Anterior chamber depth important for IOL calculation in short eyes

This retrospective study found that in eyes with short axial lengths, the difference between the predicted refractive errors of the Hoffer Q and Haigis formulas increased significantly as anterior chamber depth (ACD) decreased.

Previous studies have shown that both formulas are more accurate in short eyes. But unlike the Haigis formula, the Hoffer Q formula, a third-generation formula, doesn’t take ACD into account.

The authors evaluated the accuracy of the Hoffer Q and Haigis formulae using the IOLMaster in 75 patients with an axial length of less than 22 mm implanted with an Acrysof IQ IOL.

The formulae were similarly accurate in eyes with axial lengths shorter than 22.0 mm. However, in the subgroup analysis based on ACD, when the ACD was < 2.40 mm, the Haigis formula was significantly more accurate than the Hoffer Q formula. There was no significant difference in the results in eyes with ACDs deeper than 2.40 mm.

They conclude that ACD should be considered for IOL power calculation in short eyes and recommend the Haigis formula or the Hoffer Q formula with more hyperopic correction for eyes with a short axial length and ACD < 2.40 mm.