AIM: To evaluate the accuracy of intraocular lens (IOL) power calculation formulas with/without preoperative aphakic anterior chamber depth (aph-ACD) in pediatric aphakia. METHODS: A total of 102 pediatric patients (150 eyes) undergoing secondary IOL implantation were divided into two groups (in-the-bag or ciliary sulcus). Prediction error was calculated for 9 IOL power calculation formulas, including: 1) not requiring ACD: Hoffer Q, Holladay 1, SRK/T; 2) usable without or with entering ACD: Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) 2.0, and Ladas Artificial Intelligence Super (Ladas AI); 3) requiring ACD: Haigis, Kane, and Pearl-DGS. Mean prediction error (ME), mean absolute error (MAE), median absolute error (MedAE) and the percentage of eyes within ±0.25, ±0.50, ±0.75, and ±1.00 D were calculated. RESULTS: For the BUII, EVO 2.0, and Ladas AI, with aph-ACD demonstrated a higher MedAE compared to without aph-ACD (BUII: 1.27 vs 1.13 D, EVO 2.0: 1.26 vs 1.06 D, Ladas AI: 1.30 vs 1.10 D; all P<0.05). Formulas requiring ACD (Haigis, Kane, and Pearl-DGS) exhibited larger MedAE than those not requiring aph-ACD (Hoffer Q, Holladay 1, and SRK/T; P<0.05). In the capsular group, the percentage of eyes within ±1.00 D ranged from 44.83% to 74.14%, and it was 19.57% to 32.61% in the sulcus group. CONCLUSION: The introduction of aph-ACD does not improve the accuracy of IOL calculation for pediatric aphakia, regardless of in-the-bag or sulcus IOL secondary implantation. The relationship between aph-ACD and effective lens position in pediatric aphakia warrants further study.