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Diagnosis and surgical treatment of unilateral restrictive hypotropia and esotropia
Major Articles Diagnosis and surgical treatment of unilateral restrictive hypotropia and esotropia Qi Lin, MD,a Fengyuan Man, MD,b Ningli Wang, MD, PhD,c Tao Chen, MD,c Gang Yu, MD,a Zhenchang Wang, MD, PhD,b Qinglin Chang, MD,b Yonghong Jiao, MD, PhD,c and Kanxing Zhao, MD, PhDd PURPOSE METHODS
RESULTS
CONCLUSIONS
To describe the clinical features, radiological findings, and surgical treatment of patients with congenital unilateral restrictive hypotropia and esotropia. Retrospective analysis of patients presenting with unilateral restrictive hypotropia and esotropia. In all patients, magnetic resonance imaging (MRI) or computed tomography (CT) of the brain, brainstem, and orbits was obtained before surgery. Surgery consisted of inferior rectus recession combined in some cases with resection and upward transposition of the upper half of the horizontal rectus muscles. Minimum follow-up was 6 weeks. Four patients meeting inclusion criteria were identified. All patients had amblyopia. Radiological findings included thickening of the posterior inferior rectus muscle belly (2 patients), inferior orbital fat hernia (2 patients), and an irregular soft tissue mass in the nasal inferior orbit (2 patients). The oculomotor nerve appeared to be normal in 3 patients and was not studied in 1. After surgery, 3 of 4 patients were aligned within 10D. One patient showed lower eyelid retraction and limitation of depression after a large recession of the inferior rectus muscle. Unilateral hypotropia and esotropia can be associated with severe inferior rectus muscle restriction. Amblyopia may be common in these patients. Surgery to relieve the restriction can also correct the esotropia, suggesting a role for orbital connective tissue in the motility defect in these cases. ( J AAPOS 2011;15:5-8)
R
estrictive hypotropia with esotropia may occur in patients with dysthyroid ophthalmopathy, fibrosis of the extraocular muscles, orbital floor fracture, structural anomalies of the extraocular muscles or adjacent tissues, and high myopia (“fallen eye syndrome”).1-5 It occurs less commonly as a congenital, unilateral, restrictive esotropia with hypotropia. Little has been reported about anomalies of the extraocular muscle and adjacent tissue in these patients. We report 4 cases of unilateral hypotropia and esotropia presumed on clinical grounds to be caused by mechanical restriction, which was confirmed by preoperative imaging and surgical findings. Author affiliations: aBeijing Children’s Hospital Affiliated to Capital Medical University, Beijing, China; bBeijing Tongren Medical Imaging Centre, Beijing Tongren Hospital, Capital Medical University, Beijing, China; cBeijing Tongren Eye Centre, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab; d Tianjin Eye Hospital, Clinical College of Ophthalmology, Tianjin Medical University Tianjin, Tianjin, China This study was conducted at Beijing Tongren Hospital, Capital Medical University. Yonghong Jiao was the recipient of Funds for Clinical-Basic Cooperation of Capital Medical University (No. 09JL36). Submitted January 19, 2010. Revision accepted September 20, 2010. Reprint requests: Yonghong Jiao, MD, PhD, 1 Dongjiao Minxiang, Dongcheng District, Beijing, 100730, China (email: [email protected]). Copyright Ó 2011 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 doi:10.1016/j.jaapos.2010.09.019
Journal of AAPOS
