- Email: [email protected]
High sensitivity of binocular retinal birefringence screening for anisometropic amblyopia without strabismus
Volume 18 Number 4 / August 2014 Discussion: For 3 of 4 AS-20 domains, poorer HRQOL was associated with higher depression scores, indicating subthreshold depressive symptoms. Conclusion: The association of subthreshold depressive symptoms with poor HRQOL should be considered when interpreting patient reported outcomes.
013 The role of health-related quality of life when evaluating outcomes of strabismus surgery. Jonathan M. Holmes, Sarah R. Hatt, David A. Leske, Laura Liebermann Introduction: Strabismus surgery outcomes are typically defined using motor and diplopia criteria. Nevertheless, some patients designated failure by these criteria report subjective improvement. We aimed to evaluate the role of health-related quality of life (HRQOL) measures in patients who might be classified as failures. Methods: We studied adults undergoing strabismus surgery who had preoperative and 1-year postoperative HRQOL data using the Adult Strabismus-20 (AS-20) questionnaire. Motor and diplopia criteria were applied to classify outcomes as: success, partial success, or failure. For those classified as failure, the medical record was reviewed to determine whether there was subjective improvement at 1 year, independent of AS-20 scores. Improvement in HRQOL score was defined as exceeding 95% limits of agreement on at least one AS-20 domain. To determine whether HRQOL scores reflected subjective improvement in patients otherwise classified as failure, we compared HRQOL scores between those who reported improvement and those who did not. Results: Of 227 patients, 39 (17%) were classified as failure by motor and diplopia criteria; 25 of 39 reported subjective improvement, of which 16 (64%) met improved HRQOL score criteria. Fourteen of 39 had no subjective improvement, of which 5 (36%) met improved HRQOL criteria. Discussion: For many apparent surgical failures, objective motor and diplopia criteria do not capture subjective improvement, but improvement is often reflected in HRQOL scores. The few patients who had no subjective improvement but better HRQOL scores may represent a placebo effect. Conclusion: Quantitative HRQOL criteria should be considered when evaluating outcomes following strabismus surgery.
014 Factors affecting stereopsis after surgical alignment of acquired partially accommodative esotropia. Yiannis Iordanous, Inas Makar Introduction: The goal of strabismus surgery is to correct ocular alignment, promoting the development of stereopsis and binocular single vision (BSV). Despite successful surgical ocular alignment, many children do not develop stereopsis postoperatively. The purpose of this study was to determine preoperative factors that affect stereopsis in patients with acquired partially accommodative esotropia (APAET). Methods: We retrospectively reviewed the charts of all patients who underwent strabismus surgery for APAET from a single surgeons practice. Patients were eligible for inclusion if they had a final motor alignment within 8D of orthophoria for distance and near (successful alignment). We compared preoperative factors between patients achieving postoperative stereopsis better than 100 arcsec (i.e. achieving BSV) versus those with worse than 100 seconds of stereopsis. These factors included age of onset, delay in referral, duration of misalignment and age at surgery.
Journal of AAPOS
e5 Results: A total of 65 patients met our inclusion criteria. 27 (42%) had a final stereopsis of 100 arcsec or better. The mean AO for patients achieving postoperative BSV was 32.3 12.5 months, versus 22.4 9.2 months (P \ 0.0005) for the group not attaining BSV. Those achieving BSV presented to clinic later (57.4 19.2 vs 41.6 23.6 months; P 5 0.005) and had a later age at surgery (66.4 18.2 vs 50.3 21.7 months; P 5 0.002) when compared to those not achieving BSV. There was no significant difference in the duration of misalignment between the two groups (34.0 16.4 for those attaining BSV versus 27.9 19.0 for those not attaining BSV; P 5 0.2). A regression analysis found only older age of onset to be predictive of better postoperative BSV (OR 1.08; 95% CI 1.03-1.14). Discussion: Our results suggest that for every month delay in onset of esodeviation, a child with APAET is 8% more likely to regain BSV postoperatively. Surprisingly, DOM did not appear to be related to final stereoacuity outcomes in this patient population. Conclusion: These results may allow physicians to better predict surgical outcomes for children with APAET. It may also aid in surgical planning, as DOM appears to not be correlated with final outcomes.
