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Atypical mycobacteria or non-tuberculous mycobacteria (NTM) are a group of acid-fast bacteria that are pathogenic to different parts of the eye. The organisms can cause a spectrum of ocular infections including keratitis, scleritis, uveitis, endophthalmitis and orbital cellulitis. Trauma, whether surgical or nonsurgical, has the highest correlation with development of this infection. Common surgeries after which these infections have been reported include laser in situ keratomileusis (LASIK) and scleral buckle surgery. The organism is noted to form biofilms with sequestration of the microbe at different inaccessible locations leading to high virulence. Collection of infective ocular material (corneal scraping/necrotic scleral tissue/abscess material/vitreous aspirate, etc.) and laboratory identification of the organism through microbiologic testing are vital for confirming presence of the infection and initiating treatment. In cluster infections, tracing the source of infection in the hospital setting via testing of different in-house samples is equally important to prevent further occurrences. Although the incidence of these infections is low, their presence can cause prolonged disease that may often be resistant to medical therapy alone. In this review, we describe the various types of NTM-ocular infections, their clinical presentation, laboratory diagnosis, management, and outcomes., (Copyright © 2023 Copyright: © 2023 Indian Journal of Ophthalmology.)

Purpose: The aim of this study was to evaluate the risk factors, microbiology, and treatment outcomes of polymicrobial keratitis (PMK)., Methods: We retrospectively analyzed 65 patients diagnosed with PMK between 2016 and 2019. The clinical and microbiological characteristics and outcomes were evaluated. The primary outcome measure was clinical resolution of keratitis. Absolute success (group A) was defined as resolution of infection with medical treatment, qualified success (group B) was resolution with medical therapy and additional minor procedures, and failure (group C) was defined as worsening of infection and presence of corneal melting or perforation requiring therapeutic penetrating keratoplasty or evisceration., Results: Of 4764 cases of microbial keratitis, PMK was identified in 65 eyes of 65 patients (1.36%). Infiltrate was central in 60% (39 eyes). Predisposing factors were higher in group C and included uncontrolled diabetes mellitus in 25% (7/28), history of trauma/foreign body in 57.1% (16/28), and poor presenting visual acuity (0.9 for group A vs. 1.79 for group B vs. 3.00 logarithm of the minimum angle of resolution for group C; P = 0.02). Microbiological profiling revealed that a majority (95%: 62/65) had bacterial with fungal keratitis. High fluoroquinolone resistance was noted (57%; 34/59). Absolute success was achieved in 28.3% (17/60), qualified success in 16.6% (10/60), and treatment failure was noted in 55% (33/60). The final best corrected visual acuity in group A was significantly better than that in group B and C (0.44 vs. 3.00 vs. 2.78; P < 0.001)., Conclusions: PMK is extremely rare but responds poorly to medical therapy. Bacterial with fungal etiology is predominant. Early surgical intervention to improve overall outcome is advocated., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The authors describe two cases of corneal ocular surface squamous neoplasia (OSSN), presenting at our rural eyecare centre, which were initially misdiagnosed as viral epithelial keratitis and corneal pannus with focal limbal stem cell deficiency. Both the cases were refractory to initial treatment and corneal OSSN was suspected. Anterior segment-optical coherence tomography (AS-OCT) revealed a thickened, hyper-reflective epithelium with abrupt transition and an underlying cleavage plane, features typical of OSSN. Topical 1% 5-fluorouracil (5-FU) therapy was initiated and in two cycles (first case) to three cycles (second case), complete resolution was noted both clinically and on AS-OCT, with no significant side effects. Both patients are currently free of tumour at the 2-month follow-up period. The authors report the rare, atypical presentations of corneal OSSN, discuss the masquerades and highlight the role of primary topical 5-FU in managing corneal OSSN in limited resource settings., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

