Retinal Vessel Reaction to Short-Term IOP Elevation in Ocular Hypertensive and Glaucoma Patients

Purpose Regulation of ocular blood flow might be impaired in glaucoma patients. We compared the reaction of retinal vessels to a short-term increase of intraocular pressure (IOP), using a retinal vessel analyzer (RVA), in normal volunteers, ocular hypertensive patients (OH) and primary open angle glaucoma patients (POAG). Methods Ten healthy subjects (56 ± 8 years, IOP 13.7 ± 1.6 mmHg), 10 OH patients (55 ± 12 years, IOD 23.4 ± 4.1 mmHg) and 11 POAG patients (60 ± 11 years, IOP 23.3 ± 1.95 mmHg) were evaluated. Arterial and venous retinal vessel diameter was measured continuously before, during and after raising IOP to suprasystolic values by the suction cup method, described as ocular oscillo-dynamography. Results The change in vessel diameter after the IOP rise differed in its temporal sequence and in absolute values depending on the group examined. In the retinal branch veins the reduction of vessel diameter during the IOP rise was significantly different in POAG (0% ± 6.7) and volunteers (-6.7% ± 8.5; p = 0.06) and in POAG and OH (-6.7% ± 7.0; p = 0.04). At 70–130 sec after IOP increase a dilatation occurred, again differing significantly in POAG (+5.8% ± 3.9) and volunteers (+9.7% ± 4.3; p = 0.03). Systemic blood pressure did not show any significant differences between groups or during the course of the examination. Discussion At short-term rise in IOP leads to less retinal vessel reaction in POAG patients than in volunteers and OH. This might be due to impaired autoregulation to ocular perfusion changes in POAG patients.