Circumferential Internal Limiting Membrane Demarcation with a Flexible Loop for Inverted Flap Creation in Macular Hole Surgery: A Preliminary Study

Technical Summary: Circumferential ILM Demarcation with a Flexible Loop for Inverted Flap Creation

Problem Statement
While peeling the internal limiting membrane (ILM) is routine in idiopathic macular hole (IMH) surgery and improves closure rates, conventional forceps-based "pinch-and-peel" techniques rely on anteroposterior traction. This method exerts concentrated point-contact stress on the inner retina, potentially causing focal trauma, iatrogenic eccentric retinal defects, and inner retinal dimpling (Dissociated Optic Nerve Fiber Layer or DONFL appearance). Furthermore, when creating an inverted ILM flap, the propagation of the peel in a circular direction using forceps often requires repeated repositioning, leading to unpredictable tear propagation, irregular peel margins, or inadvertent extension beyond the intended boundary. These microarchitectural alterations may delay the recovery of outer retinal structures and visual function.

Methodology
This retrospective interventional case series evaluated a novel technique combining circumferential ILM demarcation with an inverted ILM flap. The study included 10 eyes of 9 patients (mean age 64.8 years) with IMH who underwent 25-gauge pars plana vitrectomy (PPV) by a single surgeon.

The surgical protocol proceeded as follows:

1. Staining: The ILM was stained with indocyanine green (ICG) for 20–30 seconds.
2. Circumferential Scoring: Before any flap elevation, a Finesse Flex Loop (a retractable nitinol loop with microserrated tines) was positioned approximately one disc diameter from the fovea. The loop was used to perform nearly 360-degree tangential scoring of the intended peel boundary. This step utilized tangential forces parallel to the retinal surface rather than anteroposterior traction.
3. Flap Elevation: End-gripping forceps were used to elevate a flap at the pre-scored margin. Because the ILM was already partially separated along the defined edge, the contact force required for initial pickup was minimized.
4. Flap Inversion: The ILM was peeled within the pre-determined boundary and inverted over the macular hole.
5. Tamponade: Fluid-air exchange was performed, followed by gas tamponade (SF6 or C3F8) and 7–14 days of face-down positioning.

Outcomes were assessed at 3 months postoperatively using spectral-domain optical coherence tomography (SD-OCT) and best-corrected visual acuity (BCVA).

Key Contributions
The primary contribution of this study is the description and preliminary evaluation of a technique that utilizes the Finesse Flex Loop not merely for flap initiation, but for systematic, circumferential pre-demarcation of the entire peel boundary.

• Mechanism: By scoring the full perimeter in advance, the technique creates a defined margin that confines subsequent peel propagation. This aims to prevent the unpredictable radial tear extension associated with conventional forceps peeling.
• Force Vector Modification: The method shifts the initial dissection from anteroposterior traction (forceps) to tangential forces (loop), theoretically reducing focal trauma and the initial tractional force required for flap elevation.
• Precision: The technique offers precise control over the peel margin, ensuring a consistent flap geometry which may enhance stability during fluid-air exchange.

Results
In this preliminary series of 10 eyes:

• Anatomical Outcomes: Anatomical closure was achieved in 100% of eyes (10/10). The closure morphology was favorable, with 80% (8 eyes) showing a U-shaped configuration and 20% (2 eyes) showing a V-shaped configuration. No Type 2 closures were observed.
• Functional Outcomes: Mean BCVA improved significantly from 0.58 ± 0.39 logMAR preoperatively to 0.20 ± 0.17 logMAR at 3 months (p = 0.002). Visual improvement was observed in all 10 eyes.
• Retinal Surface: Inner retinal surface irregularity consistent with retinal dimpling was noted in 60% of eyes (6/10).
• Safety: No intraoperative or postoperative complications occurred.

Significance and Claims
The authors claim that circumferential ILM demarcation with a flexible loop is a feasible and reproducible technique for IMH repair. The study suggests that this approach provides precise margin control and achieves high anatomical closure rates with significant visual recovery.

The paper posits that the technique's potential advantage lies in minimizing iatrogenic retinal change by reducing the focal traction associated with forceps engagement. However, the authors maintain a modest stance regarding the clinical impact of these findings:

• They acknowledge that while the observed rate of retinal dimpling (60%) appears lower than historical rates for conventional peeling (up to 76–100%), the assessment was limited by the use of B-scan OCT rather than the more sensitive en face OCT.
• They explicitly state that the functional significance of any reduction in dimpling remains controversial and cannot be assumed without dedicated functional assessment.
• The authors conclude that while the preliminary results are promising, comparative studies with larger cohorts, longer follow-up (beyond the 3-month mark), and quantitative en face OCT analysis are warranted to confirm the technique's superiority and its potential to reduce DONFL and improve long-term functional recovery.