Uveitis; iritis and iridocyclitis (anterior uveitis), and choroiditis (posterior uveitis)

Any part of the uveal tract can become inflamed[md]the iris (iritis), the ciliary body (cyclitis), or the choroid (choroiditis). More than one part may be involved at the same time (iridocyclitis). The terms ''iritis' and ''uveitis' are often used loosely and interchangeably, and we will do the same here. Although iridocyclitis may be caused by bacteria invading the eye through a corneal ulcer (24.3), it and other forms of uveitis are more often due to a sterile inflammation, usually from an unknown cause. Uveitis of several kinds is common in the developing world.

Iritis (more strictly iridocyclitis) has several consequences: (1) A patient's inflamed iris may stick to his lens by posterior synechiae (adhesions, common) or less often to the back of his cornea by anterior synechiae. (2) If the entire margin of his pupil sticks to his lens, his iris balloons forwards (iris bomb[ac]e, B, 24.7), and he has secondary glaucoma (24.6). (3) Small separated pieces of iris may stick to his lens, or less often to his cornea. (4) Abnormal proteins enter his aqueous, and cause an aqueous flare, which you can see with a slit lamp. You can also see leucocytes as tiny particles floating in his aqueous. (5) These particles may stick to the back of his cornea as keratic precipitates (KP), and they may be numerous enough to gather at the bottom of his anterior chamber as a hypopyon. Unlike the hypopyon that results from the entry of bacteria through a corneal ulcer, the hypopyon of iridocyclitis is usually sterile. Untreated iridocyclitis eventually subsides spontaneously, typically in about 6 weeks, leaving his eye severely damaged. It may relapse, or it may be insidious and chronic, with few symptoms except progressive loss of vision.

Uveitis presents in two ways (or in both of them together, panuveitis, see below): (1) Anterior uveitis (iritis) presents as an ''acute red eye'; it is thus one of the important differential diagnoses of of this condition, and particularly of conjunctivitis (24.3). He has pain in and around his eye varying from mild to severe, photophobia, watering, and often blurred vision. He has ciliary hyperaemia, and often general hyperaemia also. His pupil is constricted. (2) Posterior uveitis (choroiditis) presents as progressive loss of vision, without other obvious symptoms, in a white eye (24.4).

Iritis is usually a sterile reaction to one of the infections listed below. If onchocerciasis (24.7) is endemic in your district, it will certainly be the most common cause. Usually, no cause is found, and iritis is presumed to be an autoimmune disease.

Atropine will keep his pupils well dilated, and break down synechiae.

Steroids are controversial. Opinions differ as to their long-term benefit, and whether they are safe in non-expert hands. They probably hasten resolution, and justify the risks associated with their use, but only provided that you don't use them if there is any sign of infection, especially a corneal ulcer. Remember also that: (1) Steroids will make a red eye white, regardless of the cause, without necessarily curing it. (2) They will suppress the normal inflammatory response, without killing the causative agent. (3) They may raise his intraocular pressure, and may cause a secondary glaucoma that could blind him (unusual). (4) If you give steroids long term, they may cause a cataract, but they will not do this during the few weeks that are necessary to treat acute iritis.

UVEITIS, [s8]iritis, iridocyclitis, choroiditis DIAGNOSIS. Uveitis may be unilateral, or bilateral, and presents in various ways.

Acute anterior uveitis (iritis, iridocyclitis) presents as a red, painful eye, with photophobia and tearing; for the differential diagnosis see Section 24.3.

Posterior uveitis involves mainly a patient's choroid, and presents as fairly sudden loss of vision over 24[nd]48 hours in a white and usually painless eye, due to damage to his retina and an exudate of cells and pigment into his vitreous. After dilatation, you can see these as a vitreous haze with an indistinct retina. At a later stage, when the haze has cleared, you may see foci of white depigmentation, surrounded by heaped up black pigment which results in impaired vision, especially if it involves his macula.

Panuveitis (quite common) is a combination of anterior and posterior uveitis, and causes loss of vision in a red, painful eye.

SPECIAL TEST. Dilate his pupil and look for posterior synechiae which will confirm the diagnosis of iritis.

CAUSES. You will probably find no cause, but if he has any of these, it may be responsible: syphilis, leprosy, herpes, toxoplasmosis, toxocariasis, onchocerciasis (24.7), tuberculosis (29.1), trauma, or the leakage of the lens protein from a hypermature cataract.

TREATMENT. Dilate his pupil with short acting mydriatics (cyclopentolate and phenylephrine). When his pupil is dilated, maintain him on atropine ointment 1% three times a day, until his uveitis is no longer active, as shown by the absence of KP bodies and redness. This will prevent posterior synechiae, which would lead to the blinding complication of secondary glaucoma and cataract. So, keep his pupil dilated until all the inflammation has subsided.

If his disease is unilateral, cover his eye with a shield (24.1) if it is severe, and a shade if it is not. If it is bilateral, give him eye shades made from exposed X-ray film.

STEROIDS. His iritis will subside spontaneously, but topical steroids will hasten its departure.

CAUTION ! NEVER give steroids if: (1) There are signs of infection. (2) He has a corneal ulcer.

If he has anterior uveitis (iridocyclitis), instil hydrocortisone drops 1% into his conjunctival sac 3 hourly.

If he has posterior uveitis, give him tablets of prednisolone 20[nd]30 mg/day for 3 to 6 weeks. Don't continue beyond 6 weeks. Tail these off for a week at the end of the course.

If his IOP is raised, also give him acetazolamide 250 mg 6-hourly, until the inflammation is under control. Double the dose if it remains raised. If possible monitor his IOP weekly by tonometry.

DIFFICULTIES [s7]WITH UVEITIS If POSTERIOR SYNECHIAE develop, they may be followed by a cataract. Or they may occlude his pupil and cause pupil block glaucoma (iris bomb[ac]e), with an increased IOP. Be sure to dilate his iris vigorously with atropine, so that it does not stick to his lens.

If he gets SECONDARY GLAUCOMA, his pupil will not dilate. You can refer him for an iridectomy, but it is usually too late.