Treatment of fungal keratitis by penetrating keratoplasty

Abstract

Aim: To study the use of penetrating keratoplasty (PKP) for the treatment of severe fungal keratitis that could not be cured by antifungal medication.

Methods: A retrospective analysis of 108 cases of severe fungal keratitis in which PKP was performed served as the basis for this study. Fungal keratitis was diagnosed by KOH staining of corneal scrapings or by confocal microscopic imaging of the cornea. All patients received a combination of topical and oral antifungal medicines without steroids as the first course of therapy. Patients whose corneal infection was not cured or in whom the infection progressed during antifungal treatment were given a PKP. After surgery, the patients continued to receive antifungal therapy with gradual tapering of the dose over a 1-2 month period. Cyclosporine was used to prevent graft rejection beginning 2 weeks after PKP. Topical steroid only was administered to the patient whose donor graft was over 8.5 mm and with a heavy iris inflammation 2 weeks after PKP. The surgical specimens were used for microbiological evaluation and examined histopathologically. The patients were followed for 6-24 months after PKP. Graft rejection, clarity of the graft, visual acuity, and surgical complications were recorded.

Results: Corneal grafts in 86 eyes (79.6%) remained clear during follow up. There was no recurrence of fungal infection and the visual acuity ranged from 40/200 to 20/20. Complications in some patients included recurrent fungal infection in eight eyes (7.4%), corneal graft rejection in 32 eyes (29.6%), secondary glaucoma in two eyes (1.9%), and five eyes (4.6%) developed cataracts. 98 of 108 of the recipient corneas had PAS positive fungal hyphae in tissue sections; 97 of 108 were culture positive for various fungi, including Fusarium (63), Aspergillus (14), Candida (9), Penicillium (4), and seven cases in which septate hyphae were seen but identification of the organism was not conclusive.

Conclusions: PKP is an effective treatment for fungal keratitis that does not respond to antifungal medication. Early surgical intervention before the disease becomes advanced is recommended. It is critical that the surgical procedure remove the infected tissue in its entirety in order to effect a cure.

Figure 1

A large corneal ulcer 9 days after injury. The cornea is ulcerated and necrotic. Vision was reduced to light perception.

Figure 2

Rehabilitation of vision by PKP. Nine months after PKP the graft which extended into the limbus is clear and the corrected visual acuity is 20/40.