Persistent Binocular Diplopia in Childhood Following Successful Treatment for Esotropia: A Case Series Tara Tae, B.S. Chantel Devould, C.O. Luke Skilbeck, C.O. Mary Ellen Hoehn, M.D. Natalie Kerr, M.D.
ABSTRACT Introduction: Diplopia is rare in children with nonpathological esotropia because facultative suppression develops prior to visual maturation. Our aim is to present five cases of children with binocular diplopia following treatment of childhood esotropia, exploring possible mechanisms for the development of diplopia based upon the patient’s history and findings, and discussing treatment for diplopia in this setting. Methods: A retrospective chart review of five sequential patients presenting with binocular diplopia following treatment of esotropia was performed. Treatment of esotropia included correction of hyperopic error, correction of anisometropic amblyopia to 20 / 30 or better, and strabismus surgery as indicated. Results: Diplopia developed in two children with accommodative esotropia, one child with infantile esotropia and partially accommodative esotropia, and two children with a history of infantile esotropia and consecutive exotropia following surgical correction. Diplopia onset occurred between ages 7 and 11. Four of the five children experienced resolution of diplopia with prism glasses. Conclusion: Children with esotropia before visual maturation may develop persistent diplopia. Clinical features of the children with diplopia in our case series include poor fusion, poor stereopsis, consecutive exotropia, refractive changes, onset of diplopia after 7 years of age, and occlusion therapy for amblyopia. Prisms may be beneficial in controlling the diplopia.
INTRODUCTION
From the Hamilton Eye Institute, Memphis, Tennessee. Requests for reprints should be addressed to: Natalie Kerr, M.D., Hamilton Eye Institute, 930 Madison Avenue, Suite 400, Memphis, Tennessee 38103.
The common forms of childhood esotropia are nonaccommodative infantile esotropia and accommodative esotropia. Infantile esotropia does not typically present with a significant refractive error. Children with infantile esotropia are
© 2014 Board of Regents of the University of Wisconsin System, American Orthoptic Journal, Volume 64, 2014, ISSN 0065-955X, E-ISSN 1553-4448
American Orthoptic Journal
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typically treated with strabismus surgery prior to age 2. Uncorrected hypermetropia and / or an abnormally high accommodative convergence to accommodation (AC/A) ratio can cause accommodative esotropia through an accommodative effort.1 In children without adequate fusional divergence to counteract the increased convergence, a manifest esotropia develops. Amblyopia may be associated with esotropia, particularly when anisometropia is present.2 The majority of patients with childhood esotropia develop facultative suppression to overcome symptoms of binocular diplopia in the presence of a manifest strabismus. Facultative suppression develops rapidly in childhood during the sensitive period of visual development and before visual maturation is complete.3 Thus, diplopia in children with infantile or accommodative esotropia should not develop due to suppression. We present a case series of persistent binocular diplopia that developed in children after treatment of childhood esotropia. METHODS We conducted a retrospective case series of five consecutive children presenting with persistent binocular diplopia following treatment of esotropia. These five children presented for treatment of strabismus between the ages of 7 months and 3 years to pediatric ophthalmologists at the University of Tennessee Hamilton Eye Institute from 1999 to 2006. Treatment of infantile esotropia included strabismus muscle surgery. Accommodative esotropia and partially accommodative esotropia were treated with correction of hyperopic refractive error to a fusible range of 10Δ of esotropia or less. Treatment of amblyopia included patch penalization or atropine penalization to achieve a visual acuity of 20 / 30 or better in the amblyopic eye. Binocular diplopia
