Presentations - Hyderabad Eye Research Foundation - Research - L V Prasad Eye Institute

Research Publications And Abstracts

Research Publications

Abstracts

Scientists at LVPEI present at national and international conferences and publish in a wide variety of eye science journals. Below are abstracts of some of the most recent publications. For more details on any of the studies mentioned here, please get in touch with the authors or with the Research Centre at L V Prasad Eye Institute.

Major studies in progress.

  • The epidemiological features and laboratory results of fungal keratitis.
  • Gopinathan U, Garg P, Fernandes M, Sharma S, Athmanathan S, Rao GN. Cornea 2002 Aug;21(6):555-9
    PURPOSE: To report the epidemiological features and laboratory results of 1,352 cases of fungal keratitis diagnosed at the L.V. Prasad Eye Institute (LVPEI) in south India. 
    METHODS: The medical and microbiology records of 1,352 culture proven cases (1,354 eyes) of fungal keratitis diagnosed at the LVPEI between January 1991 to December 2000 was retrospectively reviewed for demographic features, risk factors, seasonal variation, and laboratory findings. 
    RESULTS: Males (962) were affected significantly more (p< 0.0001) than females (390). Of 1,352 patients, 853 (64.4%) were in the younger age group (16-49 years). Ocular trauma predisposed to infection in 736 (54.4%) of 1,354 eyes. There was a higher incidence of fungal keratitis during the monsoon and winter than summer. A fungal cause was established by smears of corneal scrapings in 1,277 (95.4%) eyes. The potassium hydroxide preparation (KOH), Calcofluor white (CFW), Gram-, and Giemsa-stained smears revealed fungus in 1,219 (91.0%), 1,224 (91.4%), 1,181 (88.2%), and 1,139 (85.1%) eyes, respectively. Fusarium(506, 37.2%) and Aspergillus species (417, 30.7%) predominated the hyaline fungal spectrum (1,133) and Curvularia species (39, 2.8%) were the highest among the dematiaceous isolates (218).
  • Trabeculectomy with or without mitomycin-C for paediatric glaucoma in aphakia and pseudophakia following congenital cataract surgery.
  • Mandal AK, Bagga H, Nutheti R, Gothwal VK, Nanda AK. Eye. 2003 Jan;17(1):53-62
    PURPOSE: To evaluate the safety and efficacy of trabeculectomy with or without mitomycin-C (MMC) in the management of glaucoma in aphakia and pseudophakia following congenital cataract surgery. 
    PATIENTS AND METHODS: All patients of glaucoma with aphakia or pseudophakia who underwent trabeculectomy with or without MMC from January 1989 to April 2000 were included. The medical records of 19 consecutive patients (23 eyes)were reviewed. Data collected from a retrospective chart review were analysed. Outcome measures were evaluated using Kaplan-Meier survival analysis. Pre- and postoperative intraocular pressures (IOPs), visual acuities, success rate, bleb characteristics, surgical failure and complications were the main outcome measures. Successful IOP control was defined as an IOP between 6 and 21 mmHg, without antiglaucoma medications, without further antiglaucoma surgery and without any sight-threatening complication.
    RESULTS: The mean age of patients was 8.8+/-5.5 years at the time of trabeculectomy with MMC compared to 11.0+/-12.4 years for trabeculectomy without MMC. Eight patients underwent trabeculectomy with MMC and 11 patients underwent trabeculectomy without MMC. There was no statistically significant difference between the two groups in terms of visual acuity, IOP, antiglaucoma medications, age at cataract surgery and at trabeculectomy. The IOP reduced from a preoperative level of 34.2+/-8.9 mmHg (range: 20-52) to a postoperative level of 18.4+/-12.2 mmHg (range: 2-60) with a mean follow-up of 24.2+/-17.9 months. The mean reduction in IOP in the MMC group was 15.5+/-17.3 and 16.3+/-13.8 mmHg in the other group (P = 0.967). Overall, complete success was achieved in 36.8%, qualified success in 21.1% and surgical failure in 42.1% of patients with a mean follow-up of 24.2+/-17.9 months. There was no difference in the success between the two groups at the last follow-up. One patient developed bleb-related endophthalmitis in both eyes following trabeculectomy with MMC.  
    CONCLUSIONS: The success rate of trabeculectomy in glaucoma following congenital cataract surgery was 36.8% at the end of 3 years. The present study proves a poor success rate of trabeculectomy in a small series of aphakic Asian Indian patients even with the use of MMC.
  • Trends in contact lens-associated microbial keratitis in Southern India.
