Stepwise Protocol for Cytospin-enhanced Smearing for Scraped Corneal Epithelial Cells.

Proteins and antigens present on the cell surface are usually determined by immunofluorescence staining. Uniform distribution of cells is required to appreciate the presence of surface proteins. Improper smearing or crushing of the corneal epithelial cells can potentially destroy the cellular integrity. Thus a simplified, systemic method was designed to smear the cells scraped from the cornea. The procedure includes trypsinisation for dissociation of corneal epithelial cells and cytospinning for concentrating the cells in a smear. The standardized protocol was found to be efficient in maintaining the integrity of the corneal epithelial cells and also the distribution of the cells in the smear.

A study on the characterization of Propionibacterium acnes isolated from ocular clinical specimens.

BACKGROUND & OBJECTIVES: There are only a few reports available on characterization of Propionibacterium acnes isolated from various ocular clinical specimens. We undertook this study to evaluate the role of P. acnes in ocular infections and biofilm production, and also do the phylogenetic analysis of the bacilli. METHODS: One hundred isolates of P. acnes collected prospectively from ocular clinical specimens at a tertiary care eye hospital between January 2010 and December 2011, were studied for their association with various ocular disease conditions. The isolates were also subjected to genotyping and phylogenetic analysis, and were also tested for their ability to produce biofilms. RESULTS: Among preoperative conjunctival swabs, P. acnes was a probably significant pathogen in one case; a possibly significant pathogen in two cases. In other clinical conditions, 13 per cent isolates were probably significant pathogens and 38 per cent as possibly significant pathogens. The analysis of 16S rRNA gene revealed four different phylogenies whereas analysis of recA gene showed two phylogenies confirming that recA gene was more reliable than 16S rRNA with less sequence variation. Results of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) had 100 per cent concordance with phylogenetic results. No association was seen between P. acnes subtypes and biofilm production. INTERPRETATION & CONCLUSIONS: RecA gene phylogenetic studies revealed two different phylogenies. RFLP technique was found to be cost-effective with high sensitivity and specificity in phylogenetic analysis. No association between P. acnes subtypes and pathogenetic ability was observed. Biofilm producing isolates showed increased antibiotic resistance compared with non-biofilm producing isolates.

Genotypic Detection of Epstein Barr Virus in Pediatric Transplant Recipients From India.

OBJECTIVE: To determine the rate of occurrence and genotypes of Epstein-Barr Virus (EBV) among pediatric renal and liver transplants recipients. DESIGN: Observational study. SETTING: Vision Research Foundation referral center and Institute of Liver Disease and Transplantation, Chennai, India. PARTICIPANTS: 70 pediatric solid organ transplant recipients and 60 voluntary healthy donors. METHODS: Polymerase chain reaction (PCR) for detection and genotyping of EBV were carried out using genes targeting Viral capsid antigen, Nuclear antigen 1, 2 and 3, followed by real time PCR for viral load determination and further confirmed by phylogenetic analysis. RESULTS: EBV was detected in 35 (51.4%) samples (32 liver and 4 renal transplants) with high viral load. Type A was detected in 33 samples, Type B in 2 liver transplant patients, and co-infection in one liver transplant patient who developed Post-transplant Lymphoproliferative Disorder (PTLD). Real time PCR results correlated with conventional PCR. The mean viral load for patients who did not develop PTLD was 50,424 copies/mL. Overall EBV load in patient with PTLD ranged from 1,40,392 copies/mL prior to PTLD diagnosis to 62,124 copies /mL post treatment. CONCLUSION: EBV infection is the high risk factor for PTLD after liver transplantation. PCR targeting of EBV can be applied to diagnose EBV infections and monitor treatment for EBV in pediatric solid organ transplant recipients.

Detection of novel and reported mutations in the rpoB, katG and inhA genes in multidrug-resistant tuberculosis isolates: A hospital-based study.

