Abstract
Purpose :
Ellipsoid zone (EZ) loss on optical coherence tomography (OCT) correlates with diminished retinal sensitivity on static perimetry (SP) in patients with retinitis pigmentosa (RP). We explore a topographical overlay analysis using SP and OCT data in USH2A-related RP to develop novel endpoints of structure and functional changes over time.
Methods :
RUSH2A primary cohort subjects (N=105) had SP with Octopus 900 (3 times at baseline and once annually for 4 years) and annual OCT 121 line volume scans with Spectralis, (Heidelberg, Germany). B-scans were segmented to outline the intact EZ area. Overlays were made using an adaptation of visual field modeling and analysis (VFMA) software (VFMA Webtool, Casey Reading Center, Portland, OR) so that 3D hill of vision (HOV) analysis was superimposed on to the OCT image. The EZ area border at baseline and 3 planar ribbons of different widths (1.65 deg, 1.05 deg, 0.5 deg) straddling the EZ border were ray cast onto the HOV. HOV volume, mean sensitivity (MS), and HOV slope were measured within the EZ area and 6 ribbons (Figure). Mixed effect longitudinal models were used to estimate annual change rates.
Results :
Among the 4-year cohort (n= 86), 57% had syndromic hearing loss and 42% had autosomal recessive RP, with mean age of 37±13 years. Median duration of disease at enrollment was 13 years (Interquartile range, 7 to 19). MS along the EZ boundary decreased significantly for all ribbons and zones (annual rate: 0.71 to 0.84 dB) over 4 years (Table). MS in outer zones showed statistically significant greater progression than inner zones. The inner zones had larger decreases in HOV volume and in HOV slope than the outer zones.
The repeated baseline tests exhibited consistent results for all measures (all intra-class correlation (ICC) > 0.74).
Conclusions :
The reported SP-OCT overlay analysis showed faster loss of sensitivity outside the EZ. More specifically, the narrowest ribbon outside the EZ (C outer) showed greatest progression, suggesting more rapid vision loss occurring at the EZ margin. HOV slope progressed most within the widest inner ribbon (A inner), which could mean that HOV slope change is a precursor to EZ loss.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.