Vitritis (Inflammation of the Vitreous)

What happens in vitritis

The vitreous is a clear, jelly-like substance that fills about two-thirds of the eyeball, between the lens and the retina. Light passes through it to reach the retina. When nearby tissue is inflamed, white blood cells and leaked protein spill into the gel. These cells cast shadows on the retina, which you see as floaters, and they scatter light, which makes vision look foggy.

Vitritis is not a diagnosis in itself. It is a finding that tells the eye doctor there is inflammation in the middle or back of the eye. Under the international uveitis classification, the amount of inflammation is graded by counting cells and judging how hazy the view of the retina is, from 0 (none) to 4+ (retina barely visible). This grading guides treatment and tracks response.

Causes

Non-infectious uveitis

Most vitritis comes from uveitis, inflammation of the middle layer of the eye.

• Intermediate uveitis, including pars planitis, mainly affects the vitreous and is common in children and young adults. It is linked with multiple sclerosis and sarcoidosis.
• Posterior uveitis and panuveitis, linked with sarcoidosis, Behçet's disease, birdshot chorioretinopathy, Vogt-Koyanagi-Harada disease and sympathetic ophthalmia.
• Idiopathic cases, where no cause is found despite testing, are common.

Infection

• Toxoplasmosis: the most common infectious cause of posterior uveitis worldwide. Dense vitritis over a white patch of retinitis is described as "headlight in the fog".
• Endophthalmitis: a bacterial or fungal infection inside the eye, usually after cataract surgery, an eye injection or a penetrating injury. It causes pain, redness and rapidly worsening vision.
• Other infections: syphilis, tuberculosis, Lyme disease, toxocariasis, herpes viruses (acute retinal necrosis), cytomegalovirus in people with weak immunity, and fungal infection (candida) in people with IV lines or who inject drugs.

Masquerade syndromes

In people over about 50, persistent vitritis that does not respond to steroids may be primary vitreoretinal lymphoma, a rare cancer that can also affect the brain. Retinal detachment, retained material from an injury and some other tumors can also release cells into the vitreous.

Symptoms

• New floaters: dots, threads or cobwebs that drift as your eye moves
• Blurred, hazy or "foggy" vision
• Reduced contrast, or difficulty seeing in dim light
• Sometimes light sensitivity, eye pain or redness, if the front of the eye is also inflamed
• Symptoms in one or both eyes, depending on the cause

Many people with intermediate uveitis notice only floaters. Pain and redness are more typical of infection or inflammation in the front of the eye.

Diagnosis

An ophthalmologist dilates the pupils and examines the vitreous with a slit lamp and ophthalmoscope, counting cells and grading haze. They also look for retinitis, inflamed blood vessels and swelling at the center of the retina (macular edema).

Further tests depend on the suspected cause:

• Optical coherence tomography (OCT): a scan of the retina for macular edema, the main cause of vision loss in uveitis.
• Fluorescein angiography: dye photographs that show leaking blood vessels.
• Blood tests: for syphilis, tuberculosis (interferon-gamma release assay), sarcoidosis (ACE, calcium), toxoplasma, Lyme disease and HIV.
• Chest X-ray or CT for sarcoidosis and tuberculosis.
• Brain MRI if multiple sclerosis or lymphoma is suspected.
• Vitreous sample (tap or vitrectomy): fluid from the eye is tested for infection or lymphoma when the cause is unclear.

Treatment

Infection

Infectious causes need specific treatment: antibiotics for toxoplasmosis, syphilis or tuberculosis; antivirals for herpes viruses; and for endophthalmitis, antibiotics injected straight into the eye, sometimes with urgent vitrectomy surgery.

Non-infectious inflammation

• Corticosteroids: eye drops reach the front of the eye but not the vitreous well, so vitritis usually needs steroid injections around or into the eye, a slow-release steroid implant, or steroid tablets.
• Steroid-sparing medicines: methotrexate, mycophenolate, or biologic drugs such as adalimumab for chronic or bilateral disease.
• Vitrectomy: surgical removal of the vitreous gel, used for dense persistent haze, complications or diagnosis.
• Laser or cryotherapy: sometimes used for pars planitis.

Steroids can raise eye pressure and cause cataract, so regular checks are part of treatment.

Complications

• Macular edema, causing blurred central vision
• Cataract and glaucoma, from inflammation or steroid treatment
• Epiretinal membrane, retinal detachment or vitreous hemorrhage
• Permanent vision loss if the cause is not controlled

Outlook

Mild vitritis from intermediate uveitis often settles with treatment, and many children with pars planitis improve over years. Infectious vitritis can resolve once the infection is treated, although scars may remain. Chronic uveitis needs long-term follow-up, but with modern immune-suppressing treatment most people keep useful vision.

Frequently asked questions

What is vitritis?

Vitritis is inflammation of the vitreous, the clear gel inside the back of the eye. White blood cells float in the gel, causing floaters and hazy vision. It is a sign of uveitis or infection inside the eye rather than a separate disease, and needs specialist assessment.

What causes vitritis?

The most common causes are non-infectious uveitis, often linked with sarcoidosis or multiple sclerosis, and infections such as toxoplasmosis, syphilis, tuberculosis and endophthalmitis after eye surgery. In older adults, persistent vitritis can rarely be caused by vitreoretinal lymphoma.

Is vitritis serious?

It can be. Mild vitritis may cause only floaters, but uncontrolled inflammation can lead to macular edema, cataract, glaucoma and permanent vision loss. Vitritis with pain and worsening vision after eye surgery can mean endophthalmitis, which is an emergency.

Can vitritis go away on its own?

Mild inflammation sometimes settles without treatment, but vitritis should not be left untreated without an eye doctor's assessment. The underlying cause, especially infection, needs to be found. Floaters from old inflammatory debris can persist even after the inflammation has cleared.

How is vitritis different from ordinary floaters?

Ordinary floaters come from age-related clumping of the vitreous gel and do not affect sharpness of vision. Vitritis floaters come with haze, reduced vision or other signs of inflammation. Only a dilated eye exam can reliably tell the difference.