Sir,

We report a rare case of infective crystalline keratopathy (ICK) secondary to non-tuberculous mycobacterium.

Case report

A 55-year-old Pakistani myopic gentleman with primary open-angle glaucoma was taking three ocular hypotensive drops in his right eye. He complained of discomfort in his right eye. Examination revealed pseudoproptosis, inferior punctate staining, and filamentary keratitis more in the right eye. Lubricants and punctal plugs were applied. As symptoms deteriorated, he was changed to preservative-free (PF) drops and started doxycycline 100 mg o.d. with lid hygiene for posterior blepharitis.

Two weeks later, while in Pakistan, a dendritic ulcer in the right eye was treated with occ-acyclovir 3%. On returning the following week, disciform keratitis developed with no epithelial defect. Mild inflammation was present, and therefore, g-Predsol 0.5% PF t.d.s., g-chloramphenicol, and oral acyclovir 400 mg (5 × /day) were started.

There was a marked improvement in his condition. However, after 5 weeks of reducing g-Predsol, he developed bacterial keratitis. Steroids were stopped and hourly g-ofloxacin 0.3% was commenced. Cultures showed fast-growing non-tuberculous mycobacterium (Mycobacterium abscessus) sensitive to amikacin and clarithromycin, but resistant to ciprofloxacin/chloramphenicol/vancomycin/erythromycin/cefotaxime/penicillin/rifampicin/imipenem/gentamicin. Despite intensive topical g-amikacin 1.25% monotherapy, the ulcer grew with stromal crystalline keratopathy at the edges (Figure 1a and b). Clarithromycin 500 mg b.d. and g-clarithromycin 1% were added. g-Clarithromycin was poorly tolerated and g-amikacin was recommenced.

Figure 1
figure 1

(a) Right cornea. (b) Magnified right cornea: mid-stromal crystalline keratopathy at the edges of the epithelial defect.

Gradual deterioration with eventual perforation occurred. Therapeutic penetrating keratoplasty was performed. Crystalline keratopathy due to M. abscessus recurred while on topical g-dexamethasone 0.1%, g-chloramphenicol, and oral clarithromycin and acyclovir. The patient obtained g-gatifloxacin 0.3% from the United States, which was effective with resolution at 4 weeks.

Comment

Less than 30 cases of non-tuberculous mycobacterial ICK have been described.1, 2 Previous surgery or trauma is commonly associated with it. Candida has also been found to be a cause of post-surgical ICK.3 This is the first reported case of non-tuberculous mycobacteria without iatrogenic or accidental corneal trauma. Similarly,4 we found fourth generation fluoroquinolones effective in treatment and recommend first line use for these cases. As M. abscessus can be found in soil and water, patients at risk of infection should be warned of hygiene to prevent the severe consequences of ICK.