一般的な治療法
一般的な治療としてまず手術がある。DSの手術の目的は顔の傾きを正すこと(またはその軽減)、両目のバランス(一直線上同じ位置に両目があるように)を正すこと、左右を見る時に生じる目の上跳ね、下跳ねを正す(または軽減)ことである。
手術は元来の問題あるinnervationを治療することはできないし、異常な動きをする目を完全に治療できるという手術方法はまだない。基本的な水平筋肉後退、rectus筋肉の垂直転位, またはその2つの方法のコンビネーションが顔の傾きの軽減と目の位置のバランスを正すのには効果があるだろう。どちらの方法が向いているかは個人によって異なる。
治療と患者への補助
どのような治療であれ、顔の傾きの軽減と斜視を正すことが目的である。
学校では患者である子供が授業を受けやすい席に座らせる配慮が必要なこともあると思われる。
車の運転をする際には、患者であるドライバーの助けになるように、特別なバックミラーを取り付けると便利である。
プリズム入りの眼鏡をかけることで顔の傾きを正すことができる(ただし、これは一般的に使われる治療法ではない)。
ビジョン・セラピーは収斂(しゅうれん)"secondary convergence"を鍛えることはできる。
手術
顔の傾きを正すことができる可能性は79-100%である(*ただし、統計のセクションを読むとこの数字は必ずしも正しいとはいえないことが分かる---コミュ管理人筆記)。
手術後のコンディションは術後8.75年変わらないとされる。
Surgery does not improve motility.
Surgery does not improve stereo or fusion.
A risk of diplopia may be present with or without surgery.
The goal of surgery is to correct the face turn, decrease upshoots and downshoots, eliminate globe retraction, and align the eyes in primary position.
手術は患者の年齢に問わず行なえるが、普通患者が子供である場合、歩けるようになってから行なうことが多い。
治療/手術は患者の肉体的発達(歩けるか、キャッチボールができるかなど)を考慮する必要がある。
Types of surgery
DS type I: Recession of the medial rectus (no effect on abduction), posterior fixation suturing on the normal medial rectus (may diminish adduction innervation slightly to the involved eye, decreasing the esodeviation), or resection involving the lateral rectus (but may turn type 1 into a severe type 2)
DS type II Recession of the lateral and medial rectus muscles in the involved eye (may need to recess the contralateral lateral rectus if deviation or retraction is severe), or medial rectus recession on the affected side
DS type III Recession of the medial and lateral rectus for retraction or an upshoot or downshoot (best for severe cases), Y split of the lateral rectus can reduce retraction upshoot or downshoot, or posterior fixation suturing on the lateral rectus reduces upshoot and downshoot
DS type IV: Recession of both lateral rectus muscles (larger amount on the involved side than on the uninvolved side), or surgery designed for the unique patient with rare types
Surgical Care:
General considerations
Strabismus surgery can be performed if the patient has a clinically significant anomalous head position.
The results of surgical treatment of the retraction syndrome often have been disappointing. For this reason, surgical intervention is not performed when binocular vision is present with the eyes in primary position or if vision can be maintained with a slight head turn. However, the aberrant innervation in DS produces different manifestations, any one of which may require surgery. The clinically significant manifestations include a face turn with strabismus in primary position, an upshoot or downshoot during adduction, vertical deviation in primary position, retraction during adduction, and enophthalmos.
Indications
Although none of the findings listed above is an absolute indication for surgery, the need for surgery depends on the severity of the manifestations and the degree to which patients believe that they are disfigured or functionally compromised (as can be the case with a large face turn). The most common indication for surgical treatment is an unacceptable face turn. The face turn is a secondary manifestation of strabismus in primary position and develops to permit fusion. If it is sufficiently large, the face turn may be disfiguring and functionally debilitating.
Patients who have DS with exotropia in primary position usually have a face turn away from the affected eye. Most commonly, esodeviation in primary position leads to a face turn toward the side of the affected eye. This face turn is usually most pronounced with distant fixation. The face turn and measured deviation with near fixation may be minimal, but this situation is not a contraindication to surgery because a procedure designed to fully correct the face turn at a distance generally does not produce secondary overcorrection at near fixation.
On occasion, fusion is impossible in a patient with DS, usually because bilateral involvement or a vertical deviation prevents fusion with any head posture. In these cases, the strabismus itself rather than the secondary head posture can be the main indication for surgical correction.