Patients and Methods Consecutive patients with hypotropia, esotropia, and severe limitation of elevation and abduction treated between October 2007 and February 2009 were retrospectively identified. Patients whose condition was not present at birth as well as those whose strabismus was presumed, on clinical grounds, to be caused by cranial neuropathies were excluded. All patients had signed informed consents approved by the local institutional review board. A GE 1.5-T TwinSpeed scanner (GE Medical Systems, Milwaukee, WI) was used for magnetic resonance imaging (MRI). Oculomotor nerves in the brainstem were imaged in 0.8 mm thickness planes with the 3D-FIESTA sequence. Extraocular muscles and their associated connective tissues were imaged with a T1- and T2-weighted FSE at 2 mm thickness with a 224 256 matrix over a 10 cm square field of view by dual-phased coils. Intravenous gadodiamide was administered as a contrast agent. Computed tomography (CT) imaging was acquired on a GE LightSpeed 16-slice CT scanner (GE Medical Systems); all films were taken with 3 mm slice thickness. After imaging and relevant examinations, patients were treated surgically, undergoing inferior rectus muscle exploration intraoperatively. Restriction of the muscles was determined by intraoperative passive duction testing. On the basis of the imaging findings, the forced duction findings, and the degree of esotropia,
5
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Volume 15 Number 1 / February 2011
Table 1. Clinical characteristics and MRI findings Visual acuity Patient (age, yrs)
Measurements in primary position (PD)
OD
OS
Pre-op
Post-op
Duction limitation
1 (16)
20/20
20/1000
30 L ET 80 L HoT
15 L HoT
2 (26)
20/250
20/20
80 R ET 60 R HoT
8 R HoT 5 R XT
3 (4)
20/200
20/25
Alignment
4 (5)
20/200
20/100
80 R ET 50 R HoT 50 R ET 40 R HoT
Elevation 4 Depression 4 Abduction 3 Elevation 4 Depression 2 Abduction 2 Elevation 4 Abduction 2 Elevation 4 Abduction 3
8 R HoT 5 R ET
Treatment of involved eye Freeing adhesions Recession IR 5 mm 1 hang-back .8 mm Freeing adhesions Recession IR 7.5 mm 1 ½ tendon width of LR resection and superior transposition Freeing adhesions Recession IR 5mm 1 hang-back .8 mm Freeing adhesions Recession IR 5 mm 1 ½ tendon width of horizontal muscles superior transposition
ET, esotropia; HoT, hypotropia; IR, inferior rectus muscle; L, left; LR, lateral rectus; MRI, magnetic resonance imaging; OD, right eye; OS, left eye; PD, prism diopters; Post-op, postoperatively; Pre-op, preoperatively; R, right; Rec, recession; XT, exotropia.
FIG 1. MRI of the left orbit, Case 1. A, Quasicoronal MRI of the left orbit showing hypoplasia of the inferior rectus muscle (arrow). B, Oblique-sagittal MRI in a plane along the nasal side of inferior rectus muscle showing the inferior orbital fat hernia (arrow). C, Oblique-sagittal MRI in a plane along the lateral side of inferior rectus muscle showing the abnormal signal of the posterior aspect of the globe (arrow). IR, inferior rectus muscle; LPS, levator palpebrae superioris; LR, lateral rectus muscle; MR, medial rectus muscle; ON, optic nerve; SR, superior rectus muscle.
FIG 2. MRI of the right orbit, Case 2. A, Quasicoronal MRI of the right orbit demonstrated the abnormal pathway of inferior oblique muscle (arrow). B, Quasicoronal MRI of the right orbit showing inferior displacement of the lateral rectus (open arrow), enlargement, and nasal displacement of the right inferior rectus muscle inferior rectus near the orbital apex (arrow). C, Oblique-sagittal MRI showing abnormal signal of the anterior aspect of inferior rectus (open arrow), inferior orbital fat hernia (arrow). IR, inferior rectus muscle; SR, superior rectus muscle. patients received inferior rectus muscle recession, with the surgeon placing the sutures 5 mm posterior to the original insertion and then suspending the muscle an additional 8 mm or more.2
The recession was combined in some cases with half-tendon resection of the horizontal rectus muscles with transposition to the superior rectus muscle insertion.
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Volume 15 Number 1 / February 2011
Lin et al
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FIG 3. MRI of the orbits, Case 3. A, Quasicoronal MRI of the right orbit demonstrated the abnormal soft tissue densities around inferior muscle (arrow). B, Axial MRI of the right orbit demonstrated an irregular soft tissue mass in the nasal inferior orbit (arrow). C, Quasicoronal MRI showing enlargement of the right inferior rectus near the orbital apex (arrow). IR, inferior rectus muscle; MR, medial rectus muscle; ON, optic nerve; SO, superior oblique muscle; SR, superior rectus muscle.
