Evaluation of inner retinal dimples and internal limiting membrane flap configuration after temporal inverted ILM flap technique

Abstract

Purpose: To quantitatively evaluate structural changes associated with inner retinal dimples (IRDs) and qualitatively classify the internal limiting membrane (ILM) flap configuration after temporal inverted ILM flap technique using spectral domain optical coherence tomography (SD-OCT). Methods: Twenty-three eyes of 23 patients with successfully closed idiopathic, large (>400 μm) macular hole were enrolled. Patients were treated with pars plana vitrectomy followed by temporal inverted ILM flap technique. A complete ophthalmologic examination including cross sectional and en face OCT in addition to multicolor blue reflectance imaging of confocal scanning laser ophthalmoscopy (cSLO) was performed preoperatively and at postoperative month-12. The location, number, depth, and width of the IRDs were analyzed using blue reflectance images of multicolor cSLO and en face OCT. The ILM flap is also classified as smooth, wrinkled, and folded with en face OCT. Results: The mean number of IRDs visualized on en face OCT ( n = 23.08 ± 22.05) was statistically significantly higher compared with multicolor cSLO blue reflectance module (5.91 ± 10.58; p < 0.001). The mean depth of IRDs measured on en face OCT was 8.08 ± 3.1 μm (3–14 μm) which referred to the nerve fiber layer. The final visual acuity was associated with neither ILM flap configuration ( p = 0.408), nor number of the IRDs on en face OCT ( p = 0.112). Conclusion: En face OCT is a novel imaging modality that offers improved visualization and accuracy in identifying the features of the IRDs and the ILM flap. Additionally, it provides clear visualization of the vitreoretinal interface to distinguish whether ILM was peeled or not in the initial surgery.