KEY TAKE-AWAYS

Posterior corneal astigmatism (PCA) is important in the selection of the toric IOL power

Not considering PCA results in an overcorrection in eyes with-the-rule (WTR) astigmatism and an undercorrection in eyes with against-the-rule (ATR) astigmatism

A majority of comparative studies using the Barrett toric IOL calculator are suggesting that the use of predicted and measured PCA does not impact clinical outcomes

One report showed benefits of utilizing predicted PCA in refractive outcomes of eyes with WTR and ATR astigmatism

Two reports supported the use of measured PCA in (1) eyes with high PCA of more than 0.8D and (2) a whole group analysis but not in the subgroup analysis of WTR, ATR and oblique eyes

Reasons for not detecting a clear benefit when applying PCA measurements in the Barrett toric IOL calculator may include: different technologies used for measuring PCA, limited sample size, limitations in technology precision in determining PCA, or presence of a newly found and clinically relevant leftover astigmatism