Microbial keratitis following intracorneal ring implantation

The aim of this study is to identify predisposing factors, the clinical course and visual outcomes in patients with keratitis after intracorneal ring implantation.

In a retrospective study, 11 patients with documented keratitis after intracorneal ring implantation and 71 matched controls with uncomplicated surgery were enrolled. Patients were examined for slitlamp findings and corrected distance visual acuity at time of the initial presentation, one month later and six months later. Smears and cultures were provided in all cases. Relevant data in controls were extracted from their medical records, and statistical analysis was done.

Keratitis onset time ranged from three to 56 days. The incidence was 2.7 per cent over two years. All pathogens were Gram-positive cocci, and the most frequent was Staphylococcus spp. No relationship was found between keratitis occurrence and the ring type or the femtosecond procedure, but the rate of keratitis was higher in patients with the horizontal position of intracorneal ring segments (p = 0.001; Fisher's exact test). All cases were treated with implant explantation and tunnel irrigation with antibiotics. In three cases, amniotic membrane transplantation was performed, and two cases finally underwent penetrating keratoplasty. The final six month corrected distance visual acuity was 0.68 ± 0.35. Poor corrected distance visual acuity improvement was associated with the ulcer size at the first day of the diagnosis (p = 0.011; Spearman's rho).

The only predisposing factor was the horizontal position of the ring. A careful evaluation in the early post-operative period for any sign of the infiltration would be helpful. Early diagnosis with proper management including fortified antibiotic therapy specifically against Gram-positive cocci and removal of the intracorneal ring seems to result in acceptable visual outcomes in later follow-up. However, a corneal transplant may be the only choice in advanced infectious complications.