Results Four female patients, 2 adults and 2 children, were identified (Table 1). Systemic and neurologic examinations were negative in all cases. MRI was performed in 3 patients; a CT scan of the orbits was obtained in one patient (Case 4). Visual acuity was poor in the affected eye in all patients. All patients had a large-angle esotropia and hypotropia, limited elevation, and variable limitation of abduction that had presented at a young age. Case 1 (Figure 1) had a suspected obstetric forceps injury to the facial nerve and the orbit of the affected side. The other patients had no history of swelling or bleeding in the orbits at birth. Case 4 had a right orbital malformation, bilateral corneal maculae at the inferior limbus, and dysmorphic ears. None of the patients had a history of red eye or ocular trauma. Imaging studies revealed a normal brainstem and normal, symmetric oculomotor nerves in all patients. Various structural anomalies of inferior rectus and adjacent soft tissues were observed (Figure 2). In Case 1 the MRI revealed obvious fibrosis of inferior rectus muscle, severe adhesion between inferior rectus muscle, and adjacent fasciae extending to the deep part of the orbit (Figure 2A, C). Cases 2 and 3 showed thickening of the posterior inferior rectus muscle belly on the affected side (Figures 3B and 4C). Oblique-sagittal MRI showed inferior orbital fat herniation in Cases 1 and 2 (Figures 2B and 3C). Axial MRI or CT demonstrated an irregular soft tissue mass in the nasal inferior orbit in Cases 3 and 4 (Figures 4B and 5). For surgery, subconjunctival anesthesia was used in both adults and general anesthesia in both children. Inferior rectus muscle recession was performed in all cases, with transposition procedures in 2. Fibrotic conjunctival scarring was present over the anterior part of the inferior rectus muscle in Cases 2, 3, and 4; a broad area of connective tissue adherence around the inferior rectus and the inferior orbit was found in Case 1. Passive elevation and abduction improved after the inferior rectus restriction was relieved. Of the 4 patients, 3 were aligned to within 10D of hypotropia postoperatively; Case 1 had 15D of residual hypotropia. Case 3 had lower eyelid retraction and limitation of depression.
Journal of AAPOS
FIG 4. Axial CT imaging in Case 4 showing an abnormal signal at the inferior aspect of nasal side (arrow) and the orbital malformation.
Discussion Ocular motility examination and the passive duction test have traditionally been used to diagnose restrictive strabismus. The cause is often multifactorial, involving muscle, surrounding tissue, orbital abnormalities, and craniofacial abnormalities. Orbital imaging, particularly MRI, has given us the opportunity to visualize the functional anatomy of extraocular muscles and the surrounding orbital connective tissue.6-8 Anomalies of the fascial system are more common than those of the muscles themselves and play a role in the development of some forms of strabismus.9 In our series, the imaging results revealed various structural anomalies of the inferior rectus muscle and surrounding tissue; Cases 3 and 4 also showed an irregular soft-tissue mass in the nasal inferior orbit. It is notable that the esotropia improved in all 4 cases although surgery was performed only for the
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FIG 5. Ocular versions of Case 2. In primary gaze, there was a large-angle esotropia and hypotropia of the right eye. The right eye had marked limitation of elevation on abduction, adduction, and from the primary position.
hypotropia; this may be explained by the pulley band theory proposed by Demer and colleagues,10,11 who note that the band between the medial rectus and inferior rectus pulleys is not only the thickest such intercoupling but also contains the most collagen, elastin, and smooth muscle.12 Alternatively, the esotropia and its response to therapy might be explained by unique anatomical features of the inferior orbit, including the configuration of Lockwood’s ligament. We used preoperative imaging studies to help plan the surgical approach. Specifically, the imaging in Case 3 showed fibrotic conjunctiva between inferior rectus and adjacent fasciae, but inferior rectus muscle recession alone left a large undercorrection. Therefore, because Cases 2 and 4 had imaging findings similar to those in Case 3, we chose a stronger surgical procedure, that is, adding a halftendon horizontal rectus resection and transposition. In all 4 cases, visual acuity of the restricted eye was poor. We assume that the large-angle hypotropia and esotropia since birth led to amblyopia because the eyes were structurally normal. References 1. Murthy R. Unilateral restrictive ophthalmoplegia and enophthalmos associated with an intraorbital tissue band. J AAPOS 2007;11:626-7.
