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Abstract
Purpose
To report three cases with bitemporal hemianopsia after using ethambutol to treat tuberculosis.
Case summary
A 50-year-old male with chronic renal failure and tuberculous pleurisy, a 57-year-old male with diabetic retinop-athy and pulmonary tuberculosis, and a 59-year-old male with diabetes and pulmonary tuberculosis were referred for evaluation due to decreased visual acuity for several months after taking ethambutol to treat tuberculosis. All 3 patients had abnormal color vision and visual evoked potential in both eyes. Visual field showed bitemporal hemianopsia with or without central scotoma. Brain imaging tests were normal. Although ethambutol was discontinued in all three patients, one patient with renal disease showed further decrease in visual acuity and visual field worsened to total field defect.
Conclusions
Ethambutol-induced optic neuropathy is a wide spectrum disorder and based on our cases, can present as bi-temporal hemianopsia mimicking compressive chiasmal lesions. A thorough history should be taken and immediate discontinua-tion of ethambutol is recommended in cases when bitemporal hemianopia occurs.
References
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Figure 1.
Case 1. VF (A), fundus photography (B) and VEP (C) shows asymmetric ceco-central scotoma, normal fundus, and de-layed latency at the initial presentation. Although discontinuation of ethambutol, VF demonstrates temporal hemifield defects worse after one month (D) and 2 months (E). VF after 6 months (F) shows bitemporal VF defects with alignment on vertical midline. Follow-up 6 months later fundus photography (G) and VEP (H) demonstrates bilateral optic disc pallor and no response of VEP. VF and optical coherence tomography shows near complete VF loss worse in the temporal hemifields (I) and thinning of superior and inferior peripapillary retinal nerve fiber layer (J) in both eyes after 1 year. RNFL = retinal nerve fiber layer; S = superior; N = nasal; I = inferior; T = temporal; NA = not applicable; VF = visual field; VEP = visual evoked potential.
Figure 2.
Case 2. (A) VF shows bitemporal hemianopsia with alignment on vertical midline. (B) Epiretinal membrane in the right eye and mild nonproliferative diabetic retinopathy are observed on fundus photography. No response of VEP (C) and relatively nor-mal optical coherence tomography (D) are observed. Follow-up 1 (E), 2 (F), 6 (G) months and 1 year (H) later, VFs show improve-ment of bitemporal hemianopsia persisting central scotoma. RNFL = retinal nerve fiber layer; S = superior; N = nasal; I = in-ferior; T = temporal; NA = not applicable; VF = visual field; VEP = visual evoked potential.
Figure 3.
Case 3. (A) Initial VF demonstrates bitemporal visual field defects respecting vertical midline without central scotoma. (B) Normal fundus photography. (C) Visual evoked potential shows delayed latency. Follow-up 2 weeks (D), 1 month (E), and 3 months (F) later, VFs show near complete resolution of defects except paracentral scotoma in the left eye. VF = visual field.
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