  • Sharma S, Gopalakrishnan S, Aasuri MK, Garg P, Rao GN. Ophthalmology. 2003 Jan;110(1):138-43
    OBJECTIVE: To review the microbiologic profile, clinical course, treatment, and outcome in patients with contact lens-associated microbial keratitis in the setting of a tertiary eye care center in a developing country in the Tropics. 
    DESIGN: Retrospective noncomparative case series selected from an ongoing prospective series. PARTICIPANTS: Twenty-eight subjects examined in the contact lens clinic of L. V. Prasad Eye Institute, Hyderabad, south India, between February 1991 and September 2000, who presented with corneal stromal infiltrate on slit-lamp examination, were included in the study. INTERVENTION: All patients underwent standard diagnostic microbiologic evaluation and smear and culture-guided topical antimicrobial therapy. Penetrating keratoplasty was performed in some patients. 
    MAIN OUTCOME MEASURES: Culture results and clinical response to antimicrobial therapy. RESULTS: Twenty eight (0.11%) of 23,889 contact lens-wearing patients presented with laboratory-proven infectious keratitis; this constituted 0.56% of 4967 corneal ulcer patients seen during the same period. Most (15/28) of the patients wore soft contact lenses on a daily basis. Rigid gas-permeable lenses were worn by six patients, therapeutic bandage contact lenses by four, and Silsoft lenses by four. Laboratory results showed bacterial infections in 25 patients (89.2%); Pseudomonas was the most common organism (13/25; 52%). Acanthamoeba, herpes simplex virus, and spergillus niger were isolated in one case each. Laboratory-based medical therapy led to the healing of ulcers in 24 (85.7%) of 28 patients, whereas 4 patients required penetrating keratoplasty. Most of the organisms were sensitive to antibiotics.
    CONCLUSIONS: Contact lens-associated microbial keratitis is rare in southern India. Soft contact lens wear is the most common risk factor; Pseudomonas keratitis is the predominant causative agent. Fungal, viral, and Acanthamoeba keratitis are rare. The offending bacteria are usually sensitive to antibiotics, and the treatment outcome with medical therapy is good. 
  • Clinico-microbiological correlation of suture-related graft infection following penetrating keratoplasty.
  • Sonavane A, Sharma S, Gangopadhyay N, Bansal AK. Am J Ophthalmol. 2003 Jan; 135(1): 89-91.
    PURPOSE: To report the clinical and microbiological profiles of suture-related graft infections following penetrating keratoplasty. DESIGN: Interventional case series. 
    METHODS: The medical and microbiology records of all patients who presented with suture-related graft infections and were seen between January 1999 and December 2001 were reviewed. 
    RESULTS: Of 105 patients (105 eyes) who developed corneal infiltrates following penetrating keratoplasty, 37 patients (24 optical and 13 therapeutic) were identified as having suture-related graft infection. The median onset of infiltrates after penetrating keratoplasty was 87 days for 31 patients who presented within one year. Gram-stained smears of corneal scrapings were positive in 27 (73%) of 37 patients, whereas cultures were positive in 32 (only bacteria, 30; mixed bacteria and fungi, 2). Thirty-seven isolates were obtained from 32 patients (gram-positive bacteria, 32; gram-negative bacteria, 3; fungus, 2). All gram-positive isolates were sensitive to cefazolin, chloramphenicol, and vancomycin, whereas one of three gram-negative isolates (Pseudomanas species) was resistant to all the antibiotics tested. Of 32 patients, 30 (82%) responded satisfactorily to medical management. 
    CONCLUSIONS: Suture-related graft infections are usually caused by bacteria that are sensitive to ciprofloxacin, cefazolin, and gentamicin, and the patients respond satisfactorily to medical therapy.
  • Clinical experience with N-butyl cyanoacrylate tissueadhesive in fungal keratitis.
  • Garg P, Gopinathan U, Nutheti R, Rao GN. Cornea. 2003 Jul; 22(5): 405-8.
    PURPOSE: To evaluate the role of tissue adhesive in the management of corneal thinning or perforation associated with active fungal keratitis. 
    DESIGN: Retrospective noncomparative interventional case series. 
    METHODS: Seventy-three eyes of 73 patients with microbiologically proven keratomycosis associated with thinning or perforation participated in the study. N-Butyl cyanoacrylate tissue adhesive (medical grade) and bandage contact lens were applied Our outcome measures included resolution of the infiltrate and preservation of the structural integrity of the globe. 
