Embedding Technique Versus ILM Peeling

The purpose of this study was to determine the outcomes of two different surgical techniques in patients with lamellar macular holes associated with thick epiretinal membranes, termed lamellar hole-associated epiretinal proliferation (LHEP). Patients with LHEP may experience visual decline with both observation and conventional surgery, and surgery remains controversial. In this study, pars plana vitrectomy with LHEP-embedding was compared to the conventional surgical approach of internal limiting membrane (ILM) peeling. To the authors knowledge, this is the first report comparing LHEP-embedding to conventional ILM peeling.

The authors perform a retrospective observational study of 40 eyes from 39 consecutive patients with a diagnosis of LHEP treated surgically with primary pars plana vitrectomy. The study patients were seen at Osaka University Hospital between September 2010 and September 2021 and had a minimum of 3 months follow-up. Eyes with a history of myopic maculopathy, advanced glaucoma, diabetic retinopathy, age-related maculopathy, retinal vein occlusion, uveitis, and any previous intraocular surgery other than cataract surgery were excluded.

All patients were treated surgically with either 25- or 27-gauge pars plana vitrectomy that involved a core vitrectomy, intravitreal triamcinolone, induction of posterior vitreous detachment when it was absent, and peripheral shaving with scleral depression. Some cases had a fluid air exchange performed with air or 20% SF6 gas tamponade. In eyes treated with LHEP-embedding (Group E, 23 eyes), the epiretinal membrane proliferation was peeled circumferentially around the fovea and left attached at the foveal edge. The ILM was then peeled and the epiretinal proliferation was embedded into the lamellar hole and trimmed. Viscoelastic material was used to hold the epiretinal proliferation in place. In eyes treated with standard ILM peeling (Group I, 17 eyes), the epiretinal membrane proliferation and ILM were peeled off completely. For eyes in Group E, the embedded epiretinal proliferation was confirmed with optical coherence tomography (OCT) postoperatively.

The primary endpoints were postoperative best-corrected visual acuity (BCVA) and development of macular hole (MH) with an average follow-up of 23 months. Additional secondary outcomes included central retinal thickness (CRT) at the final visit and ellipsoid zone disruption at the final visit. OCT measurements were performed by a single masked observer.

Postoperative BCVA at 3 months follow-up and at the final visit was statistically significantly better in Group E. Postoperative BCVA at 3 months follow-up and at the final visit was not significantly better in Group I. Group I had lower BCVA at the final visit than preoperatively. There was no statistically significant difference in postoperative BCVA between Group E and Group I. MH did not develop postoperatively in Group E. Five eyes (29%) developed MH postoperatively in Group I. The postoperative CRT was statistically significantly different at the 3 months follow-up and the final visit follow-up between Group E and Group I, with Group E having more thickness (Group E 3 months 188mm vs Group I 3 months 109.5mm; Group E final visit 167.5mm vs Group I final visit 104.9mm). The postoperative ellipsoid zone disruption was comparable between both groups at 3 months follow-up and at the final visit. Linear regression analyses demonstrated final BCVA correlated significantly to ellipsoid zone disruption and development of MH.

While there are sample size and retrospective limitations to this study, this study demonstrates better visual and anatomic outcomes using LHEP-embedding surgical technique for LHEP as well as less postoperative complications. The study highlights additional areas that merit further research, including distinguishing between tractional epiretinal membranes versus degenerative epiretinal membranes as well as the role of LHEP-embedding in ellipsoid zone restoration, reducing MH development, and postoperative visual functioning. The authors should be commended for taking on the difficult analyses required to assess surgical technique.