Papilloedema is defined as swelling of the optic nerve head (optic nerve takes visual sensations to the brain) secondary to raised intracranial pressure. It is nearly always bilateral but may have asymmetrical presentation.
All other causes showing disc swelling but not associated with raised intracranial pressure are labelled as disc oedema. All patients with disc oedema should be investigated to rule out intracranial mass.
All patients with raised intracranial pressure do not develop papilloedema. Patients who had papilloedema before may not develop it again due to scarring of optic nerve head on subsequent rise in intracranial pressure. Conversely, patients of benign intracranial hypertension will not show papilloedema.
Vision is usually well preserved in cases of papilloedema. In contrast, optic disc swelling due to optic nerve diseases is associated with defect in vision.
Papilloedema is due to axoplasmic flow stasis which results in disc oedema. Subarachnoid space of brain containing cerebrospinal fluid (CSF) is continuous with that of optic nerve sheath. Therefore, rise in CSF pressure impedes axoplasmic transport which leads to papilloedema.
Kanski, Jack J. Clinical Ophthalmology, A Systematic Approach.Third Edition.UK. Butterworth Heinemann, 1994.
Papilloedema may be asymptomatic and is found on routine examination of the eyes.
Most symptoms in papilloedema are due to rise in intracranial pressure. The main systemic features of raised intracranial pressure are:
- Headache which is characteristically most severe on awakening in the morning. It may be generalised or localised and may intensify with coughing, head movement , bending or with Valsalva manoeuvre ( forced expiration against closed mouth and nostrils). Pattern of headache may change in patients with previous chronic headache. Rarely, headache may be absent in patients with raised intracranial pressure.
- Nausea and projectile vomiting may be precipitated by fluctuations in intracranial pressure.
- Pulsatile tinnitus is ringing in the ear associated with pulse.
- Horizontal diplopia may be a false localising sign due to stretching of sixth intracranial nerve caused by raised intracranial pressure.
Visual symptoms are usually absent but patient may have blurring of vision, constriction of visual fields and decreased colour perception. Visual acuity may be well preserved except in advanced cases.
Raised intracranial pressure may be caused by:
- Space occupying lesions or any tumours.
- Increased CSF production.
- Obstruction in drainage of CSF.
- Decreased CSF resorption. For example, in venous sinus thrombosis, meningitis, cerebral trauma and subarachnoid haemorrhage.
- Cerebral oedema.
- Benign/ Idiopathic intracranial hypertension (pseudotumour cerebri).
- Use of certain medicines like tetracyclines, nalidixic acid and steroids.
- Craniosynostosis (closure of skull sutures leading to decreased intracranial space).
- Severe or malignant systemic hypertension.
A patient should be evaluated for neurologic diseases, febrile illness and malignant hypertension. Record visual acuity, check for colour vision and pupillary reactions to exclude causes of disc oedema. Examination of ocular movements is important to exclude false localising sign due to sixth nerve palsy.
Detailed ocular fundus (inner back surface of eye) examination is done to assess papilloedema.
Early papilloedema may be difficult to diagnose and is characterised by:
- No visual symptoms and normal visual acuity.
- Disc hyperaemia.
- Subtle oedema and blurring of peripapillary nerve fiber layer.
- Small haemorrhages of the nerve fiber layer.
- Loss of spontaneous venous pulsations which are normally present in 80 percent of the individuals. If normal venous pulsations are present, diagnosis of papilloedema is unlikely.
Established papilloedema may have following features:
- Transient obscuration of vision lasting for few seconds. Visual acuity is normal or slightly reduced.
- Indistinct disc margin and elevation of disc surface.
- Partial obscuration of small blood vessels on disc.
- Venous engorgement.
- Peripapillary flame shaped haemorrhages and cotton wool spots.
- Circumferential retinal folds on temporal side of optic disc.
- Hard exudates forming incomplete star with missing temporal part.
- Field charting shows enlargement of blind spot.
Long lasting papilloedema may show:
- Variable visual acuity with constricted visual fields.
- Absence of exudates and haemorrhages.
- Small white opacities on the disc (corpora amylacea).
Atrophic papilloedema shows following features:
- Marked impairment of visual acuity.
- Optic discs are white with indistinct margin (secondary optic atrophy).
Papilloedema should be differentiated from conditions like
- Optic neuritis.
- Anterior ischaemic optic neuropathy.
- Compressive optic neuropathy.
- Pseudopapilloedema (may be due to Hypermetropia, tilted disc, myelinated nerve fibers or optic disc drusen).
- Central retinal vein occlusion.
- Imaging studies of the brain like Computerised axial tomography(CAT) scan and Magnetic resonance imaging (MRI) with contrast.
- Magnetic resonance venography to exlude venous sinus thrombosis.
- B scan ultrasonography to exclude buried drusens.
- Fluorescein angiography may show dilatation of peripapillary capillaries with leakage of dye during late phase.
- Perimetry may show enlargement of blind spot and constriction of visual fields.
- Stereo colour photography helps in documentation of optic disc changes.
- Lumbar puncture to measure opening pressure of CSF and to tap CSF for analysis.
It depends upon the underlying pathological process. It may include:
- Carbonic anhydrase inhibitors and weight reduction may help in cases of benign intracranial hypertension.
- Corticosteroids may be helpful in inflammatory causes of raised intracranial pressure.
- Withdrawing medicines which causes raised intracranial pressure.
- Surgical removal of space occupying lesion.
- Lumboperitoneal or ventriculoperitoneal shunt to bypass CSF.
- Optic nerve sheath decompression to relieve ocular symptoms in cases of benign intracranial hypertension.
Visual prognosis is usually good if the raised intracranial pressure is well controlled. If papilloedema is not managed, it may lead to blindness.
Management is carried out under medical supervision.