When the affected eye is adducted, an upshoot, downshoot, or retraction can be sufficiently disturbing to the patient or the parents of the patient to warrant surgical treatment. The retraction may be accentuated by the face turn that is seen with the most common esotropic form of DS; this places the affected eye in an adducted position. In severe cases, clinically significant enophthalmos and pseudoptosis is present even in primary position. A reduction of 50% or more of the width of the palpebral fissure during adduction compared with primary position has been suggested as an indication for surgical treatment of the retraction.
Contraindications
Many patients with DS are orthophoric in primary position or have only an insignificant face turn. In these cases, surgery is not indicated unless another manifestation of DS, such as an upshoot or a downshoot, is causing some hardship. The fact that a patient seeks evaluation does not necessarily indicate a desire for surgical correction. Often, it is not the manifestations of the condition themselves that have motivated the consultation, but rather, a concern that they indicate some ominous underlying intracranial disease, especially in parents who bring their child with DS to be examined.
If discussion with the patient or the patient's parents reveals that fear of life-threatening disease rather than a manifestation of DS is their chief concern, then explanation and reassurance may be all that is needed.
Because fusion can usually be achieved by means of a face turn, most children with DS have normal binocular function and stereopsis. Therefore, in distinction to congenital esotropia, for which the goal is to restore ocular alignment as early as possible, the goal in DS should be to avoid disrupting normal binocular development. Therefore, a young age is a relative contraindication for surgery.
Severe cases may warrant early treatment, but it is usually preferable to delay surgery until patients are aged 4-5 years. At this age, patient cooperation facilitates detailed examination, and their visual system is relatively mature and less susceptible to damage from a temporary disruption of binocularity than before, as can occur postoperatively if an unfavorable response to surgery occurs.
Procedures
Recession of the medial rectus muscle
Recession of the medial rectus muscle in the involved eye aligns the eye but does not improve abduction beyond the primary position. In rare cases, large weakening procedures performed on the medial rectus lead to consecutive exotropia because of poorly understood mechanisms. Small medial rectus recession in the opposite eye helps the involved eye in primary position by application of the Hering law.
Resection of the lateral rectus muscle is avoided because it increases retraction and does not improve abduction. Recession of the ipsilateral medial rectus muscle is the mainstay of surgical treatment for DS. In patients with esotropia in primary position, this procedure improves the face turn and the esotropia by weakening the antagonist of an effectively paretic lateral rectus muscle.
Medial rectus recession alone may improve the enophthalmos and vertical overshoots in adduction, in part by limiting adduction of the eye. However, additional measures are usually needed to adequately manage these problems if they are severe. To effectively reduce or eliminate the face turn, recession must be larger than that typically performed on a medial rectus muscle, often in the range of 8-10 mm, as measured from the original insertion.
Standard recession or a hang-back technique may be used; this can decrease the difficulty of the procedure when a large recession is needed. When clinically significant mechanical restriction due to contracture or fibrosis of the medial rectus muscle is present, a relatively small recession is usually sufficient. A large recession can easily cripple a fibrotic muscle, which often has contractile properties that are almost as severely compromised as its elastic properties.
For adults with mechanical restriction of the medial rectus muscle, techniques for adjustable-suture recession is helpful for finding the best compromise between adequate relief of the face turn and crippled adduction.
Recession of the contralateral medial rectus muscle in addition to the ipsilateral medial rectus muscle may be performed in cases in which the patient has primary position esotropia greater than 20 diopters and marked co-contraction of the lateral rectus muscle, as shown by limited adduction, massive retraction, or reduced adduction saccadic velocities.
Recessing the contralateral medial rectus muscle may allow for decreased recession of the ipsilateral medial rectus muscle. However, millimeter for millimeter, this procedure is less effective than it is in concomitant esotropia because it is an attempt to treat the large secondary deviation. The ipsilateral medial rectus recession still must be sufficient to permit abduction of the ipsilateral eye to at least midline; otherwise, the addition of a contralateral medial rectus recession, regardless of size, cannot correct the face turn. Recession of the contralateral medial rectus muscle may also reduce the long-term risk of contracture of the ipsilateral medial rectus muscle by reducing its tonic innervation (Hering law).
Vertical rectus muscle transposition
Transposition of the vertical rectus muscles to a position adjacent to the lateral rectus, with or without recession of the ipsilateral medial rectus, has been suggested as a means of correcting the primary position esotropia, of improving abduction, and of enlarging the field of single binocular vision.
This procedure may provide better abduction than that possible with medial rectus recession alone. However, it is more difficult to perform, that the other procedure; it may exacerbate retraction, upshoot, or downshoot; it can create new vertical deviations; and, particularly in adults in whom medial rectus recession is performed concurrently, it poses some risk of anterior segment ischemia. This procedure should probably be considered only as primary treatment for patients with no abduction at all, for those with minimal retraction, and for those with no upshoot or downshoot.