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was confirmed in all patients using a red filter. Sensory status in all patients was evaluated with the Titmus circles test for stereopsis and Worth 4-Dot test for fusion. Bifixation was defined as < 60 seconds of arc while gross stereopsis was defined as < 800 seconds of arc using Titmus cicles.4 Fusion was defined as seeing two red and two green dots on the Worth 4-Dot test, measured at distance and at near with correction. All measurements of the angle of strabismus reported are the distance angle with correction using prism and alternate cover testing unless otherwise noted. RESULTS Case One A 3-year-old Asian female presented with recent onset esotropia and an initial measurement of 30Δ esotropia. Her esotropia was treated with spectacle correction of hyperopia, and bifocals were added to her glasses to treat a high AC / A ratio. Amblyopia (20 / 50 OS) was detected at age 4 and treated with patch penalization for 1-2 hours per day for 4 months. Both her esotropia and amblyopia were successfully treated. With glasses, her angle of strabismus was reduced to 4Δ esophoria with correction, and she demonstrated some gross stereopsis and intermittent fusion at near on Worth 4-Dot testing. She developed intermittent uncrossed diplopia at the age of 7 years, while her angle of strabismus was flick esophoria. The diplopia was confirmed with red filter testing and she was determined to have normal retinal correspondence. After the onset of diplopia, she had no fusion but maintained gross stereopsis. She was treated with a change in her glasses prescription to increase the hyperopic correction an additional +0.75 OD and +0.50 OS to match her cycloplegic refraction. This did not resolve her symptoms of dip-
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lopia, and she switched back to her original glasses for clarity of vision (patient’s choice). At age 8, she did not have resolution of her diplopia before she was lost to follow-up. However, she stated that the diplopia was not distressing to her, and mother confirmed that she was not hindered in any activity after the onset of the diplopia. Her last measurement was 4Δ esophoria. Case Two A 7-month-old white male presented with an initial measurement of 70Δ esotropia (Krimsky) and amblyopia OD. He underwent patch treatment. At 9 months, he had a bilateral medial rectus recession of 6 mm with a preoperative measurement of 45Δ esotropia and postoperative measurement of 10Δ esotropia (Krimsky). He was given glasses at 14 months to correct his hyperopic error of +3.00 sphere OD and +2.75 sphere OS and to treat the accommodative component of his esotropia. At 2 years of age, he suffered recurrent esotropia and bilateral inferior oblique overaction, which prompted another surgery (bilateral lateral rectus resection and bilateral inferior oblique recession). He had a preoperative measurement of 20Δ esotropia and postoperative measurement of 8Δ esotropia. Following the second surgery, his angle of esotropia was stabilized from age 2 to 5. At age 5, his angle of esotropia increased to 15-18Δ esotropia. He developed amblyopia at 2.5 years (8 / 30 Allen cards OD with correction) and was treated with both patch penalization and atropine until the vision improved to 20 / 30 at age 5. Beginning at age 7, this child began to report diplopia. His angle of strabismus was 16-18Δ esotropia and 2-3Δ left hypertropia. He had not had a significant change in his angle of strabismus or in his glasses prescription prior to the onset of diplopia. At time of presentation, he demonstrated
American Orthoptic Journal
anomalous retinal correspondence, which improved symptomatically with 4Δ basedown OD and 2Δ base-up OS. By age 12, he no longer had diplopia and did not require prisms in his glasses. He was reported to have monofixation syndrome when he was 6 years old with fusion on Worth 4-Dot at near. After the development of diplopia at age 7, he never had any fusion or stereopsis. At his last exam, he was 15 years old with a measurement of 6-8Δ right exotropia and 6-8Δ left hypertropia with no stereopsis or fusion by Worth 4-Dot. Case Three A 4-year-old white female presented with consecutive exotropia following bilateral medial rectus recessions elsewhere for infantile esotropia. Her measurement at presentation was 20-25Δ exotropia. At 4 years, she underwent a bilateral medial rectus advancement to correct the consecutive exotropia. She had a preoperative measurement of 20-25Δ exotropia and postoperative measurement of 6Δ esotropia. She was given bifocal glasses for hyperopia and high AC / A ratio, and continued to have a small angle of esotropia following surgery (see Table 1). She had amblyopia OD at presentation, and was treated with patch penalization until the vision improved to 20 / 30 after 6 months. This child developed diplopia at age 8 with an angle of 10-12Δ esotropia. The diplopia was treated with 4 D base-out prism, which relieved her symptoms. She had developed monofixation syndrome with intermittent gross stereopsis and intermittent fusion throughout her course of treatment prior to developing diplopia. She continues to wear her bifocals for partially accommodative esotropia with prism to correct for diplopia. At her last clinic visit, she was 11 years old with a measurement of 2Δ right esotropia and no stereopsis or fusion.
