Rotational Stability of Intraocular Lenses: A Standardized Method for More Accurate Measurements in Future Studies

Purpose To assess the reliability and reproducibility of a new semi automated evaluation method Rotix for intraocular lens rotation (IOL) and to define a standardized evaluation method for future toric IOL studies. Design Reliability and reproducibility study Setting Department of Ophthalmology, Medical University of Vienna Patient Population A dataset of 25 patients with 2 consecutive follow-up visits was created to test the intra- and inter-rater reliability. A datatest set of 10 patients including 30 pictures taken 5 minutes apart was created to test the short-term reproducibility. Intervention Evaluation of IOLs rotational stability using non-toric implants in 25 × 2 consecutive follow-up visits. Two experienced graders performed axis evaluation 3 times in a randomized order. One experienced grader performed axis evaluation for the short-term reproducibility study. Reference landmarks at the end of operation were used to assess the IOL axis. Main Outcome measures Intra-, inter-rater reliability and short-term reproducibility of axis measurements. Results Mean standard deviation for intra-rater reliability was 0.16 degrees. The intra-class correlation coefficients (ICC) were 0.97 for grader 1 and 0.96 for grader 2, respectively. A very high inter-rater correlation of 0.95 was found. The mean individual difference between grader 1 and grader 2 was 0.061± 0.28 degrees. Short-term reproducibility showed a mean standard deviation of 0.22±0.14 degrees. Conclusion The novel semi automated evaluation method showed an accurate inter- and intra-rater reliability. Short-term reproducibility was below 0.25 degrees. The method of using non-movable reference landmarks showed reliable results and should be used as a standard in future toric IOL studies.