Uveitis
Uveitis is an inflammation of the eye that appears suddenly. The eye is red and tender, but unlike conjunctivitis, there is no abnormal discharge. The inflammation is extremely damaging to vision and ocular structures. Anti-inflammatory treatment with corticosteroid eye drops, combined if necessary with treatment of the underlying cause, is essential. The disease will progress in successive flare-ups throughout your life. Early treatment of each attack and specialized follow-up are therefore crucial.
What is uveitis?
Uveitis is a group of inflammatory conditions affecting the uvea. Most often, the eye will be red, painful, accompanied by a more or less marked decrease in visual acuity and often photophobia (sensitivity to light).
This condition is most often unilateral, although both eyes are sometimes affected (either simultaneously or at different times). Other symptoms, such as floaters (the sensation of seeing floaters in the field of vision), can also indicate uveitis.
Uveitis is a fairly common condition that constitutes a genuine ophthalmological emergency. Indeed, early and well-managed treatment will allow for rapid pain relief and limit the occurrence of major complications (iridocorneal synechiae, cataracts, ocular hypertension, etc.).
The symptoms
Symptoms vary greatly from one case of uveitis to another and from person to person. They are generally quite sudden. Some cases of uveitis may, rarely, be asymptomatic. Most often, they manifest as a red eye, pain, blurred vision associated with light sensitivity known as photophobia, which can affect one or both eyes and is likely to recur.
Anterior uveitis – This is the most common form, known as "acute anterior uveitis". It is often accompanied by pain, redness, visual disturbances, and photophobia.
Intermediate uveitis – This is the least common form and its progression is gradual. It is characterized by an absence of pain, the appearance of floaters (myodesopsia), and a decrease in vision.
Posterior uveitis – also called retinitis or chorioretinitis – can cause a decrease in deep visual acuity and the appearance of floaters. Pain is not always present. This type of uveitis is often serious and can sometimes lead to blindness.
Panuveitis – A severe form, it encompasses all three conditions.
The causes
This is an important aspect of this disease. Indeed, while 80% of uveitis cases are "idiopathic" (with no identifiable cause), the ophthalmologist will most often prescribe a fairly comprehensive "etiological" workup (to search for a cause). This will include blood tests, a chest X-ray, and testing for tuberculosis. In cases of secondary uveitis, the most frequently associated conditions are:
Autoimmune diseases – Ankylosing spondylitis (HLAB27+), Crohn's disease or psoriasis.
Infectious diseases – such as toxoplasmosis, syphilis and tuberculosis (the latter two being fortunately very rare).
Focus on toxoplasmosis – Recurrent infectious chorioretinitis.
A parasite called toxoplasma gondii is present in a dormant state in 50 to 80% of French people.
We become infected in childhood by petting a cat or eating raw fruits or vegetables.
Sometimes the infection reactivates in the retina, causing a sudden inflammation of the retina and its nourishing covering: the choroid.
This is toxoplasmic chorioretinitis, the most frequent cause of posterior uveitis! A chapter is dedicated to ocular toxoplasmosis (link).
Pathophysiology and anatomy
The uvea corresponds to the tissues composed of the iris, ciliary bodies and choroid.
The iris is the colored part of the eye that regulates the amount of light reaching the retina, the ciliary body is a set of muscles connected to the lens that allow the eye to engage in the accommodation process, and the choroid is a layer between the sclera and the retina that allows for the vascularization of the retina.
Depending on the area of the inflamed uvea, different types of uveitis can be distinguished: anterior (the most frequent), intermediate, posterior, and panuveitis, which includes the three previous types.
In cases of anterior uveitis, the anterior segment (particularly the anterior chamber) is affected. Iriditis refers to the involvement of the iris, while iridocyclitis affects both the iris and the ciliary body.
Intermediate uveitis involves the aqueous humor and vitreous body, which constitute the majority of the ocular volume.
Posterior uveitis, or choroiditis, is an inflammation of the choroid. On the day of the consultation, a fundus examination will be routinely performed to check for posterior uveitis.
We will speak of panuveitis when the entire uvea is affected.
Diagnosis
The diagnosis of uveitis is clinical and made using a slit-lamp microscope and fundus examination. The ophthalmologist most often finds:
Hyperemia – Red eye and dilated blood vessels.
A Tyndall effect – Inflammatory cells are suspended in the anterior chamber (between the cornea and the iris).
Precipitates – Inflammatory cells stick to the back surface of the cornea.
Synechiae – The iris sticks to the lens.
In complex cases, particularly posterior uveitis, the ophthalmologist will complete their assessment with:
An OCT – High-resolution scan of the retina, to look for inflammation or edema of the macula.
An angiogram – A dye is injected into a vein in the arm. It spreads to the blood vessels of the retina. The ophthalmologist then takes special photographs to look for areas of inflammation.
Action to take and treatment
It is essential to seek urgent medical attention in cases of uveitis to prevent complications. A fundus examination, along with assessment for ocular hypertension and synechiae, will be performed routinely during the consultation. If posterior uveitis is present, angiography will be performed. Treatment relies on anti-inflammatory eye drops, administered very frequently, to reduce inflammation.
Corticosteroid anti-inflammatory eye drops
Administered hourly at the beginning of the illness, then decreasingly, these are what will ensure recovery.
Sometimes, a first dose can be administered by injection (subconjunctival or latero-bulbar route).
Corticosteroids are continued for an extended period, on average for 4 to 6 weeks.
Mydriatic eye drops
When systematically combined with corticosteroids, they dilate the pupil, which relieves pain and prevents the occurrence of iridocrystalline synechiae.
These eye drops are responsible for temporary blurred vision that will last for the entire duration of their use.
Treat the underlying cause if necessary
Depending on the underlying cause, a treatment plan will be proposed. For example, in the case of tuberculosis, it will be treated with antibiotics for several months.
Can uveitis be cured permanently?
Unfortunately not! Experiencing a first bout of uveitis remains a real sword of Damocles for the rest of one's life.
Indeed, a new flare-up can occur at any time and without warning. Most often, patients remain deeply affected by the initial episode and the delayed diagnosis. Subsequent episodes tend to consult an ophthalmologist very early on.
It should be noted that some ophthalmologists sometimes leave a prescription for self-initiating treatment, so that patients who know their disease very well can start treatment at the first sign of symptoms.
Complications
Uveitis is an ophthalmological emergency. The faster the diagnosis is made and the earlier treatment is started, the better the prognosis.
In the event of a flare-up resistant to medical treatment, or a delay in treatment, certain complications may occur:
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Ocular hypertension and glaucoma – Due to the formation of synechiae (adhesions) between the iris and the filter regulating ocular pressure (trabecular meshwork).
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Cataract – Eye inflammation damages the lens, the part of the eye that allows for focusing. It becomes opaque and blurs vision: this is a cataract.
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Exudative retinal detachment – In cases of severe eye inflammation, pockets of edema can form under the retina. This is called exudative retinal detachment. Note that this is a specific type of retinal detachment and should not be treated surgically.