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Case Four An 18-month-old male presented with a history of prematurity and developmental delay presented with esotropia. Onset was reported to have occurred prior to 6 months of age. His initial measurement was 25Δ esotropia with a V-pattern. At 2 years of age, he underwent a bilateral medial rectus recession with vertical transposition to correct his V-pattern esotropia. His preoperative measurement was 25Δ esotropia and postoperative measurement was orthotropia. He developed consecutive exotropia with an A-pattern at 6 years, which was treated with alternate patching for 6 months. The alternate patching did not correct the consecutive exotropia. A bilateral lateral rectus recession with vertical transposition for A-pattern was performed at age 7. His preoperative measurement was 10Δ exotropia and postoperative measurement was 2Δ esophoria for this procedure. His small-angle esophoria was stable for 5 years with no development of amblyopia or need for spectacles during the course of treatment. During this time period, he never developed gross stereopsis or fusion by Worth 4-Dot. Diplopia began at age 11. His angle of strabismus was 8-10Δ esotropia. The patient was able to fuse with 6 D base-out prism, and his diplopic symptoms were successfully treated with prism glasses. He had normal retinal correspondence and no stereopsis or fusion. At his last exam, he was 11 years old and with a measurement of 6Δ esotropia. Case Five A 12-month-old female presented with esotropia of 30Δ. She also had high hyperopia. Her accommodative esotropia was successfully treated with glasses and she was orthoptropic with her corrective spectacles. She was never treated for amblyopia, and she remained orthotropic for
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13 years. She developed monofixation syndrome with Worth 4-Dot fusion at near and gross stereopsis. At age 14, her esotropia decompensated to 20Δ esotropia and 4Δ right hypertropia, at which time she began to develop diplopia. Her glasses prescription was increased to her full cycloplegic prescription, which corrected her to a small angle of esotropia. Her diplopic symptoms persisted. She was treated with 10 D of baseout prism OS, which relieved her diplopia. At her last exam, she was 14 years old and had fusion at near but no stereopsis. She had 12Δ esotropia with correction and was still relying on prisms to correct her diplopia. DISCUSSION It is assumed that suppression develops early and rapidly in life, and diplopia in the presence of a manifest strabismus does not occur.3 In the five cases presented, children developed binocular diplopia after the successful treatment of esotropia, although all were diagnosed and successfully treated for strabismus prior to visual maturation. One important observation from our case series is that diplopia was almost an incidental finding in these children. The children would mention that they were having it, but could not say when it had started and were not distressed by it. Therefore, it is possible that diplopia has been under-reported because it is not troubling to the children. Although we have reported all of the cases we have observed, many others may have gone “undetected” because the children did not report diplopia and we do not routinely check for diplopia in children because we assume that they have suppression. The main limitation to our case series is the small size, which makes it difficult to draw generalized conclusions about the incidence and etiology of this finding. How-
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ever, several possible explanations may be entertained for the occurrence of diplopia in these cases. First, instead of being truly diplopic, the children with poor fusion and small angle strabismus may be rapidly alternating between the two eyes. However, demonstration of binocular diplopia with red filter testing in all reported patients makes this an unlikely explanation. Secondly, successful treatment of amblyopia to 20 / 30 or better in the amblyopic eye may have “unmasked” diplopia in children who had failed to develop a suppression scotoma or effectively had anti-suppression therapy from patch penalization. However, the complaint of diplopia was remote from the attainment of good vision in the amblyopic eye. In Cases One, Two, and Three, elapsed time from attainment of good vision to diplopia was 4 years, 5 years, and 5 years, respectively. The length of time from attainment of good vision to complaints of diplopia makes this an unlikely explanation. Another possibility is that, when the angle of strabismus changes following visual maturation, the previous suppression scotoma no longer allows for the suppression of binocular diplopia—a mechanism of diplopia seen in adult patients with a history of childhood strabismus.5 The ages of presentation for diplopic symptoms support this possibility, as they were all 7 years or older when the children first reported diplopia and may have had a change in strabismic angle after visual maturation that allowed diplopia to occur because the strabismic angle was different than the one for which a suppression scotoma had developed before visual maturation. However, the findings in Case Five (the child with decompensated esotropia), do not support this explanation. Though the angle of strabismus at the onset of diplopia was larger than previously measured and not in a fusible range (which could have explained her initial symptoms of
American Orthoptic Journal
