The Haemodialysis Session Effect on the Choroidal Thickness and Retinal and Choroidal Microcirculation—A Literature Review

Abstract

Haemodialysis (HD) is currently the most commonly used method of renal replacement therapy. The process of dialysis involves numerous changes that affect many systems, including the eye. The changes occurring in the course of HD may affect the ocular parameters, such as intraocular pressure, central corneal thickness, retinal thickness, retinal nerve fibre layer thickness, and choroidal thickness (CT). The choroid, being one of the most vascularized tissues, is characterized by the highest ratio of blood flow to tissue volume in the entire body, may be particularly susceptible to changes occurring during HD, and at the same time reflect the microcirculatory status and its response to HD. Patients with end-stage renal disease subjected to dialysis are highly susceptible to systemic microvascular dysfunction. Moreover, it is considered that the process of HD itself contributes to vascular dysfunction. Nowadays, thanks to the development of imaging techniques, the widely available optical coherence tomography (OCT) tests allow for the assessment of CT, while OCT-angiography allows for a quick, non-invasive, and repeatable assessment of the condition of retinal and choroidal microcirculation, which significantly expands our knowledge regarding the reaction of ocular microcirculation due to HD. The assessment of both retinal and choroidal circulation is even more attractive because retinal circulation is autoregulated, while choroidal circulation is mainly controlled by extrinsic autonomic innervation. Thus, assessment of the choroidal response to an HD session may provide the possibility to indirectly evaluate the functions of the autonomic system in patients subjected to HD. At a time when the importance of microcirculation in systemic and renal diseases is becoming increasingly evident, the assessment of ocular microcirculation appears to be a potential biomarker for assessing the condition of systemic microcirculation. In this work, we present a review of the literature on the effect of the HD session on CT and the retinal and choroidal microcirculation.

The Impact of a Single Haemodialysis Session on the Retinal Thickness and Optic Nerve Morphology

“…There is no doubt that further research is needed, including the use of OCT-A, which will allow us to address changes in microcirculation and their potential impact on RT. It should also be noted that the retina is vascularised in 2/3 by the central retinal artery and in 1/3 by the choroidal circulation; therefore, changes in the choroidal thickness during HD may also affect the RT thickness [22,37,38]. In addition, the blood supply to the optic nerve and optic nerve head remains under the influence of the nervous system.…”

“…Blood flow in the retinal vessels themselves is controlled at the level of the central retinal artery, short ciliary arteries and the choroid, as well as by local retinal metabolic regulatory mechanisms and neurovascular coupling [37]. In the context of the thinning of the retina and choroid observed in patients with CKD, attention is also drawn to disturbances in the functions of the autonomic system, which, depending on the degree of damage, may influence the observed changes in the morphology of the retina and choroid, also in response to a single HD session [4,38]. Moreover, a number of changes in ocular parameters that occur during HD may be interconnected and be a part of the overall response of the eye to HD-related stress, which has not been known yet.…”