    RESULTS: Outcome data were available for 66 eyes. The infiltrate resolved with scar formation in 42 (63.6%) eyes. In an additional eight (12.1%) eyes, tissue adhesive maintained the structural integrity of the globe while the patients awaited penetrating keratoplasty. Sixteen (24.2%) eyes showed progressive worsening or persistence of the infiltrate after application of tissue adhesive. Twenty-five (37.8%) eyes required multiple applications of tissue adhesive. The outcome was better in cases where the infiltrate measured less than 30 mm2 at the time of presentation and application of tissue adhesive (P < 0.01). 
    CONCLUSION: In view of the poor outcome of penetrating keratoplasty in active fungal keratitis, N-butyl cyanoacrylate tissue adhesive is a useful modality for the management of progressive thinning or perforation associated with active fungal keratitis. However, close observation is mandatory to assess the progression of disease.
  • Nomogram for spherical RGP contact lens fitting in patients with pellucid marginal corneal degeneration (PMCD).
  • Raizada K, Sridhar MS. Eye Contact Lens. 2003 Jul; 29(3): 168-72
    PURPOSE: To present a nomogram for spherical rigid gas-permeable (RGP) contact lens fitting in patients with ellucid marginal corneal degeneration (PMCD). 
    METHODS: Retrospective review of the medical records of 24 patients diagnosed with PMCD who underwent an RGP contact lens trial at the Bausch & Lomb contact lens center between April 1995 and March 2002 at L.V. Prasad Eye Institute in Hyderabad, India. Data collected included age and sex of patients, duration of presenting symptoms, associated ocular conditions, presenting visual acuity, and degree of astigmatism. For the purpose of analysis, the astigmatism was classified into four groups: group 1, less than 5.00 diopters (D); group 2, 5.00 to 10.00D; group 3, 10.00 to 15.00D; and group 4, 15.00 to 20.00D. The final lens parameters, the patient's comfort level, and the duration of follow-up were analyzed. 
    RESULTS: Forty eyes of 24 patients were fitted with RGP contact lenses during the study period. Sixteen were male patients and eight were female patients. The age of the patients ranged from 13 to 59 years, with a mean of 35.5 years. Twenty-two (91.7%) patients had typical inferior PMCD, whereas the other two (8.3%) had superior PMCD. The mean corneal curvature was 7.1 mm (range, 5.9-7.8 mm) in group 1, 6.9 mm (range, 6.6-7.9 mm) in group 2, 7.5 mm (range,6.5-7.8 mm) in group 3, and 7.9 mm (range, 6.8-7.8 mm) in group 4. The mean base curve of the final fitting lens was 6.3 mm (range, 5.7-7.8 mm) in group 1, 6.8 mm (range, 5.9-7.8 mm) in group 2, 7.5 mm (range, 6-8.2 mm) in group 3, and 7.2 mm (range, 6.6-7.8 mm) in group 4. The mean lens diameter of the final fitting lens was 8.7 mm (range, 8.6-10.6 mm) in group 1, 9.5 mm (range, 8.8-10.5 mm) in group 2, 10.2 mm (range, 8.8-11.5 mm) in group 3, and 10.4 mm (range, 8.8-11.3 mm) in group 4. The common fluorescein patterns were central touch with midcentral peripheral pooling in 14 (35%) and dumbbell pattern in seven (17.%). The final visual acuity range with an RGP lens in the four astigmatism groups was 20/40 to 20/20 in group 1, 20/30 to 20/20 in group 2, 20/40 to 20/20 in group 3, and 20/200 to 20/50 in group 4. Twenty-one patients were comfortable with an RGP lens, and the mean duration of follow-up was 13 months. Three patients discontinued lens wear. In one patient, the lens was not stable, and the other two experienced discomfort with their lenses.
    CONCLUSIONS: Spherical rigid gas-permeable lenses are a good option for patients even with advanced PMCD. In patients with astigmatism of less than 10D, a lens with a base curve of 6.0 to 7.0 mm and a diameter of 8.0 to 9.5 mm seems to be a good initial lens for trial, and for patients with astigmatism of more than 10D, a lens with a base curve of 7.0 to 7.5 mm and a diameter of 10.0 to 10.5 mm seems to be a good initial lens.
  • Mutational screening of the RB1 gene in Indian patients with retinoblastoma reveals eight novel and several recurrent mutations.
  • Kiran VS, Kannabiran C, Chakravarthi K, Vemuganti GK, Honavar SG. Hum Mutat. 2003 Oct;22(4):339.
