Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs, it can spread to other organs, including the eyes. Ocular tuberculosis is an underdiagnosed but it can lead to vision impairment or even blindness if untreated.
Types –
Tuberculosis (TB) can be classified into different types .
1. Based on Infection Status:
Latent TB: In this state bacteria can inactive in the body without symptoms, it is not contagious but can become active later.
Active TB: The bacteria multiply, causing symptoms and spreading to others.
2. Based on Location in the Body:
Pulmonary TB: Affects the lungs and it spreading to others. Extrapulmonary TB: Affects other organs like the brain, kidneys, bones, and lymph nodes.
3. Specific Forms of TB:
Miliary TB: A severe form where TB spreads through the bloodstream, affecting multiple organs.
TB Meningitis: TB infects the brain’s meninges, it can lead to neurological problems.
Skeletal TB : Affects the spine and bones, causing pain and deformity.
Genitourinary TB: Affects the kidneys, bladder, or reproductive organs.
Tuberculosis Affects the Eyes-
TB can affect the eyes through two main routes:
1. Hematogenous Spread: The bacteria travel through the bloodstream from a primary infection in the lungs or elsewhere in the body.
2. Direct Contamination: Less commonly, TB can spread through direct contact with infected secretions or by extension from adjacent tissues.
Ocular Manifestations of Tuberculosis
1. Eyelid and Conjunctival Tuberculosis- it is rare but it can cause chronic granulomatous inflammation, which can lead to Symptoms include swelling, redness, and non-healing ulcers on the eyelid or conjunctiva. May mimic other infections or inflammatory conditions.
2. Scleritis and Episcleritis – Inflammation of the episclera (a thin layer between the conjunctiva and sclera) it is known as episcleritis. Symptoms -Redness (sectoral or diffuse)Mild discomfort or irritation, no significant pain or vision loss , self-limiting, often resolves in 1–2 weeks. Causes: Often idiopathic but may be associated with systemic diseases (e.g., rheumatoid arthritis). Inflammation of the sclera, involving deeper eye structures it is known as scleritis. Symptoms:
Severe, deep, boring eye pain (worse at night or with eye movement), Redness with bluish or violaceous hue possible vision loss ,photophobia and tearing
Causes: Often linked to systemic autoimmune diseases (e.g., rheumatoid arthritis, lupus, granulomatosis with polyangiitis).
3. Corneal Tuberculosis – It is rare , but TB can cause chronic keratitis (corneal inflammation) or corneal ulcers. Symptoms: Blurred vision, eye pain, and photophobia (light sensitivity).
4. Uveitis (Inflammation of the Uveal Tract) – Uveitis is inflammation of the uvea, the middle layer of the eye, which includes the iris, ciliary body, and choroid. It can lead to vision loss if untreated.
Types of Uveitis:
Anterior Uveitis (Iritis): it is the most common type eye pain, redness, photophobia, blurred vision.
Causes: Autoimmune diseases (e.g., ankylosing
spondylitis, rheumatoid arthritis), infections
Intermediate Uveitis: Involves the vitreous (pars planitis) ,Symptoms: Floaters,
mild vision loss ,Causes: Multiple sclerosis, sarcoidosis.
Posterior Uveitis: Affects the retina and choroid ,Symptoms: Floaters, blurred
vision, scotomas ,Causes: Toxoplasmosis, tuberculosis, syphilis
Panuveitis: Involves all parts of the uvea ,Symptoms: Severe vision loss, pain,
photophobia, Causes: Behçet’s disease, sarcoidosis
5. Retinal and Choroidal Tuberculosis – TB can cause choroiditis, leading to
yellowish lesions in the choroid. Symptoms: Blurred vision, scotomas (blind
spots), and floaters. In severe form it can cause retinal detachment.
6. Optic Nerve Involvement – TB can cause optic neuritis or optic disc
tuberculoma, leading to vision loss. Symptoms: Blurred vision, pain with eye
movement, and loss of color vision.
7. Endophthalmitis and Panophthalmitis – Rare but severe complications where TB causes widespread infection inside the eye. Symptoms: Severe pain, redness, vision loss, and pus formation.
Diagnosis of Ocular Tuberculosis – The following tests help in diagnosis:
1. Tuberculin Skin Test (TST) or Interferon-Gamma Release Assays (IGRAs) – Helps determine if the person has been exposed to TB.
2. Chest X-ray or CT Scan – To check for pulmonary TB.
3. Ocular Imaging – Fluorescein angiography, optical coherence tomography (OCT), and ultrasound B-scan help identify ocular TB lesions.
4. Polymerase Chain Reaction (PCR) and Culture – Detects Mycobacterium tuberculosis in eye fluids.
5. Histopathology – Biopsy of ocular lesions for definitive diagnosis.
Treatment of Ocular Tuberculosis –
Treatment involves anti-tuberculosis therapy (ATT) and sometimes additional medications to manage inflammation.
1. Anti-TB Drugs (ATT):- Isoniazid, Rifampicin, Ethambutol, and Pyrazinamide for 6-12 months. Longer treatment duration for ocular TB compared to pulmonary TB.
2. Corticosteroids:- Used to reduce inflammation, particularly in uveitis and scleritis. Given as oral or topical steroids but must be used cautiously alongside ATT.
3. Immunosuppressive Therapy:- In cases of severe inflammation, additional immunosuppressants like methotrexate or biologics may be used.
4. Surgical Intervention: Rarely required but may include vitrectomy (removal of vitreous gel) or drainage of abscesses.
Prognosis and Complications:- Early detection and treatment lead to a good prognosis. However, delayed treatment can result in: permanent vision loss, retinal detachment, glaucoma or cataracts due to chronic inflammation
