About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Commonest cause of reversible blindness worldwide — predominantly age-related
- Three main types: nuclear sclerotic (most common, central yellowing), cortical (spoke-like opacities), posterior subcapsular (younger patients, steroids)
- NICE NG77: do NOT restrict access to surgery based on visual acuity alone — decision based on impact on quality of life
- Definitive treatment: phacoemulsification with intraocular lens (IOL) implantation — day-case procedure under local anaesthetic
- Intracameral cefuroxime during surgery reduces endophthalmitis risk (NICE NG77)
Overview
A cataract is any opacity in the crystalline lens of the eye. Age-related cataracts are by far the most common type, resulting from oxidative damage and protein aggregation within the lens. The three morphological subtypes are nuclear sclerotic (gradual central yellowing, often shifting refraction towards myopia), cortical (spoke-like peripheral opacities progressing centrally), and posterior subcapsular (rapidly progressive, causing significant glare and reading difficulty, associated with steroid use). Other causes include trauma, metabolic disorders (diabetes, galactosaemia), congenital infection, and radiation exposure.
Epidemiology
Cataracts affect approximately 30% of people aged over 65 in the UK and are the leading cause of visual impairment globally. Cataract surgery is the most frequently performed elective operation in the NHS, with over 450,000 procedures annually in England. Risk factors include advancing age, smoking, UV light exposure, diabetes mellitus (2–5 times increased risk), systemic or topical corticosteroid use, myopia, previous eye surgery or trauma, and alcohol excess.
Clinical Features
Symptoms
Gradual painless blurring of vision — usually bilateral but asymmetric
Glare and difficulty with bright lights, especially driving at night
Faded or yellowed colour perception
Frequent changes in spectacle prescription (myopic shift with nuclear sclerosis)
Monocular diplopia or polyopia (multiple images in one eye)
Difficulty reading in posterior subcapsular cataract (near vision affected early)
Sudden painless vision loss or new floaters — suggests alternative pathology
Signs
Diminished red reflex on direct ophthalmoscopy — absent in dense cataract
Lens opacity visible on slit-lamp examination
Reduced visual acuity on Snellen chart testing
White pupil (leukocoria) in very advanced/mature cataract
Investigations
First-line
Visual acuity (Snellen or LogMAR)Quantifies degree of visual impairment — but NICE says do not use VA alone to determine surgery eligibility
Slit-lamp biomicroscopyGold standard for cataract classification, grading, and assessment of morphological type
Red reflex assessmentDiminished or absent red reflex indicates significant lens opacity
Second-line
Biometry (IOL Master or A-scan ultrasound)Measures axial length, corneal curvature, and anterior chamber depth — essential for calculating IOL power preoperatively
Dilated fundus examinationAssess for co-existing retinal pathology (e.g. macular degeneration, diabetic retinopathy) that may limit visual improvement post-surgery
Specialist
OCT maculaIf fundal view is limited by cataract — assess macular health before surgery to predict visual outcome
B-scan ultrasoundIf dense cataract prevents fundal view — exclude retinal detachment or intraocular tumour
1
Conservative management
- Updated spectacle prescription may help in early cataract
- Advise on modifiable risk factors: smoking cessation, UV protection, diabetes control
- Surgery is the only definitive treatment — no effective pharmacological treatment exists
2
Referral for surgery
- NICE NG77: do NOT restrict access to cataract surgery on the basis of visual acuity alone
- Refer based on impact on quality of life, symptoms (glare, difficulty driving/reading), and patient preference
- Same criteria for first-eye and second-eye surgery
3
Surgical management: phacoemulsification + IOL
- Day-case procedure under topical or sub-Tenon local anaesthesia
- Phacoemulsification: ultrasound emulsification of the lens nucleus through a small incision
- Foldable IOL implanted into the remaining capsular bag
- Intracameral cefuroxime at end of surgery (NICE NG77) — reduces endophthalmitis risk
- Do NOT offer retrobulbar anaesthesia (NICE NG77)
- Postoperative: topical steroid (dexamethasone) and antibiotic drops for 4 weeks
4
Postoperative complications to manage
- Posterior capsule opacification (PCO): commonest late complication — treat with YAG laser capsulotomy
- Endophthalmitis: rare (0.03–0.1%) but sight-threatening — presents with pain, redness, reduced vision days to weeks post-op
- Cystoid macular oedema: topical NSAIDs/steroids
- Retinal detachment: low risk (~0.5–1%) but counsel patient about symptoms
Complications
- Posterior capsule opacification (PCO): Occurs in ~20% within 5 years — fibrotic thickening of the remaining lens capsule; treated with YAG laser capsulotomy
- Endophthalmitis: Rare but devastating infection inside the eye — requires urgent intravitreal antibiotics
- Retinal detachment: Small increased risk post-surgery, especially in myopic eyes
- Refractive surprise: Post-op refraction different from predicted
- Falls and fractures: Untreated cataracts significantly increase falls risk in elderly patients
UKMLA Exam Tips
- 1Gradual painless visual loss + absent red reflex = cataract until proven otherwise
- 2NICE NG77: do NOT restrict surgery based on visual acuity thresholds — this is a quality-of-life decision
- 3Posterior subcapsular cataract = steroids, diabetes, younger patients — causes glare and reading difficulty early
- 4Nuclear sclerotic cataract causes a "myopic shift" — patient temporarily sees better for near work ("second sight")
- 5Leukocoria (white pupil) in a child = urgent referral to exclude retinoblastoma
- 6Post-op blurred vision months/years later = posterior capsule opacification (PCO) — treat with YAG laser
- 7Intracameral cefuroxime during surgery is NICE-recommended to prevent endophthalmitis
practicetest your knowledge on cataractsApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — ophthalmology and beyond.
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