Serial Retinal Nerve Fiber Layer Changes in Patients With Toxic Optic Neuropathy Associated With Antituberculosis Pharmacotherapy

Abstract

To analyze serial changes in retinal nerve fiber layer (RNFL) thickness after development of visual loss in patients with toxic optic neuropathy (TON) associated with antituberculosis pharmacotherapy, as well as to determine if RNFL changes correlate with clinical findings. Five patients with TON underwent serial optical coherence tomography (OCT) and ophthalmologic examination, which consisted of visual acuity, color vision, pupillary light reflexes, visual fields, and funduscopy. Four of the five patients showed normal RNFL thickness on initial OCT. RNFL thickness remained within normal range throughout the follow-up period (range 5.5-50.5 months, average 22.0 +/- 24.8 months after initial visual symptoms) in 3 patients and gradually decreased in 2 patients (4 and 26.5 months after initial visual symptoms), especially in the temporal segment. All patients exhibited improved visual acuity and visual fields. Four patients showed improved color vision. RNFL changes may not be obvious at initial presentation, but became manifest in 2 of the 5 patients over time. OCT may not be useful in identifying the RNFL defect in the early stage, but may be helpful for the follow up of the patients with TON.