Secondary glaucoma associated with advanced acanthamoeba keratitis

PURPOSE. To describe the association of acanthamoeba keratitis and glaucoma, to establish an incidence of glaucoma in patients with acanthamoeba keratitis, to discuss treatment options and outcomes in these patients, and to describe the histopathologic findings and pathogenesis of glaucoma secondary to acanthamoeba keratitis. METHODS. After Institutional Review Board approval, the charts of all patients suspected of having acanthamoeba keratitis at Aston Ambulatory Center at The University of Texas Southwestern Medical Center were reviewed. Inclusion criteria were as follows: diagnosis of acanthamoeba keratitis by positive confocal microscopy or culture, diagnosis of glaucoma or ocular hypertension secondary to acanthamoeba keratitis, and at least 6 months of follow-up. Exclusion criteria included a previous diagnosis of glaucoma or ocular hypertension and any history of intraocular surgery before the development of glaucoma. The date of keratitis development, pneumotonometry on initial and follow-up examinations, glaucoma medications used, and surgical procedures performed were tabulated. RESULTS. Twenty patients (20 eyes) were included. Six (30%) eyes developed secondary glaucoma during the review period. Of the patients treated for glaucoma with medication alone, the visual acuity of three (75%) of four became light perception or no light perception. Three of six patients required glaucoma drainage device implantation for intraocular pressure control. Of these, the vision of one eye became no light perception, and the other two eyes maintained better than 20/100 vision. Histopathologic examination showed chronic inflammation of the trabecular meshwork and angle closure. No acanthamoeba organisms were found in the angle structures. CONCLUSIONS. The development of secondary glaucoma is not uncommon in acanthamoeba keratitis and is a poor prognostic sign in patients with acanthamoeba keratitis, because most progress to light perception or no light perception vision. Histopathologic findings suggest an inflammatory angle-closure mechanism, apparently without direct infiltration of the organism. The glaucoma associated with acanthamoeba keratitis is often severe and frequently requires surgical intervention for intraocular pressure control and vision preservation.