Difference in presentation
| Infective | Allergy |
|---|---|
| Subacute | Acute |
| Pyrexial | Apyrexial |
| Unilateral | Bilateral |
| Eyelid oedema and erythema | Eyelid oedema and erythema |
| Conjunctivitis | Pruritis and conjunctivitis |
| Chemosis | Blepharitis |
| Painful restricted eye movements | Normal eye movements |
| Altered visual acuity | Normal visual acuity |
| Relative afferent papillary defect | Normal pupils |
| Proptosis | History of topical medication/allergen |
| Meningism | |
| Possible other cranial nerve palsy |