The objective of this study was to detect mutations associated with isoniazid (INH) and rifampicin (RIF) resistance in Mycobacterium tuberculosis isolates from newly diagnosed and previously treated tuberculosis patients using a PCR-based DNA sequencing technique. Phenotypic drug susceptibility testing was performed using a BACTEC™ MicroMGIT Culture System in 354 M. tuberculosis isolates. Among the 354 isolates, 18 were multidrug-resistant tuberculosis (MDR-TB). PCR-based DNA sequencing was performed targeting the rpoB gene for RIF and the whole of the katG gene and the promoter and coding region of the inhA gene for INH. Results were analysed using MultAlin analysis to identify the presence of polymorphisms or mutations by comparing with already available GenBank sequences. Only 37.5% of RIF-resistant isolates showed the presence of the most commonly reported mutation (Ser531Leu). The most commonly reported mutation (Ser531Leu) was detected in six MDR-TB isolates. The frequency of mutations associated with INH resistance was 31.5% (17/54) and 29.6% (16/54) for katG and inhA, respectively. Comparing the relative distribution of mutations in the two target loci revealed that 12 isolates (22.2%) had a mutation in both katG and inhA. Apart from previously reported mutations in the katG gene, there were three novel deletion and six novel substitution mutations. As reported in previous studies, Ser531Leu was the most common mutation detected in RIF-resistant isolates. The genetic mechanism of INH resistance in M. tuberculosis is highly complex involving several genes, and much remains to be explored to achieve a better understanding of this complex mechanism.

Application of real time polymerase chain reaction targeting kex 1 gene & its comparison with the conventional methods for rapid detection of Pneumocystis jirovecii in clinical specimens.

BACKGROUND & OBJECTIVES: As there are no standard laboratory techniques for the rapid detection of Pneumocystis jirovecii in India, this study was undertaken to evaluate and establish an optimal and rapid technique for the detection of P. jirovecii by comparing three different techniques - staining technique, application of a real time polymerase chain reaction (RT-PCR) targeting kex 1 gene and application of nested PCR targeting mitochondrial large subunit (mtLSU) gene for rapid detection of P. jirovecii in HIV positive patients. METHODS: One hundred and fifty sputum specimens from HIV positive (n = 75) and HIV negative (n = 75) patients were subjected to three different techniques -KOH/Calcoflour and Grocott methanamine silver staining (GMS), RT-PCR targeting kex1 gene, PCR targeting mtLSU region followed by DNA sequencing and BLAST analysis. RESULTS: Among the 75 HIV positive patients, P. jirovecii was detected in 19 (25.33%) patients by the staining techniques, and in 23 (30.65%) patients each by PCR targeting mtLSU region and by RT- PCR targeting kex1 gene of P. jirovecii. PCR based DNA sequencing targeting mtLSU region revealed 97-100 per cent sequence homology with P. jirovecii sequences in GenBank. INTERPRETATION & CONCLUSIONS: Of the three techniques for detection of P. jirovecii evaluated in this study, false negativity was found to be more in staining technique and it also required high technical expertise to interpret the result. Both nested PCR and RT-PCR were reliable and equally sensitive, in rapid detection of P. jirovecii, but RT-PCR technique also generated the copy numbers for knowing the severity of infection.

Study on polymethylmethacrylate ring in protecting limbal stem cells during collagen cross-linking.

OBJECTIVE: The UV rays used in the collagen cross-linking (CXL) procedure seem to cause potential damage to the limbal stem cells. This study was designed to evaluate the ability of polymethylmethacrylate (PMMA) hemiannulus as an alternative to protect corneal limbal stem cells during CXL. METHODS: Ten freshly enucleated human cadaveric eyeballs were subjected to the corneal CXL procedure. The cadaveric eye ball was divided into 2 sectors: A and B. Sector A was left unprotected, while sector B was covered by a PMMA shield. Limbal biopsies from both sectors before and after the procedure were analyzed. Each limbal tissue was placed on human amniotic membrane (HAM) to check the cultivability and was subjected to marker studies using reverse transcriptase PCR. RESULTS: Before CXL, biopsies from both sectors showed growth on HAM. After CXL, biopsies from sector A showed no growth on HAM while 2 out of the 10 from sector B covered with the PMMA ring did show growth on HAM. The putative stem-cell marker ABCG2 was negative in all the samples from sector A after CXL and was positive in 2 out of the 10 samples from sector B. CONCLUSION: Covering the limbal region with PMMA offers partial protection of the limbus from the UV rays during the CXL procedure.

Acute postoperative Bacillus cereus endophthalmitis mimicking toxic anterior segment syndrome.

