Short-term refractive and corneal astigmatism after canal-based microinvasive glaucoma surgery

Area of Science:

• Ophthalmology
• Glaucoma Surgery
• Refractive Surgery

Background:

• Microinvasive glaucoma surgery (MIGS) aims to reduce intraocular pressure (IOP) while minimizing surgical trauma.
• The Hydrus Microstent is an MIGS device used to improve aqueous humor outflow.
• Understanding the impact of MIGS devices on ocular optics is crucial for patient outcomes.

Purpose of the Study:

• To evaluate changes in refractive and corneal astigmatism following Hydrus Microstent implantation.
• To compare astigmatic changes when the Hydrus Microstent is implanted as a standalone procedure versus combined with phacoemulsification.

Main Methods:

• A retrospective, non-randomized, observational cohort study was conducted at a single German medical center.
• Subjective refraction and keratometry were performed preoperatively and at 3 months post-implantation.
• Astigmatism was analyzed using 3D power vectors (M, J0, J45, B) for refractive and corneal surfaces.

Main Results:

• Ninety eyes were analyzed; 60 underwent Hydrus implantation with phacoemulsification, and 30 had standalone Hydrus implantation.
• Refractive astigmatism showed significant changes in the phacoemulsification group (P=0.0003) but not in the standalone group (P=0.5).
• Corneal astigmatism (anterior and posterior surfaces) remained stable over time in both groups.

Conclusions:

• Hydrus Microstent implantation is neutral for refractive astigmatism in standalone procedures.
• Combined Hydrus Microstent and phacoemulsification may induce refractive astigmatism changes, likely due to lens exchange factors.
• The Hydrus Microstent does not appear to compromise prior refractive treatments when used alone.