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Background/aim: Intraocular pressure (IOP) is not a fixed constant value but rather has pulsatile components associated with cardiac action. The SmartLens dynamic observing tonometer (odc, Ophthalmic Development Company AG, Zurich, Switzerland) can measure and record simultaneously lop and ocular pulse amplitude (CPA). It was the aim of this study to evaluate CPA in patients with primary open angle glaucoma (POAG) and high IOP, normal tension glaucoma (NTG), and ocular hypertension (OHT). Furthermore, the authors examined whether there were any correlations with blood pressure.
Methods: 80 subjects were divided into four groups (n=20): 20 patients each with POAG, NTG, and OHT and 20 volunteers without any ocular pathology except for cataract served as a control group.
Results: The CPA of the POAG group was not statistically significant different from the control group and from the OHT group. However, CPA was statistically significant lower (p<0.01) in the NTG group compared with all other groups. The CPA of the OHT group was slightly higher compared to the healthy volunteers (p=0.09) and to the POAG patients (p=0.09). No statistically significant correlations with blood pressure could be detected. A logistic regression model was established which identified CPA as an independent risk factor for NTG.
Conclusions: The study demonstrated a decrease in CPA of patients suffering from NTG. Thus, measuring of CPA by the SmartLens dynamic observing tonometer could be helpful in the detection of NTG patients.
Other factors than intraocular pressure (IOP) such as cardiovascular diseases, systemic blood pressure, vasospasms, and migraine are involved in the pathogene sis of primary open angle glaucoma (POAG), especially of normal tension glaucoma (NTG). (1-12) The importance of the perfusion pressure could be demonstrated (4 13 14) and defects of blood flow in the optic disc, detected by fluorescein angiography, could be associated with glaucoma. (15) The ocular pulse amplitude (OPA) could be a parameter of interest, (16 17) since differences in OPA values were measured in ocular hypertension, normal tension, and chronic open angle glaucoma. (17 18) "The OPA depicts the pulsatile component of the intraocular blood flow and therefore could be a measure of ocular perfusion independent of baseline IOP.
The SmartLens dynamic observing tonometer (odc, Ophthalmic Development Company AG, Zurich, Switzerland) can measure and record simultaneously IOP and OPA. (19 20) 20 It was the aim of this study to evaluate OPA in patients suffering from POAG and high IOP, normal tension glaucoma (NTG), and ocular hypertension (OHT). Furthermore, the correlation of the OPA with systemic blood pressure, corneal thickness, and IOP was …