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Monika Ewa Danielewska, Michal Marcin Placek, Aleksandra Kicinska, Katarzyna Lewczuk, Marek Rekas; The effect of canaloplasty on changes in corneal pulse parameters: a follow-up study. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2022. doi: https://doi.org/.
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To assess changes in the corneal pulse (CP) signal complexity (entropy) after canaloplasty for primary open-angle glaucoma patients during the first 6 months of follow-up.
Seventeen eyes of 17 patients undergoing canaloplasty or canaloplasty and phacoemulsification were included in the study. Before surgery, glaucoma eyes were washed out from antiglaucoma medications. Full eye examination was done at pre-washout, post-washout (the day of the surgery), 3 and 6 months after surgery, including intraocular pressure measurement (IOP, Goldman). In addition, 10-second in-vivo continuous recordings of the CP signal were performed using non-contact ultrasonic distance sensor. Recorded CP signals were pre-processed and then their entropy was estimated using the refined composite multiscale fuzzy entropy. Next, temporal changes of the considered parameters were tested by means of the repeated measures ANOVA followed by a post-hoc analysis with the Bonferroni correction.
The highest entropy of the CP signal was observed at post-washout, where IOP reached the highest value of 22.2 ± 1.0 mmHg (mean ± SEM). Statistically significant differences in the entropy of the CP signal were found between the post-washout and the 6-month post-op (p = 0.047, Fig. 1b). At a 3 and 6 months after canaloplasty, IOP significantly decreased to 14.1 ± 0.9 (p = 0.019) and 13.5 ± 0.7 mmHg (p = 0.002), respectively, in relation to pre-washout (Fig. 1a). At 6-month follow-up only one patient required glaucoma medication.
Our study provides evidence that canaloplasty leads to a decrease in the complexity of the CP signal corresponding to a decrease in IOP values. Tensioning suture inserted into the Schlemm’s canal stiffens the limbus area as reflected in higher CP frequencies. In consequence, this leads to maintaining high complexity of the CP signal up to 3 months after surgery. Our results bring new knowledge about the effect of canaloplasty on biomechanical properties of the cornea.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Changes of IOP (a) and entropy of the CP signal (b). Results are mean ± standard error of mean. *indicates p < 0.05.
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