A 38-year-old welder wakes at 2 a.m. with severe burning pain, tearing, light sensitivity, and a gritty feeling in both eyes. He had been arc welding for several hours yesterday without a protective mask — he says he ‘only looked for a second’. Vision is blurred but he can still see shapes. He has no eye discharge and no contact lens wear.
Examination Findings
Visual acuity: 6/18 both eyes, improving with blinking. Both eyes: intense blepharospasm, conjunctival injection, and diffuse fine punctate epithelial erosions staining brightly with fluorescein across the interpalpebral cornea. Anterior chambers quiet, pupils reactive. No foreign body on lid eversion. Fundus normal.
Investigations
Fluorescein staining under cobalt blue light is diagnostic — the classic diffuse punctate pattern. Lid eversion excludes a retained foreign body masquerading as photokeratitis. No imaging is needed; the history plus the staining pattern establishes the diagnosis.
Questions to Think About
- Why does the pain start hours after the welding, not during it?
- What is the expected course, and what reassurance can be given?
- What workplace change prevents the next case?
Diagnosis
Bilateral ultraviolet photokeratitis (arc eye) from unprotected welding.
Reasoning
Reasoning: Ultraviolet radiation from the welding arc damages the corneal epithelium, but the pain follows the epithelial cells’ death and sloughing — typically 6–12 hours later, hence the classic midnight presentation. The diffuse punctate staining across the exposed interpalpebral zone, in both eyes, with a clear UV history, is diagnostic. Diagnosis: bilateral ultraviolet photokeratitis (arc eye). Management: typical management is supportive — preservative-free lubricants, oral analgesia, a short course of topical antibiotics per local protocol if the epithelial defect is large (to prevent secondary infection), and rest in a dark room. Patching is not routinely needed and topical anaesthetics must never be sent home. The epithelium heals within 24–48 hours with full visual recovery. Prevention: a proper welding mask with the correct UV filter, worn for every arc strike — ‘just a second’ is enough to cause this.
Differential Diagnosis
- Ultraviolet photokeratitis (arc eye) — confirmed: bilateral, delayed onset 6–12 hours after unprotected UV exposure, diffuse punctate erosions.
- Corneal foreign body — ruled out: no localised lesion, bilateral and symmetric, nothing on lid eversion.
- Bacterial conjunctivitis — ruled out: no purulent discharge, cornea is the main site, pain is severe and bilateral.
Management
Supportive: lubricants, oral analgesia, topical antibiotics per local protocol for large defects, no topical anaesthetic drops to take home. Reassurance of full recovery in 1–2 days. Mandatory welding mask with correct UV filtration going forward.
Key Learning Points
- Arc eye is bilateral, delayed 6–12 hours, and shows diffuse punctate staining — the history makes the diagnosis.
- It heals fully in 24–48 hours with supportive care; never dispense topical anaesthetics for home use.
- Every case is a workplace-safety failure — the welding mask is the treatment for the next worker.
Red Flags
- Unilateral severe pain with a focal lesion — think foreign body, not photokeratitis.
- No improvement by 48 hours — re-examine for retained foreign body or secondary infection.
- Reduced vision persisting after the epithelium heals — look for another cause.
Educational content only — not medical advice. Clinical decisions must be made by a qualified professional for the individual patient.