diplopia), her diplopia still required prism correction even after the angle of esotropia was reduced to a fusible range with full hyperopic correction, suggesting that the suppression mechanism was no longer in existence. Similarly, it would seem that, for the two children with consecutive exotropia (Cases Three and Four), the esotropic scotoma was lost during the period of exotropia, resulting in diplopia even at small angles of esotropia noted at the onset of diplopia. In 3 of 5 patients (Cases Two, Three, and Five), monofixation syndrome developed prior to the onset of diplopia. Diplopia has been reported after monofixation syndrome decompensates.6, 7 These studies demonstrate a higher likelihood of diplopia as a result of monofixation decompensation in patients who had surgical correction of esotropia and in patients who decompensated in the late postoperative period (many years following surgery).7 In our case series, surgical correction of esotropia was performed in 2 of the 3 children (Cases Two and Three), and decompensation of monofixation with onset of diplopia occurred in the late postoperative period at 5 and 4 years after surgery, respectively. We hypothesize that monocular treatment with patch penalization may contribute to the outcome of diplopia in our reported cases. After treatment, 4 of 5 patients had small angles of strabismus that were in fusible ranges, but fusion was low to nil in these patients. These same four patients were treated with patch penalization for either amblyopia (Cases One, Two, and Three) or consecutive exotropia (Case Four). Evidence now suggests that patients with amblyopia may have an intact binocular visual system that becomes functionally monocular if inhibition of the visual system is caused by monocular occlusion treatment of amblyopia prior to the development of binocular combination.8 Although diplopia in the setting of childhood esotropia is rare and is not
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symptomatically debilitating, the role of patch treatment and the possibility of using alternate methods to treat amblyopia warrants further exploration. With randomized clinical trials showing the same visual acuity outcomes for atropine and patch penalization,9, 10 and other binocular treatment for amblyopia showing promise, our findings support further investigation of non-occlusion based therapy for amblyopia, as diplopia, though rare, may occur at a time remote from the course of patch treatment.11-13 CONCLUSION Although rare, children with infantile or accommodative esotropia treated before visual maturation may develop persistent binocular diplopia. Features of the children in our case series with persistent diplopia included reduced binocularity, poor sensory outcomes (fusion and stereopsis), refractive changes, and a history of patching for the treatment of amblyopia. These children all reported the onset of diplopia after the age of 7. In contrast to adult-onset diplopia, diplopia was never reported by the children or the parents to be debilitating or restrictive in any way to the affected child performing daily tasks of living. However, the parents were initially quite distressed that this new symptom of diplopia represented a negative outcome for treatment. Our series suggests that, following a complete evaluation to rule out pathology other than the childhood strabismus, reassurance is in order when children present with complaints of diplopia following treatment of childhood esotropia. Finally, further evaluation of non-occlusive treatment for amblyopia is warranted, occlusion was used to treat amblyopia in 4
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of our 5 cases reporting diplopia after successful treatment of childhood esotropia. REFERENCES 1. Mohney BG, Lilley CC, Green-Simms AE, Diehl NN: The long-term follow-up of accommodative esotropia in a population-based cohort of children. Ophthalmology 2011; 118:581-585. 2. Berk AT, Kocak N, Ellidokuz H: Treatment outcomes in refractive accommodative esotropia. J AAPOS 2004; 8:384-388. 3. Harrad R, Sengpiel F, Blakemore C: Physiology of suppression in strabismic amblyopia. BJO 1996; 80:373-377. 4. Wu H, Sun J, Xia X, Xu L, Xu X: Binocular status after surgery for constant and intermittent exotropia. Am J Ophthalmol 2006; 142:822-826. 5. William E. Scott PJK, Won Ryul Lee: Richard G. Scobee Memorial Lecture: Diplopia in adult strabismus. Am Orthopt J 1994; 44:66-69. 6. Hunt MG, Keech RV: Characteristics and course of patients with deteriorated monofixation syndrome. J AAPOS 2005; 9:533-536. 7. Ing MR, Roberts KM, Lin A, Chen JJ: The stability of the monofixation syndrome. Am J Ophthalmol 2014; 157:248-253e1. 8. Li J, Thompson B, Ding Z, et al.: Does partial occlusion promote normal binocular function? Invest Ophthalmol Vis Sci 2012; 53:6818-6827. 9. Menon V, Shailesh G, Sharma P, Saxena R: Clinical trial of patching versus atropine penalization for the treatment of anisometropic amblyopia in older children. J AAPOS 2008; 12:493-497. 10. Repka MX, Kraker RT, Beck RW, et al.: A randomized trial of atropine vs. patching for treatment of moderate amblyopia: Follow-up at age 10 years. Arch Ophthalmol 2008; 126:1039-1044. 11. Spierer A, Raz J, Benezra O, et al.: Treating amblyopia with liquid crystal glasses: A pilot study. Invest Ophthalmol Vis Sci 2010; 51:3395-3398. 12. Birch EE: Amblyopia and binocular vision. Prog Retin Eye Res 2013; 33:67-84. 13. Hess RF, Thompson B, Black JM, et al.: An iPod treatment of amblyopia: An updated binocular approach. Optometry 2012; 83:87-94.
