Relative afferent pupillary defects in optic neuritis

Area of Science:

• Ophthalmology
• Neuro-ophthalmology
• Optic Nerve Diseases

Background:

• Optic neuritis is an inflammatory condition affecting the optic nerve.
• Relative afferent pupillary defect (RAPD) is a key clinical sign of optic nerve dysfunction.
• Accurate detection of RAPD is crucial for diagnosing and monitoring optic neuritis.

Purpose of the Study:

• To quantify the prevalence of relative afferent pupillary defects (RAPDs) in patients with optic neuritis.
• To assess the diagnostic utility of RAPD testing across different stages and forms of optic neuritis.
• To investigate the association between RAPD and subclinical optic neuropathy in the fellow eye.

Main Methods:

• Prospective measurement of relative afferent pupillary defects (RAPDs) using a swinging flashlight test.
• Inclusion of 105 patients with various stages of optic neuritis (acute unilateral, recovered unilateral, acute bilateral, recovered bilateral).
• Correlation of RAPD findings with clinical presentation and, where applicable, visual-evoked potential (VEP) results.

Main Results:

• RAPDs were detected in 96% of acute unilateral optic neuritis cases.
• Prevalence of RAPDs was 92% in recovered unilateral cases and 91.7% in acute cases with contralateral optic neuropathy.
• RAPDs were found in 65.8% of recovered bilateral cases, highlighting the sensitivity of the test.

Conclusions:

• Relative afferent pupillary defects are highly prevalent in unilateral optic neuritis, present in nearly all patients.
• RAPD testing is a valuable tool for detecting optic nerve dysfunction in both acute and recovered stages of optic neuritis.
• Absence of RAPD in suspected unilateral optic neuritis warrants further investigation, such as VEPs, to rule out subclinical disease in the other eye.