Key learning points - ophthalmology

Key questions – ocular disorders

Half of cases of infectious conjunctivitis will be viral and the vast majority of bacterial conjunctivitis is self-limiting.
A Cochrane review examined use of antibiotics versus placebo for acute bacterial conjunctivitis and found symptoms resolved more quickly with antibiotics but the benefits were marginal.
The typical signs of an acute conjunctivitis are grittiness, redness and discharge without visual disturbance.
Swabs should be taken for neonatal conjunctivitis, highly purulent, or where there is lack of response to treatment.
There is very little evidence from clinical trials of antibiotic against placebo for corneal abrasions.
Serious complications from laser refractive surgery are now extremely rare.
Smoking is a clear risk factor for both cardiovascular disease and age-related macular degeneration.
Hyperlipidaemia has been linked to age-related maculopathy
But a Cochrane review concluded that statins do not have a role in preventing or delaying the onset or progression of ARMD
Eating oily fish at least twice a week has been associated with a reduced risk of ARMD.
But there is insufficient evidence to recommend omega 3 fatty acid supplementation for ARMD prevention in the general population.
Some forms of glaucoma are both more frequent in certain ethnic groups and may take a more aggressive course.
Phakoemulsification is the most common cataract surgery – where an ultrasonic probe is used to break up or emulsify the cataractous lens.

Rational management of opticians' letters

Glaucoma

Asymmetry in disc cupping is significant
The hospital standard of visual field test is the Humphrey machine.
Often patients are referred with one or two spots missing or an edge defect, which is often an artefact.
Some visual fields are definitely abnormal in appearance and compatible with a diagnosis of glaucoma

Cataract

Include the optician's assessment with a cataract referral
Following cataract surgery some patients will develop thickening of the posterior capsule

Retinal abnormalities

Retinal pigmented lesions are important findings - ranging from an insignificant pigment spot to a dark, relatively large area.
These are usually innocent but a choroidal naevus has the potential to become malignant.
Ocular migraine episodes are usually typical and not necessarily accompanied by a headache.
Posterior vitreous detachment is extremely common and usually experienced by patients in late middle age or earlier in myopia.

Age-related macular degeneration

It's important to know the type of macular change – in order to refer appropriately
Dry macular change can cause gradual reduction and some distortion of central vision.
Wet macular change is characterised by a history of sudden visual change, particularly central distortion.

Lesions of the eyelid

Meibomian cysts are firm, painless nodules - usually solitary although multiple cysts can be found – small lesions can be left alone
Hordeolum is an acute focal infection – usually staphylococcal – and are focal abscesses and present with a painful, warm, swollen, red lump on the eyelid.
Xanthelasma are painless, soft, yellowish lesions in the inner eyelid –and medical care involves dietary advice and lipid-lowering therapy if necessary.
Anterior blepharitis centres on lashes and follicles while posterior blepharitis involves the meibomian glands - patients usually experience burning, itchy, erythematous lids.
Entropion is an inversion of the eyelid, usually the lower. It can lead to ocular surface damage if left untreated.
Ectropion is an eversion of the eyelid, usually the lower -patients may complain of epiphora, recurrent infections, irritation or the sensation of a foreign body.

Ten Top Tips- managing red eye

Anyone presenting with a red eye needs to be examined and have visual acuity checked.
If anyone who wears contact lenses develops a red eye – irrespective of whether there is pain, photophobia or visual blurring – they must be referred to eye casualty immediately
The main causes of photophobia are corneal lesions and anterior chamber inflammation – commonly seen as iritis.
Viral conjunctivitis is irritating but shouldn't be painful and doesn't cause much visual disturbance.
Allergic conjunctivitis is generally seasonal but can occur with winter allergens and tends to be itchy and less red.
Chlamydial conjunctivitis tends to have more redness and discharge but less itch.
Conjunctivitis occurring five to 19 days after birth is a medical emergency and a notifiable disease.
Some 15% of all shingles cases affect the first division of the trigeminal nerve - herpes zoster ophthalmicus.

Ophthalmology referral dilemmas

The sixth and third nerve palsies are the most common in clinical practice.
Most obvious cases will be seen as a convergent squint when looking straight ahead (sixth nerve palsy) and a divergent squint (third nerve palsy).
There are two main diagnoses to tease out with transient visual loss– amaurosis fugax and ocular migraine
Both are neurological but routinely dealt with by ophthalmology
In ocular migraine there is a visual disturbance of spiralling or zigzagging lights culminating in loss of central vision and eventual recovery- the whole process takes 20-30 minutes.
Amaurosis fugax is a form of TIA and is a potential precursor to stroke.
Acutely, cases of facial palsy are best referred to ENT but ophthalmology referral is required fairly promptly if there is concern about corneal exposure.