A Human Amniotic Membrane Plug to Promote Retinal Break Repair and Recurrent Macular Hole Closure
Rizzo S, Caporossi T, Tartaro R, Finocchio L, Franco F, Barca F, et al. A Human Amniotic Membrane Plug to Promote Retinal Breaks Repair and Recurrent Macular Hole Closure. Retina 2019;39.
Chronic, large macular holes that are refractory to initial, conventional surgical approaches (e.g. pars plana vitrectomy, internal limiting membrane peel, and gas) are challenging cases. Multiple approaches have been previously described including those involving internal limiting membrane (ILM) free flaps, ILM inverted or hinged flaps, lens capsule, autologous blood or platelet rich plasma, hydrodissection, and autologous neurosensory retinal free flap, among others. In this paper, Rizzo and colleagues describe the novel use of human amniotic membrane (HAM) “plugs” to repair macular holes and retinal breaks. The use of HAM for ocular surface surgery was described over 70 years ago, but its use for this purpose is a novel concept.
Study Design: This was a prospective, consecutive case series involving 14 patients from July 2017 to January 2018 who underwent surgery by Drs. Stanislao Rizzo and Tomaso Caporossi in Florence, Italy.
Macular Hole Group: Eight patients had a history of recurrent macular holes (all of these patients previously had had pars plana vitrectomy with internal limiting membrane peeling, though it is unclear how many previous operations each patient underwent). The average pre-operative BCVA for the macular hole group was 20/800 (range 20/100-20/2000) and the average post-operative visual acuity 6 months after the surgery was 20/50 (range 20/40-20/200). No patient developed decreased visual acuity and the hole was closed after a single surgery in all patients. The follow-up ranged from 3-10 months.
OCT outcomes in macular hole patients: The authors showed the evolution of the HAM plug in the months following surgery and claim that outer retinal bands (e.g. external limiting membrane, XLM, and ellipsoid zone, EZ) begin to appear at the margin of the plug.
Retinal Detachment Group: Six patients had retinal detachment with either grade B or C1 proliferative vitreoretinopathy and all but one patient had previously undergone pars plana vitrectomy for retinal detachment repair. Two of the retinal detachment patients also had concurrent macular holes and three others had posterior pole breaks. The average pre-operative BCVA for the retinal detachment group was 20/2000 (range 20/2000-20/20000) and the average post-operative visual acuity 2 months following silicone oil removal was 20/125 (range 20/25-20/2000). No patient developed decreased visual acuity and the retina was attached after a single surgery in each patient. The follow-up ranged from 4-12 months.
Adverse Effects: No eyes in either group suffered endophthalmitis, hypotony, IOP elevation, significant intraocular inflammation, or “rejection” of the HAM plug.
Surgical Technique: Phakic eyes (n = 4) first underwent phacoemulsification and intraocular lens implantation. A 23-gauge pars plana vitrectomy (Alcon Constellation) was performed. A 23-gauge system (as opposed to a 25- or 27-gauge system) was used to allow for easier insertion of the HAM through the valved trocars. A chandelier was placed. The HAM was cut to the necessary size with vitreoretinal scissors and introduced into the eye through the trocar with forceps. It was then manipulated under perfluorocarbon liquid (PFCL, perfluorodecalin) or under fluid such that it covered the macular hole/retinal break and was tucked into the subretinal space. In the surgical video accompanying the article, the amniotic membrane is maneuvered under PFCL with forceps and then gently tucked under the edges of the macular hole with a lighted pick. The paper does not describe the orientation (i.e. which side should be in contact with the retinal pigment epithelium) of the HAM. PFCL was then added to a level beyond the macular hole/retinal break. No laser retinopexy was performed. A fluid-air exchange was performed followed by addition of 20% sulfur hexafluoroide (SF6) for the macular hole group and 1000 centistoke silicone oil for the retinal detachment group (which was removed 3-4 months later).
Limitations: The limitations of this study include the small sample size and absence of long-term follow-up (only one patient in each group had follow-up for 12 months). The surgical technique is fairly well described, but a description of how best to orient the HAM is missing and a description of the use of a lighted pick to tuck the HAM under the macular hole edges missing (though it is shown in the surgical video). Additionally, the claims that the amniotic membranes “stimulate retinal proliferation and organization in layers, which can virtually recover the original retinal function” and that “the new retina showed a time-dependent external layer differentiation that in the macular hole group can be associated with the visual acuity improvement” may be controversial. This is because it may be argued that the included OCT images only show hyperreflective bands possibly suggestive of outer retinal bands (XLM and EZ) at the margins of the amniotic membrane rather than directly overlying the center of the amniotic membrane in the central foveal region. In other words, some may argue that the claim of HAM’s seemingly regenerative properties may be overstated.
Strengths: The strengths of this surgical technique are that every patient achieved anatomic success and the post-operative visual acuity outcomes are rather impressive.
This technique appears to be worth considering in chronic, large, refractory macular holes and it will be exciting to read long-term outcomes of this procedure as well as the findings of additional follow-up studies featuring microperimetry, OCT angiography, and adaptive optics imaging.