Cataracts
Exam Tips
- In UK exams, state that cataract referral is based on functional impact and patient choice, not visual acuity threshold alone.
- Classic symptom cluster: painless progressive blur + glare/halos + frequent prescription changes.
- Posterior subcapsular cataract often causes disproportionate near-vision and glare problems despite moderate Snellen change.
- Always check and document red reflex; absent or asymmetric reflex in a child is an urgent ophthalmology referral.
- For paediatrics, mention time-critical surgery windows (unilateral congenital around 4-6 weeks; bilateral around 6-8 weeks) to reduce irreversible amblyopia.
- After surgery, counsel on red flags for endophthalmitis (pain, photophobia, worsening vision, increasing redness) requiring same-day specialist review.
- See Figure: red reflex attenuation and lens opacity patterns on slit lamp in cataract teaching atlases for OSCE image stations.
Definition
A cataract is a clinically significant opacification of the crystalline lens that causes progressive reduction in visual quality, typically with blurring, glare, and reduced contrast. In UK practice it is most often age-related and may be unilateral or bilateral, but cataracts can also be congenital, developmental, traumatic, or secondary to systemic/ocular disease and medicines.
Pathophysiology
Ageing lens fibres accumulate oxidative damage and post-translational protein changes (especially crystallin aggregation), causing loss of transparency and increased light scatter. Lens epithelial dysfunction, hydration changes, and pigment/protein compaction alter refractive index and reduce retinal image quality. Different anatomic patterns produce different symptoms: nuclear sclerosis often causes myopic shift and reduced distance vision, cortical spokes cause glare, and posterior subcapsular cataract disproportionately impairs near vision and causes disabling glare in bright light. In infants, lens opacity during the critical visual-development period causes sensory deprivation amblyopia if not corrected early.
Risk Factors
- Increasing age (especially over 60 years)
- Diabetes mellitus (approximately doubled risk)
- Female sex
- Hypertension and obesity
- Smoking and regular excess alcohol intake
- Ultraviolet-B exposure
- Systemic, inhaled, topical, or intravitreal corticosteroid exposure
- Myopia
- Previous ocular trauma, radiation, electric injury, or prior ocular surgery
- Ocular comorbidity (for example uveitis, hereditary vitreoretinopathy)
- Family history/genetic susceptibility
- Metabolic or hereditary disorders (for example galactosaemia, Wilson disease, Marfan syndrome, myotonic dystrophy, Down syndrome, neurofibromatosis type 2)
- For congenital cataract: intrauterine infection (for example rubella, CMV, toxoplasmosis), genetic syndromes, and first-degree family history
Clinical Features
Symptoms
- Gradual, painless decline in visual clarity affecting reading, driving, and face recognition
- Blurred or cloudy vision with reduced contrast sensitivity
- Glare disability and halos around lights, often worse at night
- Monocular diplopia or polyopia
- Frequent spectacle prescription changes (including possible myopic shift)
- Reduced colour intensity, especially blues
- In infants/children: poor fixation, leukocoria noted by carers, squint, or nystagmus
Signs
- Reduced visual acuity on Snellen testing
- Dull, reduced, asymmetrical, or absent red reflex
- Lens opacity seen on slit-lamp examination
- Potential reduced fundus view on ophthalmoscopy due to media opacity
- Associated findings on assessment: glare sensitivity, impaired contrast, possible strabismus/nystagmus in paediatric cases
Investigations
Management
Lifestyle Modifications
- Explain natural history: no proven drops/tablets reverse established cataract
- Optimise lighting, contrast, and up-to-date refractive correction while awaiting surgery
- Advise smoking cessation and reduction of harmful alcohol intake
- Encourage UV eye protection (sunglasses/hat) and cardiometabolic risk optimisation (especially diabetes control)
- Assess driving safety against DVLA visual standards; advise stopping driving if standards are not met
- Discuss functional goals and patient preference, as UK referral is based on quality-of-life impact rather than visual acuity alone
- See Figure: slit-lamp patterns of nuclear, cortical, and posterior subcapsular cataract in standard ophthalmology atlases (cataract chapter)
Pharmacological Treatment
Peri-operative mydriatics (for surgery preparation)
- Tropicamide 1% eye drops: 1 drop 15-30 minutes before surgery, repeated per theatre protocol
- Phenylephrine 2.5% eye drops: 1 drop pre-operatively, often combined with tropicamide
Used to dilate pupil for operative access; not disease-modifying. Avoid/monitor phenylephrine in severe cardiovascular disease, hyperthyroidism, or with interacting monoamine oxidase inhibitors/tricyclics due to hypertensive risk.
Post-operative anti-inflammatory therapy
- Dexamethasone 0.1% eye drops: typically 1 drop four times daily then taper over 3-4 weeks
- Prednisolone acetate 1% eye drops: commonly 1 drop four times daily then taper per local protocol
- Nepafenac 0.1% eye drops: 1 drop three times daily (often started around surgery and continued up to 3 weeks; longer in selected high-risk patients)
Regimen varies by local NHS pathway. Topical steroids can raise intraocular pressure and increase infection risk; monitor prolonged use. Topical NSAIDs may increase corneal adverse effects and should be used cautiously in ocular surface disease.
Intra-operative endophthalmitis prophylaxis
- Cefuroxime intracameral 1 mg/0.1 mL single dose at end of cataract surgery
Given by operating surgeon; reduces postoperative endophthalmitis risk. Use alternatives if severe beta-lactam allergy per local ophthalmology protocol.
Surgical / Interventional
- Standard adult treatment: phacoemulsification with intraocular lens implantation (usually day-case local anaesthesia)
- Second-eye surgery can provide additional binocular function and stereopsis gains when indicated
- Paediatric cataract requires urgent specialist management; congenital dense unilateral cataract generally targeted for surgery by 4-6 weeks, bilateral by 6-8 weeks to reduce deprivation amblyopia risk
- Post-paediatric-surgery visual rehabilitation includes optical correction and amblyopia therapy (for example occlusion patching), often over years
Complications
- Progressive visual impairment with loss of independence, reduced quality of life, and increased falls/fracture risk
- Driving restriction or cessation
- Depression and social isolation related to visual disability
- In children: irreversible deprivation amblyopia, strabismus, and nystagmus if treatment is delayed
- Postoperative posterior capsule opacification
- Postoperative cystoid macular oedema
- Postoperative endophthalmitis (rare but vision-threatening)
- Retinal detachment (uncommon, higher risk in myopia and after surgery)
- Raised intraocular pressure/glaucoma, including notable long-term glaucoma risk after infant congenital cataract surgery
Prognosis
Without surgery, age-related cataract usually progresses with no spontaneous recovery, although the speed is variable. With modern NHS cataract surgery, outcomes are generally excellent: most patients achieve meaningful visual improvement, around 95% can reach approximately 6/12 best-corrected vision when no other ocular pathology is present, and a substantial proportion reach 6/6. In children, prognosis is more variable and depends strongly on age at intervention, associated ocular/systemic disease, and adherence to postoperative amblyopia treatment.
Sources & References
🏥BMJ Best Practice(1)
💊BNF Drug References(1)
- Cefuroxime[cautions]
✅NICE Guidelines(1)
- Cataracts[overview]