Presentation
- Progressive, painless blurring of vision.
- Nuclear sclerotic: gradual myopic shift ("second sight"), possible monocular diplopia, colours appear more yellow/brown.
- Cortical: glare and reduced contrast sensitivity, may be minimally symptomatic if opacities remain peripheral (spoke-like).
- Posterior subcapsular (PSC): glare and haloes, disproportionately symptomatic for its size because of its central location; worse in bright light/miosis (night driving, reading in bright sun); tends to occur in younger patients.
Findings
★ Signature Finding
Type-specific slit-lamp appearance: Nuclear sclerosis — central yellow-to-brown opalescence; Cortical — peripheral wedge-shaped ("spoke") opacities on retroillumination; PSC — plaque-like opacity just beneath the posterior capsule, central, best seen on retroillumination.
- Patients often have overlapping opacities in more than one zone.
Etiology & Mechanism
- Age-related (senile) cataract — the most common type — is multifactorial: compaction/stiffening of central lens fibres as new cortical layers accumulate, plus oxidative damage and crystallin protein aggregation.
- Diabetes mellitus — accelerated cortical/PSC change via osmotic lens fibre swelling (sorbitol pathway).
- Corticosteroid use (topical, systemic, or inhaled) — classic cause of PSC cataract.
- Blunt or penetrating trauma — can produce rosette/stellate cataract.
- Chronic uveitis and/or its steroid treatment.
- Ionizing radiation exposure — classically produces a PSC pattern.
- High (pathologic) myopia — accelerated nuclear sclerosis.
- Smoking and UV exposure — recognized environmental risk factors.
Red Flags — Do Not Miss
Critical — Do Not Miss
- Unilateral, rapidly progressive cataract in a young patient — consider trauma, chronic intraocular inflammation, or an intraocular tumor-related (masquerade) process.
- Cataract with a red or painful eye, or with iris neovascularisation — consider phacolytic or phacomorphic glaucoma, lens-induced uveitis, or intraocular malignancy.
- A white/mature (hypermature) cataract — risk of phacomorphic angle closure or phacolytic glaucoma; needs prompt surgical planning rather than routine elective scheduling.
Investigations
- Comprehensive slit-lamp exam and dilated fundus exam to detect coexisting posterior-segment pathology.
- B-scan ultrasound if the fundus cannot be visualised, to exclude retinal detachment or intraocular mass before surgery.
- Ocular biometry (optical or ultrasound) for intraocular lens power calculation.
- Potential acuity/glare testing to correlate degree of visual complaint with cataract severity.
- Specular microscopy if coexisting endothelial disease (e.g., Fuchs dystrophy) is suspected preoperatively.
Management
- Non-surgical measures for early/mild disease: updated refraction, brighter task lighting, anti-glare strategies.
- Surgical timing is generally guided by the degree of functional visual impairment and the patient's needs rather than a fixed visual-acuity cutoff.
Treatment
- Definitive treatment is surgical: phacoemulsification with intraocular lens implantation is the standard of care in most settings.
- Manual small-incision cataract surgery or extracapsular extraction may be used for very dense/mature cataracts or in resource-limited settings.
- No medical or topical therapy is proven to reverse cataract.
Follow-up
- Preoperative interval monitoring based on symptoms.
- Standard postoperative visits (commonly day 1, week 1, and around month 1) to monitor for endophthalmitis, IOP spikes, and cystoid macular oedema.
- Long-term monitoring for posterior capsular opacification ("secondary cataract"), treatable with Nd:YAG laser capsulotomy when visually significant.
Clinical Pearl
💡 Clinical Pearl
A cataract that develops rapidly and asymmetrically — especially with a shallow anterior chamber or elevated intraocular pressure — should raise suspicion for lens-induced (phacomorphic or phacolytic) glaucoma and prompt urgent rather than routine surgical referral.
Differential Diagnoses
| Condition | Key Distinguishing Point |
|---|---|
| Age-related macular degeneration | Metamorphopsia/central scotoma with macular findings on exam; can coexist with and be masked by cataract. |
| Fuchs endothelial corneal dystrophy | Corneal guttae on exam, vision characteristically worse in the morning. |
| Primary open-angle glaucoma | Optic nerve/visual field changes with a clear lens exam. |
| Diabetic retinopathy | Fundus findings (microaneurysms, haemorrhages) rather than lens opacity. |
| Posterior capsular opacification | History of prior cataract surgery; resolves with YAG laser capsulotomy. |