Non-Occlusive Retinal Vascular Inflammation and Role of Red Blood Cell Deformability in Birdshot Chorioretinopathy

ABSTRACT

Purpose: To investigate differences in red blood cell (RBC) deformability between birdshot chorioretinopathy (BCR) subjects and matched controls, and to postulate its relationship with lack of vascular occlusion in BCR.

Methods: In a single center, prospective, non-randomized mechanistic study, blood samples were collected from eight healthy controls and nine BCR patients, and subjected to biochemical and hematological tests, as well as RBC indices assessment using dual-beam optical tweezers.

Results: The mean age of the controls was 52.37 ± 10.70 years and BCR patients was 53.44 ± 12.39 years. Initial cell size (I_o) for the controls was 8.48 ± 0.25 μm and 8.87 ± 0.31 μm for BCR RBCs (p = 0.014). The deformability index (DI) for the controls was 0.066 ± 0.02 and that for BCR RBCs was 0.063 ± 0.03 (p = 0.441).

Conclusion: There was no statistically significant difference in DI between RBCs from BCR and healthy controls. This may explain the rare occurrence of retinal vascular occlusion despite the underlying vasculitic pathophysiology of BCR.

Keywords:

• Birdshot chorioretinopathy
• dual-beam optical tweezers
• RBC deformability
• red blood cell (RBC)
• vascular occlusion

Acknowledgments

We will like to acknowledge support from National Medical Research Council (NMRC), Ministry of health Singapore for sponsoring Dr Rupesh Agrawal for overseas research training fellowship.

Declaration of Interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This research was facilitated by the National Medical Research Council overseas research training fellowship grant.