Intraocular lens calculation formula selection for short eyes: based on axial length and anterior chamber depth

PURPOSE: To evaluate the predictive accuracy of 11 intraocular lens (IOL) calculation formulas in eyes with an axial length (AL) less than 22.00 mm. METHODS: New-generation formulas (Barrett Universal II [BUII], Emmetropia Verifying Optical [EVO] 2.0, Hill-Radial Basis Function [Hill-RBF] 3.0, Hoffer QST, K6, Kane, Pearl-DGS) and traditional formulas (Haigis, Hoffer Q, Holladay 1 and SRK/T) were evaluated for predictive accuracy. Subgroup analyses were performed based on AL and anterior chamber depth (ACD). RESULTS: The study enrolled a total of 184 eyes from 184 patients. The BUII, Hoffer QST, Hoffer Q, Holladay 1, and SRK/T showed myopic shifts (-0.49 to -0.18 diopters [D], P < 0.05), whereas K6 displayed a hyperopic shift (0.11 D, P = 0.03). The Kane exhibited no systematic bias (-0.07 D), and yielded lower mean absolute error (MAE) (0.48 D, P < 0.05) and root mean square absolute error (RMSAE) (0.65 D, P < 0.01). For eyes with an AL ≤ 21.5 mm and an ACD > 2.5 mm, the Pearl-DGS displayed the smallest MAE (0.43 D) and lowest RMSAE (0.57 D), while other new-generation formulas showed relatively worse performance (MAE: 0.46 to 0.67 D; RMSAE: 0.60 to 0.84 D). CONCLUSION: The Kane formula showed the highest accuracy in short eyes, whereas the Pearl-DGS had superior performance in eyes with a relatively shorter AL and deeper ACD. CLINICAL TRIAL NUMBER: Not applicable.