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Measurable learning curve effects in femtosecond laser-assisted cataract surgery: an empirical analysis

Poster Details

First Author: J.Foerster GERMANY

Co Author(s):    T. Herbst   D. Holland           

Abstract Details


Since the implementation of a femtosecond laser for cataract surgery in our clinic, every laser-assisted cataract surgery has been comprehensively documented with regard to peri- and postoperative findings. This study wants to find out, which findings / criteria improved systematically over time after the implementation of a femtosecond laser. Besides medical raw data, the 'Quality Index Bellevue' (QIB) will be used for identifying significant learning curve effects.


For a general analysis, we included numerous peri- and postoperative findings (in the form of raw data or transformed QIBs) in order to identify significant time-depending changes. The 'Quality Index Bellevue System' transfers each medical finding into a quality index and bases upon the German school grading system. The QiB system is built up of three subarea QiBs, which includes measurable and subjectively ascertained findings as well as different aspects of patient satisfaction.


Our choice of statistical methods depends on the level of measurement: For examinations on aggregate levels, we will use ANOVA test as well as ordinary t-test. For comparisons of single finding QiBs, we will come back to Mann-Whitney-test and Kruskal-Wallis test respectively because of ordinal scale levels. Further possible examinations will be realized by appropriate statistical methods.


In preparation of analyses, we anticipated to find significant time-dependent improvements concerning suction time and effective phaco time. As a consequence, 'QiB anterior chamber' should be better for femto phaco procedure. Further improvements were anticipated for cornea finding (QiB cornea). We found significant time-dependent improvements for suction and effective phaco time. Endothelial cell loss (QiB cornea) and antior chamber finding (QiB anterior chamber) did not show continuous improvements.


The femto phaco laser technology seems to be the next important step in cataract surgery. For a surgeon, this technology means to adapt a new operation method. With the help of medical raw data and appropriate QIBs, the present study wants to identify variables, which display the learning curve effect after the introduction a femtosecond laser for cataract surgery. The analysis of the resulting data set has been done according to applicable statistical methods. Because of disparities in scale level, different methods have been used. Our first results show significant quality differences for suction and effective phaco time, which both decreased significantly over time. We did not find significant discrepancies the rest of medical criteria. Since data ascertainment is still in process, further possible findings will be identified in the context of following statistical analyses. FINANCIAL INTEREST: NONE

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