Abstract
Purpose :
The role of the choroid circulation in retinitis pigmentosa (RP) progression is not currently clear. Advances in optical coherence tomography (OCT) technology made in vivo assessment of choroidal structure of a level similar to histological evaluation possible. We investigated correlations between changes in choroidal morphology and disease progression using enhanced depth imaging OCT (EDI-OCT) and OCT angiography (OCTA) in young patients with early RP, in a cross-sectional observational study.
Methods :
We included 24 eyes from 12 patients (45.5 ± 9.0 y, 4 male) with relatively preserved visual acuity (20/25–30/20). We evaluated the subfoveal vertical EDI-OCT images using two methods. First, we measured total choroid thickness (CT) and the large choroid vessel thickness (LCVT) at the fovea. Next, the luminal and interstitial areas within 750 μm of the fovea were measured on binary images using ImageJ® software. The length of the remaining ellipsoid zone (ISe) through the fovea was also measured. The vascular density of the choriocapillaris (CC) at the fovea (250-μm diameter; 10-μm thickness) (CCVD) was obtained by OCTA. The correlations among total CT, LCVT, luminal area, interstitial areas, CCVD, age, refractive error, visual acuity, and ISe were evaluated.
Results :
The total CT was 467 ± 194 μm, LCVT was 357 ± 166 μm, luminal area was 0.531 ± 0.268 mm2, and interstitial area was 0.176 ± 0.064 mm2. The CCVD was 0.612 ± 0.061. LCVT was significantly correlated with luminal area (r = 0.947, p < 0.01). ISe was significantly negatively correlated with total CT (r = -0.473, p = 0.02), LCVT (r = -0.496, p = 0.01), and luminal area (r = -0.542, p = 0.006), and significantly positively correlated with the CCVD (r = 0.479, p = 0.02).
Conclusions :
The foveal choroidal thickness of young eyes with early RP was thicker than that previously reported; in particular, the large vessel layer was thicker in eyes with shorter ISe, which are considered to reflect comparatively advanced RP. In contrast, the CCVD was decreased in the comparatively advanced RP eyes. In the early stage of RP in the young, the enlargement of large choroidal vessel could be a compensatory mechanism for atrophy of the CC prior to the stage of atrophy of all layers of the choroid.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.