Purpose
The aim of the study was to investigate the effect of diabetic retinopathy (DR) severity on multifocal pupillographic objective perimetry (mfPOP) compared with Humphrey Matrix and short wavelength automated perimetry (SWAP).
Methods
Seventy eyes of 35 subjects with type 2 diabetes, with no to minimal (sev1, n=40), and moderate to severe (sev2) DR (n=30) based on ETDRS fundus photos, and 20 age and sex-matched control subjects were recruited from The Canberra Hospital. At visit one participants were randomly tested with a Macularfield (±15° eccentricity from fixation) and Widefield (±30° eccentricity) mfPOP stimulus protocols and Humphrey Matrix perimetry. At visit 2 the mfPOP protocols were repeated, followed by SWAP. MfPOP stimulus protocols utilized yellow luminance-balanced stimuli with a peak luminance of 150 and 288 cd/m2 for the Widefield and Macularfield protocols respectively. Visual sensitivity were calculated globally and for four eccentricities (3°, 9°, 15° and 21°) for Matrix and SWAP perimetry and five eccentricities (4°, 8°, 12°, 18° and 24°) for mfPOP. Generalised mixed models were used to determine the effect of retinopathy severity on visual field sensitivity.
Results
The mean effect of disease on Matrix mean deviation (MD) showed a significant reduction in sensitivity of -0.63 dB ± 2.7 for sev1; and -1.12 dB ± 3.0 for sev2 patients respectively compared with controls: 1.25 dB ± 2.3 (mean effect ± SE, all p<0.05). SWAP MDs were were also significantly reduced for sev1: -2.37 dB ± 3.8 and sev2: -2.44 dB ± 3.7 compared with controls: 0.11 dB ± 1.0 (both p<0.05). Ring-wise means showed reductions in sensitivity with increasing eccentricity for both sev1 and sev2 groups but did not reach significance for SWAP and Matrix. The effect of sev1 and sev2 DR on mfPOP significantly reduced amplitude deviations across the outer 3 rings, with the largest deviation presenting in the outermost ring, for both sev1 (-1.40 dB ± 0.53, p<0.05) and sev2(-3.15 dB ± 0.09, p<0.05) group in the Widefield stimulus protocol. Time to peak mfPOP responses were not significantly delayed across any rings.
Conclusions
MfPOP may be more sensitive to visual field loss than SWAP and matrix in type 2 diabetic patients with minimal to no signs of DR (n=40). Further investigation of prognostic biomarkers in mfPOP identifying eyes at risk of retinopathy progression is warranted.