015 Type I ROP, treatment with bevacizumab versus laser: comparison of visual function, structural outcome and frequency of follow-up. Maram Isaac, Kamiar Mireskandari, Nasrin Tehrani Purpose: To further elucidate the visual function, structural outcomes and frequency of follow up visits for infants with type I ROP treated with intravitreal Bevacizumab (IVB) versus laser. Methods: Retrospective comparative chart review. Results: Thirteen infants were treated with IVB and 14 infants with laser. There was no statistically significant difference in gestational age or birth weight. Eight eyes developed ROP in zone I and 15 eyes in zone II in each group. None developed unfavorable structural outcome at 6 months post treatment (1). Visual acuity (VA) was measurable for 16/23 eyes in laser and 13/23 eyes for IVB groups at 6-12 months corrected age (CA). Mean VA was (1.20 0.3) and (0.92 0.34) logMAR, (P 5 0.054) for laser and IVB groups respectively. Refraction was available for 17/23 eyes for laser and 23/23 eyes for IVB groups. Mean spherical equivalent (SE) was (-4.41 4.71) for laser and (-3.42 5.89) for IVB groups (p 5 0.5572), respectively. Infants in laser group had an average of (5.00 3.00) follow up visits versus (14.00 5.00) in IVB group, (P \ 0.001) in the 6 months post treatment. Discussion: Both treatments resulted in good structural outcome. At 6-12 months CA, there was no statistically significant difference in refractive error or VA between two groups, however more frequent follow up was observed in the IVB group. Conclusion: In view of similar structural outcomes between the two groups, frequency of follow up post IVB may need reconsideration to reduce patient exposure to distressful eye examinations and optimize resource allocation. References 1. Early Treatment for Retinopathy of Prematurity Cooperative Group. Revised indications for the treatment of retinopathy of prematurity: results of the Early Treatment for Retinopathy of Prematurity randomized trial. Arch Ophthalmol 2003;121:1684-94.
016 High sensitivity of binocular retinal birefringence screening for anisometropic amblyopia without strabismus. Reed M. Jost, Joost Felius, Eileen E. Birch Introduction: Binocular retinal birefringence scanning can detect whether fixation is bifoveal by identifying the unique polarization
e6
Volume 18 Number 4 / August 2014
signal created by the radially arranged Henle fibers (photoreceptor axons) that emanate from the fovea. Screening based on this technology has .98% sensitivity for strabismus, including microstrabismus.1,2 Surprisingly, binocular retinal birefringence scans also have been reported to have 91% sensitivity for anisometropic amblyopia in children with no strabismus.1 Here we investigate two factors that may contribute to its sensitivity to anisometropic amblyopia, fixation instability and defocus. Methods: 53 children (4-14y) with anisometropic amblyopia were screened with the Pediatric Vision Scanner, a retinal birefringence scanner; 18 with no strabismus and 35 combined with strabismus. All had a complete ophthalmic examination and an evaluation of fixation instability by Nidek MP-1 and/or EyeLink and, for a subset (n 5 37), an analysis of residual defocus with accommodation to a near target by the Grand Seiko autorefractor. Results: Screening referred 50/53 (sensitivity 5 94%). Among the 16/ 18 (89%) with no strabismus who were referred, 7 had fixation instability greater than age-matched controls, 7 had defocus .4.00 D in the amblyopic eye when fixating binocularly at near, and 2 had both. Fixation instability was correlated with amblyopic eye visual acuity (r 5 0.41; P 5 0.002). Amblyopic eye defocus was negatively correlated with the birefringent signal power (r 5 0.56, P 5 0.0003). Discussion: Sensitivity to anisometropic amblyopia in the absence of strabismus likely results from the fixation instability, which may interfere with detection of central fixation, and/or from a reduction of birefringent signal power due to defocus of the amblyopic eye when fixing at near. Conclusion: Binocular retinal birefringence scanning detects anisometropic amblyopia in children with no strabismus with high sensitivity. References 1. Loudon SE, et al. Rapid, high-accuracy detection of strabismus and amblyopia using the Pediatric Vision Scanner. Invest Ophthalmol Vis Sci 2011;52: 5043-8. 2. Jost RM, et al. High sensitivity and specificity of the pediatric vision scanner in detecting strabismus and amblyopia in preschool children. AAPOS 2013 abstract.
