This study group compared the differences in surgically induced astigmatism (SIA) vector, flattening effect, torque and wound architecture following both femtosecond laser and manual clear corneal incisions (CCIs). A double-armed, randomised, prospective case series was conducted. Cataract surgery was performed using femtosecond laser (300 eyes) or manual (300 eyes); 2.4mm CCIs in temporal or superior oblique locations. SIA, flattening effect, torque and the summated vector mean for SIA were calculated. Correlation with individual features was established and incision morphology was investigated by anterior segment optical coherence tomography at three months of follow-up. The SIA, flattening effect and torque were found to be lower in the femtosecond laser group for both incision locations, although the differences were not significant (all P>.05). The femtosecond laser group showed less dispersion of SIA magnitude and flattening effect. Temporal and superior oblique incisions resulted in flattening effect values of -0.11 and -0.21 dioptres (D), respectively, in the femtosecond laser group and -0.13 and -0.34 D respectively, in the manual group. Significant correlations with individual features were only found in the femtosecond laser group, with preoperative astigmatism being the only significant SIA predictor by multiple regression analysis (P=.003). Femtosecond laser CCIs showed less deviation from the intended length, wound enlargement, endothelial misalignment and Descemet membrane detachments (all P<.037). Femtosecond laser CCIs were found to be more reproducible. Although SIAs were smaller in femtosecond laser CCIs than in manual CCIs for both temporal and superior oblique incisions, the difference was not statistically significant. Association with individual features is highly variable. Femtosecond incisions were found to deviate less from the intended length being more precise in relation to location from the limbus, less wound enlargement, lower endothelial misalignment and fewer Descemet’s membrane detachments.

Comparison of surgically induced astigmatism and morphologic features resulting from femtosecond laser and manual clear corneal incisions for cataract surgery.
Ferreira TB, Ribeiro FJ, Pinheiro J, et al.
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Inderpaul S Sian

FRCOphth, MCOptom, PG Cert (Clin Ed), MB ChB, BOptom (HONS), Musgrove Park Hospital, Taunton & Somerset Foundation Trust.

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