Authors: Austin Pereira, Sohel Somani, Eric S. Tam, Hannah Chiu, Raj Maini

Author Disclosure Block: A. Pereira: None. S. Somani: None. E.S. Tam: None. H. Chiu: None. R. Maini: None.

Purpose: The aim of this study was to assess corneal morphologic changes and the magnitude of surgically induced astigmatism (SIA) following clear corneal incisions (CCIs) created manually or with the femtosecond laser using the Catalys platform during cataract surgery. 

Study Design: Retrospective cohort analysis. 

Methods: Patients undergoing femtosecond laser-assisted cataract surgery (FLACS) or manual cataract surgery performed by 4 experienced surgeons between June 2018 - September 2018 in Toronto, Ontario, were considered for inclusion. Postoperative corneal astigmatism values were compared to preoperative astigmatism indices to determine the SIA at the postoperative 3-month (POM3) time-point using the Alpins vector method. Secondary outcomes included postoperative 1-week (POW1) and 1-month (POM1) analysis, intraoperative phacoemulsification parameters, postoperative central corneal thickness (CCT), corrected visual acuity (CDVA) and intraocular pressure (IOP). Generalized estimating equations accounting for within-patient correlation were utilized for statistical analysis. This study adhered to the tenets of the Declaration of Helsinki and was approved by the William Olser Health System Ethics Review Board. 

Results: Refractive outcomes from 104 eyes of 61 patients, 50 eyes in the FLACS cohort and 54 eyes in the manual group, were recruited for analysis. Baseline parameters between groups were not significantly different. Femtosecond laser CCIs led to a lower SIA compared to manual CCIs at POM3, however this difference was not statistically significant (FLACS: 0.42D (0.28 - 0.85), manual: 0.47D (0.30 - 1.00), p=0.41). The mean postoperative CCI was significantly thinner following FLACS procedures compared to manual cataract surgeries (FLACS: 703.56±56.75μm, manual: 744.26±86.03μm, p=0.006). While there were trends toward reduced phacoemulsification time (p=0.59), thinner postoperative CCT (p=0.20), better postoperative CDVA (p=0.52) and lower IOP (p=0.06) in FLACS procedures compared to manual cases, these differences were not statistically significant. The above trends were consistent at POW1 and POM1 time-points. 

Conclusions: There is no significant difference in SIA following FLACS CCIs using the Catalys platform in comparison to manual cataract surgery. FLACS cases lead to significantly thinner CCIs compared to manual procedures. FLACS incisions trend to reduce phacoemulsification time and lead to a thinner CCT, improved postoperative CDVA and reduced IOP postoperatively.