Optic disc edema in raised intracranial pressure. I. Evolution and resolution

Area of Science:

• Neurology
• Ophthalmology
• Neurosurgery

Background:

• Intracranial pressure (ICP) elevation is a critical condition.
• Optic disc edema (ODE) is a known clinical sign associated with increased ICP.
• The precise sequence of events and localization of ODE development remain areas of investigation.

Purpose of the Study:

• To investigate the initial presentation and progression of optic disc edema (ODE) in a primate model of raised intracranial pressure (ICP).
• To determine the temporal relationship between optic disc swelling and vascular changes in ODE.
• To identify the earliest indicators of elevated ICP in the optic disc.

Main Methods:

• Simulated intracranial space-taking lesions using balloons in the subarachnoid space of 32 rhesus monkeys.
• Observed the development and severity of optic disc edema (ODE).
• Utilized fluorescein fundus angiography to assess vascular changes.

Main Results:

• Optic disc edema (ODE) initially appeared at the lower pole, progressing to other disc regions with varying severity.
• Swelling of the optic disc preceded observable vascular changes during fluorescein fundus angiography.
• Elevated ICP for as little as 24 hours could induce ODE; atrophic optic disc portions did not exhibit edema.

Conclusions:

• Optic disc swelling is the primary and earliest sign of raised intracranial pressure (ICP).
• The edema is attributed to the swelling of optic nerve fibers within the optic disc.
• Associated vascular changes observed in ODE are secondary to the initial nerve fiber swelling.