We present a comprehensive review of existing literature on surgical corneal neurotization (SCN) as a treatment modality for neurotrophic keratopathy (NK) with an interim report of seven cases where SCN was performed using the indirect approach and followed up till 18 months postoperatively to look for improvement in ocular surface, corneal sensations, and nerve regeneration by using in vivo confocal microscopy (IVCM). A literature search was performed for publications with keywords "corneal nerves," "neurotization," "esthesiometry," "corneal anesthesia," and "neurotrophic keratopathy." All literature available till December 31, 2020 was reviewed and included to describe NK and its management options, particularly SCN. NK is associated with absent or reduced corneal sensations and is managed using a step-ladder algorithm ranging from medical management for symptomatic relief to surgical corneal neurotization. Both direct and indirect approaches of SCN have a favorable outcome with reduced surgical morbidity in the indirect approach using sural nerve graft. Post neurotization, corneal sensation recovery may take up to 3-6 months, while nerve regeneration on confocal microscopy can take as long as 6 months-1 year., Competing Interests: None

Purpose: The purpose of this study was to report 3 cases of microbial keratitis, wherein trypan blue staining was used to aid the microbiological diagnosis of fungal keratitis and Pythium keratitis in a rural setup., Methods: Three consecutive patients who presented with a diagnosis of infectious keratitis underwent corneal scraping, and the smears were assessed using trypan blue stain and potassium hydroxide (KOH) mount., Results: Of the 3 cases, the first 2 cases showed septate fungal filaments in trypan blue-stained preparation and KOH mount. Case 3 showed the presence of broad aseptate filaments with ribbon-like folds on both KOH mount and trypan blue stain, consistent with the diagnosis of Pythium keratitis. The first 2 cases improved with topical and systemic antifungals. Case 1 healed with scarring at 7 weeks with improvement in best-corrected visual acuity (BCVA) to 20/60. Case 2 healed within 2 weeks, and BCVA improved to 20/40. Case 3 received topical linezolid (0.2%), azithromycin eye ointment, and oral azithromycin. At 5 weeks the infection decreased but thinning was noted, which necessitated tissue adhesive and bandage contact lens application. Scarring was noted at 10 weeks, and BCVA improved to 20/40., Conclusions: In this case series, trypan blue staining showed promising results in the easy identification of aseptate and septate fungal elements. This is the first case series showing the utility of this stain in the management of microbial keratitis., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To report the intermediate outcomes of therapeutic penetrating keratoplasty (TPK) performed for severe microbial keratitis using glycerol-preserved corneas during the Corona virus diseases of 2019 (COVID-19)., Methods: Retrospective non-comparative case series from April to August 2020 in a network of tertiary eye care centers. Glycerol-preserved tissues were used for therapeutic keratoplasty (TPK). We reviewed the demographics, microbiology, surgical outcomes such as wound integrity, recurrence, graft melt, epithelialization, and complications., Results: A total of 49 eyes that underwent TPK with glycerol-preserved corneal tissues were analyzed. The primary indication was severe microbial keratitis in 47 eyes. The majority was a fungal infection in 33 eyes (67.3%). The mean age was 53.8 ± 12.2 years, with male predominance (3:1). The corneas were stored for an average of 85.5 ± 53 days prior to transplant. The median donor age was 65 years. The grafts were tectonically stable in 32/36 eyes (88.9%) at 1 month and 20/24 eyes (83.3%) at 3 months. The graft melt was noted in three eyes at 1 and 3 months. The recurrence of the infection was noted in four eyes and all were of fungal etiology. The graft epithelialization was delayed with a mean duration of 48.9 ± 25 days after surgery. Post-TPK, raised intra-ocular pressure (>21 mm Hg) was noted in 51.2% at 1 week, 17.4% at 1 month, and 11.8% at 3 months., Conclusion: Glycerol preservation is a reliable alternative with good therapeutic outcomes in the short and interim postoperative period. Delayed epithelialization and secondary glaucoma were the commonest postoperative complications., Competing Interests: None