017 Optic nerve optical coherence tomography versus humphrey visual field analysis in pediatric intracranial hypertension. Ellen R. Miller, Cate O. Jordan, David L. Rogers Introduction: Pediatric intracranial hypertension requires frequent monitoring. Spectral-domain optical coherence tomography (SDOCT) is a non-invasive imaging modality that may facilitate objective monitoring of optic nerve pathology in children. Methods: A retrospective review of all patients with a new or established diagnosis of intracranial hypertension over a 6 month period was performed. Optic nerve SD-OCT and Humphrey 30-2 visual fields were performed on each patient. Analysis was completed to correlate visual field defects with average and sectoral retinal nerve fiber layer (RNFL) thickness. Results: 124 eyes were identified, ages 5 to 21 years. Eyes were divided into subgroups based on exam findings: with optic nerve edema (n 5 44) and without (n 5 80). There was a statistically significant difference between the average RNFL thickness of eyes with edema: 126.68 m 24.73, and without edema: 105.86 m 11.85 (P \ 0.0001). Eyes with normal visual fields (n 5 103) had an average RNFL of 110m 13.57. Eyes with peripheral visual field deficits (n 5 10) had an average RNFL thickness of 108.67m 17.69
(P $ 0.05). Eyes with blind spots enlarged (n 5 11) had an average RNFL thickness of 154.09m 25.44 (P 5 0.002). Discussion: Eyes with clinically apparent optic nerve edema had statistically significant thickening of the RNFL compared to those without edema. There was no correlation between peripheral visual field defects and either the average or sectoral RNFL thickening. Blind spot enlargement was statistically associated with a thickened average RNFL. Conclusion: Our study found a correlation between blind spot enlargement on visual field testing and a thickened average RNFL on SD-OCT testing of the optic nerve. 018 The effect of part-time patching on near stereoacuity, control, and angle in childhood intermittent exotropia. Brian G. Mohney, Susan A. Cotter, Danielle L. Chandler, Jonathan M. Holmes; Pediatric Eye Disease Investigator Group Introduction: In a randomized trial we found part-time patching reduced the 6-month risk of IXT deterioration from 6.0% to 0.6%.1 Here we report secondary outcomes of stereoacuity, control, and angle. Methods: 358 patients aged 3 to \11 years with previously untreated IXT and near stereoacuity of at least 400 arcsec were randomly assigned to either observation or patching for 3 hours per day for 5 months, with outcome assessment at 6 months. Results: Mean near stereoacuity (Preschool Randot test) was 68 versus 69 arcsec in observation versus patching (p 5 0.38). Assessed by the Office Control Scale,2 ranging from 0 (phoria) to 5 (constant), mean scores in observation and patching groups were 2.3 versus 2.0 at distance (P 5 0.09) and 1.2 versus 0.9 at near (P 5 0.01). Among those with baseline control scores $2, improvement at distance was seen in 19% observed vs. 29% patched (p 5 0.07, n 5 238) and at near in 23% observed versus 37% patched (P 5 0.40; n 5 86). Mean exodeviations (PACT) in the observation and patching groups were 23.8D vs. 22.2D at distance (P 5 0.01) and 17.6D vs 15.4D at near (P 5 0.11). Among those who could improve more than test-retest variability ($8D at distance and $13D at near), improvement was seen in 9% observed versus 14% patched at distance (P 5 0.17, n 5 324) and 5% observed vs. 10% patched at near (P 5 0.20; n 5 218). Conclusion: Several but not all secondary outcomes were consistent with the primary finding of a small effect of part-time patching on IXT at 6 months in 3-10 year olds. References 1. Pediatric Eye Disease Investigator Group. A randomized trial comparing part-time patching with observation for children 3-10 years old with intermittent exotropia. 2013 (unpublished). 2. Mohney BG, Holmes JM. An office-based scale for assessing control in intermittent exotropia. Strabismus 2006;14:147-50.
