Structure and function in multifocal pupillographic objective perimetry (mfPOP)

Abstract

 

Purpose

 

To compare correlations between peripapillary retinal nerve fibre layer (RNFL) thicknesses and visual field changes detected using SAP and multifocal pupillographic objective perimetry (mfPOP) in glaucoma.

 

Methods

 

Structure-function correlations were computed for data from 25 glaucoma and 25 normal subjects tested using SAP thresholds and fields derived from three mfPOP stimulus protocols: 1) LumBal: luminance-balanced bright yellow stimuli on a 10 cd/m2 yellow background; 2) Lum+Col: 150 cd/m2 green stimuli on 10 cd/m2 red; and 3) Lum+ColBal = Lum+Col but with luminance balancing. Field data were grouped in arcuate clusters according to Stratus OCT sectors. Pearson correlation coefficients (r) by test region and arcuate cluster were calculated between mfPOP or SAP deviations and RNFL deviations from normative data.

 

Results

 

The strongest correlations were observed in the superior-superotemporal sector in severe glaucoma eyes: r=0.94 and r=0.90 for the mfPOP LumBal and Lum+Col protocols respectively (both n=16, p<0.05). Correlations across all test-points in both SAP and mfPOP were strongest in eyes with severe glaucoma (SAP MD<-12dB): SAP r=0.56, LumBal r=0.55, Lum+Col r=0.52, Lum+ColBal r=0.41 (all n=192, p<0.05). No significant correlation was observed in normal subjects for mfPOP or SAP. For all patient eyes taken together SAP correlations were higher than mfPOP, however scatterplots of mfPOP/RNFL deviations were quite linear while SAP data saturated.

 

Conclusions

 

For both methods the largest correlations with RNFL thickness corresponded to the inferior nasal field of more severely damaged eyes. Head to head comparison of mfPOP and SAP showed similar structure/function relationships.

 

Keywords: 667 pupil • 642 perimetry • 758 visual fields