Improving visual outcomes after 360° relaxing retinectomy
The application of sub-silicone oil TA crystals over relaxing retinectomy sites is a viable option in patients with complex RD with extreme PVR.
The use of sub-silicone oil triamcinolone acetonide (TA) crystals during a 360° relaxing retinectomy for complex retinal detachments with advanced proliferative vitreoretinopathy (PVR) can reduce the incidence of complications and improve visual outcomes compared with the procedure without TA crystals, according to a study presented by Subhendu Kumar Boral, MD, DNB, Disha Eye Hospitals Pvt Ltd (Kolkata, India), during the virtual 2020 American Society of Retina Specialists Annual Meeting. Among the potential advantages of using TA crystal applications in this procedure: Trapped TA particles in between silicone oil and bare retinal pigment epithelium (RPE)-choroid complex exert precise localized anti-PVR effect. Intra-operative use of the long-acting corticosteroid (TA) can reduce deposition of fibrin due to its anti-inflammatory effect and inhibit proliferation by its anti-proliferative effect. It may help in clot formation and does not cause a rise in intraocular pressure, he said.
Background
Relaxing retinectomy, which was first described in 1986 by Robert Machemer, MD, is used in a variety of clinical settings, including retinal detachment with incarcerated retinas, retinal shrinkage from PVR, proliferative vasculopathies, and to reattach the retina after scleral buckling, in order to remove retinal contractile elements,1 he said. The technique is viewed as last resort because complications are frequent and may include re-detachments, exaggerated PVR, and profound hypotony. It’s believed that these complications arise because relaxing retinectomy incisions expose areas of bare RPE, which leads to the absorption of intraocular fluid, thereby predisposing eyes to hypotony. However, the intravitreal injection of TA (either 2mg or 4mg) in silicone oil-filled eyes may be a safe and effective treatment for grades C or D PVR,2,3 Dr. Boral said.
Dr. Boral and his colleagues hypothesized that the application of sub-silicone oil TA crystals just before the injection of silicone oil or under the silicone oil during the procedure would lower the rate of these compilations since the anti-inflammatory effects of TA are known to reduce fibrin deposition. TA can also inhibit RPE proliferation and control further blood discharge through blood clotting.
Study design
In their institutional, retrospective, interventional case controlled study, Dr. Boral and colleagues performed TA-assisted 23- or 25-gauge vitrectomy in 24 complex retinal detachments with advanced PVR (from various etiologies) where 360 degree relaxing retinectomy was required.
“We wanted to evaluate and compare the long-term anatomical and functional outcome of 360 degree relaxing retinectomy for complex retinal detachment (RD) with advanced PVR with or without sub-silicone oil application of TA crystals over the sites of relaxing retinectomy,” he said. All surgeries were performed between May 2014 and August 2019; there were twice as many males as females (n=16 and n=8, respectively).
The cases were split into two groups: Group A (n=13; mean age, 37±24 years) included cases where additional TA crystals were applied over the retinectomy site while Group B (n=11; mean age,43±26 years) did not. In Group A, the TA crystals were applied during a very specific timepoint in the procedure: after the vitrectomy, relaxing retinectomy incision, and laser, but either before the silicone oil tamponade or injected under the silicone oil.
Functional and anatomic outcomes, including postoperative best-corrected visual acuity (BCVA) and compilations, were noted during the 6-month follow-up period.
Results
In Group A, mean pre- and postoperative BCVA at the final 6-month follow-up were Log MAR 2.69 ± 0.41 and LogMAR 1.51 ± 0.90 (p<0.05) respectively, versus LogMAR 2.9 and LogMAR 2.37 ± 0.86 (p<0.05), respectively, in Group B. Visual improvement was significantly better in the TA group, and there were fewer instances of recurrence of RD (1 in Group A vs. 4 in Group B, which was statistically significant; p=0.002). Silicone oil removal after 6 months of surgery was done significantly more in Group A than Group B (Fisher’s Exact test, p=0.0017).
Additional postoperative compilations included epiretinal membrane (7 vs. 4 cases, Group A/B, respectively), hypotony (6 vs. 5 cases, Group A/B, respectively), cystoid macular edema (2 cases, both groups), disc pallor (2 cases, both groups), and posterior pole folds (1 case, Group A).
Dr. Boral said TA crystals are safe and non-toxic based on previous literature showing no breakdown of the blood-retinal barrier and no effect on the outer retinal layer in animal models. However, it may interfere with laser retinopexy reactions at the break margin, but there were no reported incidents of reopening of break margin during follow-up.
“The application of sub-silicone oil TA crystals over relaxing retinectomy sites is a viable option in patients with complex RD with extreme PVR,” he said. “The trapped TA particles in between the silicone oil and bare RPE-choroid complex exert localized anti-PVR effects for a long time, especially during the initial periods when inflammatory activities are maximum.”
