Comparing The Femtosecond Laser Assisted Cataract Surgery To Traditional Phacoemulsification

Objective To compare the ultrastructures of anterior lens capsule flap derived from manual capsulorrhexis and femtosecond laser-assisted capsulotomy. To compare preoperative and postoperative corneal biomechanical characteristics after phacoemulsification and femtosecond laser-assisted cataract surgery(FLACS) with the application of visualization corneal biomechanics analyzer(Corvis ST) and evaluate the influence of 3 mm clear corneal incisions on the corneal biomechanics.Methods The study comprised 50 eyes of 50 patients which accepting phacoemulsification and FLACS from June 2014 to July 2014 in our hospital were enrolled. 38 eyes had phacoemulsification and intraocular lens implantation and 12 eyes had FLACS. The anterior lens capsules were divided into two groups randomly and were examined by light microscopy(LM) and transmission electron microscope(TEM) respectively. The ultrastructure of the flap edge and the tissue near the flap edge were examined carefully. All the subjects were measured by Corvis ST at 7 to 10 o’clock in the morning for corneal biomechanical parameters preoperatively, 1 week and 1 month postoperatively. Independent samples t-test is used to contrast corneal biomechanical parameters measured 1 week and 1 month preoperatively between two groups. one-way ANOVA and multiple in ANOVA are used to indicate the significance of corneal biomechanical changes. The first/second applanation time、The first/second applanation length、first/second applanation velocity、Highest concavity time、Highest concavity radius、Peak Distance、Deformation amplitude,DA).Results The flap derived from manual capsulorrhexis had smooth edges, no cell destruction, and had cells filling to the cutting edge by LM and TEM examination. The anterior capsule flap derived from femtosecond laser-assisted capsulotomy showed an approximate 60 μm banded area of cell degeneration and necrosis with dentiform prominences at the edge and had no cell structrue. Comparing biomechanical parameters of phacoemulsification group1 week postoperatively and preoperatively,1week postoperatively and 1month postoperatively, biomechanical parameters including the first/second applanation length, Peak Distance, Deformation amplitude,CCT,IOPnct,IOPpachy, differences are statistically significant. Comparing biomechanical parameters 1week postoperatively and 1month postoperatively, there was no statistically significant difference. Comparing biomechanical parameters of FLACS group1 week postoperatively and preoperatively,1week postoperatively and 1month postoperatively, biomechanical parameters including CCT,IOPnct,IOPpachy, differences are statistically significant. Comparing biomechanical parameters 1week postoperatively and 1month postoperatively, there was no statistically significant difference. Comparing corneal biomechanical parameters preoperatively and 1month postoperatively between two groups, there was no statistically significant difference. Comparing corneal biomechanical parameters 1 week postoperatively between two groups, biomechanical parameters including the first/second applanation length, Peak Distance, Deformation amplitude, CCT differences are statistically significant.Conclusion The flaps by femtosecond laser-assisted capsulotomy has banded degeneration and necrosis area and rougher edges which may be related to the shock wave caused by strong instant power of femtosecond laser. Corneal biomechanics of clear corneal incision made by femtosecond laser are superior to that made by paracentesis knife. At 1 month postoperatively the healing of the incision and corneal edema recedes, corneal biomechanical parameters recovered to preoperative levels.