A patient with papilloedema presents with bilateral optic disc swelling, blurred margins, and flame-shaped haemorrhages. Which of the following is the LEAST likely to be present on examination?

Explanation

## Papilloedema: Clinical Examination Findings **Key Point:** Papilloedema is bilateral optic disc swelling due to raised intracranial pressure. A relative afferent pupillary defect (RAPD) is NOT a feature of papilloedema because the optic nerve is compressed, not inflamed. ### Expected Findings in Papilloedema **High-Yield:** The classic findings of papilloedema include: 1. **Bilateral disc swelling** — symmetric involvement 2. **Blurred disc margins** — starting at the nasal border (less myelinated) 3. **Flame-shaped haemorrhages** — at the disc margin 4. **Obscuration of vessels** — as they cross the swollen disc 5. **Preserved pupillary light reflex** — the afferent pathway is intact 6. **Absence of RAPD** — because both optic nerves are equally compressed ### Why RAPD Is Absent in Papilloedema **Clinical Pearl:** An afferent pupillary defect occurs when there is asymmetric damage to the optic nerve's sensory fibres. In papilloedema, the raised ICP compresses both optic nerves symmetrically, so both pupils respond equally to light. If an RAPD is present in a patient with apparent papilloedema, consider: - Papillitis (optic neuritis) — inflammation, not raised ICP - Asymmetric compression (tumour, haematoma) - Coexisting optic nerve pathology ### Sequence of Disc Changes in Papilloedema ```mermaid flowchart TD A[Raised ICP]:::action --> B[Axoplasmic flow obstruction]:::action B --> C[Blurring of nasal disc margin]:::outcome C --> D[Blurring spreads circumferentially]:::outcome D --> E[Flame haemorrhages at margin]:::outcome E --> F[Obscuration of vessels]:::outcome F --> G[Elevation of disc]:::outcome G --> H[Obliteration of cup]:::outcome ``` **Mnemonic:** **BOFF** — Blurring (nasal first), Obscuration of vessels, Flame haemorrhages, Fronds (elevation). ### Table: Papilloedema vs Papillitis — Pupillary Response | Feature | Papilloedema | Papillitis | | --- | --- | --- | | **ICP status** | Raised | Normal | | **Optic nerve pathology** | Compression | Inflammation | | **Pupillary light reflex** | **Preserved (equal both sides)** | **RAPD present** | | **Vision loss** | Late | Early | | **Pain on eye movement** | No | Yes | **Tip:** If you see disc swelling + RAPD, think papillitis (or asymmetric compression), NOT papilloedema.