Conjunctival blood flow velocity in patients with retinal vasculitis assessed with the retinal function imager

Abstract

Purpose: Because studies of the conjunctival microvasculature have provided sensitive indicators of both systemic and CNS vascular diseases we herein present the feasibility and applicability in diagnostic imaging of conjunctival blood flow (BF) velocity in patients with retinal vasculitis using a commercially available Retinal Function Imager (RFI, Optical Imaging Ltd, Rehovot, Israel).

Methods: The RFI is a fundus camera-based device and was developed primarily for imaging the retinal BF velocity. To test the feasibility of using the RFI to assess the BF velocitiy of the conjunctival microvasculature in retinal vasculitis patients, 12 patients (10 patients with Birdshot Chorioretinopathy; 2 patients with retinal vasculitis of unknown origin) (n=21eyes; m:f=3:9, aged 52.4±12.2years) were recruited and compared with a healthy control group (11 individuals; n=11eyes; m:f=3:8; aged 45.5±10.8years). The temporal conjunctiva was imaged in each subject in one or both eyes by RFI and high-resolution, non-invasive capillary perfusion maps (nCPMs) were assessed in addition. The retinal BF of the right eyes (ODs) was imaged for comparison.

Results: In the control group the conjunctival blood flow velocity in ODs was 0.80±0.17mm/s and in the left eyes (OSs) 0.77±0.15mm/s. Comparing these data with the conjunctival BF velocities of the study group, we achieved significant differences. The vasculitis patients disclosed conjunctival BF velocity in ODs of 0.71±0.07mm/s (p<0.001) and a BF velocity in OSs of 0.74±0.06mm/s (p<0.05). In the control group BF velocities of the retinal arteries and veins were 3.67 mm/s and 2.32 mm/s, in the study group 2.57 mm/s (p<0.00006) and 1.56mm/s (p<0.00001), respectively. The microvasculature anatomy revealed by the nCPMs appeared unevenly distributed, and lower number of blood vessels along with lower degree of complexity of their branching patterns were evident when compared with a normal healthy eye.

Conclusions: With the RFI we could demonstrate for the first time, that in patients with reduced retinal BF velocity due to retinal vasculitis also the conjunctival BF is significantly impaired and mirror the BF velocity changes of retinal microvasculature. Thus, imaging the conjunctival vasculature with the RFI could offer an easily to assess diagnostic tool in retinal vasculitis patients.