In a study of patients undergoing diabetic pars plana vitrectomy (PPV), vitreous substitution with sulfur hexafluoride (SF6) gas tamponade proved superior to balanced saline solution (BSS) in reducing the occurrence of postoperative vitreous hemorrhage (VH).1
While the literature has been inconclusive regarding the merits of SF6 gas versus BSS, the results of this study were robust enough to suggest SF6 gas tamponade may be used during PPV as a means of reducing postoperative VH in patients with proliferative diabetic retinopathy (PDR), said Ryan B. Rush, MD, at Panhandle Eye Group in Amarillo, Texas.
HEMORRHAGE. This eye with PDR has a moderate vitreous hemorrhage. The VH is blocking the fluorescence in this early-phase photograph. This image was originally published in the ASRS Retina Image Bank. Jerald A. Bovino, MD. Proliferative Diabetic Retinopathy. Retina Image Bank. 2013; Image Number 10856. © The American Society of Retina Specialists.
How the study was conducted. The study, conducted at a university-associated teaching hospital in Montemorelos, Mexico, included 96 PDR patients who needed PPV for nonclearing vitreous hemorrhage. Patients were prospectively randomized to receive either 20% to 30% SF6 gas tamponade or BSS (the control).
All patients received a baseline ophthalmic evaluation within 28 days before undergoing PPV, followed by post-op examinations at 15, 40, and 185 days after the procedure. The primary outcome was the incidence of postoperative VH during six months of follow-up; secondary outcomes included BCVA and unplanned PPV.
What the results showed. At six months, the incidence of postoperative VH was 11.1% (6/54) in those who received gas tamponade, versus 33.3% (14/42) in those who received BSS. The incidence of unplanned PPV during the trial period for postoperative VH was 3.7% in the SF6 gas group and 14.2% in the BSS group.
Mean BCVA did not significantly differ between the groups at the six-month mark, with both cohorts improving from baseline. The SF6 gas group improved from 20/796 to 20/94, while the BSS group improved from 20/778 to 20/112.
What about complications? In this study, the concentration of SF6 gas was either nonexpansive or slightly expansive, so IOP elevation was similar in both groups. In addition, the incidence of retinal breaks and detachment was low for both groups.
As all phakic subjects underwent cataract surgery at the same time as PPV, the researchers were unable to draw a conclusion regarding cataract development. (The researchers made a compassionate decision to combine surgeries because subjects were indigent, with potentially limited access to cataract surgery.)
The only observed intraoperative difference was longer surgery time in the gas tamponade group, by approximately 9 minutes. The time might be reduced outside the research setting, as the gas mixture can be drawn while other surgical maneuvers are still being performed, the researchers noted.
Bottom line. While the conclusions may not be valid for other underlying diabetic pathology, Dr. Rush said that for cases of diabetic VH without traction, “I believe the results provide some guidance.”
1 Rush RB et al. Am J Ophthalmol. 2022;242:173-180.
Relevant financial disclosures: Dr. Rush—None.
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