Sudden painless vision loss in a 68-year-old with a crowded disc

The leading diagnosis is non-arteritic anterior ischaemic optic neuropathy (NAION).

Supporting features:

• Altitudinal field loss - classic for NAION; the field defect typically respects the horizontal midline.
• Sectoral disc swelling with splinter haemorrhage - ischaemic disc oedema rather than the diffuse oedema of papillitis.
• Crowded fellow disc (cup-to-disc 0.1, no cupping) - a small scleral canal is the strongest anatomical risk factor for NAION.
• Vascular risk profile - age, hypertension, smoking.
• No pain on eye movement - argues against optic neuritis, which also usually affects younger patients and produces a marked relative afferent pupillary defect.

Alternatives to exclude:

• Giant cell arteritis (AION): no headache, jaw claudication, or scalp tenderness, but age over 50 means you cannot dismiss it on history alone. It must be actively excluded - see next task.
• Central retinal artery occlusion: would show a cherry-red spot and retinal pallor, not disc swelling.
• Vitreous or retinal detachment: no floaters, no retinal findings described.
• Optic neuritis: wrong demographic, usually painful, and typically has a clear RAPD. The sluggish pupil here is consistent with unilateral optic nerve dysfunction but the absent RAPD is unusual and worth rechecking with a neutral-density filter.

Key point for the exam: NAION is a diagnosis of pattern recognition plus exclusion of GCA. You cannot stop at NAION without addressing GCA.

Immediate priority: exclude GCA before the patient leaves.

1. Targeted history - ask specifically about jaw claudication, scalp tenderness, temporal headache, shoulder/hip girdle stiffness (polymyalgia rheumatica), fever, weight loss, and transient visual obscurations. A negative history lowers but does not eliminate probability.
2. Examination - palpate the temporal arteries for tenderness, nodularity, and reduced pulse; check for scalp tenderness.
3. Inflammatory markers today - arrange same-day ESR and CRP. In GCA, ESR is typically markedly elevated, though a normal ESR does not fully exclude it.
4. Referral - urgent same-day ophthalmology or medical review for temporal artery biopsy and consideration of high-dose corticosteroids if suspicion is meaningful. Do not start steroids yourself without a plan for biopsy timing, because steroids can render the biopsy non-diagnostic within days.

What would change the plan:

• Any positive GCA feature, or markedly raised ESR/CRP → treat as GCA until proven otherwise: same-day referral, do not wait, and counsel the patient that the fellow eye is at risk.
• Strongly negative history and normal markers → proceed with NAION management but still refer non-urgently for confirmation and cardiovascular workup.

NAION management regardless:

• Explain that vision loss is usually stable and that there is no proven treatment that restores vision.
• Critical counselling point: the fellow eye is at risk (roughly 15–20% over five years).
• Refer to the GP for aggressive vascular risk factor control - blood pressure, lipids, smoking cessation, and diabetes screening.
• Consider low-dose aspirin after medical advice.
• Document the crowded disc in the fellow eye and arrange review.

Counselling - be honest and specific:

• Vision loss from NAION is usually permanent; a minority improve slightly, but he should not expect recovery. Some patients notice improvement as the disc swelling settles, but this is modest.
• The other eye is at risk - quoted figures are roughly 15–20% over five years, higher in the first year. This is why vascular risk factor control matters.
• The fellow disc is crowded, which is the anatomical reason for the risk; this is not something that can be surgically corrected.
• Warning symptoms: if he develops sudden vision loss in the left eye, he should seek urgent care the same day.
• Reassure on the GCA question - explain why you are checking inflammatory markers and what to do if he develops headache, jaw pain, or scalp tenderness.

Documentation:

• Presenting acuity, field defect, pupil findings, disc appearance in both eyes, IOP, and the negative GCA screen.
• The counselling given, including the fellow-eye risk figure and warning symptoms.
• Referrals made and their urgency.

Follow-up plan:

• Review in 4–6 weeks to confirm disc swelling is resolving (swelling that persists or worsens should prompt reconsideration of the diagnosis).
• GP letter requesting blood pressure, lipid, glucose, and smoking-cessation management.
• Advise he continues driving only if he meets the local visual standards; document the field defect and advise he reports it to the licensing authority if required.
• Repeat visual fields at review to establish a baseline.