2. Bandyopadhyay R, Shetty S, Vijayalakshmi P. Surgical outcome in monocular elevation deficit: A retrospective interventional study. Indian J Ophthalmol 2008;56:127-33. 3. Khan AO. Restrictive strabismus in Parry-Romberg syndrome. J Pediatr Ophthalmol Strabismus 2007;44:51-2. 4. Ela-Dalman N, Velez FG, Rosenbaum AL. Importance of sagittal orbital imaging in evaluating extraocular muscle trauma following endoscopic sinus surgery. Br J Ophthalmol 2006;90:664-5. 5. Kim JH, Hwang JM. Congenital monocular elevation deficiency. Ophthalmology 2009;116:580-84. 6. Plager DA, Parks MM, von Noorden GK. Strabismus Surgery: Basic and advanced strategies. New York: Oxford University Press; 2004. 97-106. 7. Demer JL, Clark RA. A 12-year, prospective study of extraocular muscle imaging in complex strabismus. J AAPOS 2002;6:337-47. 8. Lueder GT. Anomalous orbital structures resulting in unusual strabismus. Surv Ophthalmol 2002;47:27-35. 9. Von Noorden GK. Binocular vision and ocular motility: Theory and management of strabismus. 6th edition. St. Louis: Mosby Press; 2002. 458-66. 10. Demer JL, Oh SY, Poukens V. Evidence for active control of rectus extraocular muscle pulleys. Invest Ophthalmol Vis Sci 2000;41: 1280-90. 11. Demer JL. The orbital pulley system: A revolution in concepts of orbital anatomy. Ann N Y Acad Sci 2002;956:17-32. 12. Kono R, Poukens V, Demer JL. Quantitative analysis of the structure of the human extraocular muscle pulley system. Invest Ophthalmol Vis Sci 2002;43:2923-32.
Journal of AAPOS
RESULTS
CONCLUSIONS
To describe the clinical features, radiological findings, and surgical treatment of patients with congenital unilateral restrictive hypotropia and esotropia. Retrospective analysis of patients presenting with unilateral restrictive hypotropia and esotropia. In all patients, magnetic resonance imaging (MRI) or computed tomography (CT) of the brain, brainstem, and orbits was obtained before surgery. Surgery consisted of inferior rectus recession combined in some cases with resection and upward transposition of the upper half of the horizontal rectus muscles. Minimum follow-up was 6 weeks. Four patients meeting inclusion criteria were identified. All patients had amblyopia. Radiological findings included thickening of the posterior inferior rectus muscle belly (2 patients), inferior orbital fat hernia (2 patients), and an irregular soft tissue mass in the nasal inferior orbit (2 patients). The oculomotor nerve appeared to be normal in 3 patients and was not studied in 1. After surgery, 3 of 4 patients were aligned within 10D. One patient showed lower eyelid retraction and limitation of depression after a large recession of the inferior rectus muscle. Unilateral hypotropia and esotropia can be associated with severe inferior rectus muscle restriction. Amblyopia may be common in these patients. Surgery to relieve the restriction can also correct the esotropia, suggesting a role for orbital connective tissue in the motility defect in these cases. ( J AAPOS 2011;15:5-8)
R
estrictive hypotropia with esotropia may occur in patients with dysthyroid ophthalmopathy, fibrosis of the extraocular muscles, orbital floor fracture, structural anomalies of the extraocular muscles or adjacent tissues, and high myopia (“fallen eye syndrome”).1-5 It occurs less commonly as a congenital, unilateral, restrictive esotropia with hypotropia. Little has been reported about anomalies of the extraocular muscle and adjacent tissue in these patients. We report 4 cases of unilateral hypotropia and esotropia presumed on clinical grounds to be caused by