Abstract:  Objective To assess the effects of selecting keratometer astigmatism (KA) or total corneal astigmatism (TCA) as a reference on toric IOL calculation among subjects with age-related cataract and high posterior corneal astigmatism (PA). Design A retrospective comparative case series. Participants The present study included 77 eyes with against the role astigmatism (ATR) from age-related cataract patients and measured PA of more than 0.5 D in Aier Eye Hospital (Shenyang) from June 2017 to December 2021. Method The subjects were randomly divided into the KA and TCA groups and each group selected KA and TCA for toric IOL cylinder power calculations with Alcon Acrysoft Toric online calculator (https://www.acrysoftoriccalculator.com/). Holladay formula was choose to calculate the IOL cylinder power by using TCA and Barrett formula was choose to calculate the IOL cylinder power by using KA. Main Outcome Measures The uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), subjective refraction, magnitude of error (ME) and correction index (CI) and the centroid error in predicted residual astigmatism in two groups. Results The postoperative UCVA in the KA and TCA groups were 0.14±0.80 logMAR and 0.15±0.72 logMAR, respectively, whereas the difference between the two groups was not statistically significant（t=0.79, P=0.718）. The subjective refraction stigmatism value in the KA group was similar to that noted in the TCA group (KA group: -0.27±0.92 D, TCA group: -0.40±0.64 D, t=-0.55, P=0.582). The ME value was 0.33±0.33 D in the KA group and -0.22±0.52 D in the TCA group, suggesting postoperative undercorrection in KA group and overcorrection in TCA group. The absolute ME values of the two groups were not statistically significant (t=-0.46, P=0.542). According to the double-angle plot, the postoperative refractive prediction errors were 0.49±0.56 at 175° and 0.13±0.71 at 10°. The postoperative refractive astigmatism prediction error in KA group (48%) was similar with TCA group (43%) in ＜0.5 D. Conclusions In the eyes of high PA, the choice of TCA for Toric IOL lens calculation will lead to mild overcorrection and postoperative with the role astigmatism, which is an ideal refractive state. (Ophthalmol CHN, 2023, 32: 397-402)

Key words: cataract, posterior corneal astigmatism (PA), toric intraocular lens