OBJECTIVE: To study the clinicomicrobiologic characteristics and treatment outcomes in eyes with acute postoperative endophthalmitis (APE) owing to Bacillus cereus from a tertiary eye-care center. DESIGN: Retrospective, interventional case series. PARTICIPANTS: Case records of all eyes with culture-proven APE attributable to B cereus from January 2000 to May 2011 were identified from a computerized database and evaluated. METHODS: Clinical features at time of presentation, microbiological characteristics, and treatment measures were recorded. A thorough literature search using PubMed and the Cochrane Library databases was done to identify all cases of APE owing to Bacillus species reported to date and clinical characteristics of these eyes was compared with our series. MAIN OUTCOME MEASURES: Structural (globe salvage) and functional (visual rehabilitation) outcomes at last follow-up visit. RESULTS: We found 6 sporadic cases that experienced APE during the study period. All eyes had a fulminant onset within the first 24 hours of cataract surgery with extremely high intraocular pressure (IOP) and corneal edema similar to toxic anterior segment syndrome (TASS). However, these eyes progressed rapidly to develop corneal infiltrates, scleral and uveal tissue necrosis with hyphema, brownish exudates in anterior chamber and necrotizing retinitis within hours despite immediate initiation of intravitreal pharmacotherapy and vitrectomy. All eyes demonstrated gram-positive bacilli from the aqueous and B cereus was isolated, which was sensitive to conventional antibiotics except penicillin. Two eyes required therapeutic keratoplasty, combined with a scleral patch graft in 1 eye, 1 eye was eviscerated after 48 hours of onset of symptoms, and 2 eyes experienced phthisical changes within 10 days of onset. CONCLUSIONS: We found that APE owing to B cereus has an onset within 12 to 24 hours of intraocular surgery and simulates TASS in the first few hours. The clinical course is marked by rapidly worsening necrotizing infection, leading to very poor outcomes despite early institution of appropriate therapy. One must closely observe every case of TASS that presents with intense pain and extremely high IOP and rule out APE owing to B cereus with microbiologic testing. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

The effect of riboflavin-UV-A treatment on corneal limbal epithelial cells--a study on human cadaver eyes.

PURPOSE: To determine the effect of riboflavin-UV-A treatment on the corneal limbal epithelial cells during a corneal collagen cross-linking (CXL) procedure. METHODS: Thirty freshly enucleated human cadaveric eyeballs were subjected to a CXL procedure, mimicking the clinical protocol. During the UV-A exposure, one half of the limbus (sector A) was left unprotected, whereas the other half (sector B) was covered by a metal shield. Limbal biopsies from both sectors before and after the procedure were analyzed. Each strip of tissue was divided into 3 segments, for cell count of viable cells, for cultivation on human amniotic membrane (HAM), and for stem cell and differentiated corneal epithelial cell marker studies using reverse transcriptase-polymerase chain reaction. RESULTS: Compared with the cell count before CXL, there was a statistically significant drop in the mean number of viable cells after CXL in sector A but not in sector B. Biopsies from both sectors before CXL and from sector B after CXL showed good growth on HAM. Biopsies from sector A after CXL showed no growth on HAM. The putative stem cell marker ABCG2 was absent in all samples and p63 was absent in 3 of 10 samples taken from sector A after CXL. All markers were present in all samples from sector B after CXL. CONCLUSIONS: Riboflavin-UV-A treatment can result in damage to limbal epithelial cells, particularly the stem cells. Covering the limbal region with a metal shield effectively prevents this damage.

Detection of novel coupled mutations in the katG gene (His276Met, Gln295His and Ser315Thr) in a multidrug-resistant Mycobacterium tuberculosis strain from Chennai, India, and insight into the molecular mechanism of isoniazid resistance using structural bioinformatics approaches.

This study reports on the structural basis of drug resistance targeting the katG gene in a multidrug-resistant Mycobacterium tuberculosis (MDR-TB) strain with two novel mutations (His276Met and Gln295His) in addition to the most commonly reported mutation (Ser315Thr). A structural bioinformatics approach was used to predict the structure of the mutant KatG enzyme (MT). Subsequent molecular dynamics and docking studies were performed to explain the mechanism of isoniazid (INH) resistance. The results show significant conformational changes in the structure of MT leading to a change in INH binding residues at the active site, with a significant increase in the inhibition constant (Ki) of 5.67 µm in the mutant KatG-isoniazid complex (MT-INH) compared with the wild-type KatG-isoniazid complex (WT-INH). In the case of molecular dynamics studies, root mean square deviation (RMSD) analysis of the protein backbone in simulated biological conditions revealed an unstable trajectory with higher deviations in MT throughout the simulation process (1 ns). Moreover, root mean square fluctuation (RMSF) analysis revealed an overall increase in residual fluctuations in MT compared with the wild-type KatG enzyme (WT), whilst the INH binding residues of MT showed a decreased fluctuation that can be observed as peak deviations. Hence, the present study suggests that His276Met, Gln295His and Ser315Thr mutations targeting the katG gene result in decreased stability and flexibility of the protein at INH binding residues leading to impaired enzyme function.