    PURPOSE: Retinoblastoma is the most common primary intraocular malignancy in children, caused by inactivation of the RB1 gene on chromosome 13. 
    METHOD: We carried out a mutational screen of the exons and promoter of the RB1 gene in Indian patients with retinoblastoma in order to determine the range of mutations giving rise to disease. Forty-seven patients were screened for mutations in all exons and promoter of the RB1 gene by single strand conformation polymorphism followed by sequencing. Tumors were available from 27 patients (12 bilateral and 15 unilateral retinoblastoma) while only peripheral blood was available from 20 patients, all with bilateral disease. Mutations were found in 22 patients, 9 from the analysis of tumors and 13 from peripheral blood. Eight novel mutations were identified, including 4 single base changes, 2 small deletions and 1 duplication. These are g.64365T>G (Tyr325Ter), g.78131G>A (Trp515Ter), g.150061G>T (Glu587Ter), g.170383C>G (S834X), g.41924A>C (IVS3-2A>C),g.150064ins4, g.160792del22, and g.76940del14 (IVS15 del +20-33). 
    RESULTS: Almost all mutations produced nonsense codons or frameshifts. Recurrent mutations, especially at CpG sites were seen predominantly. Detectable mutations in exons were found in 46% of patients tested. Large deletions, epigenetic changes as well as mutations in non-coding regions may be the cause of disease in the remainder of patients. Knowledge of the full range of mutations can aid in the design of screening tests for individuals at risk. Copyright 2003 Wiley-Liss, Inc.
  • Outcome of surgery on infants younger than 1 month with congenital glaucoma.
  • Mandal AK, Gothwal VK, Bagga H, Nutheti R, Mansoori T. Ophthalmology. 2003 Oct;110(10):1909-15.
    PURPOSE: To determine the visual outcomes and surgical and anesthetic complication rates of patients with newborn glaucoma operated within 1 month of age. DESIGN: Retrospective, consecutive, noncomparative case series. PARTICIPANTS: All children with newborn glaucoma who underwent surgery between January 1990 and December 2000 were included. METHODS: The medical records of 25 consecutive patients (47 eyes) who underwent primary combined trabeculotomy and trabeculectomy either bilaterally in a single session or unilaterally were reviewed retrospectively. Outcomes were evaluated using Kaplan-Meier survival analysis. MAIN OUTCOME MEASURES: Clinical outcome assessment included corneal clarity, intraocular pressure (IOP), bleb characteristics, visual acuity, refractive errors, and identification of surgical and anesthetic complications. 
    RESULTS: The mean follow-up was 3.1+/-1.8 years (range, 9.5 months-7.4 years). The mean preoperative IOP was 26.9+/-5.2 mmHg (range, 14-42 mmHg). At the final follow-up visit, the mean IOP was 14.5+/-3.8 mmHg (range, 8-28 mmHg). The percentage reduction in IOP was 43.3+/-21.5 (P<0.0001). Twelve-, 24-, and 36-month survival rates for complete success for IOP control were 89.4%, 83.6%, and 71.7%, respectively, which were maintained for 7 years of follow-up. After surgery, complete clearance of corneal edema was achieved in 66% of the eyes. Data on visual acuity was available for 19 patients. Final best spectacle-corrected visual acuity was 20/40 or better in the better eye in 5 patients (26.3%), 7 patients (36.8%) obtained 20/60 or better in the better eye, 8 patients (42.1%) achieved final visual acuity of less than 20/60 to 20/200 in the better eye (low vision), and four patients obtained less than 20/400 visual acuity in the better eye (blind) according to World Health Organization criteria. However, there was no eye with absent perception of light in the better eye. Myopia (mean spherical equivalent, 4.6+/-3.2 diopters) was the most common refractive error, present in approximately half of the eyes (n = 23; 53.8%). There were no significant intraoperative or postoperative complications in any patient. Anesthesia-related complications developed in 2 patients; however, they were resuscitated successfully. 
    CONCLUSIONS: Primary combined trabeculotomy-trabeculectomy offers a viable surgical option in infants that have cloudy corneas at birth as a result of congenital glaucoma. It is associated with a favorable visual outcome and a low rate of anesthetic complications in an Indian population.
  • Correlations of genotype with phenotype in Indian patients with primary congenital glaucoma.
  • Panicker SG, Mandal AK, Reddy AB, Gothwal VK, Hasnain SE. Invest Ophthalmol Vis Sci. 2004 Apr;45(4):1149-56.
