Differential diagnosis of the acute red eye
The importance of this is in the management of
minor ocular complaints, and the recognition of conditions requiring expert
attention. Possible causes of the acute red eye can be divided into:
•
conjunctivitis;
•
keratitis;
•
uveitis;
•
episcleritis and scleritis;
•
acute glaucoma.
Conjunctivitis
Symptoms are grittiness, redness and
discharge. Causes are infective, viral, traumatic or allergic. In the newborn it
can be serious, and gonococcal and chlamydial infection must be excluded. Vernal
conjunctivitis (Fig. 36.25) is a form of allergic conjunctivitis, usually worse
in the spring and early summer, and often associated with other allergic
problems such as hay fever. Clinically, most signs are under the upper lid which
may have a cobblestone appearance instead of a smooth surface. Giant pupillary
conjunctivitis with large papilli under the upper lid may be seen in soft
contact lens wearers. This is usually due to an allergy to the sterilising
solutions and may be helped by either using a preservative-free solution or
using daily wear disposable lenses where these are applicable. Viral
conjunctivitis has become much more common. Chlamydial and adenovirus infections
must be considered. Adenoviral infections usually affect one eye
Considerable
conjunctival irritation can be caused by the lids turning in (entropion) (Fig.
36.27) or turning out (ectropion) (Fig 36.28 and
Fig 36.29) and by ingrowing
lashes. The lids should be repaired surgically to their normal position.
Vision
is not affected in conjunctivitis, but with some virus infections a keratitis
may be present, and result in visual loss and pain. All of the other conditions
are painful, and usually affect vision.
Cornea)
ulceration may occur due to ingrowing lashes or corneal foreign bodies, marginal
ulceration and infected ulcers. Infected ulcers can occur in patients wearing
soft contact lenses. Herpes zoster (shingles) affects the ophthalmic division
of the fifth nerve, and can give rise to a keratitis and uveitis. It is
important to exclude the use of steroid drops until a diagnosis has been made.
Local anaesthetic drops should also not be given on a regular basis.
Uveitis
This can be anterior (inns) or posterior. In
anterior uveitis the pupil will be small, sometimes irregular, there is csrcumcornea)
injection and there may be keratic precipitates (KPs) present on the posterior
surface of the cornea. Pain, photophobia and some visual loss are usually
present. Posterior uveitis can present with a white eye and blurred vision. It
usually takes a chronic course. Granulomatous diseases, Behçet’s disease,
toxoplasmosis and cytomegalovirus infection should be excluded. Systemic
steroids and cytotoxic drugs are sometimes useful in treating these conditions.
Episcleritis
and scleritis
Episcleritis or inflammation of the episcleral
tissue often occurs as an allergic reaction following an eye infection (Fig.
36.31).
Scleritis
is a more serious condition in which the deeper sclera is involved. There is
often an associated uveitis and thinning of the sclera. It may require the use
of systemic steroids in order to treat adequately
Scleritis
is often associated with severe rheumatoid conditions.
Acute glaucoma
This usually occurs in older, often
hypermetropic patients. The cornea becomes hazy, the pupil oval and dilated, the
vision very poor and the eye feels rock hard. In severe cases the pain may be
accompanied by vomiting, and the pain can be mistaken for one of an acute
abdomen. In doubtful cases the use of the tonometer to measure the intraocular
pressure is a useful diagnostic procedure. Urgent treatment to reduce the
pressure by pilocarpine, acetazolamide and mannitol should be started followed
by a surgical iridectomy or laser iridotomy. The condition is usually bilateral,
and the second eye usually needs treatment at the same time.
Except
for a simple conjunctivitis, which is self-limiting, these conditions require
expert treatment and a specialist opinion should be sought.
A
painful eye with a third nerve palsy often signifies an intracranial aneurysm
and should be investigated immediately.