Key words: esotropia, binocular diplopia, accommodative amblyopia
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ABSTRACT Introduction: Diplopia is rare in children with nonpathological esotropia because facultative suppression develops prior to visual maturation. Our aim is to present five cases of children with binocular diplopia following treatment of childhood esotropia, exploring possible mechanisms for the development of diplopia based upon the patient’s history and findings, and discussing treatment for diplopia in this setting. Methods: A retrospective chart review of five sequential patients presenting with binocular diplopia following treatment of esotropia was performed. Treatment of esotropia included correction of hyperopic error, correction of anisometropic amblyopia to 20 / 30 or better, and strabismus surgery as indicated. Results: Diplopia developed in two children with accommodative esotropia, one child with infantile esotropia and partially accommodative esotropia, and two children with a history of infantile esotropia and consecutive exotropia following surgical correction. Diplopia onset occurred between ages 7 and 11. Four of the five children experienced resolution of diplopia with prism glasses. Conclusion: Children with esotropia before visual maturation may develop persistent diplopia. Clinical features of the children with diplopia in our case series include poor fusion, poor stereopsis, consecutive exotropia, refractive changes, onset of diplopia after 7 years of age, and occlusion therapy for amblyopia. Prisms may be beneficial in controlling the diplopia.
INTRODUCTION
From the Hamilton Eye Institute, Memphis, Tennessee. Requests for reprints should be addressed to: Natalie Kerr, M.D., Hamilton Eye Institute, 930 Madison Avenue, Suite 400, Memphis, Tennessee 38103.
The common forms of childhood esotropia are nonaccommodative infantile esotropia and accommodative esotropia. Infantile esotropia does not typically present with a significant refractive error. Children with infantile esotropia are
© 2014 Board of Regents of the University of Wisconsin System, American Orthoptic Journal, Volume 64, 2014, ISSN 0065-955X, E-ISSN 1553-4448
American Orthoptic Journal
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typically treated with strabismus surgery prior to age 2. Uncorrected hypermetropia and / or an abnormally high accommodative convergence to accommodation (AC/A) ratio can cause accommodative esotropia through an accommodative effort.1 In children without adequate fusional divergence to counteract the increased convergence, a manifest esotropia develops. Amblyopia may be associated with esotropia, particularly when anisometropia is present.2 The majority of patients with childhood esotropia develop facultative suppression to overcome symptoms of binocular diplopia in the presence of a manifest strabismus. Facultative suppression develops rapidly in childhood during the sensitive period of visual development and before visual maturation is complete.3 Thus, diplopia in children with infantile or accommodative esotropia should not develop due to suppression. We present a case series of persistent binocular diplopia that developed in children after treatment of childhood esotropia. METHODS We conducted a retrospective case series of five consecutive children presenting with persistent binocular diplopia following treatment of esotropia. These five children presented for treatment of strabismus between the ages of 7 months and 3 years to pediatric ophthalmologists at the University of Tennessee Hamilton Eye Institute from 1999 to 2006. Treatment of infantile esotropia included strabismus muscle surgery. Accommodative esotropia and partially accommodative esotropia were treated with correction of hyperopic refractive error to a fusible range of 10Δ of esotropia or less. Treatment of amblyopia included patch penalization or atropine penalization to achieve a visual acuity of 20 / 30 or better in the amblyopic eye. Binocular diplopia
118
