Abstract
Purpose: :
To assess the changes of blood flow volume in eyes under high infusion pressure in conjunction with vitrectomy, based on quantitative measurements by laser speckle flowgraphy (LSFG).
Methods: :
In this study we analyzed 16 eyes of 16 patients (men:women 8:8; average age, 66.1 years old) with idiopathic epimacular membrane or idiopathic macular hole treated with vitrectomy. All procedures were in full compliance with the guidelines of the Declaration of Helsinki and were approved by the Institutional Review Board/Ethics Committee. All patients underwent micro incision vitreous surgery with a 23 gauge instrument using the Accurus® (Alcon) Vented Gas Forced Infusion (VGFI) system. Our group recently proposed that the improved LSFG for the supine position might be useful to quantify changes of blood flow volume during surgery for branch retinal vein occlusion (2010 ARVO meeting). In this study, the blood flow volume was measured in the optic nerve head using this improved LSFG for the supine position. After performing the core vitrectomy and posterior vitreous detachment, the blood flow volume of the optic nerve head was measured under a stabilized baseline infusion pressure of 10 mmHg using the VGFI system. Afterwards, the blood flow volume was measured by the same method under a high infusion pressure of 35 mmHg. During the measurement by LSFG, there were no significant changes noted in simultaneous measurements of the pulse rate and systolic and diastolic blood pressure.
Results: :
The blood flow volume of the optic nerve head significantly decreased with the 25 mmHg increase of infusion pressure from the baseline pressure of 10 mmHg (P<0.01; paired t-test) in all eyes, and the average ratio of decrease was 30.4±8.1% (n=16).
Conclusions: :
The results of this study suggest that the blood flow volume of the optic nerve head is significantly affected by infusion pressure during vitrectomy. Vitreous surgeons should be watchful for changes in infusion pressure during vitrectomy and avoid surgical procedures under high infusion pressure insofar as possible.
Keywords: imaging/image analysis: clinical • vitreoretinal surgery • optic flow