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Graefe's Archive for Clinical and Experimental Ophthalmology

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Open Access 01-03-2009 | Miscellaneous

Human error in strabismus surgery: quantification with a sensitivity analysis

Authors: Sander Schutte, Jan Roelof Polling, Frans C. T. van der Helm, Huib J. Simonsz

Published in: Graefe's Archive for Clinical and Experimental Ophthalmology | Issue 3/2009

Abstract

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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Title: Human error in strabismus surgery: quantification with a sensitivity analysis
Authors: Sander Schutte
Jan Roelof Polling
Frans C. T. van der Helm
Huib J. Simonsz
Publication date: 01-03-2009
Publisher: Springer-Verlag
Published in: Graefe's Archive for Clinical and Experimental Ophthalmology / Issue 3/2009
Print ISSN: 0721-832X
Electronic ISSN: 1435-702X
DOI: https://doi.org/10.1007/s00417-008-0961-x

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Human error in strabismus surgery: quantification with a sensitivity analysis

Abstract

Background

Methods

Results

Conclusion

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Abstract

Background

Methods

Results

Conclusion

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