Identification of bacteria in culture negative and polymerase chain reaction (PCR) positive intraocular specimen from patients with infectious endopthalmitis.

A novel Denaturing High-Performance Liquid Chromatography (dHPLC)-based technique allows rapid high-resolution analysis of PCR products. We show the application of this PCR/dHPLC approach for direct detection and identification of bacterium from the Eubacterial PCR amplified products of aqueous and vitreous aspirates from patients with endopthalmitis and to differentially identify the culture negative cases and initiate appropriate therapy. The aim of this study is to identify culture negative PCR positive cases by the application of PCR based DNA sequencing. A total of 116 intraocular specimens were subjected for the study. Sixty-nine different bacteria were identified using dHPLC based DNA sequencing of which predominant ones were Gram-positive bacteria and cannot be cultured by conventional methods. Forty eight different bacteria detected in this study is being reported for the first time in infectious endopthalmitis.

"pp65 antigenemia and real time polymerase chain reaction (PCR) based-study to determine the prevalence of human cytomegalovirus (HCMV) in kidney donors and recipients with follow-up studies".

BACKGROUND: The present study was undertaken to determine the rate of occurrence of Human cytomegalovirus (HCMV) among kidney transplant recipients and donors by application of direct detection methods and to understand HCMV infection/disease development among transplanted patients as a prospective study. RESULTS: Peripheral blood samples collected from 76 kidney donors and 76 recipients from September 2007 to August 2009 were subjected to pp65 antigenemia and Quantitative real-time PCR (qRT-PCR) assays. Data were analyzed under Group A, B and C. Group A was further divided into sub-groups I, II, III, IV, and V for better understanding. Three, one and two donors in sub-group I, III, IV of Group A tested positive for real time PCR respectively. One recipient from group III tested positive for HCMV by qRT- PCR prior transplantation and remained positive one month post-transplantation. Three other recipients, tested negative prior to transplantation became positive a month after transplantation. Group B consisted of 18 donor-recipient pairs and one of the donor tested positive for HCMV by qRT-PCR. Eight recipients tested positive for HCMV one month after transplantation. The pp65 positivity and HCMV DNA load was high among group C recipients who mostly had symptoms of active disease. Significantly high values of pp65 antigenemia were observed among recipients of sub-group II (non-parametric chi-square test p = 0.007). Positive correlation between pp65 antigenemia and qRT-PCR value was observed. Thirty three of the recipients with disease treated with Valgancyclovir showed improved clinical outcome. CONCLUSION: Our study showed that a significant proportion of kidney recipients develop HCMV infection following renal transplantation in spite of the absence of HCMV among donors. pp65 antigenemia assay and qRT- PCR methods can be applied to detect HCMV among kidney donors and recipients to monitor development of disease and these assays were predicative of HCMV infection among them. Clinical resistant to valganciclovir was not observed.

A study on the incidence, microbiological analysis and investigations on the source of infection of postoperative infectious endophthalmitis in a tertiary care ophthalmic hospital: an 8-year study.

BACKGROUND: The objective of the study was the determination of the incidence of culture-proven postoperative endophthalmitis and probable sources of infection. MATERIALS AND METHODS: It was a prospective study on the microbiology, incidence and probable sources of infection in patients with postoperative infectious endophthalmitis carried out in a tertiary care eye hospital. Consecutive patients diagnosed with postoperative infectious endophthalmitis during the years 2000-2007 were investigated for the causative infective agent and possible sources of infection. The surgical data and microbiological data including the investigations performed to trace the source were recorded in a specific formatted form and were gathered and compiled for analysis. RESULTS: Data of analysis showed that 98 (0.042%) out of 2,31,259 patients who underwent intra-ocular surgery developed infectious endophthalmitis. Among these, 70 (0.053%) occurred after cataract, 10 (0.5%) after penetrating keratoplasty (PK) and 18 (0.018%) following other types of intra-ocular surgeries. The predominant infectious agents isolated were bacteria (89.7%), with equal proportions of gram-positive and gram-negative bacteria. Polymicrobial infection was noted in four and fungi in seven patients. Occurrence of postoperative endophthalmitis was sporadic and not related to any specific part of period in a year. Sources of infection were donor corneal rim in six post-PK patients and phaco probe in one who had postphacoemulsification endophthalmitis CONCLUSIONS: Overall incidence of postoperative endophthalmitis over an 8-year period was quite low. The sources of infection could be established in six post-PK endophthalmitis patients and in a postcataract surgery.

