Effect of Ripasudil on the Change Rates of the Circumpapillary Retinal Nerve Fiber Layer Thickness in Patients With Primary Open-Angle Glaucoma

Purpose: The effect of the Rho-kinase inhibitor ripasudil on the retinal optic nerve fiber layer (RNFL) remains unclear. We aimed to determine this effect in patients with primary open-angle glaucoma (POAG) using optical coherence tomography (OCT) measurements and linear mixed analysis.Methods: This study prospectively included outpatients from a single center with POAG without a history of vitreoretinal or glaucoma surgery from December 2014 to June 2020, in whom the circumpapillary RNFL thickness (cpRNFLT) was measured more than three times before and after ripasudil initiation, without additional medication or surgery during the period. Measurements were performed using OCT in the follow-up mode. The cpRNFLT change rates were compared before and after treatment using linear mixed models with adjustments for intraocular pressure (IOP) changes.Results: Thirty eyes of 20 patients (12 males and eight females) were included. Upon ripasudil prescription, the average cpRNFLT was 60.2 +/- 2.1 mu m. The average IOP was 15.1 +/- 0.5 and 13.5 +/- 0.5 mmHg, respectively, before and after treatment initiation, with a difference of -1.6 +/- 0.3 mmHg. Analysis of 343 cpRNFLT measurements using linear mixed models revealed that the cpRNFLT change rate was -0.91 +/- 0.15 and -0.40 +/- 0.14 mu m/year, respectively, before and after treatment onset, with an increase of 0.51 +/- 0.21 mu m/year. After adjusting for IOP changes, the improvement in cpRNFLT change rate was 0.33 +/- 0.23 mu m/year, albeit not statistically significant.Conclusion: The cpRNFLT change rate significantly increased after ripasudil administration, whereas the contribution of the IOP decline was not significant.