Early IOP rise after diabetic vitrectomy a significant risk factor

Archna Pruthi

A study recommends monitoring for early IOP spike after complicated vitrectomy because it could lead to persistently elevated IOP and poor visual outcomes.

A rise in IOP following diabetic vitrectomy may be more common in cases involving extended and complex intraoperative procedures and may be connected to poor visual outcomes, a study found.

“Patients who develop early IOP rise are more likely to have a persistent rise in IOP, which can lead to a decrease in visual gain. Hence, a vitreoretinal surgeon has to look out for any early spikes in IOP,” Archna Pruthi, MD, one of the study authors, said in an email interview with Ocular Surgery News.

The longitudinal, prospective study sought to determine the incidence and risk factors for an early IOP spike, as well as correlation with postoperative vision.

“With the advancement of surgical techniques, complications pertaining to pars plana vitrectomy for proliferative diabetic retinopathy have diminished, but outcomes continue to be dismal. In view of this, we studied various pre-, intra- and postoperative factors leading to poor visual outcome,” Dr. Pruthi said.

For cases in which diabetic vitrectomy becomes more complicated, Dr. Pruthi said she recommends a perioperative peribulbar injection of Depo-Medrol (methylprednisolone acetate, Pfizer) to control the probable spike in IOP.

“This might control postoperative peripheral chorioretinal inflammation and hence decrease the likelihood of any peripheral effusions,” she said.

Methods, results

IOP and best corrected visual acuity were recorded at postoperative day 1, week 1 and months 1, 3 and 6 for 73 eyes of 73 patients who underwent pars plana vitrectomy for proliferative diabetic retinopathy in the study. An IOP of 30 mm Hg or more on postop day 1 denoted a significant increase, and risk factors for this spike were assessed using cross-tabulation and t-test.

“The study took into account almost all of the systemic parameters that could be evaluated so as to find out the cause of poor visual gain despite a successful vitrectomy,” Dr. Pruthi said.

A significant IOP increase on postop day 1 occurred in 15 patients (20.5%), five of whom developed consistently raised IOP, defined as a pressure of greater than 21 mm Hg during the first three follow-up exams. A significant correlation between early IOP spike and consistently raised IOP was demonstrated, as well as a positive correlation between IOP on postop day 1 and final BCVA.

Preoperative factors, such as sex, type of diabetes mellitus, previous panretinal photocoagulation and coexistent vitreous hemorrhage, were not significantly correlated with early IOP rise. However, positive correlations were found between intraoperative fibrovascular frond removal, which was performed in 52.1% of patients, lens removal and intraoperative vitreous bleeding.

Topical and systemic glaucoma medications successfully controlled pressure spike in 12 out of 15 patients, but the remaining three developed neovascular glaucoma. According to Dr. Pruthi, these patients all underwent intraoperative fibrovascular frond removal and had massive intraoperative bleeding.

Possible causes

The study authors emphasized the potential causative effect of inflammatory or erythroclastic trabecular meshwork obstruction and ciliary body edema on IOP spike.

“These events themselves suggest complicated diabetic vitrectomy involving more intraoperative manipulations and prolonged surgery; this can affect both the ciliary body and the trabecular meshwork function,” the study authors wrote.

Dr. Pruthi said that the additional complications from more involved surgery may also explain early rise in IOP.

“It is known from previous studies that complex and prolonged diabetic vitrectomies are associated with trabeculitis or small peripheral effusions leading to an anterior lens iris diaphragm displacement, which can also lead to an increase in IOP,” she said.

The transition from early IOP spike to poor visual acuity outcomes was portrayed as a progressive process in the study.

“An early rise of IOP is more likely to have persistently raised IOP requiring medical or surgical therapy … hence leading to poorer BCVA at 6 months of follow-up,” the study authors wrote. – by Michelle Pagnani

• Archna Pruthi, MD, can be reached at the Baba Deep Singh Ji Charitable Hospital, Green Avenue, Amritsar, Punjab, India 143001; +91-9781333079; email: archnapruthi@gmail.com.
• Disclosure: Dr. Pruthi has no direct financial interest in the products discussed in this article, nor is she a paid consultant for any companies mentioned.

The study authors evaluated post-vitrectomy rise in IOP at day 1, week 1 and months 1, 3 and 6 in 73 posterior segment surgical procedures for proliferative diabetic retinopathy. The authors found that early rise in IOP was a predictor of later elevated pressures at 6 months and that 20% of all patients had an IOP of greater than or equal to 30 mm Hg on postoperative day 1. Of this subpopulation, one-third experienced continued elevated pressures at 6 months. This group was associated with either the surgical removal of a neovascular frond or the development of an intraoperative vitreous hemorrhage.

The take-home message is to anticipate elevated pressures postoperatively when neovascular manipulation and hemorrhage result during diabetic vitrectomy. Aggressive topical therapy is warranted. Additionally, preoperative gonioscopy should be considered when planning vitrectomy for advanced proliferative diabetic cases.

— Timothy W. Olsen, MD
OSN U.S. Edition Retina/Vitreous Board Member
Disclosure: No products or companies are mentioned that would require financial disclosure.