Inverted internal limiting membrane flap technique in eyes with large idiopathic full-thickness macular hole: long-term functional and morphological outcomes

Abstract

Purpose: To investigate morphological and functional outcomes of the inverted internal limiting membrane (I-ILM) flap technique in large (≥ 400 μm) idiopathic full-thickness macular holes (FTMH) over a follow-up period of 12 months.

Methods: In this retrospective study, 55 eyes of 54 consecutive patients were enrolled. Best-corrected visual acuity (BCVA) and spectral-domain optical coherence tomography (SD-OCT, Heidelberg, Spectralis) were performed preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively. Special focus was put on the reintegration of outer retinal layers and the different ILM flap appearances.

Results: FTMH closure rate was 100% (55/55). BCVA significantly improved over the follow-up period of 12 months from 0.98 ± 0.38 LogMAR preoperatively to 0.42 ± 0.33 LogMAR at 12 months postoperatively (p < 0.001). There was no significant correlation between the three different ILM flap appearances and BCVA. Better preoperative BCVA, complete restoration of the external limiting membrane (ELM), higher macular hole index (MHI), and smaller MH base diameter were associated with higher improvement of BCVA.

Conclusion: Our study highlights the favorable morphological and functional outcomes of the I-ILM flap technique in the short as well as in the long term. While complete ELM restoration revealed to be an important factor for improvement in BCVA, the different postoperative ILM flap appearances seem not to be related to BCVA.

Keywords: External limiting membrane; Flap appearance; Inverted internal limiting membrane flap technique; Large macular hole; Macular hole index; Spectral-domain optical coherence tomography.

Fig. 1

SD-OCT scan of a full-thickness macular hole (FTMH) using our measurement protocol with the caliper tool (Spectralis, Heidelberg). Minimum linear diameter 698 μm, base diameter 1257 μm, central retinal thickness 462 μm

Fig. 2

Optical coherence tomography scan of a closed FTMH at 3 months postoperative with gradings of ELM = 0 (continuous), EZ = 1 (disrupted), and OS = 0 (disrupted). The integrity of the ELM, EZ, and OS was nominally graded as 0 if the layer was fully restored and continuous or as 1 if the layer was absent or partially restored but disrupted

Fig. 3

Inverted ILM flap technique. a Visualization of the inverted internal limiting membrane (I-ILM) flap technique in a schematic drawing. Circumferential ILM peeling 2.0–2.5 disk diameters surrounding the full-thickness macular hole (MH), leaving the edges attached to the margins of the FTMH. An ILM rosette is created and inverted to cover the FTMH. b Microscope image demonstrating the preparation of the ILM flap in a patient with large FTMH. Edges of the flap were trimmed with a vitreous cutter

Fig. 4

Patients’ lens status preoperatively as well as 1, 3, 6, 9, and 12 months postoperative. At 12 months postoperative, 80% of the patients were pseudophakic compared to 25.5% at baseline

Fig. 5

The mean BCVA improved from 0.98 ± 0.38 LogMAR preoperatively to 0.60 ± 0.34 to 0.51 ± 0.27, 0.58 ± 0.39, 0.47 ± 0.33, and 0.42 ± 0.33 at 1, 3, 6, 9, and 12 months after surgery, respectively (p < 0.001). Error bars 95% CI

Fig. 6

The three different ILM flap appearances. In type A, the ILM flap was not visible at all (32.1%, n = 17); in type B, the ILM flap was partly visible (18.9%, n = 10); and in type C, the ILM flap was visible over the whole foveal area (49.1%, n = 26)

Fig. 7

The mean retinal thickness (in μm) 1 month postoperative decreased significantly compared to the preoperative mean retinal thickness (p > 0.001). There were no significant differences in retinal thickness over further time points. Error bars 95% CI

Fig. 8

Regeneration of retinal layers in percentage after 1, 3, 6, 9, and 12 months postoperative. SD-OCT showed complete restoration of foveal microstructures (ELM, EZ, and OS) at the end of the follow-up period in 31.3% (5/16) of the eyes. The ELM, EZ, and OS were fully restored in 62.5% (10/16), 31.3% (5/16), and 31.3% (5/16) eyes at the end of the follow-up period, respectively. Restoration of the ELM preceded the restoration of the EZ and OS in all cases

Fig. 9

Representative case of a 70-year-old patient with large FTMH (417 μm), preoperatively (a); 3 months postoperatively, ELM intact, EZ/OS defects (b); 6 months postoperatively, ELM intact, EZ/OS defects (c); 9 months postoperatively, ELM and EZ/OS intact (d), 12 months postoperatively, ELM and EZ/OS intact (e). BCVA (decimal) improved from 0.1 preoperatively to 0.3 after 3 and 6 months and to 0.6 after 9 and 12 months, respectively. An additional follow-up measurement after 24 months showed a stable visual acuity of 0.6, ELM and EZ/OS intact (f)