orbital aspergilloma of the exenterated orbit in an immunocompromized patient.

Aspergilloma is a fungal ball that usually forms in a preformed stationary cavity, mostly in lung and paranasal sinuses. We report a rare case of primary orbital Aspergilloma following exenteration for an invasive ocular surface squamous neoplasia, clinically mimicking a recurrence of the tumor. The fungal ball showed the presence of conidiophores with a globular head and a complete row of uni and biserrate phialides, suggestive of Aspergillus flavus species. The exposure to air in the orbit, possibly promoted the formation of conidiophores, which are normally seen when the organism is located in air cavities.

AIDS-Related Opportunistic Infections↗
PubMed2005

Microsporidia: emerging ocular pathogens.

Microsporidia are eukaryotic, spore forming obligate intracellular parasites, first recognized over 100 years ago. Microsporidia are becoming increasingly recognized as infectious pathogens causing intestinal, ocular, sinus, pulmonary, muscular and renal diseases, in both immunocompetent and immunosuppressed patients. Ocular microsporidiosis, though uncommon, could be isolated or part of systemic infections. It occurs mainly in two forms: keratoconjunctivitis form, mostly seen in immunocompromised individuals; stromal keratitis form seen in immunocompetent individuals. Recent reports indicate increasing number of cases of ocular microsporidiosis in immunocompetent individuals. The ocular cases present as superficial keratitis in AIDS patients, and these differ in presentation and clinical course from the cases seen in immunocompetent individuals which mainly appear to be as deep stromal keratitis. For most patients with infectious diseases, microbiological isolation and identification techniques offer the most rapid and specific determination of the etiologic agent, however this does not hold true for microsporidia, which are obligate intracellular parasites requiring cell culture systems for growth. Therefore, the diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves, either in scrapings or tissues. Although the diagnosis of microsporidiosis and identification of microsporidia by light microscopy have greatly improved during the last few years, species differentiation by these techniques is usually impossible and electron microscopy may be necessary. Immuno fluorescent-staining techniques have been developed for species differentiation of microsporidia, but the antibodies used in these procedures are available only at research laboratories at present. During the last 10 years, molecular techniques have been developed for the detection and species differentiation of microsporidia.

Americas↗
PubMed2005

Granulomatous inflammation in Acanthamoeba keratitis: an immunohistochemical study of five cases and review of literature.

PURPOSE: Acanthamoeba keratitis usually presents as a necrotizing stromal inflammation. We report a rare presentation of granulomatous inflammation in Acanthamoeba keratitis METHODS: Retrospective clinico-pathologic case series. RESULTS: Five corneal tissues (3 corneal buttons, 2-eviscerated contents) from patients suffering from severe Acanthamoeba keratitis not responding to anti-Acanthamoeba treatment, revealed a florid granulomotous inflammation with multinucleated giant cells in the posterior stroma and around Descemet's membrane. Phagocytosed parasites were noted within the giant cells. Vascularization of the corneal stroma was noted in two cases. Immunophenotyping revealed a predominance of T lymphocytes and macrophages. Clinically, four of five cases had shown features of limbal and scleral involvement. CONCLUSION: Granulomatous inflammation in the posterior corneal stroma, is not an uncommon finding in Acanthamoeba keratitis and could possibly be immune-mediated, contributing to persistence and progression of disease. CLINICAL RELEVANCE: Presence of granulomatous inflammation in Acanthamoeba keratitis, in most cases is associated with limbal and scleral involvement and therefore could be considered as one of the poor prognostic markers. Further studies are required to ascertain the specific clinical features and appropriate management strategies in these cases.

Acanthamoeba↗
PubMed2001

Atypical Herpes simplex keratitis (HSK) presenting as a perforated corneal ulcer with a large infiltrate in a contact lens wearer: multinucleated giant cells in the Giemsa smear offered a clue to the diagnosis.

PURPOSE: To report a case of atypical herpes simplex keratitis initially diagnosed as bacterial keratitis, in a contact lens wearer. RESULTS: Case report of an 18-year-old woman using contact lenses who presented with pain, redness and gradual decrease in vision in the right eye. Examination revealed a paracentral large stromal infiltrate with a central 2-mm perforation. Corneal and conjunctival scrapings were collected for microbiological investigations. Corneal tissue was obtained following penetrating keratoplasty. Corneal scraping revealed no microorganisms. Giemsa stained smear showed multinucleated giant cells. Conjunctival, corneal scrapings and tissue were positive for herpes simplex virus - 1 (HSV) antigen. Corneal tissue was positive for HSV DNA by PCR. CONCLUSIONS: Atypical HSV keratitis can occur in contact lens wearers. A simple investigation like Giemsa stain may offer a clue to the diagnosis.