Lateral rectus muscle recession
Exodeviation in primary position with a face turn away from the side of the affected eye is an uncommon presentation of DS. In this case, the face turn is treated with recession of the ipsilateral lateral rectus muscle. In patients who have both primary position exotropia and a marked upshoot or downshoot, a lateral rectus recession is usually combined with an additional measure—either a Y-splitting procedure or a posterior fixation suture—to minimize sideslip of the lateral rectus muscle across the globe.
Recession of the lateral rectus is also effective in reducing the upshoot or downshoot during adduction when it is due to sideslip of a tight lateral rectus, particularly if it is combined with recession of the medial rectus. Recession of the lateral rectus muscle alone improves the retraction with adduction somewhat. However, large recessions (10-12 mm) of both the medial and lateral rectus muscles of the ipsilateral eye are effective, particularly when enophthalmos in primary position is a major complaint. As with medial rectus recessions, recessions of the lateral rectus muscles should be decreased when restriction of the lateral rectus muscle is clinically significant.
Y-splitting procedure
Co-contraction of the medial and lateral rectus muscles on attempted adduction can cause a striking upshoot or downshoot of the eye. This effect is attributed to sideslip of a tight lateral rectus over the globe (mechanical factors) in most cases.
The Y-splitting procedure effectively results in a broad lateral rectus insertion that stabilizes its position and prevents it from flipping superiorly or inferiorly over the globe, eliminating or greatly reducing the upshoot or downshoot of the affected eye in attempted adduction. The Y-splitting procedure may be combined with a moderate recession of the lateral rectus muscle, particularly if associated primary position exotropia exists.
Placement of a posterior fixation suture
Placement of a posterior fixation suture on the lateral rectus muscle can effectively prevent slippage of the muscle belly over the globe. This may be used as an alternative procedure to treat upshoots and downshoots. As with the Y-splitting procedure, posterior fixation suturing can be combined with a lateral rectus recession when appropriate.
Procedures to weaken the vertical rectus and inferior oblique muscles
Besides the mechanical factors discussed above, innervational factors, presumably aberrant co-contraction of the vertical rectus or inferior oblique muscles, may contribute to an upshoot or downshoot in some patients with DS. When vertical deviation in primary position is clinically significant, surgery on the horizontal rectus muscle alone generally does not correct the problem adequately, and recession of the appropriate vertical rectus muscle is needed. The upshoot in adduction that often is seen in DS bears some resemblance to inferior oblique overaction, but inferior oblique weakening procedures usually are ineffectual in correcting the problem.
Expected results
Horizontal muscle recession reportedly eliminates the face turn in 79% of patients and substantially reduces the face turn in most of remaining patients. In a patient with esotropic DS, recession of the ipsilateral medial rectus muscle usually provides a modest improvement in abduction if some abduction past the midline was present preoperatively; however, this improvement often comes at the expense of some reduction of adduction. The field of single binocular vision is shifted to include primary position but remains relatively unchanged in size.
On the contrary, if the patient does not have abduction past the midline before surgery, medial rectus recession that is sufficiently large to eliminate the primary position esotropia and face turn substantially limit adduction while providing little or no improvement in abduction.
The size of the field of single binocular vision may be reduced under the circumstances just described, though the addition of a contralateral medial rectus recession, possibly with a Faden procedure, may reduce or eliminate the reduction. Vertical rectus transposition may provide improve abduction and enlarged the field of single binocular vision, particularly in patients with problems with the latter. However, no studies have been conducted to directly compare the efficacy of transposition with that of unilateral or bilateral medial rectus recession.
