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Jacob Diskin, John Zeiter, Nariman Nassiri, Sarah Syeda, Aman Shukairy, Bret A Hughes; Comparing Refractive Outcomes of Three Minimally Invasive Glaucoma Surgery (MIGS) Implants. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6618.
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© ARVO (1962-2015); The Authors (2016-present)
Many factors determine refractive outcomes of patients undergoing cataract extraction with intraocular lens implantation. In this study, we compare three Micro-Invasive Glaucoma Surgery (MIGS) implants to determine if the type of MIGS implant affects the refractive outcome of the procedure.
This is a retrospective study of patients who underwent MIGS procedures along with cataract extraction and IOL implantation. MIGS implants included were iStent, Ex-Press mini glaucoma shunt, and Cypass Micro-Stent. Refractive outcome was defined as the residual refractive error at least 2 weeks after the procedure. Refractive error was defined as the difference between predicted spherical equivalent, determined with the Holladay 1 formula, and measured spherical equivalent at a follow-up appointment between 2 weeks and 1 year post-op.
710 patients were identified using CPT codes for cataract extraction and IOL implantation with implantation of one of three MIGS implants between February 2011, and January 2018. Patients were excluded if a capsular tension ring was used or if pertinent information, including the type of IOL used or the post-operative refraction, was missing. IOL type was selected at the surgeons’ discretion based on anatomic measurements which were also recorded. 506 patients were ultimately included in the analysis based on the above criteria, including 403 patients with iStent implantation, 53 patients with Ex-Press shunt implantation, and 49 patients with Cypass Micro-Stent implantation. Throughout all groups, the patients were 60% female, the average age was 75 years old, and the mean time between surgery and refractive measurements was 72 days. Mean refractive error was calculated for each of the implants and a paired t-test was used to calculate statistical significance. Mean refractive error for iStent was -0.07 (p=0.07), for Ex-Press shunt was 0.21 (p=0.67), and for Cypass was 0.23 (p=0.04). The mean difference in absolute refractive error was 0.56 for iStent, 0.67 for Ex-Press shunt, and 0.61 for Cypass. The median refractive error for iStent was 0.02, for Ex-Press shunt was 0.00 and for Cypass was 0.42.
These results suggest that the use of the Cypass Micro-Stent implant may be associated with an increased hyperopic refractive error, while the Ex-Press shunt and iStent do not show statistically significant differences in terms of refractive outcome.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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