2009
Human error in strabismus surgery: Quantification with a sensitivity analysis
Publication
Publication
Graefe's Archive for Clinical and Experimental Ophthalmology , Volume 247 - Issue 3 p. 399- 409
Background: Reoperations are frequently necessary in strabismus surgery. The goal of this study was to analyze human-error related factors that introduce variability in the results of strabismus surgery in a systematic fashion. Methods: We identified the primary factors that influence the outcome of strabismus surgery. For each of the human-error related factors we quantified variation with clinical assessments: measurement of the angle of strabismus, surgical strategy and surgical accuracy. Firstly, six patients were examined by six orthoptists, and accuracy of prism cover tests was assessed. Secondly, a questionnaire with sample cases (10°, 15° and 20° of infantile esotropia) was put to orthoptists, to determine variation in current surgical strategy. Finally, photographs made during surgery were analyzed to assess surgical accuracy. The influence of human-error related factors was related to the influence of inter-patient differences with a mechanical model. The relative contribution of all factors was assessed with a sensitivity analysis, and results were compared to clinical studies. Results: The surgical trajectory of strabismus surgery could be modeled mathematically. Measurement of angle of strabismus, surgical technique, anatomy and physiology were considered. Variations in the human-error related factors were: (1) the latent angle at distant fixation was measured with a 90% confidence interval of 5°, and comprised 20% of the total variance of the postoperative angle, (2) orthoptists decided for bilateral recessions of, respectively, 7.3±1.7° mm (total amount of two recessions), 9.1±1.2 mm and 10.3±1.3 mm, which comprised 15% of the total variance, and (3) surgical accuracy was estimated at ±0.5 mm, which comprised 20% of the total variance. Conclusion: The human error in strabismus surgery could be quantified with a sensitivity analysis. Approximately half of the reoperations in strabismus surgery are caused by inaccuracy in the measurement of the angle of strabismus, variability in surgical strategy and imprecise surgery.
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doi.org/10.1007/s00417-008-0961-x, hdl.handle.net/1765/25017 | |
Graefe's Archive for Clinical and Experimental Ophthalmology | |
Organisation | Erasmus MC: University Medical Center Rotterdam |
Schutte, S., Polling, J. R., van der Helm, F., & Simonsz, H. (2009). Human error in strabismus surgery: Quantification with a sensitivity analysis. Graefe's Archive for Clinical and Experimental Ophthalmology, 247(3), 399–409. doi:10.1007/s00417-008-0961-x |