The structure-function relationship between multifocal pupil perimetry and retinal nerve fibre layer in glaucoma

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Imaging

Background:

• Multifocal pupillographic objective perimetry (mfPOP) is a novel functional assessment tool for glaucoma.
• mfPOP responses are thought to involve the main visual pathway via the extrastriate cortex, unlike the melanopsin response.

Purpose of the Study:

• To investigate the correlation between peripapillary retinal nerve fiber layer (pRNFL) thickness and glaucomatous visual field changes detected by mfPOP.
• To compare mfPOP with standard automated perimetry (SAP) in assessing structure-function relationships in glaucoma.

Main Methods:

• 25 glaucoma patients and 24 normal subjects underwent SAP, 3 mfPOP variants, and optical coherence tomography (OCT).
• pRNFL thickness and visual field sensitivities were correlated using weighted arcuate clusters.
• Structure-function correlation coefficients (r) were computed for pRNFL sectors and local visual field sensitivities.

Main Results:

• Strongest correlation (r=0.93) between pRNFL thickness and mfPOP LumBal was in the superior-superotemporal disc sector of severely damaged eyes (SAP MD < -12 dB).
• Overall correlations were strongest in severe disease for both SAP (r=0.54) and mfPOP (r=0.55).
• SAP showed higher correlations in milder disease, while mfPOP showed higher correlations in more advanced disease and in normal subjects.

Conclusions:

• Both mfPOP and SAP demonstrate similar structure-function relationships in glaucoma, with strongest correlations in the inferior nasal field of severely damaged eyes.
• These findings support the role of mfPOP in assessing glaucomatous visual field defects via the cortical pathway.