Visual Function of Tuberculosis Patients Receiving Ethambutol in Kassala, Sudan: A Cross-Sectional Study
DOI:
https://doi.org/10.54536/ajmhc.v1i2.8192Keywords:
Ethambutol, Malnutrition, Toxic Optic Neuropathy, Tuberculosis, Visual AcuityAbstract
Ethambutol is a first‑line antituberculosis drug whose dose‑dependent optic neuropathy may lead to irreversible vision loss if undetected. However, real-world data on its ocular impact from Sudan remain scarce, despite a high tuberculosis burden and prevalent malnutrition. To describe the visual function findings (visual acuity, color vision, pupillary reactions, intraocular pressure, and fundoscopic appearance) in tuberculosis patients receiving ethambutol-containing regimens. A hospital‑based cross-sectional study was conducted from July to December 2024. Seventy‑three adult TB patients receiving ethambutol without pre-existing vision problems were interviewed, and ocular assessments, including visual acuity, Ishihara color vision, pupil reactions, intraocular pressure, and direct fundoscopy, were performed by ophthalmologists. Data were analyzed descriptively. Most participants were 25–34 years old (42.5 %) and male (53.4 %). After commencing ethambutol, 13.7 % reported subjective vision changes, and symptoms suggestive of ocular toxicity (e.g., blurred central vision, difficulty reading) were present in 15.1 %. Despite this, 94.5 % of right eyes and 95.9 % of left eyes maintained 6/6 visual acuity, and abnormal color vision was documented in only 1.4 % of eyes. Fundoscopy revealed optic‑nerve or retinal abnormalities in 1.7 % of patients. Notably, no participant reported any chronic comorbidity, and 82.2% consumed vitamin-rich or diverse diets. Clinically significant ethambutol‑induced ocular toxicity was infrequent in this Sudanese cohort, possibly due to the absence of comorbidities and favorable nutritional status.
Downloads
References
Ahmed Mustafa, G. M., Yassin, M. E., Shami, A., & Rahim, S. A. (2021). Screening of human immunodeficiency virus (hiv) among newly diagnosed tuberculosis patients in eastern sudan Pol J Microbiol, 70(2), 201–206. https://doi.org/10.33073/pjm-2021-017
An, H. R., Lee, B. J., & Moon, Y. (2024). Visual recovery time in patients with ethambutol-induced toxic optic neuropathy. Korean Journal of Ophthalmology: KJO, 38(2), 91.
An, S., & Kim, J. (2024). Monitoring ethambutol-induced optic neuropathy in tuberculosis treatment: a systematic review of guidelines and recommendations. Pharmacoepidemiology and Risk Management, 16(2), 124–134.
Chen, H.-Y., Lai, S.-W., Muo, C.-H., Chen, P.-C., & Wang, I.-J. (2012). Ethambutol-induced optic neuropathy: a nationwide population-based study from Taiwan. British journal of ophthalmology, 96(11), 1368–1371.
Dahiya, M., Rathi, M., Dua, M., Sachdeva, S., & Dabas, R. (2024). Ethambutol induced optic neuropathy: a remerging ocular emergency needing strict vigilance and screening. Indian Journal Of Clinical And Experimental Ophthalmology Учредители: IP Innovative Publication Pvt Ltd, 10(3), 545–548.
Diaz-Quijano, F. A., Bartholomay, P., Andrade, K. B., Pelissari, D. M., Arakaki-Sanchez, D., Costa, F. D., & Pinheiro, R. S. (2026). Effect of introducing ethambutol and integrating drugs into fixed-dose tablets on mortality in tuberculosis patients. Trans R Soc Trop Med Hyg, 120(2), 107–117. https://doi.org/10.1093/trstmh/traf100
Elmadhoun, W. M., Noor, S. K., Bushara, S. O., Ahmed, E. O., Mustafa, H., Sulaiman, A. A., Almobarak, A. O., & Ahmed, M. H. (2016). Epidemiology of tuberculosis and evaluation of treatment outcomes in the national tuberculosis control programme, River Nile state, Sudan, 2011-2013. East Mediterr Health J, 22(2), 95–102. https://doi.org/10.26719/2016.22.2.95
Ganeshee Lal, S., Parmesh, P., Prahlad, D., & Dimple, S. (2021). A hospital based prospective study to assess the ocular manifestations of anti-tubercular drugs in patients receiving anti- tuberculosis treatment.International Journal of Health and Clinical Research, 4(21), 260–263.
