Background: Modern cataract surgery not only consists of a minimally invasive lens extraction but also of the implantation of a suitable intraocular lens.
Objective: The aim of this prospective trial was a comparison of the predicted refractive error of two optical biometers, the IOLMaster 500 and LenStar LS 900 for intraocular lens power calculation in cataract surgery.
Material and methods: This was a prospective, analytical, comparative, non-masked study. A total of 86 eyes of 86 patients were examined and measured with both instruments before and after uneventful cataract surgery. Primary outcome measures were the differences of the predicted refractive error of both instruments. The predicted refractive error was calculated with different formulas. The results were compared to each other, to the desired target refraction as well as to the postoperative spherical equivalent.
Results: The mean differences in predicted refractive error of both instruments varied between 0.9 ± 0.19 (standard deviation) diopters (D) and 0.18 ± 0.30 D depending on the chosen formula. The IOLMaster 500 predicted less difference to the desired target refraction as well as to the spherical equivalent than the LenStar LS 900 with nearly all formulas.
Conclusion: Both devices generated reproducible exact data with only a small deviation from the desired target refraction and from the postoperative spherical equivalent. There were statistically significant differences based on the chosen a‑constants as well as the utilized measurement methods of both instruments.
Keywords: IOLMaster 500; LenStar LS 900; Optical biometry; Predicted refractive error.