019 The slippery slope: early signs of instability after surgery for esotropia. Bharti Nihalani-Gangwani, Miriam Ehrenberg, Patrice Melvin, Adebona Olumuyiwa Adebona, Linda R. Dagi Introduction: Reoperation rates for strabismus surgery remain high even after initial successful realignment. We studied onset of instability with longitudinal analysis comparing postoperative outcomes of esotropia surgery at 2-4 months versus 1 year. Methods: Outcomes of surgery for all classes of esotropia in patients $18 years of age (N 5 550) were included if postoperative sensorimotor examinations were documented at 2-4 months as well as 1 year (N 5 419). Four possible goals for surgical intervention
Journal of AAPOS
013 The role of health-related quality of life when evaluating outcomes of strabismus surgery. Jonathan M. Holmes, Sarah R. Hatt, David A. Leske, Laura Liebermann Introduction: Strabismus surgery outcomes are typically defined using motor and diplopia criteria. Nevertheless, some patients designated failure by these criteria report subjective improvement. We aimed to evaluate the role of health-related quality of life (HRQOL) measures in patients who might be classified as failures. Methods: We studied adults undergoing strabismus surgery who had preoperative and 1-year postoperative HRQOL data using the Adult Strabismus-20 (AS-20) questionnaire. Motor and diplopia criteria were applied to classify outcomes as: success, partial success, or failure. For those classified as failure, the medical record was reviewed to determine whether there was subjective improvement at 1 year, independent of AS-20 scores. Improvement in HRQOL score was defined as exceeding 95% limits of agreement on at least one AS-20 domain. To determine whether HRQOL scores reflected subjective improvement in patients otherwise classified as failure, we compared HRQOL scores between those who reported improvement and those who did not. Results: Of 227 patients, 39 (17%) were classified as failure by motor and diplopia criteria; 25 of 39 reported subjective improvement, of which 16 (64%) met improved HRQOL score criteria. Fourteen of 39 had no subjective improvement, of which 5 (36%) met improved HRQOL criteria. Discussion: For many apparent surgical failures, objective motor and diplopia criteria do not capture subjective improvement, but improvement is often reflected in HRQOL scores. The few patients who had no subjective improvement but better HRQOL scores may represent a placebo effect. Conclusion: Quantitative HRQOL criteria should be considered when evaluating outcomes following strabismus surgery.
014 Factors affecting stereopsis after surgical alignment of acquired partially accommodative esotropia. Yiannis Iordanous, Inas Makar Introduction: The goal of strabismus surgery is to correct ocular alignment, promoting the development of stereopsis and binocular single vision (BSV). Despite successful surgical ocular alignment, many children do not develop stereopsis postoperatively. The purpose of this study was to determine preoperative factors that affect stereopsis in patients with acquired partially accommodative esotropia (APAET). Methods: We retrospectively reviewed the charts of all patients who underwent strabismus surgery for APAET from a single surgeons practice. Patients were eligible for inclusion if they had a final motor alignment within 8D of orthophoria for distance and near (successful alignment). We compared preoperative factors between patients achieving postoperative stereopsis better than 100 arcsec (i.e. achieving BSV) versus those with worse than 100 seconds of stereopsis. These factors included age of onset, delay in referral, duration of misalignment and age at surgery.
Journal of AAPOS
e5 Results: A total of 65 patients met our inclusion criteria. 27 (42%) had a final stereopsis of 100 arcsec or better. The mean AO for patients achieving postoperative BSV was 32.3 12.5 months, versus 22.4 9.2 months (P \ 0.0005) for the group not attaining BSV. Those achieving BSV presented to clinic later (57.4 19.2 vs 41.6 23.6 months; P 5 0.005) and had a later age at surgery (66.4 18.2 vs 50.3 21.7 months; P 5 0.002) when compared to those not achieving BSV. There was no significant difference in the duration of misalignment between the two groups (34.0 16.4 for those attaining BSV versus 27.9 19.0 for those not attaining BSV; P 5 0.2). A regression analysis found only older age of onset to be predictive of better postoperative BSV (OR 1.08; 95% CI 1.03-1.14). Discussion: Our results suggest that for every month delay in onset of esodeviation, a child with APAET is 8% more likely to regain BSV postoperatively. Surprisingly, DOM did not appear to be related to final stereoacuity outcomes in this patient population. Conclusion: These results may allow physicians to better predict surgical outcomes for children with APAET. It may also aid in surgical planning, as DOM appears to not be correlated with final outcomes.
