A cataract is an opacification of the lens of the eye. Cataracts tend to cause gradual loss of visual acuity, with normal pupillary response.
Cataracts are the most common non-refractive cause of visual impairment worldwide.
They usually occur with age (although can be congenital, or secondary to medication trauma or other conditions). They can be cured with cataract surgery – which in modern times is usually a relatively straightforward procedure.
Patients should be considered for surgery when the cataract is causing visual acuity of <6/18 in one or both eyes.
Epidemiology and Aetiology
- Main one is AGE!
- UV light
- Regular wearing of sunglasses in sunny climates or those who work outdoors (particularly wrap-around sunglasses) may reduce the risk
- Smoking (as usual- if in doubt say smoking!)
- Alcohol use
- Other metabolic disorders eg fabry disease, hypocalcaemia, galactosaemia (you’ll get points for saying these)
- Systemic drugs (eg, corticosteroids)
- 65% of people over 50 have some sort of opacity
- 100% of people of 80 have some form of cataracs
- Painless loss of vision
- Misting or blurring
- Change in refractive error
- (in infants may cause amblyopia)
- Often manifests as
- Difficulty reading
- Difficulty recognising faces
- Problems driving – especially at night
- May have haloes around lights (but beware of glaucoma in these instances)
- Occasionally an elderly patient may present with sudden loss of vision in one eye. Cataracts are never an acute event, but patients sometimes become acutely aware of it when vision in their other eye becomes obscured for whatever reason.
- Reduced visual acuity
- Diagnosis is best made with a dilated pupil
- Examine with a slit lamp/ophthalmoscope- a cataract is seen as black against the red reflex
- May have reduced red reflex
- If the cataract is bad enough to cause sufficient visual symptoms- “reduction in quality of life”
- Vision worse than 6/12
- Diabetic retinopathy
- Cause of intraoccular inflammation
- Bleeding – choroidal haemorrhage
- Vitreous loss
- Endopthalmitis – a very nasty infective complication, but thankfully very rare (0.3%).
- Opacification of the capsule- treated by burning holes in the capsule with YAG laser
- Most common cause of visual impairment worldwide
- Treat if affecting activities of daily living or VA <6/12
- Treatment is surgery
- Make patients aware of complications