    PURPOSE: To establish the genotype-phenotype correlations of various CYP1B1 (human cytochrome P450) mutations in patients in India with primary congenital glaucoma (PCG). METHODS: The study cohort comprised 146 patients with PCG from 138 pedigrees. Patients were analyzed for six distinct CYP1B1 mutations by sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. A severity index for grading various PCG phenotypes was constructed based on clinical parameters. 
    RESULTS: Six mutations were identified in 45 patients analyzed and genotype-phenotype correlations were established for 43 of them. The percentages of severe phenotypes associated with various mutations in at least one eye were: frameshift, 100%; G61E, 66.7%; P193L, 62.5%; E229K, 80%; R368H, 72%; R390C, 83.3%. The frameshift mutationresulted in blindness. Based on the severity index, the disease severity was graded from normal to severe and the prognosis from good to very poor (blind). De novo mutation was identified in one family.
    CONCLUSIONS: This is the first study to attempt to devise a severity index for grading various PCG phenotypes and to use genotype as an indicator to predict the prognoses of the disorder. This index may help guide therapy and counseling of the afflicted family regarding the progression of the disorder. All patients with severe phenotypes showed poor prognoses (r = 0.976; P < 0.0001). The data derived from this study could be used as an added clinical tool in disease management. Integrated management of PCG that makes use of a genetic approach could yield better results than medical, surgical, and rehabilitation interventions alone.
  • Use of autologous cultured limbal and conjunctival epithelium in a patient with severe bilateral ocular surface disease induced by acid injury.
  • Sangwan VS, Vemuganti GK, Iftekhar G, Bansal AK, Rao GN. Cornea. 2003 Jul;22(5):478-81.
    PURPOSE: Reconstruction of the ocular surface in a case of severe bilateral partial limbal stem cell deficiency (LSCD) with extensive symblephara using autologous cultured conjunctival and limbal epithelium. 
    CASE REPORT: A 31-year-old woman presented with severe bilateral ocular surface disease with partial limbal stem cell deficiency, symblephara, lid and facial scarring, with a vision of 20/400 and counting fingers at 1 m in both eyes. Limbal and conjunctival tissue was harvested from the healthy-appearing left eye and used to generate two sheets of composite epithelium consisting of central limbal and peripheral conjunctival cells. The limbal tissues were explanted in the central region while the conjunctival tissues were explanted on the periphery of the deepithelialized human amniotic membrane (HAM) and nurtured using human corneal epithelial cell medium.After successful generation of a monolayer from both tissues had been confirmed, the composite of cultivated limbal and conjunctival epithelium with HAM was transplanted in each eye after excision of fibrous tissue and release of symblephara. One year postoperatively, the patient had a best spectacle-corrected visual acuity of 20/40 in the right eye (preoperative acuity 20/400) and counting fingers at 1 m in the left eye (same as preoperative) with a stable ocular surface. 
    CONCLUSIONS: Autologous cultured epithelial transplantation is as an excellent option in selected patients with bilateral partial LSCD with small area(s) of healthy limbus in either eye and avoids the attendant risk of rejection and cost and potential toxicity of immunosuppression in allogeneic tissue transplantation. This case also highlights the feasibility of generating a composite culture of limbal and conjunctival epithelium using a single amniotic membrane.
  • Five year risk of progression of primary angle closure suspects to primary angle closure.
  • Thomas R, George R, Parikh R, Muliyil J, Jacob A. Br J Ophthalmol. 2003 Apr;87(4):450-4.
    AIM: To report progression of primary angle closure suspects (PACS) to primary angle closure (PAC) at the 5 year follow up of a population based sample. 
    METHODS: 82 of 118 PACS who could be contacted and 110 randomly selected normals from a population based survey in 1995 were invited for a follow up examination in 2000. Progression to PAC was based on the development of raised IOP or synechiae in a PACS. RESULTS: 50 of the 82 PACS contacted were examined. 11 (22%; 95% CI 9.8 to 34.2) developed PAC (seven synechial and four appositional); all were bilateral PACS. Two of 50 people previously diagnosed as PACS were reclassified as normal. One person among the 110 normals progressed to PAC. The relative risk of progression among PACS was 24 (95% CI 3.2 to 182.4). There was no significant difference in axial length, anterior chamber depth, or lens thickness between those who progressed and those who did not. None of the patients developed optic disc or field damage attributable to angle closure. One angle closure suspect was diagnosed to have normotensive glaucoma. 
    CONCLUSION: In this population based study of PACS the 5 year incidence of PAC was 22%; none developed functional damage. Bilateral PACS was a clinical risk factor for progression.
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