Elements of the Peripheral Oculomotor Apparatus

Collins, Carter C.; Scott, Alan B.; O'Meara, David M.

doi:10.1097/00006324-196907000-00004

Cited by 42 publications

(12 citation statements)

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“…With regard to the optic nerve, our model is an attempt to simplify the complexity while still providing a realistic dynamic response [44,51]. To achieve this response, the analytical springs that model the nerve are attached to the eye using simple constraint logic (Fig.…”

Section: Discussionmentioning

confidence: 99%

A finite element infant eye model to investigate retinal forces in shaken baby syndrome

Hans

Bawab

Woodhouse

2008

Graefes Arch Clin Exp Ophthalmol

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Section: Discussionmentioning

confidence: 99%

A finite element infant eye model to investigate retinal forces in shaken baby syndrome

Hans

Bawab

Woodhouse

2008

Graefes Arch Clin Exp Ophthalmol

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“…The spring constant of the lateral rectus in our model is 0.35 gram per degree of eye rotation. Collins et al [17], and Robinson et al [18], have demonstrated previously that, at higher levels of innervation, the length-tension relation of an innervated human eye muscle is linear, with equal spring constants for different levels of innervation. In other words, the tension increases proportionately to the length, like in an ordinary spring, and the spring constant remains the same at different levels of contraction.…”

Section: Methodsmentioning

confidence: 96%

Analysis of the dosage controversy in recess-resect and Faden surgery with the Robinson computer model of eye movements

Simonsz

Dijk

1987

Doc Ophthalmol

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In recess-resect surgery, the dosage depends on the preoperative angle of squint and on the ratio between squint-angle reduction and dosage that the surgeon has found in previous surgery. Recommendations pertaining to this ratio vary widely among authors. Some say a recession does more than a resection, while others believe the opposite is true. Finally, most find a lower ratio at smaller preoperative angles of squint. We investigated the matter, using our modified version of the Robinson computer model of eye movements. We calculated the amounts of surgery needed to reduce 10, 15, 20, 25, and 30 degree angles of squint to zero. The increase of the ratio at large angles of squint was indeed predicted by the model. The decrease at small angles of squint, however, was not predicted by the model. We found it impossible to model the decrease of the ratio at small preoperative angles of squint. The ratios for recess and resect surgery were approximately similar. We present an inventory of the possible causes of the discrepancies. In addition, we calculated the effects of Faden surgery and found that the predictions of the computer model correspond closely to reality.

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“…Mean and standard deviation of the eye radius [12] and muscle stiffness [13] were obtained from literature data. Some course measurements [14], of stiffness in passive rotation were used in the sensitivity analysis. Result of this evaluation was the variance (in degrees) of the postoperative angle of strabismus for each error source.…”

Section: Mathematical Model Of the Surgical Trajectorymentioning

confidence: 99%

Human error in strabismus surgery: quantification with a sensitivity analysis

Schutte

Polling

Helm

et al. 2008

Graefes Arch Clin Exp Ophthalmol

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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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Elements of the Peripheral Oculomotor Apparatus

Cited by 42 publications

References 0 publications

A finite element infant eye model to investigate retinal forces in shaken baby syndrome

A finite element infant eye model to investigate retinal forces in shaken baby syndrome

Analysis of the dosage controversy in recess-resect and Faden surgery with the Robinson computer model of eye movements

Human error in strabismus surgery: quantification with a sensitivity analysis

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