A 75-year-old Chinese Han man weighting 65 kg came to the Department of Ophthalmology, Beijing Tsinghua Changgung Hospital on March 11, 2016, and complaint of mistiness of vision since February 2016. He received treatment of ethambutol (1500 mg/day) from April 2015 to December 2015 because he suffered from tuberculosis. He did not have any family history of neuropathy.
This study was approved by the Institutional Review Board for the Protection of Human Subjects of Beijing Tsinghua Changgung Hospital and adhered to the tenets of the Declaration of Helsinki. The patient signed an informed consent before the start of examinations.
We performed series of ophthalmic examinations to see the severity of his ocular condition. His BCVA (best-corrected visual acuity) was 0.12 (OS) and 0.15 (OD), whereas the IOP (intraocular pressure) was 10.4 mm Hg and 12.2 mm Hg (Goldmann applanation tonometry, Suzhou City, Jiangsu Province, China), respectively. The slit-lamp microscope examination of bilateral anterior segments indicated no abnormity. The pupils were normal with no relative afferent pupillary defect (RAPD). The funduscopy examination did not indicate any abnormity, either (Fig. 1). Automated perimetry (Humphrey Field Analyzer, Carl Zeiss Meditec, Inc, Dublin, CA, and Octopus Perimeter, Haag-Streit, Mason, OH) indicated typical cecocentral visual field defects (Fig. 2). The retinal nerve fiber layer (RNFL) thickness was measured using optical coherence tomography (OCT) (spectral-domain OCT, Heidelberg Engineering, Heidelberg, Germany). The results showed that the bilateral RNFL thickness was within the normal range (Fig. 3). Furthermore, we took electroretinogram (ERG) examination and found that the amplitude of b-wave was definitely decreased. Based on the ocular examinations listed above, this patient was diagnosed as EON. Since he stopped taking ethambutol in the end of 2015, we just offered some neurotrophic agents to him and asked him to come back for return visit within 1 month.
On May 5, 2016, the patient came back to the Department of Ophthalmology, Beijing Tsinghua Changgung Hospital for return visit. This time, his BCVA (best-corrected visual acuity) was 0.8 (OS) and 0.8 (OD), whereas the IOP was 11.9 mm Hg and 11.2 mm Hg (Goldmann applanation tonometry), respectively. The examinations of bilateral anterior segments and fundus also indicated no abnormity. The Goldmann perimetry was performed again to see the outcome of therapies with neurotrophic agents. The results showed completely recovery of cecocentral scotoma (Fig. 4). Thus, the prognosis of the disease in the present case-report was pretty good.