Variation in Axial Length and Anatomical Landmarks in Strabismic Patients

Kushner, Burton J.; Lucchese, Neil; Morton, Gail V.

doi:10.1016/s0161-6420(91)32282-6

Cited by 33 publications

(10 citation statements)

References 9 publications

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“…Our model predicted that the size of the eye plays only a minor role in average patients. This agrees with the clinical data from Kushner et al [31,32]. To decrease the influence of anatomy and physiology, new devices should be aimed at measuring the individual mechanical properties of patients and relating these parameters to the effect of surgery.…”

Section: Discussionsupporting

confidence: 88%

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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Section: Discussionsupporting

confidence: 88%

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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“…29 Some reports explained the relationship between refractive error and surgical response by axial length. 30,31 For instance, small variations in the radius of the eyeball can have a significant effect on the amount of surgery needed to correct horizontal strabismus. In other words, to correct IXT for eyes with longer axial lengths, surgeons should increase the amount of surgery and vice versa.…”

Section: Discussionmentioning

confidence: 99%

Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery

et al. 2015

Eye

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Purpose To evaluate and compare surgical outcomes with respect to refractive errors in strabismus surgery for the treatment of intermittent exotropia (IXT). Methods The medical records of patients with IXT who were treated by one surgeon from January 2005 and June 2011 were reviewed. Three hundred and thirty-three IXT patients were included and divided into three groups according to preoperative refractive error: IXT with hyperopia (group I), IXT with emmetropia (group II), and IXT with myopia (group III). The surgical outcomes with respect to sensory and motor criteria were compared among the three groups. Results The surgical success rates according to motor criteria and sensory and motor criteria combined were higher in groups I (29 patients) and III (124 patients) than in group II (180 patients) at postoperative 3 and 6 months and at the last follow-up. Stereopsis was significantly better in groups II and III than in group I preoperatively (P = 0.002 by one-way analysis of variance test); however, the difference was not significant postoperatively. Twenty patients in group I (69.0%) were prescribed undercorrected hyperopic spectacles postoperatively, while only 22 patients in group III (17.7%) were prescribed spectacles with more myopic power than their refractive errors. Conclusion In the surgical treatment of IXT, hyperopia was not an indicator of poor prognosis. Taking into consideration the age effect, follow-up period after IXT surgery, and stereopsis improvement, hyperopic refractive error is rather a good prognostic factor.

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“…[15] The three (8.3%) failures of our calculation method had ALs outside this range. Of these two eyes were hypermetropic with AL of 18 and 17.5 and one was myopic with AL of 27.4 mm.…”

Section: Discussionmentioning

confidence: 99%

Evaluating a new surgical dosage calculation method for esotropia

Agrawal

Singh

Gupta³

et al. 2013

Oman J Ophthalmol

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Purpose:To evaluate a simplified method for correction of ocular deviation in patients of infantile and acquired basic esotropia.Materials and Methods:Thirty-six consecutive patients of infantile and acquired basic esotropia were selected for this study. Patients underwent unilateral recession–resection surgery as per the new norm gram. Patients underwent 3.5-7 mm recession of medial rectus (MR) in one eye depending on the pre-operative deviation and patient's age. Together they also underwent 6 or 7 mm resection of the lateral rectus (LR) in the same eye depending on patient's age (6 mm for 3 years and below and 7 mm for older age). In patients 3 years and below, a correction of 6, 7, or 8 PD/mm of recession of MR was expected when the pre-operative deviation was lesser than 30 PD, between 30 and 60 PD, or above 60 PD, respectively. Similarly, these values were 5, 6, and 7 PD/mm of MR recession in patients above 3 years. A ratio between achieved and expected correction was calculated and the calculation was deemed successful for a patient if this ratio fell between 0.9 and 1.1.Methods:Thirty-six consecutive patients of infantile and acquired basic esotropia were selected for this study. Patients underwent unilateral recession-resection surgery as per the new norm gram. Patients underwent 3.5-7 mm recession of medial rectus (MR) in one eye depending on the pre-operative deviation and patient's age. Together they also underwent 6 or 7 mm resection of the lateral rectus (LR) in the same eye depending on patient's age (6 mm for 3 years and below and 7 mm for older age). In patients 3 years and below, a correction of 6, 7, or 8 PD/mm of recession of MR was expected when the pre-operative deviation was lesser than 30 PD, between 30 and 60 PD, or above 60 PD, respectively. Similarly, these values were 5, 6, and 7 PD/mm of MR recession in patients above 3 years. A ratio between achieved and expected correction was calculated and the calculation was deemed successful for a patient if this ratio fell between 0.9 and 1.1.Results:The calculation procedure was successful in 33 out of 36 patients (91%). The two-tailed probability on paired Wilcoxon test was 0.187.Conclusions:This simplified method of surgical dosage calculation using MR recession as basis is predictable in patients of infantile and basic Esotropia. It may serve as a useful tool for minimizing variability of surgical results.

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Variation in Axial Length and Anatomical Landmarks in Strabismic Patients

Cited by 33 publications

References 9 publications

Human error in strabismus surgery: quantification with a sensitivity analysis

Human error in strabismus surgery: quantification with a sensitivity analysis

Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery

Evaluating a new surgical dosage calculation method for esotropia

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