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M.T. Nicolela, K. Wallace, M.L. Archibald, T.L. LeVatte, R.P. LeBlanc; Ocular Blood Flow Effects of Betaxolol and Dorzolamide and Its Relation to Cold–Induced Endothelin–1 Release in Newly Diagnosed Glaucoma Patients: A Cross–Over, Double–Masked Comparative Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4793.
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To evaluate the ocular blood flow effects, as measured with scanning laser Doppler flowmeter (SLDF) and pulsatile ocular blood flowmeter (POBF), after one month of use of Dorzolamide or Betaxolol and investigate a possible correlation between blood flow changes and cold–induced release of endothelin–1 (ET–1).
Newly diagnosed glaucoma patients with screening intraocular pressure (IOP) lower than 22mmHg were enrolled. During baseline visit, subjects were submitted to a visual field test, SLDF and POBF measurements. Additionally, patient’s ET–1 response to cold was assessed by measuring plasma levels of ET–1 before and after an upper–body cooling test, in a protocol described previously. Subjects were then randomly assigned to receive Dorzolamide BID or Betaxolol BID in the study eye in a masked fashion for one month. After a four week wash–out period, subjects were back for a second baseline visit, and then crossed–over to the other study medication. Measurements (intraocular pressure; SLDF; and POBF) were performed one week and one month after initiation of the study medication. All visits were scheduled for 10 am, two hours after instillation of the morning dose of the study medication.
12 patients were enrolled. Both Dorzolamide and Betaxolol induced a significant decrease in IOP (P<0.005) measured at 10 am after one month, although the drop in IOP was greater with Betaxolol than Dorzolamide (mean change of 4.2+2.3 mmHg and 2.6+2.4 mmHg respectively, P=0.09). No significant changes in peripapillary retinal blood flow (measured with SLDF) or pulsatile ocular blood flow were observed after therapy with Dorzolamide or Betaxolol (P>0.14). No correlations between change in plasma ET–1 after cold provocation test and change in ocular blood flow after initiation of any of the two study drugs were observed.
In the present study, no significant effects on peripapillary retinal blood flow and pulsatile ocular blood flow were observed after one month of therapy with Dorzolamide or Betaxolol in newly diagnosed glaucoma patients with normal intraocular pressure.
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