Abstract
Purpose :
MIGS procedures are a burgeoning area in the field of glaucoma. We performed a retrospective study of patients undergoing Xen or Cypass surgery to determine IOP reduction superiority. Our null hypothesis recogizes no difference in IOP reduction between the 2 groups, while the alternate hypothesis does.
Methods :
A retrospective review of IOP lowering effectiveness of patents with Primary Open Angle Glaucoma (POAG) and Xen or Cypass surgery by the same surgeon was undertaken. The Xen cohort included 20 eyes of 19 patients, the Cypass group 73 eyes of 52 patients. Visual acuities, IOP, and glaucoma medications were recorded pre-operatively, one day, one week, 1 month, 3 months and 6 months. Failure to control the patient’s IOP and a second procedure excluded patients from further participation in the study. Mean IOP reduction and number of IOP medications with standard deviation were calculated at all time intervals and analysis of the two groups was undertaken utilizing a two-tailed t-test.
Results :
Initial IOP in the Xen group was 23.25 vs. 20.39 mm Hg in the Cypass group as seen in the respective data tables. Initial medications used were higher in the Xen group. Both groups demonstrated a large drop in IOP early in the study with a trend upward over time. The Xen group experienced a mean IOP drop of 62% at one day, 54% at one week, 20% at one month, 22% at three months, and 20% at 6 months while Cypass measured 44% at one day, 46% at one week, 33% at one month, 32% at three months, and 16% at 6 months. Medication use increased over time in both groups with increasing IOP.
Statistical analysis showed superiority in measured IOP reduction for the Xen stent at one day (p=0.020), one week (p=0.018), and 6 months (p=0.012). The Cypass stent showed statistical superiority in IOP reduction at 1 month (p=0.016) and 3 months (p=0.014).
Conclusions :
Our results demonstrate a significant drop in IOP for both surgical procedures. We measured a higher preop IOP and greater initial drop in IOP in the Xen group than the Cypass group. Both stents have potential to reduce IOP, with Xen superior in the first 4 weeks. The Cypass is superior at 1 and 3 months. Six month IOP reduction favors the Xen group. While only a 20% drop overall in IOP is maintained at 6 months including increased use of glaucoma medications, the Xen stent maintains an advantage over the Cypass. Long-term further study is needed.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.