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Geraint P Williams, Ben L George, Yoke Wong, Gary Hin-Fai Yam, Marcus Ang, Shian Chao Tay, Jodhbir Mehta; Using a femtosecond laser to overcome corneal edema during lens capsulotomy. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1808.
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© ARVO (1962-2015); The Authors (2016-present)
Determination of the effects of the Ziemer LDV Z8 liquid interface femtosecond laser platform during capsulotomy under different energy settings in the context of corneal oedema.
Cadaveric porcine eyes harvested at <6 and 24>post hours enucleation to simulate clear and oedematous corneas were evaluated with the Ziemer LDV Z8 femtosecond laser during capsulotomy (5mm diameter, energy 90%, 130% or 150) (n=36). Lens capsules were removed for evaluation by scanning electron microscopy (SEM) and rupture strength was determined by the single column universal testing system (Instron 3343). Following ethical approval, a cohort of 23 patients (median age 70) had lens capsules removed during routine cataract surgery following manual or Z8 capsulotomy and subjected to TUNEL assay.
No difference in the edge morphology or in rupture strength (120, 113 and 118mN at increasing energy, p=NS) was observed in clear corneas. Only 50% of capsulotomies succeeded at 90% energy in an oedematous cornea. This was abrogated at increased energy (75% completion at 130%, 100% at 150%). Rupture strength in oedematous corneas was not significantly different at 112, 133 and 114mN for 90, 130 and 150% respectively, p=NS). 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).
Capsulotomy could be achieved in the presence of corneal edema with a femtosecond laser. Low energy delivered by the Ziemer Z8 platform had minimal effect on lens capsule morphology and strength and negligible influence on cell death, even with incremental increases in energy. Furthermore, increasing energy appears to enhance consistency in the ability to complete a capsulotomy in an oedematous cornea.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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