015 Type I ROP, treatment with bevacizumab versus laser: comparison of visual function, structural outcome and frequency of follow-up. Maram Isaac, Kamiar Mireskandari, Nasrin Tehrani Purpose: To further elucidate the visual function, structural outcomes and frequency of follow up visits for infants with type I ROP treated with intravitreal Bevacizumab (IVB) versus laser. Methods: Retrospective comparative chart review. Results: Thirteen infants were treated with IVB and 14 infants with laser. There was no statistically significant difference in gestational age or birth weight. Eight eyes developed ROP in zone I and 15 eyes in zone II in each group. None developed unfavorable structural outcome at 6 months post treatment (1). Visual acuity (VA) was measurable for 16/23 eyes in laser and 13/23 eyes for IVB groups at 6-12 months corrected age (CA). Mean VA was (1.20 0.3) and (0.92 0.34) logMAR, (P 5 0.054) for laser and IVB groups respectively. Refraction was available for 17/23 eyes for laser and 23/23 eyes for IVB groups. Mean spherical equivalent (SE) was (-4.41 4.71) for laser and (-3.42 5.89) for IVB groups (p 5 0.5572), respectively. Infants in laser group had an average of (5.00 3.00) follow up visits versus (14.00 5.00) in IVB group, (P \ 0.001) in the 6 months post treatment. Discussion: Both treatments resulted in good structural outcome. At 6-12 months CA, there was no statistically significant difference in refractive error or VA between two groups, however more frequent follow up was observed in the IVB group. Conclusion: In view of similar structural outcomes between the two groups, frequency of follow up post IVB may need reconsideration to reduce patient exposure to distressful eye examinations and optimize resource allocation. References 1. Early Treatment for Retinopathy of Prematurity Cooperative Group. Revised indications for the treatment of retinopathy of prematurity: results of the Early Treatment for Retinopathy of Prematurity randomized trial. Arch Ophthalmol 2003;121:1684-94.
016 High sensitivity of binocular retinal birefringence screening for anisometropic amblyopia without strabismus. Reed M. Jost, Joost Felius, Eileen E. Birch Introduction: Binocular retinal birefringence scanning can detect whether fixation is bifoveal by identifying the unique polarization
e6
Volume 18 Number 4 / August 2014
signal created by the radially arranged Henle fibers (photoreceptor axons) that emanate from the fovea. Screening based on this technology has .98% sensitivity for strabismus, including microstrabismus.1,2 Surprisingly, binocular retinal birefringence scans also have been reported to have 91% sensitivity for anisometropic amblyopia in children with no strabismus.1 Here we investigate two factors that may contribute to its sensitivity to anisometropic amblyopia, fixation instability and defocus. Methods: 53 children (4-14y) with anisometropic amblyopia were screened with the Pediatric Vision Scanner, a retinal birefringence scanner; 18 with no strabismus and 35 combined with strabismus. All had a complete ophthalmic examination and an evaluation of fixation instability by Nidek MP-1 and/or EyeLink and, for a subset (n 5 37), an analysis of residual defocus with accommodation to a near target by the Grand Seiko autorefractor. Results: Screening referred 50/53 (sensitivity 5 94%). Among the 16/ 18 (89%) with no strabismus who were referred, 7 had fixation instability greater than age-matched controls, 7 had defocus .4.00 D in the amblyopic eye when fixating binocularly at near, and 2 had both. Fixation instability was correlated with amblyopic eye visual acuity (r 5 0.41; P 5 0.002). Amblyopic eye defocus was negatively correlated with the birefringent signal power (r 5 0.56, P 5 0.0003). Discussion: Sensitivity to anisometropic amblyopia in the absence of strabismus likely results from the fixation instability, which may interfere with detection of central fixation, and/or from a reduction of birefringent signal power due to defocus of the amblyopic eye when fixing at near. Conclusion: Binocular retinal birefringence scanning detects anisometropic amblyopia in children with no strabismus with high sensitivity. References 1. Loudon SE, et al. Rapid, high-accuracy detection of strabismus and amblyopia using the Pediatric Vision Scanner. Invest Ophthalmol Vis Sci 2011;52: 5043-8. 2. Jost RM, et al. High sensitivity and specificity of the pediatric vision scanner in detecting strabismus and amblyopia in preschool children. AAPOS 2013 abstract.
