Introduction:

Two cases of patients with left internal carotid artery agenesis are presented, the first case with symptoms of open angle glaucoma and ipsilateral cataract and the second case of a patient with tension headache, as well as a review of the literature due to the Low frequency of this development anomaly.

Clinical cases:

case 1, A 66-year-old woman with visual disorders associated with cataract and glaucoma in whom, due to suspicion of a carotid fistula, a left internal carotid agenesis was documented, with collaterality through the posterior system, case 2, patient A 58-year-old man with tension headache underwent an MRI where the agenesis of the left carotid artery, segments from C3 to C7, was documented.

Conclusion:

Abnormalities in the development of the carotid system occur early in embryogenesis. In relation to the moment in which the alteration occurs, different circulatory patterns have been described. It is possible that the presence of collateral circulation is the reason that the majority of cases are reported asymptomatic from the vascular neurological point of view. Despite being a rare entity, it must be known in order to differentiate it from other conditions and monitor the appearance of associated complications.