Intraocular lens power calculation in eyes with a shallow anterior chamber depth and normal axial length.

We compared the accuracy of three intraocular lens (IOL) calculation formulas in eyes with a shallow anterior chamber depth (ACD) and normal axial length (AXL) and control eyes. We retrospectively reviewed eyes with a shallow ACD (<2.5 mm from the corneal epithelium) with normal AXL (22.5≤AXL<24.0 mm) and controls (3.0≤ACD<3.5 mm and normal AXL). Prediction error (PE) and median absolute error (MedAE) were evaluated with SRK/T, Barrett Universal II (BUII), and Kane formulas after adjusting the mean PE to zero for all patients. Percentages of eyes achieving a PE within 0.25 to 1.00 D, and correlations between ACD, lens thickness (LT), and PE were analyzed. Thirty-five shallow ACD and 63 control eyes were included. PE in the shallow ACD group showed more hyperopic results with BUII and Kane but not with SRK/T compared to controls. Within the shallow ACD group, PE showed more hyperopic results in BUII and Kane compared to SRK/T. However, the standard deviation (SD) of PE among formulas was not different. In the shallow ACD group, SRK/T showed a higher percentage of PE within 0.25 D than BUII and Kane, but the percentages within 0.50 to 1.00 D were similar. PE was negatively correlated with ACD in BUII and Kane, and positively correlated with LT in all formulas. BUII and Kane may induce slight hyperopic shift in eyes with a shallow ACD and normal AXL. However, the performance of the three formulas was comparable in the shallow ACD group in terms of MedAE, the SD of PE, and the percentage of eyes achieving PE within 0.50 D.