was confirmed in all patients using a red filter. Sensory status in all patients was evaluated with the Titmus circles test for stereopsis and Worth 4-Dot test for fusion. Bifixation was defined as < 60 seconds of arc while gross stereopsis was defined as < 800 seconds of arc using Titmus cicles.4 Fusion was defined as seeing two red and two green dots on the Worth 4-Dot test, measured at distance and at near with correction. All measurements of the angle of strabismus reported are the distance angle with correction using prism and alternate cover testing unless otherwise noted. RESULTS Case One A 3-year-old Asian female presented with recent onset esotropia and an initial measurement of 30Δ esotropia. Her esotropia was treated with spectacle correction of hyperopia, and bifocals were added to her glasses to treat a high AC / A ratio. Amblyopia (20 / 50 OS) was detected at age 4 and treated with patch penalization for 1-2 hours per day for 4 months. Both her esotropia and amblyopia were successfully treated. With glasses, her angle of strabismus was reduced to 4Δ esophoria with correction, and she demonstrated some gross stereopsis and intermittent fusion at near on Worth 4-Dot testing. She developed intermittent uncrossed diplopia at the age of 7 years, while her angle of strabismus was flick esophoria. The diplopia was confirmed with red filter testing and she was determined to have normal retinal correspondence. After the onset of diplopia, she had no fusion but maintained gross stereopsis. She was treated with a change in her glasses prescription to increase the hyperopic correction an additional +0.75 OD and +0.50 OS to match her cycloplegic refraction. This did not resolve her symptoms of dip-
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TAE
lopia, and she switched back to her original glasses for clarity of vision (patient’s choice). At age 8, she did not have resolution of her diplopia before she was lost to follow-up. However, she stated that the diplopia was not distressing to her, and mother confirmed that she was not hindered in any activity after the onset of the diplopia. Her last measurement was 4Δ esophoria. Case Two A 7-month-old white male presented with an initial measurement of 70Δ esotropia (Krimsky) and amblyopia OD. He underwent patch treatment. At 9 months, he had a bilateral medial rectus recession of 6 mm with a preoperative measurement of 45Δ esotropia and postoperative measurement of 10Δ esotropia (Krimsky). He was given glasses at 14 months to correct his hyperopic error of +3.00 sphere OD and +2.75 sphere OS and to treat the accommodative component of his esotropia. At 2 years of age, he suffered recurrent esotropia and bilateral inferior oblique overaction, which prompted another surgery (bilateral lateral rectus resection and bilateral inferior oblique recession). He had a preoperative measurement of 20Δ esotropia and postoperative measurement of 8Δ esotropia. Following the second surgery, his angle of esotropia was stabilized from age 2 to 5. At age 5, his angle of esotropia increased to 15-18Δ esotropia. He developed amblyopia at 2.5 years (8 / 30 Allen cards OD with correction) and was treated with both patch penalization and atropine until the vision improved to 20 / 30 at age 5. Beginning at age 7, this child began to report diplopia. His angle of strabismus was 16-18Δ esotropia and 2-3Δ left hypertropia. He had not had a significant change in his angle of strabismus or in his glasses prescription prior to the onset of diplopia. At time of presentation, he demonstrated
American Orthoptic Journal
anomalous retinal correspondence, which improved symptomatically with 4Δ basedown OD and 2Δ base-up OS. By age 12, he no longer had diplopia and did not require prisms in his glasses. He was reported to have monofixation syndrome when he was 6 years old with fusion on Worth 4-Dot at near. After the development of diplopia at age 7, he never had any fusion or stereopsis. At his last exam, he was 15 years old with a measurement of 6-8Δ right exotropia and 6-8Δ left hypertropia with no stereopsis or fusion by Worth 4-Dot. Case Three A 4-year-old white female presented with consecutive exotropia following bilateral medial rectus recessions elsewhere for infantile esotropia. Her measurement at presentation was 20-25Δ exotropia. At 4 years, she underwent a bilateral medial rectus advancement to correct the consecutive exotropia. She had a preoperative measurement of 20-25Δ exotropia and postoperative measurement of 6Δ esotropia. She was given bifocal glasses for hyperopia and high AC / A ratio, and continued to have a small angle of esotropia following surgery (see Table 1). She had amblyopia OD at presentation, and was treated with patch penalization until the vision improved to 20 / 30 after 6 months. This child developed diplopia at age 8 with an angle of 10-12Δ esotropia. The diplopia was treated with 4 D base-out prism, which relieved her symptoms. She had developed monofixation syndrome with intermittent gross stereopsis and intermittent fusion throughout her course of treatment prior to developing diplopia. She continues to wear her bifocals for partially accommodative esotropia with prism to correct for diplopia. At her last clinic visit, she was 11 years old with a measurement of 2Δ right esotropia and no stereopsis or fusion.
