Soumyava Basu

Factors influencing polymerase chain reaction outcomes in patients with clinically suspected ocular tuberculosis.

BackgroundPolymerase chain reaction (PCR) assay can be a useful method for definitive diagnosis in paucibacillary infections such as ocular tuberculosis (TB). In this study, we have evaluated factors affecting PCR outcomes in patients with clinically suspected ocular TB. Patients with clinically suspected ocular TB were investigated by PCR of aqueous or vitreous samples. Three control groups were also tested: group 1 included culture-proven non-tuberculous endophthalmitis, group 2 culture-negative non-tuberculous endophthalmitis, and group 3 patients undergoing surgery for uncomplicated cataract. PCR targeted one or more of following targets: IS6110, MPB64, and protein b genes of Mycobacterium tuberculosis complex. Multiple regression analysis (5% level of significance) was done to evaluate the associations between positive PCR outcome and laterality of disease, tuberculin skin test (TST)/interferon-gamma release assay (IGRA), chest radiography, and type of sample (aqueous or vitreous). The main outcome measures were positive PCR by one or more gene targets, and factors influencing positive PCR outcomes.ResultsAll 114 samples were tested for MPB64, 110 for protein b, and 88 for IS6110. MPB64 was positive in 70.2% (nu2009=u200980) of tested samples, protein b in 40.0% (nu2009=u200944), and IS6110 in only 9.1% (nu2009=u20098). DNA sequencing of amplicons from four randomly chosen PCR reactions showed homology for M. tuberculosis complex. Of the 80 PCR-positive patients, 71 completed a full course of antitubercular therapy, of which 65 patients (91.5%) had complete resolution of inflammation at final follow-up. Among controls, 12.5% (3 out of 24) in group 1 and 18.7% (6 out of 32) in group 2 also tested positive by PCR. No PCR-positive outcome was observed in control group 3 (nu2009=u200925). Multiple regression analysis revealed significant association of positive PCR outcome with bilateral presentation, but not with a positive TST/IGRA, chest radiography, or type of sample (aqueous/vitreous) used.ConclusionsCareful selection of gene targets can yield high PCR positivity in clinically suspected ocular TB. Bilateral disease presentation but not any evidence of latent systemic TB influences PCR outcomes. False-positive results may be seen in ocular inflammation unrelated to ocular TB.

Degree, duration, and causes of visual impairment in eyes affected with ocular tuberculosis

BackgroundOcular tuberculosis (TB) can affect nearly every ocular tissue, leading to a variety of vision-threatening clinical manifestations. The goal of this study is to estimate the degree, duration, and causes of visual impairment in eyes affected by ocular TB.ResultsThis was a retrospective study of patients diagnosed as ocular TB based on polymerase chain reaction (PCR) for Mycobacterium tuberculosis complex. We applied the World Health Organization definition of visual impairment (VI) to affected eye(s), instead of better-seeing eye. Best-corrected visual acuity (BCVA) of <6/18 and ≥6/60 in the affected eye was classified as moderate VI and <6/60 and ≥3/60 as severe VI. Data collected included presenting and final BCVA of affected eyes and the worst BCVA during the study period. Sixty-one eyes of 40 patients were analyzed. Twenty-five patients (52.1%) had bilateral disease. The mean worst BCVA and mean final BCVA (logMAR) were 1.26u2009±u20090.87 and 0.61u2009±u20090.85, respectively, and their difference was highly significant (pu2009<u20090.0001, Friedman test). The median worst and final BCVA results were 1.30 (range 0.0 to 3.0) and 0.20 (range 0.0 to 3.0), respectively. The mean duration of follow-up was 98.34u2009±u200981.81xa0weeks. Moderate and severe VIs were seen in 14 (22.9%) and 12 (19.7%) eyes, respectively, during the course of follow up. Twenty eyes (32.8%) had BCVA of <3/60. Moderate VI or worse was most commonly seen in eyes with multifocal serpiginoid choroiditis (nu2009=u20096; 100%), retinal vasculitis (nu2009=u200925; 80.6%), and panuveitis (nu2009=u200912; 80%). The mean duration of visual loss was 25.2u2009±u200942.37xa0weeks (median 6.43xa0weeks, range 0 to 206.42xa0weeks). Vitreous hemorrhage, complicated cataract, and macular scarring were the common causes of VI.ConclusionOcular TB can result in prolonged visual impairment, more commonly in patients with posterior uveitis or panuveitis.

Development of a Loop-Mediated Isothermal Amplification Assay Targeting the mpb64 Gene for Diagnosis of Intraocular Tuberculosis

ABSTRACT A loop-mediated isothermal amplification (LAMP) assay targeting the mpb64 gene for the diagnosis of intraocular tuberculosis was highly specific (100%), sensitive (85.7%), rapid, and easy to perform. The LAMP assay can be an alternative to conventional PCR for the diagnosis of ocular tuberculosis in resource-limited settings.