Purpose: To evaluate the efficacy of trypan blue in direct microscopic examination of corneal scrapings in the diagnosis of non-viral microbial keratitis., Methods: In a prospective, interventional, masked study, 82 consecutive patients were investigated. Direct microscopic examination of the corneal scrapings involved three smears stained with potassium hydroxide with calcofluor white (KOH + CFW), Gram stain (not analyzed), and trypan blue stain and culture for bacteria, fungus, and Acanthamoeba. While KOH + CFW stained slides were examined under a fluorescence microscope, trypan blue-stained slides were examined by two microbiologists (masked to KOH + CFW and culture results) under normal light microscopy. Thirty samples were reexamined for interobserver and intraobserver variability., Results: Out of 82 samples, fungal/fungus-like elements were seen in 48 (58.5%) in KOH + CFW and 38 (46.3%) in trypan blue stain. One microsporidial case, detected in KOH + CFW was negative in trypan blue stain (culture not done). Fungal growth was positive in 23 out of 81 (28.3%) cases cultured, single bacterial species in 18 (22.2%), Pythium insidiosum in three, mixed bacteria and fungus/Pythium in 7 (8.6%), Acanthamoeba in none and 30 (37.0%) samples were sterile. With culture as gold standard, the respective sensitivity (84.9%, 75.7%) and specificity (90.9%, 68.2%) of KOH + CFW stain and trypan blue stain were comparable (p = 0.16, P = 0.06). The interobserver linear weighted kappa score between the two microbiologists was 1.00 while it was 0.86 for intraobserver agreement., Conclusion: Trypan blue stain, an easily available dye to ophthalmologists, is highly efficacious in the diagnosis of fungal keratitis., Competing Interests: None

Purpose: To report the incidence, clinical features, microbiologic profile, and risk indicators in the development of microbial keratitis in Thyroid Eye Disease (TED)., Methods: All patients who were diagnosed to have TED and developed microbial keratitis between the years 2009 to 2017 at the Ophthalmic Plastic Surgery service, LV Prasad Eye Institute were included in this retrospective interventional study. The clinical features, microbiological profile, and treatment outcome of the infection were studied. Possible risk factors leading to the development of microbial keratitis were studied., Results: A total of 1,000 patients of TED were evaluated in the 10-year period. Of the 1,000, 13 patients (14 eyes, 1.4%) were diagnosed with microbial keratitis. The average age at presentation was 44 years (range 1969 years). Of the 13 patients, 10 (77%) were men, 12 (92%) were hyperthyroid, and 12 (92%) were active (average clinical activity score 3) at presentation. Average exophthalmometry value in the involved eye was 24.75mm, and severe eyelid retraction (>2mm scleral show) was noted in 13 of 14 eyes. None of the patients had optic nerve compression. Moderate motility restriction (2 in all gazes) was noted in 6 eyes, and severe motility restriction (4 in all gazes) in 8 eyes. At presentation, 11 (85%) had visual acuity of counting fingers at 1 meter or less, The mean follow up from the time of presentation was 18.3 months (range 566 months). Majority of the eyes (8/14) presented with severe infection (panophthalmitis with microbial keratits = 1, total corneal infiltrate with/without melt = 4, severe thinning/perforation = 4). Microbiological work up of 14 eyes revealed presence of gram-negative bacteria in 5 eyes which included Escherichia coli, Pseudomonas sp., and Acinetobacter sp., and gram-positive bacteria in 4 eyes including Streptococcus pneumoniae, Corynebacterium sp., and Staphylococcus sp. Three eyes revealed a mixed infection of E. coli with Alternaria sp, and E. coli with Corynebacterioum amycolatum while 1 had Corynebacterium pseudodiptheriticum, and S. pneumoniae. Two eyes of the bilateral case showed no growth. Antibiotic susceptibility revealed 6 of the 7 gram-negative isolates were multidrug resistant, whereas the gram-positive isolates were susceptible to most drugs tested. Surgical procedures required were tarsorrhaphy in 7 eyes, tissue adhesive with bandage contact lens in 4, evisceration in 4, levator recession in 2, 3-wall orbital decompression in 2, and penetrating keratoplasty in 1 eye. The visual acuity at presentation was counting fingers or worse in 10/14 eyes. Posttreatment, 10 eyes achieved resolution of infiltrate (with visual improvement in 2), and 4 required evisceration., Conclusions: In the authors large series of TED, microbial keratitis was noted in 1.3% of patients presenting to a tertiary eye center. Majority presented with advanced diseases and ended with a poor outcome. Gram-negative isolates showed multidrug resistance. An association with early phase of active TED (CAS 3 or more), severe eyelid retraction, and moderate-severe motility restriction is suggested.Microbial Keratitis occurs in 1.3% cases of Thyroid Eye Disease. It is more common in men, and in active disease. The microbiological spectrum and possible clinical risk factors are presented.

