Performing Reliable Lens Capsulotomy in the Presence of Corneal Edema With a Femtosecond Laser.

Purpose: To determine the effects of the Ziemer LDV Z8 liquid interface femtosecond laser platform during capsulotomy under different energy settings in the presence of corneal edema. Methods: Cadaveric porcine eyes (n = 36) employed at less than 6 and greater than 24 post enucleation hours to simulate clear/edematous corneas, underwent capsulotomy with the Ziemer LDV Z8 femtosecond laser (5-mm diameter, energy 90%, 130%, or 150%). Lens capsules were removed for evaluation by scanning electron microscopy and rupture strengths determined by the single column universal testing system. Following ethical approval, 23 patients had lens capsules removed during routine cataract surgery following manual or Z8 capsulotomy and subjected to TUNEL assay. Results: There was no difference in edge morphology or rupture strength (120, 113, and 118 mN at increasing energy, P = 0.42) in the clear cornea. Only 50% of capsulotomies succeeded at 90% energy in an edematous cornea, improving with increased energy (75% completion at 130%, 100% at 150%). Rupture strength in edematous corneas was not significantly different at 112, 133, and 114 mN for 90%, 130%, and 150%, respectively (P = 0.3). In human samples, increased TUNEL-positive cells were seen at 130% energy, but not at 150% (0.0 manual vs. 0.2 [90%] vs. 2.1 [130%] vs. 0.6 [150%], P < 0.05). Conclusions: Because of the low energy delivered by a femtosecond nanojoule platform, even incremental increases in energy appeared to have minimal effect on lens capsule morphology and strength and negligible influence on cell death. Furthermore, increasing energy appeared to enhance consistency and the ability to complete a capsulotomy in an edematous cornea.

The effects of a low-energy, high frequency liquid optic interface femtosecond laser system on lens capsulotomy.

The introduction of femtosecond laser assisted cataract surgery (FLACS) is a paradigm changing approach in cataract surgery, the most commonly performed surgical procedure. FLACS has the potential to optimize the creation of an anterior lens capsulotomy, a critical step in accessing the cataractous lens. The merits of using a laser instead of a manual approach include a potentially more circular, consistent, and stronger aperture. In this study we demonstrated for the first time in both a porcine and human experimental setting that with a low energy, high repetition FLACS system, that a circular, smooth and strong capsulotomy was achievable. While there was no demonstrable difference in the resistance to rupture before or after the removal of the nucleus, larger capsulotomies had an increase in tensile strength. The LDV Z8 system appeared to create circular, rupture-resistant and smooth capsulotomies in both porcine and more importantly human globes.