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Monika Ewa Danielewska, Aleksandra Kicinska, Katarzyna Lewczuk, Marek Rekas, Robert Iskander; Assessment of early changes in corneal pulsation following canaloplasty in eyes with open-angle glaucoma. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3143.
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To assess the influence of canaloplasty on changes in corneal pulse (CP) characteristics measured with non-contact ultrasonic technique in primary open-angle glaucoma patients.
Eleven patients undergoing canaloplasty or canaloplasty and phacoemulsification were enrolled for this study. Eyes not previously operated were included with pre-op washout from antiglaucoma medications. Before and after washout, and 3 months postoperatively the patients’ eyes were fully examined, comprising intraocular pressure measurement (IOP, Goldman). In addition, the 10-second records of the CP signal were taken in-vivo and in non-contact manner using ultrasonic distance sensor, synchronically with blood pulse and electrocardiography (ECG) signals. Raw signals were processed to estimate the CP signal parameters related to ocular dicrotic pulse (ODP) – incidence of two distinct maxima in CP signal for one heart cycle [Danielewska et al., OVS, 2014]. ECG and blood pulse signals are components for accurately assessing the ODP. Then, considered CP parameters were compared between pre- and post-op results.
Mean post wash-out IOP was 21.8±4.1 mmHg and decreased to 13.8±4.0 mmHg after canaloplasty (p=0.001). After surgery, all eyes were characterized with ODP, while before and after washout the ODP appeared in 8 of 11 eyes (73%) and 7 of 11 eyes (64%), respectively. Statistically significant differences were found between the pre washout and 3-month post-op, as well as between the post washout and 3-month post-op for three parameters including: the depth of dicrotic valley (DDV), the amplitude and slope of ODP second maximum (Wilcoxon, p<0.05). Post-op increase in the amplitude of the ODP second maximum by 4.1 µm (49%) (p=0.027) and in DDV by 10.5 µm (97%) (p=0.015) in relation to post washout was observed.
Canaloplasty was shown to influence the corneal pulse characteristics leading to the presence of a more prevalent ODP. Insertion of tensioning sutures into the Schlemm’s canal stiffens the limbus area, resulting in cornea having lower internal damping that consequently leads to higher harmonic vibrations. Our study provides more evidence on the effect of canaloplasty on biomechanical properties of the cornea.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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