To investigate diurnal change in blood pressure (BP), intraocular pressure (IOP), and ocular perfusion pressure (OPP) in patients with unilateral branch retinal vein occlusion (BRVO) and compare the results with healthy controls.

We conducted a prospective case-control study which included 50 patients with unilateral BRVO and 50 age-matched volunteers as controls. Each participant underwent a comprehensive ophthalmic examination including optical coherence tomography (OCT). BP and IOP were evaluated 4 times daily at 8 AM, 10 AM, 2 PM and 6 PM. The mean and fluctuation of BP, IOP, mean arterial pressure (MAP), mean OPP (MOPP), and diastolic OPP (DOPP) were compared between fellow eyes of BRVO patients and normal control eyes.

The average retinal nerve fiber layer (RNFL) thickness was significantly reduced in the fellow eyes of BRVO patients compared to control eyes ( p < 0.001). Mean IOP and IOP fluctuation did not differ, but BP fluctuation (systolic BP fluctuation, p = 0.045; diastolic BP fluctuation, p = 0.037) and MAP fluctuation ( p = 0.011) were greater in the fellow eyes of BRVO patients compared to normal eyes. The mean MOPP and DOPP did not differ between groups, however, the fluctuation of MOPP ( p < 0.001) and DOPP ( p < 0.001) were significantly increased in the fellow eyes of BRVO patients. The mean and fluctuation of BP, MAP, MOPP and DOPP were associated with reduced average RNFL thickness in the fellow eyes of BRVO patients.

These results suggest the fellow eyes of unilateral BRVO patients may be at risk of developing glaucomatous damage.