Association of retinal biomarkers and choroidal vascularity index on optical coherence tomography using binarization method in retinitis pigmentosa.

Purpose: To investigate the association of retinal biomarkers with the choroidal parameters in retinitis pigmentosa (RP).

Methods: This prospective study included 69 eyes of 36 patients with RP. Choroidal vascularity index (CVI) was defined as the ratio of luminal area to stromal area after binarization on EDI-OCT images. Choroidal thickness (CT); peripapillary CT, the disruptions of the ellipsoid zone (EZ) and external limiting membrane (ELM); and the existence of disorganization of the retinal inner layers (DRIL) and epiretinal membrane (ERM) in central 1000 μm were noted.

Results: Having DRIL and the disruption of EZ and ELM was significantly associated with higher CVI (p < 0.001, p = 0.001, and p = 0.002 respectively) and lower peripapillary CT in temporal sector (p = 0.031, p = 0.012, and p = 0.043 respectively). Having ERM, the disruption of EZ and ELM was significantly associated with lower visual acuity (VA) (p = 0.044, p < 0.001, and p < 0.001 respectively). The eyes with ERM had significantly lower peripapillary retinal nerve fiber thickness (pRNFLT) (p = 0.040). The mean peripapillary CT significantly and positively correlated with the temporal, nasal, superonasal, and the mean pRNFLT (r = 0.258, p = 0.036, r = 0.252, p = 0.041, r = 0.260, p = 0.035, r = 0.280, p = 0.023 respectively). VA did not significantly correlate with CT, peripapillary CT, or CVI (p > 0.05).

Conclusion: The disruption outer retinal segment integrity was significantly associated with higher CVI and lower peripapillary CT in temporal segment. ERM and disruption of ELM and EZ were associated with worse VA. VA did not significantly correlate with CT, peripapillary CT, or CVI.