Diagnostic utility of polymerase chain reaction on intraocular specimens to establish the etiology of infectious endophthalmitis.

PURPOSE: To evaluate the utility of polymerase chain reaction (PCR) on intraocular clinical specimens (aqueous humor [AH] and vitreous fluid [VF]) as an etiologic diagnostic tool relative to microbiological culture methods in infectious endophthalmitis. METHODS: Conventional bacterial and mycologic cultures and PCR for eubacterial and panfungal genomes were applied for etiologic diagnosis on pairs of AH and VF obtained from 72 patients with clinically established infectious endophthalmitis. RESULTS: Based on cultures, an infectious etiology was established in 27 (37.5%) of 72 patients. PCR detected infectious etiology in all 72 patients. PCR increased the clinical sensitivity over culture by 62.5% (p<0.0001, McNemar test). The frequency of culture positivity, single infections, and polymicrobial infection varied significantly among the types of endophthalmitis (p<0.0001, chi-square test). PCR detected an infectious etiology in 48 patients and polymicrobial infection in 24 patients. An etiology was established by PCR on 56 (77.8%) AH and 65 (90.3%) VF of the 72 patients and this difference had no statistical significance. CONCLUSIONS: PCR on intraocular specimens as an etiologic diagnostic tool has been shown to be specific and severalfold more sensitive than cultures and clinically useful. Therefore, PCR may be considered the gold standard to establish the etiology of infectious endophthalmitis. As there is no statistically significant difference in the results of PCR on AH and VF, PCR on AH could be the method of choice considering safety and simplicity of the procedure of its collection.

Seroprevalence of human immunodeficiency virus, hepatitis B virus and hepatitis C virus among eye donors.

Blood specimens collected at the time of enucleation of the eyes from 483 consecutive eye donors were tested for sero-markers of Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV). Antibodies to HIV1 were detected in 3 (0.62%), HBsAg in 17 (3.52%) and antibodies to HCV in 7 (1.45%).

The diagnostic significance of enzyme linked immuno-sorbent assay for herpes simplex, varicella zoster and cytomegalovirus retinitis.

PURPOSE: To evaluate the diagnostic usefulness of enzyme linked immuno-sorbent assay (ELISA) in single serum samples to associate herpes simplex virus (HSV), varicella zoster virus (VZV) or cytomegalovirus (CMV) with viral retinitis as against polymerase chain reaction (PCR) on intraocular specimens. It was also designed to study the seroprevalence in normal healthy individuals, and the genomic prevalence of HSV, VZV and CMV in patients without an active viral inflammatory process. METHODS: PCR for the detection of HSV, VZV and CMV genomes was done on 33 and 90 intraocular fluids from viral retinal patients and non-viral controls respectively. ELISA was done on 30 and 100 serum samples from viral retinitis patients and normal healthy controls respectively. RESULTS: PCR did not detect HSV, VZV and CMV genomes except one, in which VZV-DNA was detected. ELISA showed prevalence rates of 28%, 83% and 90% for antibodies against HSV, VZV and CMV respectively in the normal population. In the 30 viral retinitis patients, PCR detected HSV-DNA in 2 (6.7%), VZV-DNA in 7 (23.3%) and CMV-DNA in 6 (20.0%) patients, while ELISA detected antibodies against HSV, VZV and CMV in 13 (43.3%), 24 (80.0%) and 23 (76.7%) patients respectively. ELISA was of value in indirect diagnosis only in 6 (20.0%) as compared to 15 (50.0%) of 30 patients by PCR, this difference was statistically significant (McNemar test, P value = 0.005). CONCLUSION: Serology by ELISA is no longer a useful diagnostic tool to associate HSV, VZV and CMV viruses with viral retinitis.

Endophthalmitis caused by Acinetobacter calcoaceticus. A profile.

