Pupil perimetry using M-sequence stimulation technique

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Multifocal electroretinography (ERG) maps retinal function but is limited for optic nerve and higher visual pathway diseases.
• Pupil responses offer a potential alternative to electrical retinal responses for enhanced diagnostic capabilities.
• Detecting subtle pupillomotor responses is crucial for effective pupil perimetry.

Purpose of the Study:

• To evaluate the efficacy of M-sequence stimulation technique for objective pupil perimetry.
• To assess the potential of using pupillary responses to diagnose visual field defects beyond retinal function.
• To explore the clinical applicability of a novel pupil perimetry method.

Main Methods:

• Pupillography was performed using infrared video, real-time image processing, and a custom videoboard.
• A monitor displayed 37 hexagons (25-degree visual field) with M-sequence binary contrast changes.
• Local pupillograms were calculated via cross-correlation of stimulus sequences and pupil diameter.

Main Results:

• Pupillomotor fields in normal subjects mirrored conventional pupil perimetry findings.
• Artificial paracentral scotomas were successfully demonstrated.
• Visual field defects were evident even in patients with optic nerve lesions.

Conclusions:

• M-sequence pupil perimetry is a promising method for objective perimetry.
• This technique shows potential for clinical application in diagnosing visual field impairments.
• The study highlights the value of pupillary responses in assessing visual pathways.