The response of the light reflex of retinal vessels to reduced blood pressure in hypertensive patients

The response of retinal arteries and veins to 3 months of antihypertensive medication was studied in 10 patients (39-56 years old) with essential hypertension. We used computerized microdensitometry on fundus photographs, a technique allowing for objective and simultaneous measures of the caliber of blood columns and the width and intensity of their central 'light reflex'. A moderate lowering of diastolic and systolic blood pressures (P less than 0.001) resulted in a significant reduction in the intensity of reflection from retinal arteries (38.6%; P less than 0.005). An increase in the width of the blood column (2.8%; n.s.) and the reflex (8.6%; n.s.) was indicated. Traditionally, changes in light reflectivity has been associated with arteriosclerosis of the vessel wall. The study shows, however, that the vascular reflex is most sensitive to changes in the systemic blood pressure. This signals a need for critical reviewal of interpretation and usefulness of classical grading systems of ophthalmoscopic signs of hypertensive retinopathy.