Differential Diagnosis for Blurring of Vision in a Patient on ATT for TBM
Single most likely diagnosis
- Ethambutol toxicity: This is a common side effect of ethambutol, a medication used in the treatment of tuberculosis, including tubercular meningitis (TBM). The patient has been on ATT for a month, and ethambutol is known to cause optic neuritis, leading to blurred vision, especially in the first few months of treatment.
Other Likely diagnoses
- Vitamin B12 deficiency: This can occur due to malabsorption or poor dietary intake, especially in patients with chronic illnesses like tuberculosis. Vitamin B12 deficiency can cause neurological symptoms, including blurred vision.
- Steroid-induced glaucoma: If the patient is on corticosteroids as part of the treatment for TBM, there is a risk of developing steroid-induced glaucoma, which can cause blurred vision.
- Tubercular meningitis complications: TBM can cause increased intracranial pressure, which may lead to papilledema and subsequent blurred vision.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Papilledema due to increased intracranial pressure: This is a potentially life-threatening condition that requires immediate attention. Increased intracranial pressure can be caused by various factors, including TBM, and can lead to permanent vision loss if not treated promptly.
- Cranial nerve involvement: TBM can cause cranial nerve involvement, including the optic nerve, which can result in blurred vision.
Rare diagnoses
- Optic nerve tuberculosis: Although rare, tuberculosis can directly affect the optic nerve, causing blurred vision.
- Sarcoidosis: This is a rare condition that can cause uveitis, leading to blurred vision, and can be associated with tuberculosis.
- Toxoplasmosis: This is a rare opportunistic infection that can cause choroiditis, leading to blurred vision, especially in immunocompromised patients.