Acyclovir↗
PubMed2001

Enzymatic, clinical and histologic evaluation of corneal tissues in experimental fungal keratitis in rabbits.

Mycotic keratitis, being frequently refractive to most of the currently available antifungal therapy, continues to pose a therapeutic challenge to the clinician. In keratitis of infectious etiology stromal dissolution may be brought about by a combination of agent and host factors. An understanding of the source and nature of corneal tissue damage is essential for evolving more effective therapeutic modalities in the treatment of fungal keratitis. In the present study, we have characterized the extracellular proteases produced in vitro by corneal fungal pathogens namely the Aspergillus flavus and Fusarium solani when collagen was provided as the sole nitrogen source. In addition, fungal infected rabbit corneas were investigated for proteolytic activities and nature of inflammatory reaction. Gelatin zymography detected protease bands with molecular mass ranging from 100 to 200 kDa in the culture extracts of A. flavus, and a single major band of molecular mass approximately 200 kDa in the culture extracts of F. solani. A basal proteolytic activity of mass 65 kDa was visualized in all uninfected and infected rabbit corneal extracts. Infected corneas in addition revealed the presence of additional proteolytic species of mass 92 and 200 kDa. The enzyme inhibitory profile suggested that fungal cultures in vitro contained predominantly serine protease activity and to a lesser extent metalloprotease activity. However, fungal infected corneal homogenates showed the presence of metalloproteinase activity alone, the enzymatic activities entirely being sensitive to ethylene diamine tetra acetate (EDTA), a metalloprotease inhibitor. Interestingly, the serine proteolytic activity detected in fungal cultures in vitro was not present in the fungal infected corneas in vivo. However, the possible role of fungal serine proteases in the activation of corneal matrix metalloproteinases (MMPs) cannot be ruled out. Based on the criteria of molecular mass, proteolytic activity in the presence of calcium at neutral pH, and sensitivity to inhibition by a metalloprotease inhibitor, the 65 and 92 kDa gelatinases were identified as MMP 2 and MMP 9, respectively. The expression of 92 and 200 kDa gelatinases correlated positively with the amount of polymorphonuclear cells present in the infected tissues. Activated resident corneal cells or inflammatory cells may largely contribute to the increased proteolytic activities in fungal infected corneas resulting in tissue matrix degradation in fungal keratitis.

Animals↗
PubMed2001

Bilateral infectious keratitis after laser in situ keratomileusis: a case report and review of the literature.

OBJECTIVE: To report a case of bilateral infectious keratitis after simultaneous bilateral laser in situ keratomileusis (LASIK) and to explore appropriate preventive, diagnostic, and therapeutic measures. DESIGN: Interventional case report and literature review. INTERVENTION: A 22-year-old woman had bilateral corneal infiltrates after simultaneous bilateral LASIK. The same set of instruments was used for surgery on both eyes. Corneal scrapings from the edge of the infiltrate and underneath the flap were taken for microscopic examination and inoculation on culture media. Treatment consisted of irrigation of stromal bed with amikacin sulphate (2.5%) solution along with half hourly instillation of amikacin (2.5%) and cefazolin (5%) eye drops. MAIN OUTCOME MEASURES: Causative organism and response to medical treatment. RESULTS: Culture revealed a significant growth of Mycobacterium chelonae from the corneal scrapings of both eyes. There was progressive thinning of corneal stroma in the right eye requiring cyanoacrylate tissue adhesive application. The left eye showed progressive worsening after initial response and required penetrating keratoplasty. CONCLUSIONS: The risk of bilateral sight-threatening complications must be kept in mind when contemplating bilateral simultaneous LASIK. Nontuberculous mycobacteria should be considered as an etiologic agent in cases of infectious keratitis occurring after LASIK. Microbiology work-up of a specimen collected directly from the site of lesion can help in early diagnosis and institution of appropriate therapy.

Adult↗
PubMed2001

Enucleation in a tertiary eye care centre in India: prevalence, current indications and clinicopathological correlation.

