Study Finds 5% Risk of Developing Glaucoma Within Five Years After PPV

Improved methods for screening, such as using molecular markers to monitor for glaucomatous neurodegeneration, may enhance optometrist’s ability to diagnose glaucoma in patients who underwent PPV. Photo: Derek Cunningham,OD, and Walter Whitley, OD. Click image to enlarge. While elevated intraocular pressure (IOP) after pars plana vitrectomy (PPV) can occur in the early post-operative period within the first few days or weeks after surgery, ocular hypertension and associated glaucomatous optic nerve changes can also be seen farther down the road in patients’ recovery. To investigate this further, in a recent study Stanford researchers examined the risk of glaucoma in patients after undergoing PPV and found the risk of this condition after surgery is a bit over 5%.Of 42,242 patients in the TriNetX network who underwent PPV between 2013 and 2018 without prior history of glaucoma, 5.4% were newly diagnosed with glaucoma between three months and five years after surgery. Of these, over 9% began topical IOP-lowering medications for the first time during this same period. The five-year cumulative risk of requiring incisional glaucoma surgery remained relatively low at less than 1%, and analysis of a pre-COVID pandemic cohort yielded a slightly higher estimate of the five-year cumulative risk of glaucoma to be just over 7%.The mechanism by which PPV may contribute to risk of glaucoma remains unclear. One theory is that PPV may increase the exposure of trabecular meshwork cells to oxidative stress and thereby cause dysfunction of aqueous humor outflow. “Others have shown that internal limiting membrane peeling for epiretinal membrane or macular hole, which is sometimes done in association with PPV, can contribute to glaucomatous progression of visual field loss can, by itself, cause ganglion cell layer thinning, though it is unclear whether this is progressive and pathologic,” the researchers wrote in their Ophthalmology Science paper. Steroid responsiveness as well as the potential for intraocular endotamponade to affect aqueous production or outflow are other possibilities.What the authors found intriguing is that the risk of glaucoma after PPV was higher in patients after rhegmatogenous or tractional retinal detachment. Prior studies in animal models have shown that retinal ganglion cells exhibit cellular changes after experimental retinal detachment, possibly causing retinal ganglion cells to be more vulnerable to glaucoma-related damage.“This may also explain, in part, why some prior studies have yielded contradictory findings regarding risk of glaucoma after PPV; the risk may differ based on surgical factors, as well as the underlying disease process necessitating PPV,” the authors explained in their article.Another notable finding was that while there was a difference in risk of being diagnosed with glaucoma in patients with a preoperative diagnosis of epiretinal membrane/macular hole versus retinal detachment, there was no difference in the risk of requiring topical glaucoma meds when comparing these same sub-cohorts. The authors speculate that this may be related to the fact that glaucoma medications have other indications, such as carbonic anhydrase inhibitors for macular edema and alpha-adrenergic agonists for conjunctival injection, which may confound the results.“Additionally, patients who develop postoperative or rebound inflammation may require steroid treatment and be started on anti-glaucoma drops for prophylaxis against steroid response in the absence of true diagnosis of glaucoma,” the authors noted in their article.Because of these findings, the authors suggest that patients may need lifelong monitoring for potential risk of glaucoma beyond the acute postoperative period.The study’s reliance on aggregated EHR data creates some limitations, of course. “Using CPT codes to identify patients who underwent PPV did not allow us to explore whether specific surgical factors, such as choice of endotamponade, presence of macular peeling or surgical time, among other factors, influenced risk of glaucoma,” the team acknowledged in their paper. They also noted that risk of glaucoma after PPV may be different in phakic vs. pseudophakic patients.  Click here for the journal source.  Lin JB, Wai KM, Mruthyunjaya P, Rahimy E. Risk of glaucoma after pars plana vitrectomy in a large federated health record network. Ophthalmol Sci. April 18, 2025. [Epub ahead of print].