Alendronate induced chorioretinitis: The importance of meticulous assessments

PURPOSE: To report a case of presumed bilateral chorioretinitis secondary to alendronate therapy. OBSERVATIONS: A 71-year-old female presented to the clinic in July 2017 with six months history of difficulty in reading along with floaters in both eyes which were more severe in the right eye. Past medical and surgical history revealed a history of hypertension, gout, hyperthyroidism, osteoporosis, and humerus fracture. She was started on alendronate three months before developing ocular symptoms. On ocular examination, best corrected visual acuity was 20/30 in the right and 20/25 in the left eye. Slit-lamp examination demonstrated normal anterior chamber examination in both eyes. Dilated fundus examination revealed geographic chorioretinal lesions around the optic nerve head in both eyes, more extensively in the right eye; and superior and temporal to the macula in the right eye. Past ocular records in February 2015 did not reveal any such findings. Fundus autofluorescence demonstrated hyper-autofluorescence in the peripapillary lesions in both eyes. The lesion adjacent to the macula in right eye displayed mixed hyper and hypo-autofluorescence. Fluorescein angiography showed combined hyper- and hypo-fluorescence compatible with window defect, staining and blockage. However, no leakage was appreciated in the macula, peripapillary, and peripheral lesions in both eyes. Optical coherence tomography scan showed septate hyporeflective intraretinal spaces in the right eye. CONCLUSION AND IMPORTANCE: The index report underscore the importance of considering alendronate as an etiologic cause of chorioretinitis, especially in subjects with atypical lesions developing after alendronate therapy. We, therefore, recommend discontinuation of this medication in subjects who develop chorioretinitis after employing this medication.