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Effects of Nimodipine on Ocular Circulation in Low-tension Glaucoma at Rest and During Increase of Blood-pressure by External Counterpulsation
1Michalk F., 2Michelson G., 3Harazny J., 4Werner U., 1Daniel W. G., 1Werner D.,
1Friedrich-Alexander-Universität, II. Medizinische Klinik (Erlangen)
2Friedrich-Alexander-Universität, Augenklinik (Erlangen)
3Friedrich-Alexander-Universität, Augenklinik, Labor für okuläre Perfusion (Erlangen)
4Friedrich-Alexander-Universität, Institut für klinische und experimentelle Pharmakologie und Toxikologie (Erlangen)
Purpose: Nimodipine is known to improve visual fields and clinical course of low tension glaucoma (LTG). In this study, we measured the changes in ocular circulation after nimodipine administration to investigate the hemodynamic causes for the known clinical benefit of nimodipine.
Methods: The following parameters were measured in 16 patients with LTG and 10 healthy age-matched controls before and 45 minutes after a single oral dose of 30 mg nimodipine: 1. Retinal capillary blood flow by Scanning-Laser-Doppler-Flowmetry in both eyes. 2. Mean blood flow velocity in ophthalmic artery by Doppler sonography in one randomly selected eye of each participant at rest and during increase of blood pressure by external counterpulsation (ECP).
Results: 1. Before administration of nimodipine, retinal blood flow was sig-nificantly reduced in LTG-patients compared with controls (262 ± 80 versus 487 ± 164 AU, p < 0.001). Nimodipine increased retinal blood flow in LTG-patients by 91 ± 73 % (p < 0.001) to values of healthy controls. In controls, retinal blood flow showed no changes by nimodipine. 2. Neither before nor after administration of nimodipine differences could be found in flow velocity of ophthalmic artery between LTG-patients and controls. Nevertheless, nimodipine increased in flow velocity of ophthalmic artery in LTG-patients by 7.3 ± 12.6 % (p < 0.05) and did not change flow velocity of ophthalmic artery in controls. ECP did not change flow velocity of ophthalmic artery at baseline or after nimodipine uptake.
Conclusions: Nimodipine normalizes impaired retinal circulation in LTG patients up to values of healthy controls, explaining the clinical effects. In controls nimodipine did not show any effects on retinal blood flow. In both groups maintenance of flow velocity of ophthalmic artery is not effected by nimodipine or by increase of blood pressure by ECP.