Meta-analysis of accuracy of intraocular lens power calculation formulas in short eyes

Intraocular lens (IOL) power selection is a critical factor affecting visual outcome after IOL implantation in short eyes. Many formulas have been developed to achieve a precise prediction of the IOL power. However, controversy regarding the accuracy remains.

To investigate the accuracy of different IOL power calculation formulas in short eyes.

Meta-analysis.

Patients with the axial length of eyes less than 22 mm from previously reported studies.

A comprehensive search in Pubmed, EMBASE, Cochrane Data Base of Systematic Reviews and the Cochrane Central Register of Controlled Trials was conducted by October 2016. We assessed the methodological quality using a modified QUADAS-2 tool and performed analysis on weighted mean differences of mean absolute errors (MAE) among different formulas.

The between-group difference of MAE was evaluated with weighted mean difference and 95% confidence intervals.

Ten observational studies, involving 1161 eyes, were enrolled to compare six formulas: Haigis, Holladay 2, Hoffer Q, Holladay 1, SRK/T and SRK II. Among them, the Holladay 2 introduced the smallest overall MAE (0.496D) without statistical significance. The difference of MAE is statistically significant between Haigis and Hoffer Q (mean difference = -0.07D, P = 0.003), Haigis and SRK/T (mean difference = -0.07D, P = 0.009), Haigis and SRK II (mean difference = -0.41D, P = 0.01). For publication bias and small-study effect, neither funnel plot nor egger's test detected statistical finding.

The overall evidence from the studies confirmed the superiority of Haigis over Hoffer Q, SRK/T and SRK II in prediction IOL power in short eyes.