PURPOSE: Enucleation is a standard surgical treatment modality for many end-stage eye diseases. Indications for enucleation vary with changing trends in disease management. Few studies have addressed the issue of the frequency and indications of enucleation of eyes in India. We aimed to determine the frequency and the current clinical indications for enucleation in patients at a tertiary eye care centre in India, and attempted a clinicopathological correlation. METHODS: Medical records of patients undergoing enucleation at a tertiary eye care centre over a period of 3 1/2 years (January 1995 to July 1998) were reviewed to obtain patients' demographic data and socio-economic status. The clinical indications and predisposing factors were assessed. The formalin-fixed, paraffin-embedded sections of all enucleated eyes were re-evaluated and histopathological findings were correlated with the clinical diagnosis. The prevalence of enucleation was calculated, and age adjustments were done using the Indian population data from 1998 mid-year statistics. RESULTS: Enucleation of the eye was performed in 150 patients (151 eyes) out of 88,991 new ophthalmic cases, constituting 0.17% of the cases seen in the hospital, and amounting to a prevalence of 0.33% (95% CI, 0.27-0.40). Males outnumbered females in a ratio of 1.85:1 (98 males, 53 females). The median age was 8 years (mean 16.8 +/- 18.3 years). Children below 15 years of age constituted 85.2% (95% CI, 81.2-89.21%) of cases that underwent enucleation. Clinical indications for enucleation included tumours in 74 (49%); staphyloma in 38 (25%); acute injury in 20 (13%); absolute glaucoma in 9 (6%); painful blind eye in 5 (3%); phthisis bulbi in 1 (1%); and others in 4 (3%). Of the 74 cases with a clinical diagnosis of tumour, histopathology revealed retinoblastoma in 55 (74%) cases, melanoma in 6 (8%) and ocular surface tumours in 4 (6%). Clinico-pathological correlation was 100% in cases with a definite clinical diagnosis of retinoblastoma and melanoma. Nine blind eyes (6%) in which an intraocular tumour was one of the differential diagnoses, were negative for a tumour on histopathology. Staphyloma was more prevalent in the low socio-economic group (p = 0.0004), with a history of childhood trauma in 34% cases. CONCLUSIONS: The prevalence of enucleation in the population reporting to this tertiary eye care centre was 33 per 10,000 population over the study period of 3 1/2 years. Major indications for enucleation were tumours, staphyloma and trauma (88% of all cases). Increased frequency in the young was due to the high proportion of retinoblastoma and staphyloma. Childhood trauma, inflammation and malnutrition may together play a role in the pathogenesis of staphyloma. Awareness at the level of primary health care providers, paediatricians and general practitioners should be promoted to identify the disease process at an early stage and facilitate early intervention measures that could result in eye and vision salvage.

Adolescent↗
PubMed2001

Impression cytology-proven corneal stem cell deficiency in patients after surgeries involving the limbus.

PURPOSE: To report three cases of limbal stem cell deficiency (confirmed by impression cytology) that followed multiple pterygium surgeries and therapeutic penetrating keratoplasty. METHODS: The first case, after multiple pterygium surgeries, presented with corneal scarring and thickened epithelium with vascularization sparing the central cornea in the right eye and involving the entire cornea in the left eye. The second case presented with superficial scarring and extensive vascularization after failed therapeutic graft performed for a large perforated corneal ulcer. The third case was a clear graft performed for a progressing fungal ulcer with signs of conjunctivalization inferotemporally. Limbal stem cell deficiency was clinically suspected in all of these cases. RESULTS: Goblet cells with mucin globules were found on the corneal surface by impression cytology in all three cases. CONCLUSIONS: We report three cases of limbal stem cell deficiency (proven by impression cytology) that followed multiple pterygium surgeries and therapeutic penetrating keratoplasty. Surgical insult to the limbus is the predisposing factor for stem cell damage in these cases. Involvement of the limbus by infection and use of intensive medications are probable contributing factors for stem cell damage in cases of therapeutic penetrating keratoplasty.

Adult↗
PubMed2001

Anterior stromal puncture in bullous keratopathy: a clinicopathologic study.

