A Rare Infection Following Combined Phacoemulsification And Intra-Ocular Lens Implantation Plus Descemet's Membrane Endothelial Keratoplasty

To raise awareness of nontuberculous mycobacteria (NTM), a rare post-surgical ocular infection.

NTM infections are rare, difficult to identify, often resulting in delayed diagnosis and ocular morbidity. NTM can affect all ocular tissues, and therefore can have diverse clinical presentations. Predisposing risk factors include ocular surgery, trauma, topical corticosteroids and immunocompromise. We present a case of an NTM infection following corneal surgery at Queen Alexandra Hospital, Portsmouth.

A 68-year-old female presented with a history Fuchs’ endothelial dystrophy and systemic lupus erythema. She had a combined right phacoemulsification and IOL implantation plus DMEK. 1 week postoperatively, all appeared routine. VA was 6/9, the graft was clear and attached.

2 weeks postoperatively, she presented with pain and blurred vision. Examination showed reduced VA to 6/60, conjunctival injection, intact corneal epithelium, diffuse corneal oedema with keratic precipitate clusters and bullae superotemporally and centrally. The graft was attached and no AC activity.

This was treated as postoperative uveitis but despite intensive topical steroids for 1 week, her VA reduced to HM, with progression of the inflammatory lesions and graft failure. She was taken to theatre for an AC tap, graft removal and intracameral voriconazole and cefuroxime. The delayed onset and progression raised suspicion of fungal infection and G natamycin 5% hourly, and G chloramphenicol 0.5% QDS was started.

She had worsening pain and inflammation over the next 4 weeks, with negative initial microbiology results. She was empirically treated for fungal infection with 3 further AC taps and intracameral voriconazole and cefuroxime. Eventually, microscopy revealed gram-positive rods, identified as mycobacterium chelonae via 16s PCR assay. Management was multidisciplinary with respiratory and microbiology, with four topical and two systemic antibiotics. Follow up showed improvement in pain and inflammation.

NTM infections are rare and difficult to identify, often resulting in delayed diagnosis and ocular morbidity. Clinicians should have a high index of suspicion of NTM infection in post-surgical cases not responding to standard treatment, particularly in immunocompromised patients. Clinical signs highly suggestive of NTM keratitis include a ‘cracked windshield’ appearance around the edge of infiltrates. Other clinical signs such as irregular margins or satellite lesions mimicking fungal keratitis or dendritic epithelial defects mimicking herpes keratitis in patients not responding treatment should be investigated. Modalities include microscopy, special NTM culture and 16s PCR. By sharing this case we hope to raise awareness and optimise care.