Han, K. E., Yoon, H., Choi, H., Lee, J. E., & Kim, S. J. (2025). Factors affecting visual outcome in patients with toxic optic neuropathy caused by ethambutol. Sci Rep, 15(1), 6257. https://doi.org/10.1038/s41598-025-90663-3
Ishihara, S. (1997). Tests for colour-deficiency. Tokyo: Kanehara.
Jin, K. W., Lee, J. Y., Rhiu, S., & Choi, D. G. (2019). Longitudinal evaluation of visual function and structure for detection of subclinical Ethambutol-induced optic neuropathy. PLoS One, 14(4), e0215297. https://doi.org/10.1371/journal.pone.0215297
Kaur, P., Singh, S., Kaur, K., Mahesh, K. V., Tigari, B., Sehgal, V., Takkar, A., Mehta, S., Singh, R., & Malhotra, S. (2022). The genetics of ethambutol-induced optic neuropathy: a narrative review. Neuroophthalmology, 46(5), 304–313. https://doi.org/10.1080/01658107.2022.2100916
Kim, J., & Ahn, S. J. (2024). Risk factors of optic neuropathy in ethambutol users: interaction with isoniazid and other associated conditions of toxic optic neuropathy. Toxics, 12(8). https://doi.org/10.3390/toxics12080549
Kim, J., & Ahn, S. J. (2025). Ethambutol optic neuropathy surveillance: variations in real-world screening practices and associated factors in a nationwide cohort study. Clin Ther, 47(6), 405–411. https://doi.org/10.1016/j.clinthera.2025.03.002
Kim, J., Kwon, H. Y., & Ahn, S. J. (2024). Nationwide usage of ethambutol and incidence and screening practices of optic neuropathy. Frontiers in Pharmacology, 15, 1461111.
Konana, V. K., Mooss, V., & Babu, K. (2024). Cone dysfunction in patients with ethambutol toxicity. Indian J Ophthalmol, 72(7), 1072–1074. https://doi.org/10.4103/ijo.Ijo_494_23
Krichene, M. A., Hassina, S., Mrad, K., Hasnaoui, I., Serghini, L., Abdallah, E., & Berraho, H. A. (2023). [Ethambutol-induced toxic optic neuropathy during treatment of tuberculosis meningitis in a child]. J Fr Ophtalmol, 46(6), 658–661. https://doi.org/10.1016/j.jfo.2023.01.027 (Original work published Neuropathie optique toxique à l’éthambutol au cours d’une méningite tuberculeuse chez un enfant.)
Lee, S., Ryu, W. Y., Kang, D., & Lee, J. K. (2025). Prevalence and Incidence of Ethambutol-Induced Optic Neuropathy and Its Risk Factors in Korea: A Nationwide Population-Based Study. J Korean Med Sci, 40(20), e65. https://doi.org/10.3346/jkms.2025.40.e65
MacVinish, S., McMaster, D., Moledina, T., Tamne, S. K., Ashworth, J., & Anderson, S. R. (2024). Ethambutol and visual assessment in England: current practice and recommendations. Eye (Lond), 38(1), 112–117. https://doi.org/10.1038/s41433-023-02643-4
Mehta, S. (2019). Patterns of ethambutol ocular toxicity in extended use therapy Cureus, 11(4), e4408. https://doi.org/10.7759/cureus.4408
Mendel, T., Fleischman, D., Allingham, R. R., Tseng, H., & Chesnutt, D. A. (2016). Spectrum and Clinical Course of Visual Field Abnormalities in Ethambutol Toxicity. Neuroophthalmology, 40(3), 139–145. https://doi.org/10.3109/01658107.2016.1173065
Mohammed, A. K. Y., Humida, E. H. M., Ali, A. M. O., & Ahmed, H. G. (2025). Common comorbidities among tuberculosis patients in Western Sudan during the Sudan armed conflict. Kordofan Journal of Medical & Health Sciences, 2(01), 22–29.
Moharrum, S. A., Bilal, N. E., & Mhmoud, N. A. (2025). The role of TGF-β1 C-509T and TGF-β1 T869C polymorphisms in susceptibility to tuberculosis infection in a Sudanese population: a case-control study. BMC Infect Dis, 26(1), 3. https://doi.org/10.1186/s12879-025-12256-9
Nusanti, S., Prakoso, B. B., Sidik, M., Burhan, E., & Kekalih, A. (2022). Changes in Pattern and Multifocal Electroretinogram in Tuberculosis Patient with Ethambutol Therapy. Ophthalmologica Indonesiana.
