Femtosecond Laser-assisted Cataract Surgery Versus Conventional Phacoemulsification: Comparison Of Wave-front Aberration And Visual Quality

Purpose:To compare the wavefront aberrations and optical quality after femtosecond laser-assisted cataract surgery(FLACS)and conventional phacoemulsification cataract surgery(CPCS).Methods:This study included patients who received FLACS or CPCS from January 2018 to July 2019 in Eye Center,Second Affiliated Hospital of School of Medicine,Zhejiang University,Hangzhou,China.Postoperative examinations were evaluated 1 year after surgery,which included wave-front measurements of total aberrations,corneal aberrations,and internal aberrations under pupil diameters of 3.0 mm and 5.0 mm.Specifically,higher-order aberrations of coma,trefoil,and spherical aberration were measured and compared between groups.Intraocular lens(IOL)tilt and decentration was calculated and evalueated based on Scheimpflug photographs.In addition,visual acuity(VA)and refractive outcomes were also compared.Visual quality was measured with Strehl ratio and modulation transfer function(MTF)and compared between groups.Finally,subgroup analyses were conducted based on monofocal or multifocal IOLs.Results:The study consisted of 221 eyes(105 eyes in FLACS group and 116 eyes in CPCS group).No intraoperative complications were observed in all cases.Patients’ baseline characteristics were comparable between the two groups.(1)With the pupil diameter of 3.0 mm,no significantly different internal aberrations were observed between groups.With the pupil diameter of 5.0 mm,the FLACS group demonstrated significantly lower root mean square(RMS)of total internal aberration(1.27±0.62 μm vs.1.65±0.61 μm,P=0.004),higher-order aberrations(HOAs)(0.40±0.18 μm vs.0.46± 0.24 μm,P=0.034),coma(0.10±0.08 μm vs.0.13±0.09 μm,P=0.004),and spherical aberration(0.18±0.11 μm vs.0.22±0.11 μm,P=0.014).(2)With the pupil diameter of 5.0 mm,IOL tilt was found to be positively correlated with total internal aberration(P<0.001),HOAs(P<0.001),and coma(P<0.001).IOL decentration was found to be positively correlated with total internal aberration(P=0.032),HOAs(P=0.049),and coma(P=0.001).In terms of patients’ baseline parameters,axial length was significantly correlated with total aberration(P<0.001)and spherical aberration(P=0.011).Average keratometry was also significantly associated with total aberration(P=0.012)and spherical aberration(P=0.031).(3)With the pupil diameter of 5.0 mm,FLACS group presented significantly smaller IOL tilt(0.29±0.12 μm vs.0.32± 0.19 μm,P=0.049)and decentration(0.17±0.07 mm vs.0.31±0.13 mm,P<0.001)than CPCS group,but there were no significant differences in terms of visual acuity and refractive outcomes between groups.(4)With either 3.0 mm or 5.0 mm pupil diameter,FLACS group and CPCS group exhibited similar optical quality with regards to Strehl ratio and MTF values at all studied frequencies.However,in the multifocal extended depth of focus(EDOF)subgroup,Strehl ratio and MTF values at all studied frequencies were significantly higher in femtosecond group with 3.0 mm pupil,suggesting superior visual quality.Conclusion:FLACS embraces the advantages of improved circularity of capsulotomy and accuracy of IOL position.Over long-term observation,FLACS induces significantly lower internal aberrations of tilt,coma,higher-order aberration,and spherical aberration than CPCS,which is mainly attributed to IOL tilt and decentration.Optical aberrations of patients implanted with Tecnis Symfony IOL were compared and decreased HOAs and enhanced image quality were found in femtosecond group.