Abstract
Purpose:
The choroid of patients with retinitis pigmentosa (RP) is thinner than that of normal patients. We investigated the relationship between the choroidal morphology and visual function in RP patients.
Methods:
Fifty-one eyes of 29 patients with typical RP were studied. The subfoveal choroidal thickness (SCT) and the subfoveal inner choroidal thickness (SICT; distance between retinal pigment epithelium and inner border of medium-large choroidal vessels) were measured by enhanced depth imaging spectral-domain optical coherence tomography. The best-corrected visual acuity (BCVA), retinal sensitivity within the central 4 points determined by Humphrey Perimetry 10-2, and central foveal thickness (CFT) were also measured. Statistical analyses were performed to determine the significance of differences between these parameters and the SCT and SICT.
Results:
The average SCT in RP eyes was thinner than that of healthy normal Japanese eyes (186±58 μm vs. 250±75 μm), and the average SICT was 42±19 μm. A significant correlation was found between the SCT and SICT (r=0.82, P<0.0001). The correlations between the SCT and BCVA (r=-0.03, P=0.14), and between the SCT and retinal sensitivity (r=-0.02, P=0.91) were not significant. The correlations between SICT and BCVA (r=-0.14, P=0.33), and between the SICT and retinal sensitivity (r=-0.03, P=0.84) were also not significant. The correlations between the CFT and SCT (r=-0.08, P=0.56), CFT and SICT (r=-0.005, P=0.97) were not significant. In eyes with choroidal thinning, 24 eyes (67%) had decimal visual acuity better than 0.8.
Conclusions:
A thinning of the choroid in RP eyes was confirmed, but two-thirds of the eyes with choroidal thinning still had good visual acuity. The lack of significant correlations between the choroidal thickness and the visual functions indicates that the thinning precedes the development of visual dysfunction in eyes with RP. We suggest that the thinning may be the preclinical stage of photoreceptor degeneration, and a longitudinal study will be needed to determine this.