Don't let me down: New intraocular lens formula effectiveness in extreme-length eyes in day-to-day practice

Abstract

Purpose: This study aimed to assess five intraocular lens (IOL) formula refractive outcomes in eyes with extreme axial length (AL) in the day-to-day practice of a secondary care center. Design: This is a retrospective consecutive case series. Methods: From all uneventful phacoemulsification cataract surgeries performed during 2018 (n = 1528), eyes with AL ≤22 mm and ≥25 mm were included and, after applying exclusion criteria, were validated (n = 114). Five IOL power formula predictions were compared to registered postsurgical refractions using IOL Master 500©. Two subgroups were created: eyes with AL ≤22 mm (n = 52) and AL ≥25 mm (n = 62). The formula performance in each subgroup was assessed by values of mean error, mean absolute error (MAE), median absolute error, standard deviation, and frequencies of eyes within lesser values of prediction error (PE). Results: The formulae presented different PE values in both subgroups. In AL ≤22 mm subgroup, the MAE was 0.622 (±0.120) for Barrett II, 0.684 (±0.153) for Haigis, 0.625 (±0.131) for Hoffer Q, 0.593 (±0.130) for Holladay I, and 0.593 (±0.119) for SRK/T, without statistical significance (P > 0.05). In AL ≥25 mm subgroup, the MAE was 0.409 (±0.110) for Barrett II, 0.739 (±0.159) for Haigis, 1.143 (±0.224) for Hoffer Q, 1.058 (±0.212) for Holladay I, and 0.928 (±0.190) for SRK/T, with statistical significance compared to Barrett II and Haigis (P < 0.001). In this subgroup, the application of Wang–Koch AL adjustment seemed an advantage in Hoffer Q and Holladay I, whereas a disadvantage in Haigis and SRK/T. Conclusions: Despite performing better than any other formulae, the 4th generation formulae performed worse than initially expected. Formula constants might explain this difference, and different IOL models can be used. However, these limitations are faced in day-to-day practice. Thus, these results hold their value as real-life refractive outcomes in eyes with extreme AL.

Keywords

• cataract extraction
• eye axial length
• intraocular lens
• phacoemulsification
• refractive errors