Incision-induced astigmatic changes in eyes undergoing simultaneous phakic intraocular lens explantation and phacoemulsification

PURPOSE: To evaluate surgically induced astigmatism (SIA) in bilensectomy, the simultaneous phakic intraocular lens (pIOL) explantation and femtosecond laser-assisted cataract surgery, comparing outcomes between corneal and scleral incision approaches. DESIGN: Retrospective consecutive case series. SETTING: Tertiary referral university hospital. METHODS: Preoperative and 3-month postoperative Scheimpflug-based tomography was used to assess anterior (simK) and total corneal refractive power (TCRP). In eyes with soft pIOL, removal was performed through a temporal 2.2 mm corneal incision that was manually enlarged to 2.4 to 2.6 mm (C-Ex group). In eyes with rigid pIOL, explantation was through a 6 mm superior scleral incision (S-Ex group). Vector analysis was performed, and SIA variability was evaluated through difference vectors (DV) and 80% and 95% confidence ellipses (CE) as well as 95% confidence polygonal areas. RESULTS: 41 eyes (29 patients) were included (23 C-Ex group and 18 S-Ex). Mean absolute astigmatism difference was 0.47 ± 0.32 diopter (D) for simK and 0.53 ± 0.38 D for TCRP. DV magnitudes were 0.66 ± 0.40 D and 0.77 ± 0.53 D, respectively, with no significant difference ( P = .998). Analysis of centroid and medoid values, as well as CE areas, showed lower variance under simK compared with TCRP (CE 80%: 0.65 D 2 vs 0.92 D 2 ; CE 95%: 1.22 D 2 vs 1.72 D 2 , respectively). After 3 months, the S-Ex group exhibited comparable astigmatic outcomes with the C-Ex group for soft pIOLs. CONCLUSIONS: simK and TCRP yield similar SIA magnitudes, although TCRP reveals greater variability. Steep meridian shifts in magnitude and axis are common after bilensectomy and must be considered when implanting toric intraocular lenses. Further large-scale, longitudinal studies are required to confirm these results.