The study was aimed to check the influencing factors on remaining astigmatism after implanting a toric intraocular lens (IOL) during cataract surgery.

This retrospective study included parameters that were considered to have an influence on toric IOL power calculation. Therefore, data from the literature and the authors’ own data were used. Ray-tracing and Gaussian error propagation analysis was performed to quantify the sources of error.

The sample of 4,949 eyes (4,365 eyes of 42 studies and 584 eyes of retrospectively analyzed study data) were included in the study. The difference vector between aimed and calculated remaining astigmatism was 0.81 diopters (D). The main source of error was the preoperative measurement of the cornea (27%), followed by IOL misalignment (14.4%) and IOL tilt (11.3%). Other factors, such as angle kappa (10.9%), pupil size (8.1%), surgically induced astigmatism (7.8%), anterior chamber depth (7.5%), axial eye length (7.5%), and decentration (5.6%), also contributed to the refractive astigmatic error.

The study concluded that the major source of error is the preoperative corneal measurement followed by IOL misalignment and tilt  in toric IOL power calculation .