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Case Four An 18-month-old male presented with a history of prematurity and developmental delay presented with esotropia. Onset was reported to have occurred prior to 6 months of age. His initial measurement was 25Δ esotropia with a V-pattern. At 2 years of age, he underwent a bilateral medial rectus recession with vertical transposition to correct his V-pattern esotropia. His preoperative measurement was 25Δ esotropia and postoperative measurement was orthotropia. He developed consecutive exotropia with an A-pattern at 6 years, which was treated with alternate patching for 6 months. The alternate patching did not correct the consecutive exotropia. A bilateral lateral rectus recession with vertical transposition for A-pattern was performed at age 7. His preoperative measurement was 10Δ exotropia and postoperative measurement was 2Δ esophoria for this procedure. His small-angle esophoria was stable for 5 years with no development of amblyopia or need for spectacles during the course of treatment. During this time period, he never developed gross stereopsis or fusion by Worth 4-Dot. Diplopia began at age 11. His angle of strabismus was 8-10Δ esotropia. The patient was able to fuse with 6 D base-out prism, and his diplopic symptoms were successfully treated with prism glasses. He had normal retinal correspondence and no stereopsis or fusion. At his last exam, he was 11 years old and with a measurement of 6Δ esotropia. Case Five A 12-month-old female presented with esotropia of 30Δ. She also had high hyperopia. Her accommodative esotropia was successfully treated with glasses and she was orthoptropic with her corrective spectacles. She was never treated for amblyopia, and she remained orthotropic for
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13 years. She developed monofixation syndrome with Worth 4-Dot fusion at near and gross stereopsis. At age 14, her esotropia decompensated to 20Δ esotropia and 4Δ right hypertropia, at which time she began to develop diplopia. Her glasses prescription was increased to her full cycloplegic prescription, which corrected her to a small angle of esotropia. Her diplopic symptoms persisted. She was treated with 10 D of baseout prism OS, which relieved her diplopia. At her last exam, she was 14 years old and had fusion at near but no stereopsis. She had 12Δ esotropia with correction and was still relying on prisms to correct her diplopia. DISCUSSION It is assumed that suppression develops early and rapidly in life, and diplopia in the presence of a manifest strabismus does not occur.3 In the five cases presented, children developed binocular diplopia after the successful treatment of esotropia, although all were diagnosed and successfully treated for strabismus prior to visual maturation. One important observation from our case series is that diplopia was almost an incidental finding in these children. The children would mention that they were having it, but could not say when it had started and were not distressed by it. Therefore, it is possible that diplopia has been under-reported because it is not troubling to the children. Although we have reported all of the cases we have observed, many others may have gone “undetected” because the children did not report diplopia and we do not routinely check for diplopia in children because we assume that they have suppression. The main limitation to our case series is the small size, which makes it difficult to draw generalized conclusions about the incidence and etiology of this finding. How-
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ever, several possible explanations may be entertained for the occurrence of diplopia in these cases. First, instead of being truly diplopic, the children with poor fusion and small angle strabismus may be rapidly alternating between the two eyes. However, demonstration of binocular diplopia with red filter testing in all reported patients makes this an unlikely explanation. Secondly, successful treatment of amblyopia to 20 / 30 or better in the amblyopic eye may have “unmasked” diplopia in children who had failed to develop a suppression scotoma or effectively had anti-suppression therapy from patch penalization. However, the complaint of diplopia was remote from the attainment of good vision in the amblyopic eye. In Cases One, Two, and Three, elapsed time from attainment of good vision to diplopia was 4 years, 5 years, and 5 years, respectively. The length of time from attainment of good vision to complaints of diplopia makes this an unlikely explanation. Another possibility is that, when the angle of strabismus changes following visual maturation, the previous suppression scotoma no longer allows for the suppression of binocular diplopia—a mechanism of diplopia seen in adult patients with a history of childhood strabismus.5 The ages of presentation for diplopic symptoms support this possibility, as they were all 7 years or older when the children first reported diplopia and may have had a change in strabismic angle after visual maturation that allowed diplopia to occur because the strabismic angle was different than the one for which a suppression scotoma had developed before visual maturation. However, the findings in Case Five (the child with decompensated esotropia), do not support this explanation. Though the angle of strabismus at the onset of diplopia was larger than previously measured and not in a fusible range (which could have explained her initial symptoms of
American Orthoptic Journal