When they are due to mechanical factors, upshoots and downshoots can usually be satisfactorily reduced or eliminated by performing Y-splitting, posterior fixation, or large recessions of both ipsilateral horizontal rectus muscles. In contrast, when the upshoot or downshoot is due to innervational factors, appropriate recession of a vertical rectus muscle eliminates the vertical deviation in primary position, but some vertical deviation usually remains when the eye is adducted. Large recessions of both horizontal rectus muscles usually provide satisfactory correction of enophthalmos in primary position, but some retraction in adduction remains. FOLLOW-UP Section 7 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography
一般的な治療としてまず手術がある。DSの手術の目的は顔の傾きを正すこと(またはその軽減)、両目のバランス(一直線上同じ位置に両目があるように)を正すこと、左右を見る時に生じる目の上跳ね、下跳ねを正す(または軽減)ことである。
手術は元来の問題あるinnervationを治療することはできないし、異常な動きをする目を完全に治療できるという手術方法はまだない。基本的な水平筋肉後退、rectus筋肉の垂直転位, またはその2つの方法のコンビネーションが顔の傾きの軽減と目の位置のバランスを正すのには効果があるだろう。どちらの方法が向いているかは個人によって異なる。
治療と患者への補助
どのような治療であれ、顔の傾きの軽減と斜視を正すことが目的である。
学校では患者である子供が授業を受けやすい席に座らせる配慮が必要なこともあると思われる。
車の運転をする際には、患者であるドライバーの助けになるように、特別なバックミラーを取り付けると便利である。
プリズム入りの眼鏡をかけることで顔の傾きを正すことができる(ただし、これは一般的に使われる治療法ではない)。
ビジョン・セラピーは収斂(しゅうれん)"secondary convergence"を鍛えることはできる。
手術
顔の傾きを正すことができる可能性は79-100%である(*ただし、統計のセクションを読むとこの数字は必ずしも正しいとはいえないことが分かる---コミュ管理人筆記)。
手術後のコンディションは術後8.75年変わらないとされる。
Surgery does not improve motility.
Surgery does not improve stereo or fusion.
A risk of diplopia may be present with or without surgery.
The goal of surgery is to correct the face turn, decrease upshoots and downshoots, eliminate globe retraction, and align the eyes in primary position.
手術は患者の年齢に問わず行なえるが、普通患者が子供である場合、歩けるようになってから行なうことが多い。
治療/手術は患者の肉体的発達(歩けるか、キャッチボールができるかなど)を考慮する必要がある。
Types of surgery
DS type I: Recession of the medial rectus (no effect on abduction), posterior fixation suturing on the normal medial rectus (may diminish adduction innervation slightly to the involved eye, decreasing the esodeviation), or resection involving the lateral rectus (but may turn type 1 into a severe type 2)
DS type II Recession of the lateral and medial rectus muscles in the involved eye (may need to recess the contralateral lateral rectus if deviation or retraction is severe), or medial rectus recession on the affected side
DS type III Recession of the medial and lateral rectus for retraction or an upshoot or downshoot (best for severe cases), Y split of the lateral rectus can reduce retraction upshoot or downshoot, or posterior fixation suturing on the lateral rectus reduces upshoot and downshoot
DS type IV: Recession of both lateral rectus muscles (larger amount on the involved side than on the uninvolved side), or surgery designed for the unique patient with rare types
Surgical Care:
General considerations
Strabismus surgery can be performed if the patient has a clinically significant anomalous head position.
The results of surgical treatment of the retraction syndrome often have been disappointing. For this reason, surgical intervention is not performed when binocular vision is present with the eyes in primary position or if vision can be maintained with a slight head turn. However, the aberrant innervation in DS produces different manifestations, any one of which may require surgery. The clinically significant manifestations include a face turn with strabismus in primary position, an upshoot or downshoot during adduction, vertical deviation in primary position, retraction during adduction, and enophthalmos.
Indications
Although none of the findings listed above is an absolute indication for surgery, the need for surgery depends on the severity of the manifestations and the degree to which patients believe that they are disfigured or functionally compromised (as can be the case with a large face turn). The most common indication for surgical treatment is an unacceptable face turn. The face turn is a secondary manifestation of strabismus in primary position and develops to permit fusion. If it is sufficiently large, the face turn may be disfiguring and functionally debilitating.
Patients who have DS with exotropia in primary position usually have a face turn away from the affected eye. Most commonly, esodeviation in primary position leads to a face turn toward the side of the affected eye. This face turn is usually most pronounced with distant fixation. The face turn and measured deviation with near fixation may be minimal, but this situation is not a contraindication to surgery because a procedure designed to fully correct the face turn at a distance generally does not produce secondary overcorrection at near fixation.
On occasion, fusion is impossible in a patient with DS, usually because bilateral involvement or a vertical deviation prevents fusion with any head posture. In these cases, the strabismus itself rather than the secondary head posture can be the main indication for surgical correction.
When the affected eye is adducted, an upshoot, downshoot, or retraction can be sufficiently disturbing to the patient or the parents of the patient to warrant surgical treatment. The retraction may be accentuated by the face turn that is seen with the most common esotropic form of DS; this places the affected eye in an adducted position. In severe cases, clinically significant enophthalmos and pseudoptosis is present even in primary position. A reduction of 50% or more of the width of the palpebral fissure during adduction compared with primary position has been suggested as an indication for surgical treatment of the retraction.
