ILM: Internal Limiting Membrane; OCT: Optical Coherence Tomography; FTMH: Full Thickness Macular Hole; PPV: Pars Plana Vitrectomy; BCVA: Best-Corrected Visual Acuity; IOP: Intraocular Pressure

Macular holes are an important cause of significant reduction in visual acuity. Macular hole surgery is a well-established method for the treatment of macular holes [1]. Vitrectomy for the treatment of macular holes was first described in 1991. Since then, numerous modifications of surgical technique have been applied, trying to get the best results after surgery. The inverted internal limiting membrane (ILM) flap (inverted ILM flap) technique has been proposed by Michalewska et al. to improve surgical treatment [2]. This technique was successfully applied for macular hole. The aim of this paper is to present the inverted ILM flap technique in iatrogenic double- full thickness macular hole.

A 79-year-old female was referred to the Ophthalmology Department due to reduced visual acuity after ineffective surgery of full thickness macular hole (FTMH). 25 gauge pars plana core vitrectomy (PPV) was performed with internal limiting membrane (ILM) peeling and SF6 gas endotamponade. The best corrected visual acuity (BCVA) was 0.1 (Snellen chart). Postoperative optical coherence tomography (OCT) revealed two full-thickness macular holes. The first one of central location 825 μm in based diameter, and the second of nasal location 575 μm in based diameter (Figures 1A and 1B). For this reason the patient was qualified for another 25G posterior vitrectomy.

Figure 1: Macula image pre-, intra- and post reoperation with the use of inverted internal lim-iting membrane flap technique. (A) Two full-thickness macular holes after failed earlier typical posterior vitrectomy, (B) Macular holes after staining in the course of the surgery, (C) Macular holes covered by inverted peeled ILM flap, (D) Visible closure of macular holes with preservation of foveal profile after surgery with the use of inverted internal limiting membrane flap technique.

Posterior pole was stained during 25-gauge vitrectomy. A fragment of retinal internal limiting membrane was found on the nasal side (Figure 1B). After ILM separation from the retinal layers, it was inverted to cover both holes (Figure 1C).

Inverted internal limiting membrane flap technique was applied [1,3]. Then, fluid-air exchange was performed and 2 cm³ of SF6 were injected via pars plana to perform endotamponade. The patient was positioned for 24 h [4].

The follow-up examinations were performed on day 1,7,30,180 postoperatively. Final visual acuity was 0.4 (Snellen chart). Postoperative OCT confirmed MHs closure with the preservation of foveal profile (Figure 1D).

To the best of our knowledge this is first report of the successful treatment double large iatrogenic full thickness macular hole. Since its first description by Kelly and Wendel vitrectomy has been the gold standard of macular hole surgery [5]. Although an initial success rate of 68% was reported most surgeons currently achieve a success rate of 90% to 98% [5-7]. Conventional vitrectomy with ILM peeling was internal limiting membrane peeling remains a method of choice for the repair of FTMH [8,9]. Large macular holes are less likely to be closed after pars plana vitrectomy. Michalewska et al. first presented the inverted ILM flap technique in 2009r [10]. They hypothesize that the inverted ILM flap technique stimulates proliferation of glial cells that fill macular holes, thereby enhancing closure, improving macular hole closure rate, and improving postoperative visual acuity [2]. All of the above approaches and the inverted ILM flap technique have one thing in common: They may induce glial cell proliferation, resulting in the macular hole filling with proliferating cells that enhance closure [2]. In idiopathic MH, ILM peeling relieves foveal traction from the retinal surface by complete removal of any epiretinal tissues and by stimulation of gliosis [11-13]. There are some complications after macular peeling including focal retinal haemorrhages and edema, which generally resolves spontaneously without the need of treatment [14-17].

Paracentral scotomas and visual field defects, usually asymptomatic, have also been reported but not directly correlated with the removal of the ILM and could result from adjuvant stain or mechanical trauma to the nerve fiber layer (RNFL) [14,17-19]. ILM peeling can cause morphologic changes to the macula, such as a dissociated optic nerve fiber (DONF) layer. Nevertheless, no functional consequences have been attributed to this anatomic change ILM peeling does require more surgical time and greater expense (for dyes and forceps), and it incurs the potential risk of iatrogenic trauma. Iatrogenic eccentric full-thickness retinal breaks have been documented after ERM and ILM removal in idiopathic FTMH and DME [20-22]. Sandali et al. had found six cases (average incidence of 0.6%) of the retrospective series of 909 patients operated on for either a macular hole (MH, n=400 patients) or an epiretinal membrane (ERM, n=509 patients) with a mean follow-up of two years [24]. It is believed that the location of the holes represents the initial or the end site of ILM elevation, or the result of a weakening in the glial structure of the retina [23,24]. MH after vitrectomy and complete ILM peeling has been reported to occur in approximately 20% of cases with myopic foveoschisis (MF) [25]. ILM peeling removes the Müller cone cells, which form the base of the fovea and serve as a plug that binds the photoreceptor cells in the foveola and supports the foveola structurally. The stretched retina in a highly myopic eye can easily induce a MH without this structure. To prevent postoperative MH, fovea-sparing ILM peeling was introduced [26,27]. Some authors propose a modification of the peeling avoiding the foveolar ILM in order to prevent damage to the Müller cone cells during surgery. In the past, the ILM was peeled completely for MHRD, but the MH closure rate was less than 50% after surgery. Recently, the inverted ILM flap procedure has been applied not only for large and chronic MHs but also for retinal detachment due to MH (MHRD) [2,28]. In this case idiopathic full thickness macular hole was not closed after first PPV with ILM peeling. Additionally developed iatrogenic macular hole near IMH. The use of inverted internal limiting membrane flap technique caused closure both macular hole.

It seems that in the case of full-thickness macular hole which was not closed after the first surgery and even there came to a complication and the formation of another full-thickness macular hole, the use of inverted internal limiting membrane flap technique can be a good solution.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

The language assistance was provided by Proper Medical Writing Ltd.

The authors declare that they have no competing interests.

In certain cases of full-thickness macular hole which was not closed after the first surgery and even there came to a complication and the formation of iatrogenic full-thickness macular hole, the use of inverted internal limiting membrane flap technique can be a good solution.