What is the role of minimally invasive glaucoma surgery in the treatment of penetrating keratoplasty and glaucoma (PKPG)?

Updated: Dec 30, 2020
  • Author: Shibandri Das, MD; Chief Editor: Inci Irak Dersu, MD, MPH  more...
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Minimally invasive glaucoma surgery can also be considered as a method for lowering IOP. Although there are many methods for minimally invasive glaucoma surgery, 2 prominent modalities include iStent and placement of a CyPass microstent. The iStent is a heparin-coated stent that is inserted into the anterior chamber and penetrates the trabecular meshwork. A CyPass microstent, on the other hand, is a stent inserted into the supraciliary space. Placement of an iStent or CyPass microstent has been commonly performed as an isolated procedure or in combination with cataract extraction. [79]

In a 5-year study of phacoemulsification combined with stent procedures, researchers found a 16% decrease in IOP, with 42% of patients requiring no further medication by the end of the follow-up period. [80]  Although minimally invasive glaucoma surgery has not been systematically studied in conjunction with PKP or other corneal transplantation techniques, these modalities have been demonstrated in preliminary studies to safely lower IOP with fewer complications than with trabeculectomy. [81]  Both the iStent and the CyPass microstent effectively decreased IOP in combination with cataract surgery or when placed as an isolated procedure.  

A study by Mahdavi and colleagues [79]  showed that this IOP-lowering effect is greatest after isolated implantation of CyPass, followed by multiple iStents, and then a single iStent, and lasts up to 2 years.

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