The central retinal artery (CRA), which can be non-invasively examined with ophthalmoscopy, may be regarded as an extracranial part of the cerebrovascular system. Assessment of CRA pressure may be of help in assessing the impediment of the intracranial blood circulation in patients with a carotid artery stenosis (CAS). The aim of this study was to explore the potential associations between diastolic central retinal artery pressure (diastCRAP) and CAS. The prospective longitudinal clinical observational study included patients with CAS and a control group without CAS. diastCRAP was assessed using ophthalmodynamometry. The study group consisted of 95 patients with CAS (50 of whom had >75% CAS and underwent surgery; the surgical study group) and a control group of 64 individuals without CAS. In all study participants, a lower diastCRAP was significantly associated with a higher degree of CAS (P<0.001). Multivariate analysis indicated that a higher CAS degree was significantly (correlation coefficient: r=0.75) associated with a higher brachial diastolic blood pressure (P<0.001) and lower diastCRAP (P<0.001). Within the surgical study group at the baseline of the study, diastCRAP was significantly lower at the surgical side than at the contralateral side (P=0.02). The diastCRAP on the surgical side increased significantly (P<0.001) after surgery. In the surgical study group at baseline, diastCRAP on the surgical side was not significantly associated with brachial diastolic blood pressure (P=0.22), whereas after surgery, diastCRAP was significantly associated with brachial diastolic blood pressure (P=0.001). DiastCRAP was found to be significantly and linearly correlated with the degree of CAS in intra-individual inter-eye, inter-individual and intra-individual follow-up comparisons. The strong and linear association between diastCRAP and the degree of CAS suggest that diastCRAP should be explored further for use as an indicator of cerebrovascular status.