Disturbed Correlation Between Arterial Resistance and Pulsatility in Glaucoma Patients

• Autor(a) principal: Abegão Pinto, L
• Data de Publicação: 2012
• Outros Autores: Vandewalle, E, Stalmans, I
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.17/2296
• topic: CHLC OFT; Blood Flow Velocity; Blood Pressure/physiology; Ciliary Arteries/physiology; Ciliary Arteries/ultrasonography; Glaucoma, Open-Angle/physiopathology; Glaucoma, Open-Angle/ultrasonography; Homeostasis; Intraocular Pressure/physiology; Low Tension Glaucoma/physiopathology; Low Tension Glaucoma/ultrasonography; Ophthalmic Artery/physiology; Ophthalmic Artery/ultrasonography; Pulsatile Flow; Regional Blood Flow; Retinal Artery/physiology; Retinal Artery/ultrasonography; Tonometry, Ocular; Ultrasonography, Doppler, Color; Visual Acuity/physiology

PURPOSE: (i) To investigate whether pulsatility index (PI) and mean flow velocities (MFV) are altered in glaucoma patients. (ii) To evaluate the significance of PI in retrobulbar autoregulation capacity. METHODS: Patients with primary open-angle glaucoma (POAG; n = 49), normal tension glaucoma (NTG; n = 62) and healthy controls (n = 48) underwent colour Doppler imaging measurements of the retrobulbar vasculature. Kruskal-Wallis test was used to compare variables between the three diagnostic groups. Restricted cubic splines were used to determine nonlinearities between the resistive index (RI) and PI correlations. RESULTS: Mean flow velocities (MFV) were lower in both short posterior ciliary arteries (SCPA) and central retinal arteries (CRA) from the two glaucoma groups (p < 0.04 versus healthy controls). No differences were detected in RI or PI in any arteries of the three diagnostic groups (p > 0.08). In healthy individuals, correlations between RI and PI were linear in all arteries. In both POAG and NTG patients, CRA presented a nonlinear curve with a cutpoint at RI 0.77 (p < 0.001) and 0.61 (p = 0.03), respectively, above which the slope increased nearly five- and tenfold (POAG: 1.96 to 10.06; NTG: -0.46-4.06), respectively. A nonlinear correlation in the ophthalmic artery was only observed in NTG patients, with a cutpoint at RI 0.82 (p < 0.001), above which the slope increased from 3.47 to 14.03. CONCLUSIONS: Glaucoma patients do not present the linear relationships between RI and PI observed in healthy individuals. Their nonlinear relations may be indicative of an altered autoregulation and suggest a possible threshold RI could be determined above which autoregulatory disturbances become more relevant.