Other Eye Diseases
Cataracts are the most common cause of blindness
in the world. The condition manifests as gradual, painless loss
deterioration of vision. Risk factors include:
Age: the most important risk factor
diabetes, galactossaemia, Wilson's disease, hypocalcaemia
Investigation is targeted towards secondary causes. such as
those listed above. Treatment is extraction of the cataract with
insertion of an intraocular lens, a procedure which is termed
This is increased pressure in the eye causing optic nerve damage. The
"cup" of the optic disc is the central region where there are no
nerves, hence when damage occurs ("cupping") the cup enlarges, which is
seen on ophthalmic inspection as a thin neuroretinal rim.
There are 2 types of glaucoma:
This is the commonest type. It arises due to
reduced outflow of aqueous humour through the Canal of Schlemm. Risk
factors include: age, family history, myopia, and being black. The
condition manifests as gradual painless loss of the peripheral visual
field (an arcuate scotoma), whilst the central vision remains intact.
Investigations include aplenation tonometry (which measures intraocular
pressure), and visual field testing. The treatment is to reduce the
Drugs: topical beta
blockers, topical prostaglandin analogues (latanoprost), carbonic
anhydrase inhibitors (acetazolamide).
Closed Angle (Acute)
This is an
emergency. a sudden increase in pressure arises when reduced drainage
of fluid occurs, due to an ageing lens pushing the iris forward against
the trabecular meshwork. The clinical features are: a sudden "aching"
painful red eye, nausea, vomiting, headache, and severe ocular pain.
Patients might see "halos" with a rainbow pattern around lights. The
pupil is fixed and dilated. Risk factors include age, hypermetropia,
women. Unlike closed angle glaucoma the condition is not familial.
The treatment is:
to preserve sight: acetazolamide and pilocarpine (which constricts the
eye, improving drainage).
treatment, which involves making a hole in the periphery of the iris of
This is a systemic vasculitis. Because of its potential to cause
irreversible blindness, it is an ophthalmological emergency.
The disease is an inflammatory granulomatous arteritis of large
arteries associated with polymyalgia rheumatica. The visual loss occurs
due o arterial inflammation and occlusion. Clinical features include a
severe headache, tenderness of the scalp, claudication of the jaw which
is worse on eating, and "coming and going" vision. Symptoms of the
associated polymyalgia rheumatica include sudden onset pain and
stiffness of the the shoulders/neck, and hips/lumbar spine.
Investigations revealed raised ESR and CRP. A temporal artery
biopsy should be performed, which reveals intimal hypertrophy, giant
cells, and inflammatory infiltrate. The biopsy may, however, miss focal
lesions and sometimes repeats are required. Treatment is immediate high
dose prednisolone on clinical grounds. The dose is reduced after a few
causes loss of visual acuity.
Drusen are seen on ophthalmoscopy. These are variably sized white or
yellow spots scattered throughout the macula.
This has the worst prognosis. Neovascularisation and leakage of serous
fluid or blood occurs. Retinal detachment is a complication.
Retinal Vein Occlusion
This is sudden unilateral painless
loss of vision that often occurs on waking. The retinal veins are
engorged, flame shaped retinal haemorrhages and cotton wool spots are
seen. The optic disc is swollen. Risk factors include diabetes,
hypertension and glaucoma.