A 68-year-old woman presents to the emergency department at 9 pm with sudden severe pain in her right eye, blurred vision, headache, nausea and one episode of vomiting. She says she sees rainbow-coloured haloes around lights. The pain started two hours ago while she was watching television in a dim room. She is farsighted and wears reading glasses. She has no previous eye surgery and takes no regular medicines. There is no trauma and no discharge from the eye.
Examination Findings
Visual acuity: right 6/60, left 6/9. Right eye: marked conjunctival injection, steamy cornea with microcystic oedema, shallow anterior chamber, mid-dilated pupil that does not react to light. Intraocular pressure: right 58 mmHg, left 18 mmHg. Gonioscopy (left eye, once the right cornea clears): narrow occludable angle with iridotrabecular contact. Fundus view is hazy in the right eye from corneal oedema; left disc is healthy.
Investigations
Gonioscopy is the key investigation: it confirms angle closure and shows whether the fellow eye has an occludable angle needing prophylactic treatment. Anterior-segment OCT or ultrasound biomicroscopy can document the narrow angle when the cornea is too oedematous for gonioscopy. Optic disc and visual field assessment of both eyes is done once the attack settles.
Questions to Think About
- Why did the attack start in the evening in a dim room?
- What does the mid-dilated, non-reactive pupil tell you?
- Why does the unaffected left eye need treatment too?
Diagnosis
Acute primary angle-closure attack in the right eye, precipitated by pupillary block in an anatomically narrow angle.
Reasoning
Reasoning: A painful red eye with sudden vision loss, haloes, headache and vomiting in an older hypermetropic woman is the textbook picture of acute primary angle closure. In dim light the pupil dilates; in an eye with a crowded anterior segment the iris bunches up and blocks the drainage angle (pupillary block), so aqueous cannot leave the eye and the pressure spikes rapidly. The mid-dilated pupil is fixed because the iris sphincter is ischaemic from the high pressure, and the cornea is oedematous for the same reason — hence the haloes. Gonioscopy of the fellow eye showing an occludable angle confirms the anatomical predisposition is bilateral. Diagnosis: acute primary angle-closure attack, right eye, with bilateral narrow angles. Management: typical management includes urgent medical lowering of pressure (systemic carbonic anhydrase inhibitor plus topical pressure-lowering drops per local protocol), then pilocarpine to constrict the pupil and pull the iris away from the angle once the pressure allows the sphincter to work. Definitive care is laser peripheral iridotomy — a small hole in the iris that bypasses the pupillary block — performed in the affected eye when the cornea clears, and prophylactically in the fellow eye, which shares the narrow-angle anatomy. The patient is warned that the fellow eye can suffer the same attack and needs the preventive laser even though it currently feels fine.
Differential Diagnosis
- Acute anterior uveitis — ruled out: the pupil is mid-dilated and fixed rather than small and reactive, there are no posterior synechiae, and the pressure is markedly raised with corneal oedema rather than low-normal.
- Neovascular glaucoma — ruled out: no rubeosis iridis on the iris or angle, no diabetic retinopathy or retinal vein occlusion in the history, and the angle closure is from pupillary block in a hypermetropic eye.
- Migraine — considered and ruled out: the headache and nausea mimic migraine, but the red painful eye with haloes, mid-dilated pupil and very high pressure localise the problem to the eye.
- Lens-induced (phacomorphic) angle closure — considered: a swollen cataractous lens can cause a similar picture; here the lens is clear, so primary pupillary block is the diagnosis.
Management
Typical management includes urgent lowering of the intraocular pressure with systemic and topical pressure-lowering medicines per local protocol, followed by pilocarpine once the pressure has fallen enough for the iris sphincter to respond. Definitive treatment is a laser peripheral iridotomy in the affected eye once the cornea clears, plus prophylactic iridotomy in the fellow eye. If laser cannot be done or the angle remains closed, lens extraction or surgical options are considered per local protocol. Patients are counselled to seek immediate care if symptoms recur.
Key Learning Points
- The classic triad of an acute attack: severe eye pain with headache and nausea, haloes around lights, and a mid-dilated non-reactive pupil with a hazy cornea.
- Haloes occur because corneal oedema splits light — a patient reporting haloes with a painful red eye should raise the alarm for angle closure.
- An acute attack in one eye means the fellow eye usually shares the anatomy — the fellow eye needs prophylactic laser iridotomy.
- Do not mistake the headache and vomiting for migraine or gastroenteritis: always look at the eye and check the pressure.
- Pupillary block is relieved by a peripheral iridotomy, which gives aqueous a bypass route around the pupil.
Red Flags
- Severe eye pain with nausea and vomiting — do not label it migraine without examining the eye.
- A hazy cornea with a mid-dilated pupil and very high pressure — an ophthalmic emergency; same-day specialist care is needed.
- Delayed treatment risks permanent optic nerve damage and vision loss within hours to days.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.
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