mechanical restriction, which was confirmed by preoperative imaging and surgical findings. Author affiliations: aBeijing Children’s Hospital Affiliated to Capital Medical University, Beijing, China; bBeijing Tongren Medical Imaging Centre, Beijing Tongren Hospital, Capital Medical University, Beijing, China; cBeijing Tongren Eye Centre, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab; d Tianjin Eye Hospital, Clinical College of Ophthalmology, Tianjin Medical University Tianjin, Tianjin, China This study was conducted at Beijing Tongren Hospital, Capital Medical University. Yonghong Jiao was the recipient of Funds for Clinical-Basic Cooperation of Capital Medical University (No. 09JL36). Submitted January 19, 2010. Revision accepted September 20, 2010. Reprint requests: Yonghong Jiao, MD, PhD, 1 Dongjiao Minxiang, Dongcheng District, Beijing, 100730, China (email: [email protected]). Copyright Ó 2011 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 doi:10.1016/j.jaapos.2010.09.019
Journal of AAPOS
Patients and Methods Consecutive patients with hypotropia, esotropia, and severe limitation of elevation and abduction treated between October 2007 and February 2009 were retrospectively identified. Patients whose condition was not present at birth as well as those whose strabismus was presumed, on clinical grounds, to be caused by cranial neuropathies were excluded. All patients had signed informed consents approved by the local institutional review board. A GE 1.5-T TwinSpeed scanner (GE Medical Systems, Milwaukee, WI) was used for magnetic resonance imaging (MRI). Oculomotor nerves in the brainstem were imaged in 0.8 mm thickness planes with the 3D-FIESTA sequence. Extraocular muscles and their associated connective tissues were imaged with a T1- and T2-weighted FSE at 2 mm thickness with a 224 256 matrix over a 10 cm square field of view by dual-phased coils. Intravenous gadodiamide was administered as a contrast agent. Computed tomography (CT) imaging was acquired on a GE LightSpeed 16-slice CT scanner (GE Medical Systems); all films were taken with 3 mm slice thickness. After imaging and relevant examinations, patients were treated surgically, undergoing inferior rectus muscle exploration intraoperatively. Restriction of the muscles was determined by intraoperative passive duction testing. On the basis of the imaging findings, the forced duction findings, and the degree of esotropia,
5
6
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Volume 15 Number 1 / February 2011
Table 1. Clinical characteristics and MRI findings Visual acuity Patient (age, yrs)
Measurements in primary position (PD)
OD
OS
Pre-op
Post-op
Duction limitation
1 (16)
20/20
20/1000
30 L ET 80 L HoT
15 L HoT
2 (26)
20/250
20/20
80 R ET 60 R HoT
8 R HoT 5 R XT
3 (4)
20/200
20/25
Alignment
4 (5)
20/200
20/100
80 R ET 50 R HoT 50 R ET 40 R HoT
Elevation 4 Depression 4 Abduction 3 Elevation 4 Depression 2 Abduction 2 Elevation 4 Abduction 2 Elevation 4 Abduction 3
8 R HoT 5 R ET
Treatment of involved eye Freeing adhesions Recession IR 5 mm 1 hang-back .8 mm Freeing adhesions Recession IR 7.5 mm 1 ½ tendon width of LR resection and superior transposition Freeing adhesions Recession IR 5mm 1 hang-back .8 mm Freeing adhesions Recession IR 5 mm 1 ½ tendon width of horizontal muscles superior transposition
ET, esotropia; HoT, hypotropia; IR, inferior rectus muscle; L, left; LR, lateral rectus; MRI, magnetic resonance imaging; OD, right eye; OS, left eye; PD, prism diopters; Post-op, postoperatively; Pre-op, preoperatively; R, right; Rec, recession; XT, exotropia.