PURPOSE: We report our experience of anterior stromal puncture (ASP) in symptomatic chronic corneal edema patients awaiting penetrating keratoplasty (PK) and hypothesize the mechanism of action of ASP in bullous keratopathy (BK). METHODS: We reviewed the medical records of 28 patients with BK who underwent ASP between November 1996 and September 1999 with at least 1 month of follow-up. In all these patients, approximately 200 punctures were given with a bent 26-gauge needle sparing the peripheral cornea. Patients were examined on days 1 and 7, 1 month, and every 3 months after the procedure. The symptoms, corneal findings, and visual acuity of the patients at last follow-up were noted and compared with the preprocedure findings. For 11 patients who underwent PK, histopathologic study of corneal buttons was performed and a clinicopathologic correlation was attempted. RESULTS: Of the 28 patients, there were 15 men and 13 women with a mean age of 61.1 years. The clinical diagnosis was pseudophakic BK in 11 (39.3%), aphakic BK in 11 (39.3%), Fuchs' dystrophy in 4 (14.3%), failed graft in 1 (3.6%), and chronic corneal edema of unknown etiology in 1 (3.6%). The follow-up ranged from 1 to 33 months with a mean of 9.5 +/- 7.5 months. Symptomatic relief was noted in all. Twenty patients (71.4%) had complete relief, whereas eight patients (28.6%) experienced mild symptoms such as tearing and occasional pain. Visual acuity improved in 7 patients (25%), decreased in 12 (42.8%), and remained the same in 9 (32.4%). Objective evidence of scarring after ASP was noted in all patients. Complete regression of epithelial bullae and epithelial edema was found in 10 (35.7%) and partial regression in 18 (62.25%) patients. There was no progression or appearance of new blood vessels except in one patient (3.6%). Histologically, puncture marks and superficial stromal scarring were noted in all corneal buttons. Adhesion of epithelium with varying degrees of subepithelial fibrosis was seen in six, whereas in the remaining five buttons, there was complete denudation of the epithelium. Vascularization was seen in five and inflammation in two buttons. Clinicopathologic correlation revealed that symptomatic patients had persistent edema and loose adhesion of the epithelium to the stroma, resulting in detachment. CONCLUSIONS: ASP is a simple, safe, and cost-effective outpatient procedure for symptomatic relief in patients with BK. The possibility of decreased visual acuity after the procedure should be explained to all patients. Although ASP promoted subepithelial fibrosis in all cases, its subsequent adhesion is variable and probably has clinical relevance. Further studies could be directed toward identifying specific mediators that promote epithelial-stromal interaction and firm anchoring of epithelium to the underlying stroma.

Adult↗
PubMed2000

Keratocyte loss in Acanthamoeba keratitis: phagocytosis, necrosis or apoptosis?

PURPOSE: Pathogenesis of Acanthamoeba keratitis involves breakdown of epithelial barrier, stromal invasion by Acanthamoeba, loss of keratocytes, inflammatory response and finally stromal necrosis. The loss of keratocytes, believed to be due to the phagocytic activity of the parasite, occurs disproportionate to and independent of the parasite load, thereby suggesting additional modes of cell loss. To test our hypothesis that the loss of keratocytes in Acanthamoeba keratitis is due to apoptosis, we did both histology and histochemistry on the corneal tissues. METHODS: Routine Haematoxylin and Eosin, Gomori's Methenamine Silver and Periodic acid Schiff stained sections of five corneal tissues from penetrating keratoplasty and eviscerated eyes were reviewed. TUNEL staining was done for morphological detection of apoptosis in three cases, using formalin-fixed, paraffin-processed tissues. RESULTS: Histological changes were epithelial ulceration, loss of keratocytes in all layers, inflammation in anterior two-thirds of the stroma with necrosis, and deeper quiet stroma. Acanthamoeba trophozoites were found in the anterior stroma while the cysts were more in the deeper stroma, with minimal or no inflammatory response. TUNEL staining was positive in keratocytic nuclei in all layers. CONCLUSIONS: This study demonstrates that one of the modes of keratocyte loss in Acanthamoeba keratitis is by apoptosis, possibly in addition to the necrotic process and phagocytic activity of the parasite. The death of inflammatory cells also appears to be mediated by apoptosis.

Acanthamoeba↗
PubMed1994

Penetrating keratoplasty in xeroderma pigmentosum. Case reports and review of the literature.

Xeroderma pigmentosum is an uncommon inherited disorder characterized by hypersensitivity to ultraviolet radiation, with defective repair of DNA damage caused by short-wavelength radiation. Corneal complications of this disorder may require penetrating keratoplasty for visual rehabilitation. Surgery is rarely undertaken in these eyes due to multiple associated problems involving the ocular surface and the lids. We report three cases of successful penetrating keratoplasty in xeroderma pigmentosum and review nine cases reported earlier. Successful grafts were achieved in all 12 eyes initially. Persistent superficial punctate keratopathy was observed in one eye and graft rejection episodes in five eyes. However, graft failure occurred due to an untreated rejection episode in only one eye. Another eye was treated by exenteration for recurrent ocular malignancies. This report highlights the encouraging results of penetrating keratoplasty in carefully selected patients of xeroderma pigmentosum with corneal pathology.

Adult↗