Purpose:

To evaluate the predictive accuracy of various IOL power formulas in short axial length (AL) eyes with the ZCB00 IOL (Johnson & Johnson Vision)

Methods:

A comprehensive chart review was performed to evaluate refractive outcomes in short AL eyes receiving a ZCB00 lens ≥+25.0D. 234 eyes were reviewed, of which 132 were included in the final analysis. 139 eyes of +15-24.0D IOL power were included as control eyes to optimize the lens constants for the dataset. Measurements were entered into multiple common IOL formulas for comparison. MPE, MedAE and percentage of eyes with MPE within ±0.50 and ±1.0D were calculated with constant optimization. Exclusion criteria include concurrent conditions impacting BCVA, prior refractive surgery, intraocular surgery, corneal ectasia, significant intraoperative complications, and post-operative complications.

Results:

Formulas were ranked according to mean absolute error (MAE) for short and control eyes. Data from the IOL Master 700 was used for the control eyes. For short AL eyes, two subsets were analyzed, depending on if IOL Master 500 or 700 biometry was used. The top-ranked formula in both subsets was OKULIX (0.422, 0.414). Hoffer Q ranked last in both subsets (0.774, 0.943). Additionally, the success of some formulas (Olsen-PhacoOptics) was highly dependent on whether lens thickness (LT) was available in biometry measurement – performing next to last without lens thickness, and second overall when lens thickness was available. Barrett formula performed poorly in both subsets (0.589, 0.829).

Conclusions:

When encountering short AL eyes, newer generation formulas appear to consistently outperform older generation formulas in the ZCB00 IOL platform, particularly the Hoffer Q formula. While popularly used and effective in normal AL eyes, the Barrett formula should be used with caution in short AL eyes when using this IOL platform.