Changes of corneal biomechanical after femtosecond laser–assisted for cataract surgery

Bruno Freitas Valbon,Luca Gualdi,Allan Luz,Renato Ambrósio Jr,Milton Ruiz Alves

doi:10.5935/0034-7280.20150061

Abstract

Purpose: To evaluate the changes of corneal biomechanical after femtosecond laser – assisted cataract and to compare the parameters derived by Corvis ST between standard phacoemulsification and femtosecond laser – assisted in cataract surgery Methods: This is a prospective study. 151 eyes of 127 patients were under went cataract surgery. 75 eyes of 65 patients were with femtosecond laser–assisted (FS)(Alcon Len Sx, Aliso Viejo,USA) and 76 eyes of 62 patients with standard phacoemulsification (SP) (Alcon Infinit, Fort Worth, USA). Lens scattering was evaluated using Scheimpflug Anterior Segment Tomography, using the new software PNS. The Scheimpflug images were taken with an ultra - high - speed camera during each measurement by the Corvis ST. The deformation amplitude (DA) and other parameters (e.g., pachyapex, intraocular pressure, 1st A time, highest concavity - time, 2nd A time, 1st A Length, 2nd A Length, curvature radius highest concavity, curvature radius normal, Vin, Vout) measured by the Corvis ST were studied in groups FLS and SP before an dafter cataract surgery. Exclusion criteria: corneal disease, retinal or optic nerves disease or previous ocular surgery. This is study analyzed was Kolmogorov-Smirnov for Normality. The Wilcoxon-test and t-test were utilized to evaluate the differences between pre and day 1in FS and SP, respectively. The Mann-Whitney test was used to compare the differences of parameters derived by Corvis ST - biomechanical properties between two groups (FS;SP). The p value less than 0.05 was considered statistically significant. Results: The mean age from patients of group FS was 67.6 y (± 9.9) and the group SP was 68.4 y (± 11.8). The mean PNS was 0.62 (±0.67). In group of FS, 9 of 11 parameters derived from Corvis ST were statisticall ysignificant (ss). In group of SP, 7 of 11 parameters derived from Corvis ST were ss. Only the HC - time was statistically significant between two groups (FS;SP) with p d” 0.0387. Conclusions: The use of the femtosecond laser – assisted system for cataract surgery and standard phacoemulsification induzed changes of biomechanical properties of the cornea by Corvis ST. Only 1 of 11 parameters studied was different statistically in two groups.

Highlights

Cataract surgery changes the biomechanical properties of the cornea[1]
The use of energy (US_ultrasound) in conventional phacoemulsification puts the endothelial cells in danger and leads to corneal edema.[2]
In the femtosecond laser group, 9 of 11 parameters studied were statistically significant between the Pre and the D1 groups; and in the facoconvencional group, 7 of 11 parameters studied were statistically significant between the Pre and the D1 groups as seen in Tables 2 and 3, respectively

Summary

Introduction

Cataract surgery changes the biomechanical properties of the cornea[1]. the mechanisms are not fully understood the structure of the modified cornea can influence the refractive results of the cataract surgery.The use of energy (US_ultrasound) in conventional phacoemulsification puts the endothelial cells in danger and leads to corneal edema.[2]. Cataract surgery changes the biomechanical properties of the cornea[1]. The mechanisms are not fully understood the structure of the modified cornea can influence the refractive results of the cataract surgery. The use of energy (US_ultrasound) in conventional phacoemulsification puts the endothelial cells in danger and leads to corneal edema.[2] Valbon et al.[3] showed that there is an increased central corneal thickness and decreased biomechanical properties of the cornea after surgery of conventional phacoemulsification. The advance in technology with the introduction of femtosecond laser allowed a fragmentation of the core of the crest, which in turn reduces the energy levels[4,5], favoring a smaller loss of endothelial cells and a faster visual recovery.[6] there are no studies on the effects of femtosecond laser in the structural and viscoelastic properties of the cornea in the cataract surgery

Methods

Results

Conclusion