Branch Retinal Vein Occlusion in Ipsilateral Harlequin Syndrome

Introduction

Retinal vein occlusions (RVO) are one of the most frequent causes of visual loss [1]. There have been multiple factors suggested to be of relevance in the pathogenesis of RVO. It is clear, however, that vascular regulation is one of the most important aspects in the development of venous stasis of the retina. In general, blood circulation is regulated by the autonomic nervous system and peptide hormones. However, circulating peptide hormones like endothelin-1 have little effect on retinal vessels due to the blood-retina barrier, whereas the fenestrated capillaries in the choroid are permeable for larger molecules such as peptide hormones [2]. The sympathetic innervation is responsible for vasoconstriction in the choroid, while several studies have shown that the sympathetic tonus influences the thickness of the basement membrane [3], [4], [5], [6]. Thus, a change in vegetative regulation leads to changes in blood flow and local resistance.

Here we present the case of a 68-year-old woman who presented with a macular branch retinal vein occlusion (BRVO) in the right eye and ipsilateral Harlequin syndrome, a vegetative dysregulation with poor sympathetic tone.

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