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Microsporidia-induced stromal keratitis: a new cause of presumed immune stromal (interstitial) keratitis
  1. Amrita Mohanty1,
  2. Himansu Sekhar Behera2,
  3. Manas Ranjan Barik2,
  4. Amanjot Kaur1,
  5. Savitri Sharma3,
  6. Sujata Das1,
  7. Merle Fernandes4,
  8. Sailendra Panda5,
  9. Srikant K Sahu1
  1. 1Cornea and Anterior Segment, LV Prasad Eye Institute, Bhubaneswar, Odisha, India
  2. 2Ocular Microbiology Services, LV Prasad Eye Institute, Bhubaneswar, Orissa, India
  3. 3Jhaveri Microbiology Centre, L V Prasad Eye Institute, Hyderabad, India
  4. 4Cornea and Anterior Segment, L V Prasad Eye Institute, Vishakapatnam, Andhra Pradesh, India
  5. 5Zeusnjove Diagnostics, Bhubaneswar, Odisha, India
  1. Correspondence to Dr Srikant K Sahu, Mithu Tulsi Chanrai Campus, Bhubaneswar, Orissa, India; srikantsahu{at}


Background and objective To describe the clinical features, diagnosis and management of immune stromal keratitis/interstitial keratitis (IK) associated with microsporidial epithelial keratitis.

Methods Between October 2020 and January 2021, medical records of IK patients microbiologically proven as microsporidia from samples collected from corneal epithelium on smear examination, and/ or molecular analysis were reviewed. Demography, clinical profile and treatment were analysed. Real-time PCR (RT-PCR) for adenovirus (ADV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) and varicella-zoster virus (VZV) was done.

Results Twenty of 152 (13%) microbiologically proven cases of microsporidial keratitis were diagnosed as IK during the study period, the mean age and duration of symptoms were 35.7±11.4 years and 46.3±27.7 days, respectively. Half had predisposing risk factors, like trauma; and 30% had prior recurrences. One-fourth of patients were using antivirals on presentation. Characteristic presentations included disciform keratitis(n=12), incomplete/complete ring(n=5), and combination(n=3), along with variable subepithelial infiltrates (n=14). All cases had stromal oedema, with an intact epithelium and fine pigment dusting on endothelium. Corneal epithelial scrapings had scanty microsporidia spores in smears of 17/20 (85%), and pan-microsporidial DNA was identified in 14/20 (70%), with Vittaforma corneae by sequencing in 11/20 (55%). Other viruses detected were ADV (14,70%), VZV (2,10%), EBV (1,5%) and HSV (1,5%). Rapid resolution of inflammation and oedema within 2 weeks of starting steroids was seen in all cases.

Conclusion Microsporidia epithelial keratitis induced stromal inflammatory keratitis; is distinguished from microsporidial keratoconjunctivitis and stromal keratitis, by characteristic clinical features, and response to topical steroids.

  • cornea
  • infection
  • inflammation
  • microbiology

Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information. All data relevant to the study are included in the article.

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Data availability statement

All data relevant to the study are included in the article or uploaded as online supplemental information. All data relevant to the study are included in the article.

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  • AM and HSB are joint first authors.

  • Contributors Conception of idea: SKS; Data collection: AM, AK, HSB, MRB and SP; Interpretation of data: SKS, AM and HSB; Drafting the manuscript: AM, HSB, SKS and SS; Literature review: AM, HSB and AK; Manuscript revision: SD, MF and SKS, Guarantor:SKS.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.