PURPOSE: To report the clinical and microbiological profile of endophthalmitis caused by Acinetobacter calcoaceticus. METHODS: A retrospective study of case series of Acinetobacter calcoaceticus endophthalmitis. Outcome measures included ability to sterilise the eye, anatomical result (clear media and attached retina) and visual recovery (visual acuity > 6/60). RESULTS: Of the 20 cases studied, 10 were cases of postoperative endophthalmitis, 3 were posttraumatic, 6 were endogenous and one was bleb-related endophthalmitis. Specific features of interest observed were relative chronicity of presentation and absence of any obvious predisposing factor in endogenous endophthalmitis cases. All cases could be sterilised except one, which needed evisceration. Cases with postoperative endophthalmitis had better anatomical outcome (7/10 with attached retina and clear media) and visual outcome (4/10 regained vision > 6/18). Higher smear positivity was seen in vitreous samples (72.2%) compared to aqueous samples (37.5%). Culture positivity was higher from the vitreous cavity compared to aqueous. The organism was sensitive to ciprofloxacin in a high percentage (88.9%) of cases. CONCLUSIONS: Visual recovery in Acinetobacter calcoaceticus endophthalmitis is modest. Ciprofloxacin is the antibiotic of choice.

Tuberculous granuloma managed by full thickness eye wall resection.

PURPOSE: To report the use of eye wall resection in the management of tuberculous granuloma. DESIGN: Interventional case report. METHODS: In a 26-year-old man with biopsy-proven tuberculous granuloma of the left eye, total eye wall resection and donor scleral grafting was performed for management of tuberculous granuloma involving the sclera, part of the cornea, the iris, the chamber angle, and the ciliary body. Adjuvant therapy included oral antitubercular medication. RESULTS: The treatment of the infection was successful. The scleral graft healed well, and the crystalline lens was preserved. CONCLUSIONS: Total eye wall resection, a technique described in the management of uveal tumors, can be adopted to manage selected cases of tuberculous granuloma of the eye.

Preparation of amniotic membrane for ocular surface reconstruction.

We describe the preparation and preservation of human amniotic membrane required for transplantation in the management of ocular surface diseases. Informed consent is obtained and the donor is screened to exclude risk of transmissible infections such as human immunodeficiency virus (HIV), hepatitis B virus, hepatitis C virus, and Treponema pallidum infections. Ideally, the media and washing solutions needed for the preparation of amniotic membrane are prepared only a week to 10 days prior to use and not stored in the freezer weeks ahead. The AM obtained under sterile conditions after elective caesarian section is washed free of blood clots and chorion. With the epithelial surface up, amniotic membrane is spread uniformly without folds or tears on individually sterilized 0.22 micron nitrocellulose membranes of the required sizes. The prepared filter membrane with the adherent amniotic membrane is placed in the preservative medium and stored at -80 degrees C. The membranes are released when the repeat serology for HIV after the window period has excluded virus infection in the donor. Depending on consumption they may be used up to 6 months after preparation, though many have recommended storage for an indefinite period. Since the amniotic membrane has only incomplete expression of HLA antigens and amniotic epithelial cells do not express them, it is not rejected after transplantation. The presence of several cytokines in the amniotic membrane promotes epithelialization with reduction of fibrosis during healing.

Clinical profile and immunological status of cytomegalovirus retinitis in organ transplant recipients.

PURPOSE: Cytomegalovirus retinitis (CMV) is the most common ocular opportunistic infection in transplant recipients. This retrospective study attempts to report the differences in occurrence of cytomegalovirus retinetis in transplant recipients from those reported in patients with acquired immunodeficiency syndrome (AIDS). METHODS: 25 eyes of 15 transplant recipients (14 renal and one cardiac) with cytomegalovirus retinitis were retrospectively reviewed. Immunological profile included CD4+ and CD8+ T lymphocyte counts, CD4+/CD8+ cell ratio (5 cases) and serology for the viral antibodies (8 cases). RESULTS: A predominantly bilateral presentation (60%) was noted. Active cytomegalovirus retinitis (72%) in zone 2 (92%) of the inferotemporal quadrant (68%) was noted. The average cell counts were within normal limits (mean CD4 cell count-711/microliter), unlike in late stages of AIDS with cytomegalovirus retinitis (CD4 count < 50/microliter). Serology revealed an IgM positivity of 53%. Retinal detachment (52%) was the most common complication occurring after an average of 5.4 months. CONCLUSION: CMV retinitis in organ transplant recipients appears to differ from that in AIDS patients. CMV retinitis presents early and has different immunological profile, probably owing to differences in pathogenesis.