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Infectious crystalline keratopathy (ICK) is a rare complication of penetrating keratoplasty characterised by an indolent infectious keratitis in which needle-like, branching crystalline opacities are seen within the corneal stroma, in the absence of appreciable corneal or anterior segment inflammation.1 We report an unusual case of recurrent ICK which occurred in two successive corneal grafts.
A 63 year old man underwent penetrating keratoplasty for aphakic bullous keratopathy. The immediate postoperative course was uneventful. Topical corticosteroid (dexamethasone 0.1%) was initially given four times daily, and then was tapered to twice daily. Seven months after transplantation, visual acuity decreased to counting fingers with no other symptoms. Slit lamp examination showed a focal area of non-suppurative branching intrastromal white opacities (Fig 1). Corneal scrapings for diagnostic smears and cultures were performed. Microscopic examination of the smears showed dense groupings of many Gram positive cocci with no inflammatory cells. Cultures grew Streptococcus viridans and were negative for fungi. The patient was treated hourly with two fortified antibiotic eyedrops (amikacin, vancomycin) and topical rifamycin. Topical antibiotic therapy was gradually tapered over 12 months. Topical dexamethasone was withdrawn and topical ciclosporin was used to maintain an immunosuppression. Despite intensive treatment with appropriate antibiotics, ICK increased in size and evolved simultaneously towards abscess and acute rejection. The subsequent corneal condition was severe residual scarring of the central cornea with diffuse neovascularisation. A second penetrating keratoplasty was then performed 19 months after the first transplantation. Topical dexamethasone, ciclosporin, and rifamycin were given four times daily. Three months after the second graft, slit lamp examination showed a large central epithelial defect with multiple diffuse white opacities confined to the anterior stroma. These multiple opacities merged into a larger confluent dense opacity near the continuous suture (Fig 2). Cytological studies and cultures of the corneal scrapings were performed. Light microscopy disclosed aggregations of many fungi with no inflammatory cells. Cultures yielded Candida albicans sensitive to amphotericin B and fluconazole. Bacterial cultures were negative. Topical amphotericin B was started every hour, along with oral fluconazole. Corticosteroids were stopped and topical ciclosporin was maintained. Despite intensive treatment, the infectious keratopathy slowly worsened over 6 months and the corneal infiltrates were replaced by scarring and neovascularisation.
Typically, ICK develops in a corneal graft after long term use of topical corticosteroids. Chronic topical corticosteroids used to prevent graft rejection produces relative immunosuppression allowing infection to develop with little or no inflammation in the cornea. Gram positive cocci, usually Streptococcus viridans, are commonly isolated from ICK lesions, but other bacteria, fungi, and mixed infections have been reported.2–5 To the best of our knowledge, recurrent ICK has never been reported in two successive corneal grafts and with two different organisms. Appropriate laboratory evaluation is therefore necessary to guide specific antimicrobial therapy. Discontinuation of topical steroids with aggressive antibiotic therapy may suffice, but continued infection, vascularisation, or scar formation may sometimes affect visual acuity and corneal graft survival. In this case, medical treatment failed, despite in vitro susceptibility of micro-organisms to antibiotics and antifungal drugs. Moreover, immunosuppression (that is, corticosteroids, ciclosporin), necessary to prevent graft rejection, worsened the infection and did not prevent the acute rejection process from developing.
In conclusion, this case suggests that local immunosuppression and factors related to the patient ocular surface may be predisposing factors for the development of ICK.