Dysbiosis, or imbalance in the gut microbiome, has been implicated in auto-immune, inflammatory, neurological diseases as well as in cancers. More recently it has also been shown to be associated with ocular diseases. In the present study, the association of gut microbiome dysbiosis with bacterial Keratitis, an inflammatory eye disease which significantly contributes to corneal blindness, was investigated. Bacterial and fungal gut microbiomes were analysed using fecal samples of healthy controls (HC, n = 21) and bacterial Keratitis patients (BK, n = 19). An increase in abundance of several antiinflammatory organisms including Dialister, Megasphaera, Faecalibacterium, Lachnospira, Ruminococcus and Mitsuokella and members of Firmicutes, Veillonellaceae, Ruminococcaceae and Lachnospiraceae was observed in HC compared to BK patients in the bacterial microbiome. In the fungal microbiome, a decrease in the abundance of Mortierella, Rhizopus, Kluyveromyces, Embellisia and Haematonectria and an increase in the abundance of pathogenic fungi Aspergillus and Malassezia were observed in BK patients compared to HC. In addition, heatmaps, PCoA plots and inferred functional profiles also indicated significant variations between the HC and BK microbiomes, which strongly suggest dysbiosis in the gut microbiome of BK patients. This is the first study demonstrating the association of gut microbiome with the pathophysiology of BK and thus supports the gut-eye axis hypothesis. Considering that Keratitis affects about 1 million people annually across the globe, the data could be the basis for developing alternate strategies for treatment like use of probiotics or fecal transplantation to restore the healthy microbiome as a treatment protocol for Keratitis.

Dysbiosis in the gut microbiome has been implicated in several diseases including auto-immune diseases, inflammatory diseases, cancers and mental disorders. Keratitis is an inflammatory disease of the eye significantly contributing to corneal blindness in the developing world. It would be worthwhile to investigate the possibility of dysbiosis in the gut microbiome being associated with Keratitis. Here, we have analyzed fungal and bacterial populations in stool samples through high-throughput sequencing of the ITS2 region for fungi and V3-V4 region of 16S rRNA gene for bacteria in healthy controls (HC, n = 31) and patients with fungal keratitis (FK, n = 32). Candida albicans (2 OTUs), Aspergillus (1 OTU) and 3 other denovo-OTUs were enriched in FK samples and an unclassified denovo-OTU was enriched in HC samples. However, the overall abundances of these 'discriminatory' OTUs were very low (< 0.001%) and not indicative of significant dysbiosis in the fungal community inhabiting the gut of FK patients. In contrast, the gut bacterial richness and diversity in FK patients was significantly decreased when compared to HC. 52 OTUs were significantly enriched in HC samples whereas only 5 OTUs in FK. The OTUs prominently enriched in HC were identified as Faecalibacterium prausnitzii, Bifidobacterium adolescentis, Lachnospira, Mitsuokella multacida, Bacteroides plebeius, Megasphaera and Lachnospiraceae. In FK samples, 5 OTUs affiliated to Bacteroides fragilis, Dorea, Treponema, Fusobacteriaceae, and Acidimicrobiales were significantly higher in abundance. The functional implications are that Faecalibacterium prausnitzii, an anti-inflammatory bacterium and Megasphaera, Mitsuokella multacida and Lachnospira are butyrate producers, which were enriched in HC patients, whereas Treponema and Bacteroides fragilis, which are pathogenic were abundant in FK patients, playing a potential pro-inflammatory role. Heatmap, PCoA plots and functional profiles further confirm the distinct patterns of gut bacterial composition in FK and HC samples. Our study demonstrates dysbiosis in the gut bacterial microbiomes of FK patients compared to HC. Further, based on inferred functions, it appears that dysbiosis in the gut of FK subjects is strongly associated with the disease phenotype with decrease in abundance of beneficial bacteria and increase in abundance of pro-inflammatory and pathogenic bacteria., Competing Interests: Commercial affiliation with TCS Research, Tata Consultancy Services Ltd. does not alter our adherence to PLOS ONE policies on sharing data and materials.