FIG 1. MRI of the left orbit, Case 1. A, Quasicoronal MRI of the left orbit showing hypoplasia of the inferior rectus muscle (arrow). B, Oblique-sagittal MRI in a plane along the nasal side of inferior rectus muscle showing the inferior orbital fat hernia (arrow). C, Oblique-sagittal MRI in a plane along the lateral side of inferior rectus muscle showing the abnormal signal of the posterior aspect of the globe (arrow). IR, inferior rectus muscle; LPS, levator palpebrae superioris; LR, lateral rectus muscle; MR, medial rectus muscle; ON, optic nerve; SR, superior rectus muscle.
FIG 2. MRI of the right orbit, Case 2. A, Quasicoronal MRI of the right orbit demonstrated the abnormal pathway of inferior oblique muscle (arrow). B, Quasicoronal MRI of the right orbit showing inferior displacement of the lateral rectus (open arrow), enlargement, and nasal displacement of the right inferior rectus muscle inferior rectus near the orbital apex (arrow). C, Oblique-sagittal MRI showing abnormal signal of the anterior aspect of inferior rectus (open arrow), inferior orbital fat hernia (arrow). IR, inferior rectus muscle; SR, superior rectus muscle. patients received inferior rectus muscle recession, with the surgeon placing the sutures 5 mm posterior to the original insertion and then suspending the muscle an additional 8 mm or more.2
The recession was combined in some cases with half-tendon resection of the horizontal rectus muscles with transposition to the superior rectus muscle insertion.
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Volume 15 Number 1 / February 2011
Lin et al
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FIG 3. MRI of the orbits, Case 3. A, Quasicoronal MRI of the right orbit demonstrated the abnormal soft tissue densities around inferior muscle (arrow). B, Axial MRI of the right orbit demonstrated an irregular soft tissue mass in the nasal inferior orbit (arrow). C, Quasicoronal MRI showing enlargement of the right inferior rectus near the orbital apex (arrow). IR, inferior rectus muscle; MR, medial rectus muscle; ON, optic nerve; SO, superior oblique muscle; SR, superior rectus muscle.
Results Four female patients, 2 adults and 2 children, were identified (Table 1). Systemic and neurologic examinations were negative in all cases. MRI was performed in 3 patients; a CT scan of the orbits was obtained in one patient (Case 4). Visual acuity was poor in the affected eye in all patients. All patients had a large-angle esotropia and hypotropia, limited elevation, and variable limitation of abduction that had presented at a young age. Case 1 (Figure 1) had a suspected obstetric forceps injury to the facial nerve and the orbit of the affected side. The other patients had no history of swelling or bleeding in the orbits at birth. Case 4 had a right orbital malformation, bilateral corneal maculae at the inferior limbus, and dysmorphic ears. None of the patients had a history of red eye or ocular trauma. Imaging studies revealed a normal brainstem and normal, symmetric oculomotor nerves in all patients. Various structural anomalies of inferior rectus and adjacent soft tissues were observed (Figure 2). In Case 1 the MRI revealed obvious fibrosis of inferior rectus muscle, severe adhesion between inferior rectus muscle, and adjacent fasciae extending to the deep part of the orbit (Figure 2A, C). Cases 2 and 3 showed thickening of the posterior inferior rectus muscle belly on the affected side (Figures 3B and 4C). Oblique-sagittal MRI showed inferior orbital fat herniation in Cases 1 and 2 (Figures 2B and 3C). Axial MRI or CT demonstrated an irregular soft tissue mass in the nasal inferior orbit in Cases 3 and 4 (Figures 4B and 5). For surgery, subconjunctival anesthesia was used in both adults and general anesthesia in both children. Inferior rectus muscle recession was performed in all cases, with transposition procedures in 2. Fibrotic conjunctival scarring was present over the anterior part of the inferior rectus muscle in Cases 2, 3, and 4; a broad area of connective tissue adherence around the inferior rectus and the inferior orbit was found in Case 1. Passive elevation and abduction improved after the inferior rectus restriction was relieved. Of the 4 patients, 3 were aligned to within 10D of hypotropia postoperatively; Case 1 had 15D of residual hypotropia. Case 3 had lower eyelid retraction and limitation of depression.
