Prior Glaucoma Surgery Can Factor Into PK Outcomes

For patients who have undergone previous incisional glaucoma surgery prior to penetrating keratoplasty (PK), having a higher intraocular pressure (IOP) before and after PK was associated with worse graft outcomes, according to a poster study presented at the Association for Research in Vision and Ophthalmology (ARVO) 2021 Annual Meeting, held virtually May 1 to May 7.

“Our results suggest that medical and surgical risk factors should be considered when optimizing PK outcomes in patients with prior glaucoma surgery,” according to investigators. “Future studies are needed to determine a possible relationship between graft failure and postoperative use of carbonic anhydrase inhibitors or prior tube shunt placement.”

While previous glaucoma surgery is already a known risk factor for graft failure and decreased visual function following PK, risk factors about specific glaucoma surgery types and the role that IOP-lowering medications might play on graft outcomes have not been extensively studied. The purpose of this retrospective cohort study, according to researchers, was to determine any association between PK outcomes and glaucoma surgical and medical interventions.

Investigators looked at the electronic medical records of patients at Wills Eye Hospital between May 1, 2007 and September 1, 2018, to find those who had PK prior to glaucoma incisional surgery. They also looked for information including type of glaucoma surgeries, topical and systemic treatments, and IOP before and after PK, with the main outcome measurement including graft failure and rejection. 

They discovered 148 PKs of 148 eyes (148 patients) who had glaucoma surgery prior to the procedure. In those cases, mean baseline IOP and maximum postoperative IOP was 15.5±5.3 mm Hg and 25.9±8.4 mm Hg, respectively. 

Investigators found that graft rejection was associated with maximum postoperative IOP (P =.011) and IOP difference (P =.015), which they defined as “the difference between baseline IOP and maximum postoperative IOP.” In addition, graft failure was associated with higher maximum postoperative IOP (P <.001), higher baseline IOP (P =.041), IOP difference (P =.017), and younger age (P =.006). Researchers did not think there was a significant association between prior tube shunt surgery and graft rejection; however, they said the relationship did approach statistical significance (P =.093). 

“Other relationships that approached statistical significance include graft failure and use of topical carbonic anhydrase inhibitors (CAIs) (P =.070) and the use of systemic CAIs among patients with tube shunts in the anterior chamber (P =.052),” they found.

Reference

Stuccio S, Shiuey E, Shukla A, et al. Graft survival after penetrating keratoplasty in patients with history of incisional glaucoma surgery. Poster presented at: The Association for Research in Vision and Ophthalmology (ARVO) 2021 Annual Meeting; May 1-7; Virtual. Abstract 3531488