Cataracts

Question 1

Define cataracts

Answer 1

Opacification of the crystalline lens resulting from the normal ageing process, trauma, metabolic disorders (hereditary or acquired), medications or congenital problems

Question 2

Classification of cataracts

Answer 2

According to the part of the lens primarily affected

Nuclear: central opacification and discoloration to the nucleus of the lens
Cortical - opacification of the cortex
Subcapsular - in the subcapsular cortex
- Anterior: ;usually from blunt trauma
- Posterior usually drug-related or metabolic

+ cerulean (blue) | snowflake (uncontrolled DM) | sunflower (Wilson’s) | Xmas tree (myotonic dystrophy) | oil droplet (galactosaemia)

Question 3

Aetiology of cataracts

Answer 3

Normal ageing process = most common cause
Eye disease: chronic anterior uveitis, closed-angle glaucoma, high myopia, retinitis pigmentosa, leber congenital amurosis
Hereditary conditions e.g. galactosaemia, Wilson’s, Marfan’s, myotonic dystrophy, Alport’s, rubella infection, down’s syndrome,, neurofibromatosis type 2
Infections e.g. rubella, varicella, CMV
Trauma
Metabolic: diabetes mellitus, hypocalcaemia
Medications e.g. steroids
Smoking
Exposure to UV

Question 4

Symptoms of cataracts

Answer 4

Blurred or cloudy vision, even with full correction
Haloes
Glare, especially driving at night (dazzling in bright lights)
Loss of night vision
Polyopia
Washed-out colour vision (Nuclear cataracts)
- Yellowish hue to the cataract
- Reduced richness in colours, especially blues

Question 5

Differentials for cataracts

Answer 5

Refractive error
Corneal disease
Dry eye
Presbyopia
Age related amcular degeneration
Infection/inflammation
Macular oedema
Primary open angle glaucoma

Question 6

Signs of cataracts on examination

Answer 6

Reduced visual acuity (myopia)
Defects in red reflex
Inadequate glasses prescription

Children: leukocoria, nystagmus, squint/strabismus

Question 7

Investigations for cataracts

Answer 7

Fundoscopy (dilated): fundus and optic nerve normal, darkened red reflex
Acuity testing
BM: exclude DM

Intra-ocular pressure: normal (exclude glaucoma)
Slit lamp exam: visible cataract
Glare vision test: significant cataract

Question 8

Management for cataracts

Answer 8

Refer to an optometrist for an eye examination and measurement of visual acuity to confirm the diagnosis and exclude other causes of visual impairment.

Conservative:
- glasses & sunglasses
- glycaemic control
- fitness to drive

Medical:
- mydriatic eye drops (tropicamide)

Surgical (if affecting lifestyle or driving) → cataract surgery

Question 9

Complications of cataract surgery

Answer 9

Posterior capsular opacification (months to years after, proliferation of lens remnants) → reduced acuity, blurred vision, glare
Posterior capsule rupture (intraoperative) → retained lens fragments, vitreous prolapse or traction
Retinal detachment
Glaucoma
Endophthalmitis (red painful eye, reduced vision)
Anterior uveitis
Vitreous haemorrhage
Corneal oedema → decompensation

Question 10

Prognosis for cataracts

Answer 10

Without treatment, history is of a steady decline without chance of recovery
With surgery around 95% of people will have 6/12 best-corrected vision without pre-existing pathology and 51% with 6/6 best corrected vision with pre-existing pathology
For people with bilateral cataracts, small but significant extra gains in visual function can be expected after surgery on the second eye, particularly in improved stereopsis (perception of depth of vision), if cataracts are removed from both eyes rather than just one
Cataract surgery is generally very safe and effective and substantially improves people’s quality of life with gains in social and emotional life