Journal of AAPOS
FIG 4. Axial CT imaging in Case 4 showing an abnormal signal at the inferior aspect of nasal side (arrow) and the orbital malformation.
Discussion Ocular motility examination and the passive duction test have traditionally been used to diagnose restrictive strabismus. The cause is often multifactorial, involving muscle, surrounding tissue, orbital abnormalities, and craniofacial abnormalities. Orbital imaging, particularly MRI, has given us the opportunity to visualize the functional anatomy of extraocular muscles and the surrounding orbital connective tissue.6-8 Anomalies of the fascial system are more common than those of the muscles themselves and play a role in the development of some forms of strabismus.9 In our series, the imaging results revealed various structural anomalies of the inferior rectus muscle and surrounding tissue; Cases 3 and 4 also showed an irregular soft-tissue mass in the nasal inferior orbit. It is notable that the esotropia improved in all 4 cases although surgery was performed only for the
8
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Volume 15 Number 1 / February 2011
FIG 5. Ocular versions of Case 2. In primary gaze, there was a large-angle esotropia and hypotropia of the right eye. The right eye had marked limitation of elevation on abduction, adduction, and from the primary position.
hypotropia; this may be explained by the pulley band theory proposed by Demer and colleagues,10,11 who note that the band between the medial rectus and inferior rectus pulleys is not only the thickest such intercoupling but also contains the most collagen, elastin, and smooth muscle.12 Alternatively, the esotropia and its response to therapy might be explained by unique anatomical features of the inferior orbit, including the configuration of Lockwood’s ligament. We used preoperative imaging studies to help plan the surgical approach. Specifically, the imaging in Case 3 showed fibrotic conjunctiva between inferior rectus and adjacent fasciae, but inferior rectus muscle recession alone left a large undercorrection. Therefore, because Cases 2 and 4 had imaging findings similar to those in Case 3, we chose a stronger surgical procedure, that is, adding a halftendon horizontal rectus resection and transposition. In all 4 cases, visual acuity of the restricted eye was poor. We assume that the large-angle hypotropia and esotropia since birth led to amblyopia because the eyes were structurally normal. References 1. Murthy R. Unilateral restrictive ophthalmoplegia and enophthalmos associated with an intraorbital tissue band. J AAPOS 2007;11:626-7.
2. Bandyopadhyay R, Shetty S, Vijayalakshmi P. Surgical outcome in monocular elevation deficit: A retrospective interventional study. Indian J Ophthalmol 2008;56:127-33. 3. Khan AO. Restrictive strabismus in Parry-Romberg syndrome. J Pediatr Ophthalmol Strabismus 2007;44:51-2. 4. Ela-Dalman N, Velez FG, Rosenbaum AL. Importance of sagittal orbital imaging in evaluating extraocular muscle trauma following endoscopic sinus surgery. Br J Ophthalmol 2006;90:664-5. 5. Kim JH, Hwang JM. Congenital monocular elevation deficiency. Ophthalmology 2009;116:580-84. 6. Plager DA, Parks MM, von Noorden GK. Strabismus Surgery: Basic and advanced strategies. New York: Oxford University Press; 2004. 97-106. 7. Demer JL, Clark RA. A 12-year, prospective study of extraocular muscle imaging in complex strabismus. J AAPOS 2002;6:337-47. 8. Lueder GT. Anomalous orbital structures resulting in unusual strabismus. Surv Ophthalmol 2002;47:27-35. 9. Von Noorden GK. Binocular vision and ocular motility: Theory and management of strabismus. 6th edition. St. Louis: Mosby Press; 2002. 458-66. 10. Demer JL, Oh SY, Poukens V. Evidence for active control of rectus extraocular muscle pulleys. Invest Ophthalmol Vis Sci 2000;41: 1280-90. 11. Demer JL. The orbital pulley system: A revolution in concepts of orbital anatomy. Ann N Y Acad Sci 2002;956:17-32. 12. Kono R, Poukens V, Demer JL. Quantitative analysis of the structure of the human extraocular muscle pulley system. Invest Ophthalmol Vis Sci 2002;43:2923-32.
Journal of AAPOS