Abstract: Objective To investigate the effect of shallow aqueous depth (AD) on the prediction error of four different intraocular lens (IOL) calculation formulas. Design Retrospective observational study. Participants A total of 176 cataract patients (176 eyes) who had cataract surgery with single focus IOL in-the-bag implantation from the First Hospital of Tsinghua University from Jan 1st, 2019 to Dec. 31th, 2021. Methods Axial length (AL), corneal curvature and AD were measured before operation. Patients were divided into shallow AD group (AD<2.5 mm) and non-shallow AD group (AD≥2.5 mm) according to AD. And the shallow AD group was further divided into short AL (AL<22.0 mm) and normal AL (AL≥22.0 mm) subgroups. Manifest refraction results were collected 1 to 3 months after operation to calculate the postoperative prediction errors of SRK/T, Hoffer Q, Haigis and Barrett formulas. Main Outcome Measures The prediction error (PE) and absolute prediction error (AE) of IOL values after operation. Results The difference of PE of 4 formulas was statistically significant (P<0.001) in the shallow AD group, while not in the non-shallow AD group (P=0.438). In the shallow AD group，the PE of Haigis (0.00±0.41) D and Barrett (0.04±0.41) D were smaller than that of SRK/T (-0.18±0.45) D and Hoffer Q (-0.21±0.41) D (P<0.05), there were no significant difference in the PE between Haigis and Barrett (P=0.614). In the shallow AD short AL group, the PE of SRK/T (-0.41±0.56) D and Hoffer Q (-0.45±0.44) D tended towards nearly a 0.50 D myopic shift which was statistically different from Haigis [(0.05±0.42) D, P<0.05]. Compared with itself, the PE of SRK/T and Hoffer Q tended towards a myopic shift under the influence of shallow AD [P(SRK/T) =0.031, P(Hoffer Q) <0.001]. There was no significant difference in the AE of different formulas within the group (the shallow AD group, P=0.393, and non-shallow AD group, P=0.369) nor between (P>0.05). In the shallow AD group, AE of SRK/T (P=0.044) and Hoffer Q (P=0.02) was statistically bigger in the short AL group. In the shallow AD short AL group, the percentage of AE within 0.50 D was 90% of Haigis, and only 50% of Hoffer Q without statistically difference (P=0.098). Through Logistic regression analysis, only SRK/T was found a greater possibility to get a >0.50 D AE with a steeper cornea (OR 1.71), a longer AL (OR 2.03) and a shallower AD (OR 0.327). Conclusions In patients with shallow AD, Haigis and Barrett formulas had more accurate predictions than SRK/T and Hoffer Q formulas. These two formulas were recommended in clinical practice. (Ophthalmol CHN, 2023, 32: 483-487)

Key words: cataract, shallow anterior chamber, refractive error, intraocular lens