A 28-year-old male farmer presented to our emergency service with bilateral painful visual loss for the past 7 days that occurred suddenly after alcohol consumption. Examination showed bilateral central corneal epithelial defects, 3+ stromal edema, and cortical cataracts. After treatment with oral and topical corticosteroids for 4 weeks the corneal edema had subsided completely with mild anterior stromal scarring. Rapid progression of cataract to intumescent stage warranted sequential cataract surgeries 1 and 2 months after first presentation. Postoperatively, visual acuity recovered to 20/20 and 20/30 in the right and left eye respectively. This case highlights the extremely rare presentation of bilateral alcohol-induced toxic endothelitis, which recovered after intensive corticosteroid therapy.

Purpose: The aim was to assess the clinical outcomes of corneal graft infections caused by multi-drug resistant Pseudomonas aeruginosa (MDR-PA)., Methods: This is a retrospective case series of 38 patients with corneal graft infections caused by MDR-PA managed from June to December 2011. Clinical and demographic details, treatment outcome on primary therapy, cases requiring a repeat graft, their outcome, and recurrence rate on treatment were analyzed. The outcome measure was resolution of infection. Success was "complete" if resolution was seen without subsequent recurrence up to 2 weeks and "partial" if it required intervention such as cyanoacrylate glue application. It was a "failure" if the infection could not be controlled and the patient required a repeat graft or the eye had to be eviscerated., Results: Thirty-one patients were initially treated with topical cefazolin 5% and ciprofloxacin 0.3%, 6 with topical colistin 0.19%, and 1 was treated with topical imipenem 1%. On this treatment, 9 cases showed complete success and 6 showed partial success. Twenty-two patients required a repeat graft, and 1 eye was eviscerated. The patients with outcome of success had smaller graft infiltrates (median area = 2 mm; range = 1-24.6 mm vs. median infiltrate area = 24.8 mm; range = 1.5-64 mm) than those with an outcome of failure (P = 0.02). At the mean follow-up of 50 days, recurrence after the repeat surgery was seen in 4/22 (18.2%) patients., Conclusions: Medical therapy can be tried in sensitive and smaller MDR-PA graft infiltrates, but larger infiltrates and those with endophthalmitis require early surgical intervention.

A 26-year-old farmer underwent deep anterior lamellar keratoplasty (DALK) for keratoconus. After 3 months, he presented with interface keratitis. Medical treatment failed and he underwent a repeat DALK. Microbiological scrapings from the interface revealed an infection caused by non-tuberculous mycobacteria. Despite the use of intensive antibiotic therapy and a repeat lamellar keratoplasty, the infiltrates recurred. The patient underwent therapeutic penetrating keratoplasty. Microbiology of the corneal tissue revealed growth of Mycobacterium chelonae, and on histopathology, the acid-fast bacilli were noted to be located deep at the pre-Descemet level. There was complete resolution of the infection with no episodes of recurrence and final best-corrected visual acuity was 20/40 at 1 year of follow-up. Medical therapy is unlikely to succeed in post-DALK interface keratitis and penetrating rather than lamellar keratoplasty may be considered the surgery of choice.

