What are the causes of a red and painful eye?

Red eyes are usually painful. The following causes are dangerous to vision and will require specialist supervision:


 * acute glaucoma


 * acute iritis


 * corneal ulcers

Other causes are more easily treated:


 * episcleritis


 * conjunctivitis


 * spontaneous conjunctival haemorrhage

All red eyes should be carefully assessed, looking especially at acuity, the cornea (use fluorescein drops) and pupillary reflexes.

Acute Closed Angle Glaucoma
This is a disease of middle-aged to older people. It is usually of sudden onset in one eye, commonly preceded by blurred vision or haloes around lights, especially at night time. It is caused by blockage of drainage of aqueous from the anterior chamber via the canal of Schlemm. Dilatation of pupils at night exacerbates drainage block. Intraocular pressure then rises from the normal 15-20mmHg to 60-70mmHg.

Pain may be severe with the following:


 * nausea/vomiting


 * decreased vision


 * corneal oedema (haze)


 * redness (circumcorneal)

The pupil is fixed, dilated (may be vertically ovoid). The raised intraocular pressure may make the eye feel hard. A shallow anterior chamber (predisposing factor) may be seen in the other eye (shine a torch from the side, half the iris lies in shadow). If suspected send to eye unit.

Treatment
Pilocarpine 2-4% drops hourly (miosis opens the blocked, 'closed' drainage angle) + acetazolamide 500mg PO stat (IV if vomiting) then 250mg/8h PO or IV

Acetazolamide decreases formation of aqueous.

IM morphine may be needed for pain.

Admit, and monitor pressure

Mannitol 20% by IVI may be needed (up to 500mL). Don't rely on newer agents alone, eg apraclonidine drops but they may have an additive effect when given with timolol and pilocarpine.

Peripheral iridectomy (laser or surgery) is done once intraocular pressure has been medically reduced (rarely as an emergency if medical management fails to control pressure). A small piece of iris is removed from the 12 O'Clock position in both eyes to allow free circulation of aqueous.

Anterior Uveitis (acute iritis)
The Uvea is the pigmented part of the eye including iris, ciliary body and choroid. The iris and ciliary body are called the anterior uvea and iris inflammation invariably involves the ciliary body as well, so inflammation is best referred to as anterior uveitis. Remember to ask about systemic disease (eg ankylosing spondylitis, sarcoid)

Presentation is with pain of acute onset, photophobia, blurred vision (due to precipitates in the aqueous), lacrimation, circumcorneal redness (ciliary congestion), and a small pupil (initially from iris spasm; later it may be irregular or dilate irregularly due to adhesions). Talbot's test is positive: pain increases as the eyes converge (and pupils constrict) as patients watch their finger approach their nose. A slit lamp reveals white precipitates on the back of the cornea and cells in the anterior chamber. Sometimes sterile anterior chamber pus (hypopyon) may be seen.

It tends to afflict the young or middle-aged. There are many causes. Associations: joint problems (eg ankylosing spondylitis, Still's). It may relapse.