Optic disc tuberculoma in a patient with miliary tuberculosis.

A 27-year-old female, on anti-tubercular therapy for miliary tuberculosis for 1 week, presented with gradual diminution of right eye vision for 4 months. Right eye visual acuity was counting fingers at 15u2009cm. Right fundus showed a yellowish-white vascularized lesion, 4 disc diameters in size, overlying the optic disc and associated neurosensory macular detachment. The left eye was normal. A Mantoux test was negative. The authors diagnosed presumed optic disc tuberculoma in the right eye. Oral prednisolone in tapering doses was added to the anti-tubercular therapy. The optic disc lesion regressed with residual scarring and vision became 20/30 at 7 months.

Presumed Tubercular Retinal Vasculitis with Serpiginous-like Choroiditis in the Other Eye

A 17-year old boy, with decreased vision in right eye for 15 days, presented with retinal periphlebitis in multiple quadrants of the right eye and partially active serpiginous-like choroiditis in the left eye. Tuberculin test was positive (16u2009mm induration), and chest X-ray showed hilar lymphadenopathy. The patient was treated with a 9-month course of anti-tubercular therapy and a tapering dose of oral corticosteroids. Both retinal vasculitis and choroiditis lesions resolved over 3–4 months. Retinal neovascularization in the right eye was treated with laser photocoagulation. There was no recurrence over an18-month follow-up. The probable pathogenic mechanism for such a presentation is discussed.

Pathogenesis and Pathology of Intraocular Tuberculosis

Abstract Intraocular tuberculosis (TB) is an extremely paucibacillary form of extrapulmonary TB. It likely results from bacterial dissemination to the eye from lungs, localization in ocular tissues, followed later by reactivation and appearance of clinical signs. These have been partly demonstrated in the guinea pig model of ocular TB. Alternative hypotheses have been suggested but are not supported by adequate evidence. Mycobacterial recognition by macrophages and dendritic cells probably leads to activation of several immune pathways, primarily the Th1 and Th17 pathways, as in other TB infections. Histopathology of bacteriologically proven ocular TB tissues reveals granulomatous inflammation with central caseous necrosis containing occasional acid-fast organisms. Recent reports have also demonstrated intraretinal granuloma in the vicinity of retinal vessels and T-cell infiltration of epiretinal membranes, in cases of TB retinal vasculitis.

Optic disc doubling.

Many developmental defects can simulate the optic disc (optic disc pseudodoubling). True optic disc duplication with 2 independent retinal vasculatures is rare. Associated optic nerve duplication is rarer still and seen in lower vertebrates. We report a rare case of unilateral double optic discs with a single optic nerve in the left eye of a 41-year-old man, otherwise asymptomatic in the affected eye.

DNA chip-assisted diagnosis of a previously unknown etiology of intermediate uveitis- Toxoplasma gondii

We report the use of DNA chip technology in the identification of Toxoplasma gondii as the etiological agent in two patients with recurrent intermediate uveitis (IU). Both patients had recurrent episodes of vitritis (with no focal retinochoroidal lesion) over varying time intervals and were diagnosed to have IU. The tuberculin test was negative in both. Blood counts, erythrocyte sedimentation rate, and serum angiotensin convertase enzyme levels were normal. In both cases, the vitreous fluid tested positive for the T. gondii DNA sequence by using a uveitis DNA chip (XCyton Pvt. Ltd., Bangalore, India). It contained complimentary sequences to “signature genes” of T. gondii, Mycobacterium tuberculosis, M. chelonae, and M. fortuitum. The enzyme-linked immunosorbent assay (ELISA) detected elevated serum antitoxoplasma IgG levels in both. They responded to the antitoxoplasma therapy with oral co-trimoxazole (and additional intravitreal clindamycin in patient 1), with no recurrence during follow-ups of 6 and 8 months, respectively.

Ocular parasitoses: A comprehensive review

Parasitic infections of the eyes are a major cause of ocular diseases across the globe. The causative agents range from simple organisms such as unicellular protozoans to complex metazoan helminths. The disease spectrum varies depending on the geographic location, prevailing hygiene, living and eating habits of the inhabitants, and the type of animals that surround them. They cause enormous ocular morbidity and mortality not because they are untreatable, but largely due to late or misdiagnosis, often from unfamiliarity with the diseases produced. We provide an up-to-date comprehensive overview of the ophthalmic parasitoses. Each section describes the causative agent, mode of transmission, geographic distribution, ocular pathologies, and their management for common parasites with brief mention of the ones that are rare.

Safety, sterility and stability of direct-from-vial multiple dosing intravitreal injection of bevacizumab

This study aims to determine the stability, sterility and safety of bevacizumab multiple dosing from a single vial without prior aliquoting.