RETINAL BLOOD-FLOW IN NONISCHEMIC CENTRAL RETINAL VEIN OCCLUSION

Objective: The authors studied the changes in retinal blood flow (RBF) and oxygen reactivity in a major temporal vein in patients with centr al retinal vein occlusion (CRVO). Participants: Eleven patients with n onischemic CRVO approximately 7 weeks from onset of disease. Intervent ion: Laser Doppler velocimetric measurement of RBF and vessel reactivi ty to inhaling 60% oxygen. Measurements were performed at baseline and 3 months. Results: Flow velocity in the affected eye had increased si gnificantly by 3 months, from 1.6 +/- 0.4 cm/second to 2.0 +/- 0.4 cm/ second (P = 0.02). Retinal blood flow, however, remained unchanged (13 .7 +/- 5.8 mu l/minute versus 15.0 +/- 6.5 mu l/minute). The two compa rable RBF values, despite differing velocity values, suggest that the relatively normal baseline value was achieved through higher intravasc ular pressure at baseline (Bernoulli's principle). This is supported b y the fact that oxygen reactivity had improved from 2.1% +/- 3.8% at b aseline to 3.8% +/- 3.1% (P = 0.001) at 3 months, which suggests an im proved ability to respond to hyperoxia from reduced intravascular pres sure. Conclusion: Intravascular pressure in CRVO appears to continue t o decrease during the first 5 months after the onset of CRVO, indicati ng continuing reduction in the degree of outflow obstruction during th is time.