diplopia), her diplopia still required prism correction even after the angle of esotropia was reduced to a fusible range with full hyperopic correction, suggesting that the suppression mechanism was no longer in existence. Similarly, it would seem that, for the two children with consecutive exotropia (Cases Three and Four), the esotropic scotoma was lost during the period of exotropia, resulting in diplopia even at small angles of esotropia noted at the onset of diplopia. In 3 of 5 patients (Cases Two, Three, and Five), monofixation syndrome developed prior to the onset of diplopia. Diplopia has been reported after monofixation syndrome decompensates.6, 7 These studies demonstrate a higher likelihood of diplopia as a result of monofixation decompensation in patients who had surgical correction of esotropia and in patients who decompensated in the late postoperative period (many years following surgery).7 In our case series, surgical correction of esotropia was performed in 2 of the 3 children (Cases Two and Three), and decompensation of monofixation with onset of diplopia occurred in the late postoperative period at 5 and 4 years after surgery, respectively. We hypothesize that monocular treatment with patch penalization may contribute to the outcome of diplopia in our reported cases. After treatment, 4 of 5 patients had small angles of strabismus that were in fusible ranges, but fusion was low to nil in these patients. These same four patients were treated with patch penalization for either amblyopia (Cases One, Two, and Three) or consecutive exotropia (Case Four). Evidence now suggests that patients with amblyopia may have an intact binocular visual system that becomes functionally monocular if inhibition of the visual system is caused by monocular occlusion treatment of amblyopia prior to the development of binocular combination.8 Although diplopia in the setting of childhood esotropia is rare and is not
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symptomatically debilitating, the role of patch treatment and the possibility of using alternate methods to treat amblyopia warrants further exploration. With randomized clinical trials showing the same visual acuity outcomes for atropine and patch penalization,9, 10 and other binocular treatment for amblyopia showing promise, our findings support further investigation of non-occlusion based therapy for amblyopia, as diplopia, though rare, may occur at a time remote from the course of patch treatment.11-13 CONCLUSION Although rare, children with infantile or accommodative esotropia treated before visual maturation may develop persistent binocular diplopia. Features of the children in our case series with persistent diplopia included reduced binocularity, poor sensory outcomes (fusion and stereopsis), refractive changes, and a history of patching for the treatment of amblyopia. These children all reported the onset of diplopia after the age of 7. In contrast to adult-onset diplopia, diplopia was never reported by the children or the parents to be debilitating or restrictive in any way to the affected child performing daily tasks of living. However, the parents were initially quite distressed that this new symptom of diplopia represented a negative outcome for treatment. Our series suggests that, following a complete evaluation to rule out pathology other than the childhood strabismus, reassurance is in order when children present with complaints of diplopia following treatment of childhood esotropia. Finally, further evaluation of non-occlusive treatment for amblyopia is warranted, occlusion was used to treat amblyopia in 4
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of our 5 cases reporting diplopia after successful treatment of childhood esotropia. REFERENCES 1. Mohney BG, Lilley CC, Green-Simms AE, Diehl NN: The long-term follow-up of accommodative esotropia in a population-based cohort of children. Ophthalmology 2011; 118:581-585. 2. Berk AT, Kocak N, Ellidokuz H: Treatment outcomes in refractive accommodative esotropia. J AAPOS 2004; 8:384-388. 3. Harrad R, Sengpiel F, Blakemore C: Physiology of suppression in strabismic amblyopia. BJO 1996; 80:373-377. 4. Wu H, Sun J, Xia X, Xu L, Xu X: Binocular status after surgery for constant and intermittent exotropia. Am J Ophthalmol 2006; 142:822-826. 5. William E. Scott PJK, Won Ryul Lee: Richard G. Scobee Memorial Lecture: Diplopia in adult strabismus. Am Orthopt J 1994; 44:66-69. 6. Hunt MG, Keech RV: Characteristics and course of patients with deteriorated monofixation syndrome. J AAPOS 2005; 9:533-536. 7. Ing MR, Roberts KM, Lin A, Chen JJ: The stability of the monofixation syndrome. Am J Ophthalmol 2014; 157:248-253e1. 8. Li J, Thompson B, Ding Z, et al.: Does partial occlusion promote normal binocular function? Invest Ophthalmol Vis Sci 2012; 53:6818-6827. 9. Menon V, Shailesh G, Sharma P, Saxena R: Clinical trial of patching versus atropine penalization for the treatment of anisometropic amblyopia in older children. J AAPOS 2008; 12:493-497. 10. Repka MX, Kraker RT, Beck RW, et al.: A randomized trial of atropine vs. patching for treatment of moderate amblyopia: Follow-up at age 10 years. Arch Ophthalmol 2008; 126:1039-1044. 11. Spierer A, Raz J, Benezra O, et al.: Treating amblyopia with liquid crystal glasses: A pilot study. Invest Ophthalmol Vis Sci 2010; 51:3395-3398. 12. Birch EE: Amblyopia and binocular vision. Prog Retin Eye Res 2013; 33:67-84. 13. Hess RF, Thompson B, Black JM, et al.: An iPod treatment of amblyopia: An updated binocular approach. Optometry 2012; 83:87-94.
Key words: esotropia, binocular diplopia, accommodative amblyopia
Volume 64, 2014
