Ocular Pulse Amplitude in Patients With Primary Open Angle Glaucoma, Normal Tension Glaucoma, and Ocular Hypertension

Abstract

Purpose:: Ocular pulse amplitude (OPA) reflects the modulation of the intraocular pressure (IOP) due to the heart beat. OPA is the difference between the diastolic and systolic IOP. Dynamic contour tonometry (DCT) measures IOP and OPA simultaneously. In our study we investigated OPA in patients with primary open angle glaucoma (POAG), normal tension glaucoma (NTG), and ocular hypertension (OHT).

Methods:: In prospective manner 84 patients were included: POAG (n=35), NTG (n=18), OHT (n=10) and controls without any ocular pathology (n=21). One eye was selected as random and OPA and IOP were measured by DCT.

Results:: OPA was statistically significant higher in the OHT group (4.5 ± 0.8 mmHg) compared with all other groups (POAG 3.2 ± 1.4 mmHg, p=0.0006; NTG 2.4 ± 1.2 mmHg, p<0.0001; controls 2.9 ± 1.2 mmHg, p=0.0004). OPA of the POAG group showed no difference compared to the control group and was statistically significant higher (p=0.0174) compared to the OPA of the NTG patients. Overall statistics showed that IOP was the major determinant of the OPA (r=0.52; p<0.0001). After correction for IOP no differences were detected in-between the four groups.

Conclusions:: This study demonstrated significant differences of the OPA in different diseases. Since there is a considerably high correlation with IOP, these differences may be attributed mainly to the different IOP level rather than differences of ocular perfusion.

Keywords: intraocular pressure • optic flow • optic nerve