We report three cases of bilateral microsporidial keratitis, which is an unusual presentation. All three patients presented with bilateral, simultaneous, asymmetrical, deep stromal corneal infiltrates with symptoms ranging from 5 to 12 months. Predisposing factors were noted in two of three patients. Corneal scrapings for microbiology and histopathology of corneal tissue revealed microsporidial spores from both eyes of all patients. There was no response to medical therapy and all underwent bilateral corneal transplantation. Case one additionally had recurrences in the graft and underwent repeat keratoplasties and eventually keratoprosthesis. Microsporidial stromal keratitis is a possible cause of keratitis in cases of very long-standing, indolent, culture-negative, deep stromal corneal infiltrates. So far, this infection has been reported as unilateral; however, we report these cases of bilateral infection, which is rare. Corneal transplantation is the preferred line of management due to lack of response to medical therapy. [ABSTRACT FROM AUTHOR]

Abstract: Infectious keratitis is an important cause of visual loss worldwide. Clinical diagnosis in the past was often supported only by microbiology and pathology to a lesser extent. Recent advances in the histological and molecular diagnosis of corneal infections have resulted in rapid and accurate diagnosis of the infectious agent. This review will provide an overview of the various corneal infections, with emphasis on histopathologic and molecular diagnosis. This is more so in cases where microbiology, the gold standard for corneal infections, comes out as negative. Thus a cumulative input from clinical, microbiology, histopathology and molecular methods of diagnosis not only helps in treating the patients but also contributes to better understanding of the disease process and paves the way to evaluate the emerging modalities of treatment like disease modifying medications, biomaterials and surgical techniques. [ABSTRACT FROM AUTHOR]

Abiotrophia defectiva is a nutritional variant of Streptococci. We describe a case of microbial keratitis due to A. defectiva in a patient who had undergone penetrating keratoplasty and was on corticosteroid therapy for recent graft rejection. Isolation of this organism confirmed this to be an opportunistic infection. [ABSTRACT FROM AUTHOR]

We report a rare case of a deep stromal keratitis with a chronic indolent course, diagnosed as microsporidial keratitis from corneal scrapings. The patient's condition worsened despite medical therapy and penetrating keratoplasty was performed. The histopathology of the corneal tissue revealed multiple microsporidial spores in the posterior stroma and the endothelial exudates, whereas there was no clinical or histopathological breach in Descemet's membrane. This is the second report in the literature to report that micropsoridial spores can cross the intact Descemet's membrane. [ABSTRACT FROM AUTHOR]

Keratitis, an inflammatory disease of the eye, when neglected could lead to sight-threatening complications and ultimately blindness. Globally, over a million people are affected by keratitis annually. Keratitis has a microbial etiology and is caused by bacteria, fungi, viruses, etc. The present study compared the ocular surface fungal microbiome of healthy individuals and individuals with fungal keratitis. Fungal microbiomes from the conjunctival swabs of healthy individuals and from conjunctival swabs and corneal scrapings of individuals with fungal keratitis were generated using ITS2 region amplicons. Microbiomes were sequenced using Illumina MiSeq 2 × 250 base pair chemistry with a paired-end protocol. Based on Alpha diversity indices, phylum and genera level diversity, abundance differences, and heat map analysis, the fungal microbiomes of conjunctival swabs and corneal scrapings of individuals with fungal keratitis exhibited dysbiosis (alterations in the diversity and abundance) compared to the ocular surface microbiome of the healthy control individuals. This is the first report indicating dysbiosis in the fungal microbiome of conjunctival swabs and corneal scrapings in individuals with fungal keratitis. A total of 11 genera present in the majority of the eyes constituted the variable core ocular microbiome. [ABSTRACT FROM AUTHOR]

