Clinical study of the treatment of acanthamoeba keratitis by penetrating keratoplasty

Abstract

To evaluate the influence of accurate diagnosis and peri-operative management on the recurrence of acanthamoeba keratitis after penetrating keratoplasty. A retrospective study of 18 cases of medically unresponsive keratitis in Shandong Eye Institute and Hospital that were confirmed as acanthamoeba keratitis based on laboratory examination or histopathological studies. The diagnosis of acanthamoeba keratitis was made prior to the surgery in 12 cases and delayed until histopathological results in six cases. All cases ran a course of one to four months prior to penetrating keratoplasty with lesions measuring larger than 7 mm at the time of surgery. Corresponding anti-microbial agents were given pre-operatively based on the suspected etiological agents. Corticosteroids were given to two eyes diagnosed as acanthamoeba keratitis, three eyes misdiagnosed as herpes simplex keratitis and two eyes misdiagnosed as bacterial keratitis. In 13 cases without recurrence (72%), 11 cases were correctly diagnosed as acanthamoeba keratitis prior to the surgery. In five cases with relapse (28%), four cases were misdiagnosed prior to the surgery. Seven cases received corticosteroid therapy more than one week in early post-operative period and four cases developed recurrence. In the four cases with relapse, two were misdiagnosed as herpes keratitis and two were misdiagnosed as bacterial keratitis. The odds ratis of the effect of two factors (misdiagnosis and using of corticosteroid in early post-operative period) on the rate of recurrence were 22 (P = 0.021) and 13 (P = 0.047), respectively. Penetrating keratoplasty is an effective treatment for medically unresponsive acanthamoeba keratitis. Accurate pre-operative diagnosis, appropriate peri-operative amoebicidal therapy and avoidance from the use of corticosteroid in the early post-operative period can decrease the incidence of recurrence of acanthamoeba keratitis after penetrating keratoplasty.