gms | German Medical Science

Objective: Timely detection of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is essential in order to improve outcome, but can pose a diagnostic challenge. Retinal vessels are easily accessible for analysis and – as an embryological part of the intracranial vasculature – may hold the key to a new and non-invasive monitoring technique. This investigation aims to determine the feasibility of standardized retinal vessel analysis (RVA) in the context of SAH.

Method: As part of a prospective pilot study, we performed RVA in 14 patients with SAH (September to November 2015) treated at our institution and 41 matched healthy controls. Data was acquired using a maneuverable retinal fundoscope (Zeiss FF450plus, Zeiss, Jena, Germany) equipped with dedicated analysis software (Retinal Vessel Analyser, IMEDOS Systems, Jena) to perform standardized static and dynamic vessel assessment including flicker light excitation for vessel dimension and autoregulation.

Results: Only awake and cooperative patients could be investigated due to current limitations of manoeuvrability of the imaging device. In this selected cohort with a total of 28 examinations, however, satisfactory imaging quality for analysis was achieved in the majority of cases (82.1%). Three patients were investigated during the acute stage of SAH (group A) and eleven patients as part of a follow-up examination (group B: mean 5.9 ± 3.7months after SAH). For group A, retinal arteries were significantly dilated when compared to the control group (125.5 ± 2.1µm vs 111.6 ± 11.4µm, p<0.001), with two out of three patients featuring a concomitant loss of autoregulation in the acute stage. The significance in change of arterial diameter was lost at the time of follow-up (group B), with recovery of autoregulation, indicating a relative improvement in a time-dependent fashion.

Conclusions: RVA is technically feasible in patients with SAH and can detect fluctuations in vessel diameter and autoregulation. Preliminary data suggests potential for RVA as a new and non-invasive tool for advanced SAH monitoring. More data will be collected to provide a meaningful correlation with clinical course and an estimate of its prognostic value. In order to include high-risk patients, modifications to improve maneuverability and positioning of the imaging unit are a mandatory next step.