Objective: To report the outcomes of ipsilateral rotational autokeratoplasty (RAK) for nonprogressive paracentral corneal opacities in children <16 years of age. Design: Retrospective, consecutive, interventional case series. Participants: Thirty-three eyes of 33 children aged <16 years undergoing RAK for nonprogressive paracentral scars. Methods: Medical records were retrospectively reviewed for the primary etiology of corneal opacity, time of onset, duration of opacity, preoperative visual acuity, formula used for calculation of trephine size, size of the trephine used, and duration of follow-up. Any intraoperative and early and late postoperative complications were noted for all patients. Postoperative visual acuity and astigmatism were noted. Visual acuity was converted to logarithm of the minimum angle of resolution units for analysis. Main Outcome Measures: Primary outcome was postoperative visual acuity. Graft clarity and complications were analyzed as secondary outcomes. Results: The mean age at surgery was 7.2±3.9 months. The mean follow-up duration was 27±37 months. The commonest etiology of corneal opacity was trauma (62.5%), followed by resolved microbial keratitis (21.9%). Postoperative visual acuity (1.25±0.84) was significantly better (P<0.001) than preoperative visual acuity (2.05±0.96). The mean astigmatism at last visit was 4.04±2.21 diopters. Postoperative visual acuity was better in older children (β = −0.01; P = 0.03) and had a shorter delay in presentation (β = 0.02; P = 0.05). At the last follow-up, the graft was clear in 27 cases (81.25%). The cumulative probability of graft survival was 85% at 2 years and 65% at 5 years. Complications included wound leak in 4 eyes, secondary glaucoma in 2 eyes, graft infiltrate and traumatic dehiscence in 1 eye each. Conclusions: Rotational is a autokeratoplasty viable alternative surgical option to allogenic keratoplasty. Graft survival at 2 years seems to be better than allogenic keratoplasty. Younger age and delay in presentation contribute to poorer visual outcomes after surgery. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. [Copyright &y& Elsevier]

Microbial keratitis is an infectious disease of the eye, in which the cornea is inflamed. Under severe conditions, keratitis can lead to significant loss of vision and enucleation of the eye. Ocular trauma is the major risk factor causing keratitis and microorganisms viz., bacteria, fungi, viruses are the causative agents. The current study characterized the conjunctival bacterial microbiomes of healthy individuals and individuals with bacterial keratitis (BK) and assessed whether ocular microbiome dysbiosis is prevalent in BK patients. Ocular bacterial microbiomes were generated from the conjunctival swabs of healthy controls (HC-SW) and conjunctival swabs (BK-SW) and corneal scrapings (BK-CR) of BK patients using V3–V4 amplicon sequencing and data analysed using QIIME and R software. The Alpha diversity indices, diversity and abundance of different phyla and genera, heat map analysis, NMDS plots and inferred functional pathway analysis clearly discriminated the bacterial microbiomes of conjunctival swabs of healthy controls from that of BK patients. Preponderance of negative interactions in the hub genera were observed in BK-CR and BK-SW compared to HC-SW. In addition, a consistent increase in the abundance of pathogenic bacteria, as inferred from published literature, was observed in the conjunctiva of BK patients compared to HC and this may be related to causing or exacerbating ocular surface inflammation. This is the first study demonstrating dysbiosis in the ocular bacterial microbiome of conjunctiva of bacterial keratitis patients compared to the eye of healthy controls. The bacterial microbiome associated with the corneal scrapings of keratitis individuals is also described for the first time. • Demonstrates dysbiosis in the ocular bacterial microbiome in BK patients. • Pathogenic bacteria are predominant in ocular surface of BK patients. • Increase in pathogenic bacteria in BK patients may support inflammation. [ABSTRACT FROM AUTHOR]