[Comparison of two optical biometric devices for intraocular lens calculation]. / Vergleich zweier optischer Biometriegeräte zur Kunstlinsenberechnung.

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 a­constants as well as the utilized measurement methods of both instruments.

[Comparison of IOL-Master 500 vs. Lenstar LS900 concerning the calculation of target refraction: A retrospective analysis]. / Vergleich IOL-Master 500 vs. Lenstar LS900 hinsichtlich der Berechnung der Zielrefraktion: Eine retrospektive Analyse.

BACKGROUND: The choice of a suitable intraocular lens (IOL) and the calculation of postoperative refractive error is one of the most intriguing challenges of modern cataract surgery. This clinical trial compared the accuracy of two laser-assisted optical biometers, the IOL-Master 500 (Carl Zeiss Meditec, Jena, Germany) and the Lenstar LS900 (Haag-Streit, Bern, Switzerland) without taking the postoperative results into consideration. MATERIAL AND METHODS: Artificial lenses (Alcon Pharma) for 114 eyes of 67 patients were measured using both biometric instruments. The deviation of the presumed refractive error from the desired preoperative refractive target was calculated with different formulae (i.e. SRK/T, HofferQ, Haigis and SRKII) based on the intraoperatively chosen IOL. The differences between both instruments were compared using Student's t-test. RESULTS: Using the SRKII formula a mean difference between the IOL-Master and the Lenstar of 0.07 D (p = 0.002) was calculated for 95 eyes, SRK/T used on 47 eyes showed a difference of 0.04 D (p = 0.27), HofferQ measured 0.09 D (p = 0.0001) between both instruments for 88 eyes and the Haigis formula also showed a mean difference of 0.09 D (p = 0.001) based on the calculations of 106 eyes. CONCLUSION: Both instruments gave reproducible and accurate results with only a small deviation from the desired target refraction and can therefore be considered as comparable for the calculation of IOLs. Statistically significant differences in the results were found when using the SRKII, HofferQ and Haigis formulae but these were too low to have any influence on the choice of IOL to be implanted.