Clinical assessment of the eye

Most eye disorders can be diagnosed by history and examination; special investigations are rarely necessary. Causes of eye symptoms are summarised in Table 20.1.

Table 20.1 Common symptoms of eye disease

Ophthalmic emergencies

Box 20.1 lists conditions which should be considered for emergency referral.

The red eye

The features of the dangerous red eye are shown in Box 20.2 and urgent referral to an ophthalmologist is required if these are present.

The presence or absence of pain helps narrow down the possible causes of the red eye (Table 20.4).

The painful eye

It is helpful to elicit if the pain is superficial or deep. Headache associated with visual symptoms occurs in migraine and giant cell arteritis and should not be confused with ocular pain. Common causes include corneal abrasion, keratitis, glaucoma and uveitis.

Corneal abrasions result from trauma, and there is usually a clear history of the injury. Abrasions may be identified with fluorescein 2% stain and cobalt blue light. Treatment is with broad-spectrum antibiotic eye drops four times a day for 5 days and an eye patch if the pain is severe.

Keratitis is an inflammation of the cornea and may be due to herpes virus infection or bacteria, for example Neisseria gonorrhoeae. Predisposing conditions include contact lenses, dry eyes and long-term use of eye drops containing steroids.

Acute anterior uveitis (inflammation of the iris and/or ciliary body) may be associated with systemic disorders, for example HLA B27-positive arthropathies and sarcoidosis. Pain is usually moderate. Redness is most marked around the cornea (Fig. 20.1). Specialist attention is required from an ophthalmologist.

Figure 20.1 Acute anterior uveitis (iritis) with ciliary flush and a fixed, oval pupil.

Glaucoma is characterised by optic nerve fibre damage resulting in typical optic disc changes of cupping and visual field loss. Raised intraocular pressure is the key feature. There are many subgroups but acute and chronic glaucoma are the most important. Acute glaucoma is more common with advancing age and causes severe distress, eye pain, blurring of vision and halos around lights. Immediate referral is necessary and urgent treatment to lower the pressure of the eye is required.

Ophthalmic injuries

Penetrating injuries

Penetrating injuries may be suspected when there is decreased visual acuity, a soft eye and a distorted iris (tear-drop shaped pupil, Fig. 20.2).

Figure 20.2 Penetrating injury of the cornea with iris prolapse causing pupillary distortion, and secondary cataract.

Visual loss

Acute loss of vision

The causes of visual loss are shown in Table 20.5. They may be acute, subacute or gradual, and either partial or total. Unilateral symptoms are likely to be from lesions of the eye or optic nerve. Bilateral lesions result from defects proximal to the optic chiasma in the brain.

Table 20.5 Causes of visual loss

Retinal artery occlusion

This occurs in the optic nerve, just behind the visible optic nerve head, usually as a result of a thrombosis of atheromatous vessels. Branch retinal artery occlusions are usually embolic, derived from atheroma from the carotid arteries. Emboli may be visualised on fundoscopy as white or yellow particles lodged in the bifurcations of the retinal arterioles. When the central retinal artery is involved, the visual loss is sudden and painless and the deficit profound. At fundoscopy, there is a pale retina with attenuated vessels and a cherry spot at the macula (Fig. 20.3). There is an impaired direct light response. Branch retinal artery occlusion affects vision, depending on the location of the vessel and a visual field defect (scotoma) results.

Figure 20.3 Central retinal artery occlusion with ‘cherry red spot’.

Retinal vein occlusion

Risk factors include diabetes, hypertension and hyperlipidaemia. Sudden loss of vision of variable severity occurs. Fundoscopy demonstrates dilated veins, haemorrhages and cotton wool spots in the affected area of the retina.

Anterior ischaemic optic neuropathy

This is an infarction of the optic nerve head. Risk factors include hypertension and angina or, in the over-70s, an arteritis usually as a result of temporal arteritis.

Retinal detachment

Retinal detachment is usually spontaneous but may be traumatic. It causes a visual field loss which may be small, and visual acuity is retained unless the macula is involved. If the detachment is small, fundoscopy may be normal. The detachment is seen as an elevated convex area of grey retina which moves with ocular movement and has a wrinkled surface (Fig. 20.4). Treatment aims to oppose the detached retinal and underlying retinal pigment epithelium using laser or cryoprobe.

Figure 20.4 Retinal detachment.

Diseases with ophthalmic manifestation

Acquired immune deficiency disease has a number of ophthalmic manifestations due either to a primary effect of HIV on retinal vasculature or to secondary opportunistic infections, for example cytomegalovirus, herpes simplex, staphylococcal and mycobacterial choroiditis. Fungal infections due to Candida or Cryptococcus may also occur. Toxoplasmosis and Kaposi’s sarcoma have also been described.

Rheumatoid arthritis may also be associated with ophthalmic manifestations, as may systemic lupus erythematosus and giant cell arteritis (temporal arteritis). Graves’ disease is described in Chapter 11.

Diabetic retinopathy is a leading cause of registration for blindness in the UK, occurring in both type 1 and type 2 diabetes. Visual loss can occur as a result of macular damage, vitreous haemorrhage or retinal detachment. The incidence of retinopathy increases with the duration of the disease and is reduced by good control of blood sugar and blood pressure. Laser treatment is effective in preventing visual loss from retinopathy and all diabetic patients should be screened for this.