Ophthalmology, A. A. o. (2011). Basic and Clinical Science Course: Neuro-ophthalmology. American Academy of Ophthalmology.
Organization, W. H. (1996). Management of cataract in primary health care services. World Health Organization.
Organization, W. H. (2025). WHO consolidated guidelines on tuberculosis. Module 4: treatment and care. World Health Organization.
Rasool, M., Malik, A., Manan, A., Aziz, K., Mahmood, A., Zaheer, S., Shuja, N., Qazi, M. H., Kamal, M. A., & Karim, S. (2014). Determination of potential role of antioxidative status and circulating biochemical markers in the pathogenesis of ethambutol induced toxic optic neuropathy among diabetic and non-diabetic patients. Saudi Journal of Biological Sciences, 22, 739 – 743.
Sachdeva, G., Dhiman, R., Raj, D., Lavanya, G., Mohan, A., Pujari, A., Phuljhele, S., & Saxena, R. (2026). Evaluation of visual function and OCT parameters in ethambutol-induced optic neuropathy: a longitudinal study. Br J Ophthalmol, 110(2), 185–190. https://doi.org/10.1136/bjo-2025-327475
Sadda, S. R., Schachat, A. P., Wilkinson, C. P., Hinton, D. R., Wiedemann, P., Freund, K. B., & Sarraf, D. (2022). Ryan’s Retina (7th Edition ed.). Elsevier.
Sheng, W.-Y., Wu, S.-Q., Su, L.-Y., & Zhu, L.-W. (2022). Ethambutol-induced optic neuropathy with rare bilateral asymmetry onset: A case report. World Journal of Clinical Cases, 10(2), 663–670. https://doi.org/10.12998/wjcc.v10.i2.663
Sheth, J., Sachdeva, V., Goyal, A., Parikh, A., Nalawade, R., Nanavati, H., & Kekunnaya, R. (2025). Clinical profile and visual outcomes in ethambutol-induced toxic optic neuropathy. Indian J Ophthalmol, 73(Suppl 3), S484–s491. https://doi.org/10.4103/ijo.Ijo_1807_24
Singh, P., Karkhur, S., & Verma, V. (2025). Ethambutol-induced optic neuropathy: a retrospective study of incidences and risk factors. Cureus, 17(2).
Spaeth, G. L. (2021). European glaucoma society terminology and guidelines for glaucoma. British journal of ophthalmology, 105(Suppl 1), 1–169.
Sudhakar, P., Acharya, K., & Kini, T. A. (2025). Ethambutol optic neuropathy [Mini Review]. Frontiers in Neurology, Volume 16 - 2025. https://doi.org/10.3389/fneur.2025.1626909
Taffner, B. M. P., da Cruz, L. G. I., de Ávila Fowler, F., Nawa, C. C., Savioli, M. T., Rodrigues, D. S., Magalhães Junior, O., & Belfort Junior, R. (2022). Campimetry and visual changes after RHZE treatment for tuberculosis. Int J Retina Vitreous, 8(1), 16. https://doi.org/10.1186/s40942-022-00367-3
Taffner, B. M. P., da Cruz, L. G. I., de Ávila Fowler, F., Nawa, C. C., Savioli, M. T. G., Rodrigues, D. S., Magalhães Júnior, O., & Belfort Junior, R. (2022). Campimetry and visual changes after RHZE treatment for tuberculosis. International Journal of Retina and Vitreous, 8.
Wang, M. Y., & Sadun, A. A. (2013). Drug-Related Mitochondrial Optic Neuropathies. Journal of Neuro-Ophthalmology, 33(2), 172–178. https://doi.org/10.1097/WNO.0b013e3182901969
Zhang, M., Tian, Y., Gao, B., Qin, X., Shen, Q., Li, Z., Shi, Y., Zhang, L., Liu, Y., & Sun, W. (2026). Interpretation of the Global Tuberculosis Report 2025: Global Epidemic Trends and China’s Control Strategy. Zoonoses, 6(1), 994.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Mohammed Ibrahem Obied Babiker, Hana Khalid Salam Ahmed, Rwanza Stayed Mohammed Sayed (Author)
This work is licensed under a Creative Commons Attribution 4.0 International License.
