Optimizing flange geometry with a 532-nm green laser for four-flanged scleral fixation: experimental comparison with thermal cautery.

Abstract

Purpose: To compare flange geometry produced with a 532-nm green laser vs thermal cautery in four-flanged scleral fixation and to identify practical heating lengths for 5-0 and 6-0 polypropylene sutures.

Setting: Dry laboratory.

Design: Bench-top experimental study.

Methods: Flanges were created on 5-0 and 6-0 polypropylene sutures using a 532-nm green laser (200 mW, 200 milliseconds, single-shot mode) or handheld thermal cautery. Heating length, defined as the distance from the suture tip to the forceps, ranged from 0.5 to 3.0 mm in 0.5-mm increments. Flange diameter and height were measured microscopically, and shape was summarized by the diameter-to-height (D/H) ratio.

Results: Flange diameter and height increased with heating length for both devices. The laser produced larger diameters than cautery for 6-0 polypropylene at 0.5 to 1.5 mm (all P < .001) and for 5-0 polypropylene at 0.5 to 2.5 mm ( P ≤ .023). At shorter heating lengths, the laser tended to produce flatter, saucer-shaped flanges with higher D/H ratios, whereas cautery often produced taller, mushroom-shaped profiles. Using guide-needle outer diameters as practical surrogate targets (30-gauge ≈ 300 μm for 6-0; 27-gauge ≈ 400 μm for 5-0), the shortest heating length at which mean flange diameter exceeded the target was 1.0 mm with laser and 1.5 mm with cautery for both suture sizes.

Conclusions: Laser-assisted flange formation seems to be a feasible alternative to thermal cautery. In this dry-laboratory model, 1.0-mm laser heating and 1.5-mm cautery heating provided practical target flange dimensions while maintaining modest flange height.