Abstract
Purpose :
Changes in the choroid have been described in patients with retinitis pigmentosa (RP). In this study, we sought to further elucidate the relationship between the choroidal vascularity index and the preserved ellipsoid zone (EZ) area.
Methods :
SD-OCT volume scans of 40 eyes of 20 subjects with autosomal dominant RP (clinically diagnosed and genetically confirmed) were collected retrospectively from the Doheny Image Reading Center (DIRC) database in this IRB approved study. SD-OCT volumes scans (20X20 degrees; 512 x 97; ART = 5) were acquired using the Spectralis HRA+OCT. The DIRC OCT grading software (OCTOR) was used to manually delineate the inner and outer borders of the OS layer and choroid. The CVI was measured using a previously-described binarization method (all pixels classified as either vessel or stroma) from a single B-scan passing through the foveal center. This analysis was performed at both baseline and month 12 in order to evaluate longitudinal changes. The CVI and OS area measurements were compared and correlated at baseline and month 12 using paired t-tests and bivariate correlations.
Results :
The mean preserved OS area showed a statistically significantly (p = 0.02) decline from baseline (2.44± 2.53 mm2) to month 12 (2.10 ± 2.42 mm2). However, there was no significant (p= 0.50) difference in CVI from baseline (57 ± 7 %) to month 12 (57± 6 %). Despite this, CVI was correlated to preserved OS area both at baseline (r = - 0.52; p = 0.02) and month 12 (r = -0.43; p = 0.04). The OS area change at month 12, however, was not significantly correlated with CVI change at month 12 (r = -0.19; p = 0.41).
Conclusions :
In subjects with autosomal dominant RP, a significant reduction in the area of preserved EZ can be measured over a 12 month period. Although the CVI appears to correlate with preserved EZ area, it does not appear to change substantially over this same 12 month period. The relationship between CVI and EZ area warrants further investigation in extended longitudinal studies.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.