Eyes have been pulsating (stronger on left side) with my heartbeat & doctors cant figure out whats causing it. i have been to a neurologist, ophthalmologist, cardiologist, had a head ct, mri, & just scheduled an mra. what could be causing this?

This merits a careful cardiovascular evaluation, including a check of one's pulse pressure ( the difference between the systolic and diastolic blood pressure), listening to the heart for evidence of a heart valve problem, and an echocardiogram to confirm any valve problem. Then, one's doctors must collaborate to decide what is the likely cause of the pulsations.