Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 7 Sept 2026Clinical review pending
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Pain or sudden visual loss is not routine cataract
An acutely painful red eye, sudden loss of sight, new flashes or floaters with a field defect, or a new neurological deficit requires urgent assessment even if cataract is already documented.
Action: Arrange same-day emergency eye assessment for acute ocular warning symptoms, using emergency services for an associated neurological or systemic emergency. Do not leave a sudden change on a routine cataract waiting pathway.
Synopsis
Assess gradual visual impairment for lens opacity, relate examination findings to daily visual function and identify features that require investigation beyond a presumed cataract.
Cataract is opacity of the natural crystalline lens and commonly causes gradual, painless visual deterioration.
Ask about glare, night driving, reading, colour perception and the effect on work or independent living.
Measure acuity in each eye with current correction and assess refraction or pinhole response, recognising their limitations.
Key red flags
Sudden visual loss, a new curtain-like field defect or painful redness requires urgent ophthalmic assessment rather than attribution to an existing cataract.
Investigation priorities
01
Monocular visual acuity and refractive assessmentFirst step
Quantify vision and identify a component that improves with optical correction.
Management branches
Initial assessmentEstablish the likely source of visual impairment
A patient reports gradually worsening vision without an acute ocular warning symptom.
Describe the functional problem, measure corrected vision in both eyes and review relevant ocular, systemic and medicine history.
Examine the anterior segment and lens, assess pupils and pressure and inspect the fundus when safe and possible.
Key medicines
Tropicamide 1% for diagnostic dilationThe cited adult single-dose product uses one drop into the eye to be examined, followed by a second drop after five minutes; a further drop may be given after thirty minutes if required.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 7 Sept 2026; clinical approval remains outstanding.