017 Optic nerve optical coherence tomography versus humphrey visual field analysis in pediatric intracranial hypertension. Ellen R. Miller, Cate O. Jordan, David L. Rogers Introduction: Pediatric intracranial hypertension requires frequent monitoring. Spectral-domain optical coherence tomography (SDOCT) is a non-invasive imaging modality that may facilitate objective monitoring of optic nerve pathology in children. Methods: A retrospective review of all patients with a new or established diagnosis of intracranial hypertension over a 6 month period was performed. Optic nerve SD-OCT and Humphrey 30-2 visual fields were performed on each patient. Analysis was completed to correlate visual field defects with average and sectoral retinal nerve fiber layer (RNFL) thickness. Results: 124 eyes were identified, ages 5 to 21 years. Eyes were divided into subgroups based on exam findings: with optic nerve edema (n 5 44) and without (n 5 80). There was a statistically significant difference between the average RNFL thickness of eyes with edema: 126.68 m 24.73, and without edema: 105.86 m 11.85 (P \ 0.0001). Eyes with normal visual fields (n 5 103) had an average RNFL of 110m 13.57. Eyes with peripheral visual field deficits (n 5 10) had an average RNFL thickness of 108.67m 17.69
(P $ 0.05). Eyes with blind spots enlarged (n 5 11) had an average RNFL thickness of 154.09m 25.44 (P 5 0.002). Discussion: Eyes with clinically apparent optic nerve edema had statistically significant thickening of the RNFL compared to those without edema. There was no correlation between peripheral visual field defects and either the average or sectoral RNFL thickening. Blind spot enlargement was statistically associated with a thickened average RNFL. Conclusion: Our study found a correlation between blind spot enlargement on visual field testing and a thickened average RNFL on SD-OCT testing of the optic nerve. 018 The effect of part-time patching on near stereoacuity, control, and angle in childhood intermittent exotropia. Brian G. Mohney, Susan A. Cotter, Danielle L. Chandler, Jonathan M. Holmes; Pediatric Eye Disease Investigator Group Introduction: In a randomized trial we found part-time patching reduced the 6-month risk of IXT deterioration from 6.0% to 0.6%.1 Here we report secondary outcomes of stereoacuity, control, and angle. Methods: 358 patients aged 3 to \11 years with previously untreated IXT and near stereoacuity of at least 400 arcsec were randomly assigned to either observation or patching for 3 hours per day for 5 months, with outcome assessment at 6 months. Results: Mean near stereoacuity (Preschool Randot test) was 68 versus 69 arcsec in observation versus patching (p 5 0.38). Assessed by the Office Control Scale,2 ranging from 0 (phoria) to 5 (constant), mean scores in observation and patching groups were 2.3 versus 2.0 at distance (P 5 0.09) and 1.2 versus 0.9 at near (P 5 0.01). Among those with baseline control scores $2, improvement at distance was seen in 19% observed vs. 29% patched (p 5 0.07, n 5 238) and at near in 23% observed versus 37% patched (P 5 0.40; n 5 86). Mean exodeviations (PACT) in the observation and patching groups were 23.8D vs. 22.2D at distance (P 5 0.01) and 17.6D vs 15.4D at near (P 5 0.11). Among those who could improve more than test-retest variability ($8D at distance and $13D at near), improvement was seen in 9% observed versus 14% patched at distance (P 5 0.17, n 5 324) and 5% observed vs. 10% patched at near (P 5 0.20; n 5 218). Conclusion: Several but not all secondary outcomes were consistent with the primary finding of a small effect of part-time patching on IXT at 6 months in 3-10 year olds. References 1. Pediatric Eye Disease Investigator Group. A randomized trial comparing part-time patching with observation for children 3-10 years old with intermittent exotropia. 2013 (unpublished). 2. Mohney BG, Holmes JM. An office-based scale for assessing control in intermittent exotropia. Strabismus 2006;14:147-50.
019 The slippery slope: early signs of instability after surgery for esotropia. Bharti Nihalani-Gangwani, Miriam Ehrenberg, Patrice Melvin, Adebona Olumuyiwa Adebona, Linda R. Dagi Introduction: Reoperation rates for strabismus surgery remain high even after initial successful realignment. We studied onset of instability with longitudinal analysis comparing postoperative outcomes of esotropia surgery at 2-4 months versus 1 year. Methods: Outcomes of surgery for all classes of esotropia in patients $18 years of age (N 5 550) were included if postoperative sensorimotor examinations were documented at 2-4 months as well as 1 year (N 5 419). Four possible goals for surgical intervention
Journal of AAPOS