Contraindications
Many patients with DS are orthophoric in primary position or have only an insignificant face turn. In these cases, surgery is not indicated unless another manifestation of DS, such as an upshoot or a downshoot, is causing some hardship. The fact that a patient seeks evaluation does not necessarily indicate a desire for surgical correction. Often, it is not the manifestations of the condition themselves that have motivated the consultation, but rather, a concern that they indicate some ominous underlying intracranial disease, especially in parents who bring their child with DS to be examined.
If discussion with the patient or the patient's parents reveals that fear of life-threatening disease rather than a manifestation of DS is their chief concern, then explanation and reassurance may be all that is needed.
Because fusion can usually be achieved by means of a face turn, most children with DS have normal binocular function and stereopsis. Therefore, in distinction to congenital esotropia, for which the goal is to restore ocular alignment as early as possible, the goal in DS should be to avoid disrupting normal binocular development. Therefore, a young age is a relative contraindication for surgery.
Severe cases may warrant early treatment, but it is usually preferable to delay surgery until patients are aged 4-5 years. At this age, patient cooperation facilitates detailed examination, and their visual system is relatively mature and less susceptible to damage from a temporary disruption of binocularity than before, as can occur postoperatively if an unfavorable response to surgery occurs.
Procedures
Recession of the medial rectus muscle
Recession of the medial rectus muscle in the involved eye aligns the eye but does not improve abduction beyond the primary position. In rare cases, large weakening procedures performed on the medial rectus lead to consecutive exotropia because of poorly understood mechanisms. Small medial rectus recession in the opposite eye helps the involved eye in primary position by application of the Hering law.
Resection of the lateral rectus muscle is avoided because it increases retraction and does not improve abduction. Recession of the ipsilateral medial rectus muscle is the mainstay of surgical treatment for DS. In patients with esotropia in primary position, this procedure improves the face turn and the esotropia by weakening the antagonist of an effectively paretic lateral rectus muscle.
Medial rectus recession alone may improve the enophthalmos and vertical overshoots in adduction, in part by limiting adduction of the eye. However, additional measures are usually needed to adequately manage these problems if they are severe. To effectively reduce or eliminate the face turn, recession must be larger than that typically performed on a medial rectus muscle, often in the range of 8-10 mm, as measured from the original insertion.
Standard recession or a hang-back technique may be used; this can decrease the difficulty of the procedure when a large recession is needed. When clinically significant mechanical restriction due to contracture or fibrosis of the medial rectus muscle is present, a relatively small recession is usually sufficient. A large recession can easily cripple a fibrotic muscle, which often has contractile properties that are almost as severely compromised as its elastic properties.
For adults with mechanical restriction of the medial rectus muscle, techniques for adjustable-suture recession is helpful for finding the best compromise between adequate relief of the face turn and crippled adduction.
Recession of the contralateral medial rectus muscle in addition to the ipsilateral medial rectus muscle may be performed in cases in which the patient has primary position esotropia greater than 20 diopters and marked co-contraction of the lateral rectus muscle, as shown by limited adduction, massive retraction, or reduced adduction saccadic velocities.
Recessing the contralateral medial rectus muscle may allow for decreased recession of the ipsilateral medial rectus muscle. However, millimeter for millimeter, this procedure is less effective than it is in concomitant esotropia because it is an attempt to treat the large secondary deviation. The ipsilateral medial rectus recession still must be sufficient to permit abduction of the ipsilateral eye to at least midline; otherwise, the addition of a contralateral medial rectus recession, regardless of size, cannot correct the face turn. Recession of the contralateral medial rectus muscle may also reduce the long-term risk of contracture of the ipsilateral medial rectus muscle by reducing its tonic innervation (Hering law).
Vertical rectus muscle transposition
Transposition of the vertical rectus muscles to a position adjacent to the lateral rectus, with or without recession of the ipsilateral medial rectus, has been suggested as a means of correcting the primary position esotropia, of improving abduction, and of enlarging the field of single binocular vision.
This procedure may provide better abduction than that possible with medial rectus recession alone. However, it is more difficult to perform, that the other procedure; it may exacerbate retraction, upshoot, or downshoot; it can create new vertical deviations; and, particularly in adults in whom medial rectus recession is performed concurrently, it poses some risk of anterior segment ischemia. This procedure should probably be considered only as primary treatment for patients with no abduction at all, for those with minimal retraction, and for those with no upshoot or downshoot.
Lateral rectus muscle recession
Exodeviation in primary position with a face turn away from the side of the affected eye is an uncommon presentation of DS. In this case, the face turn is treated with recession of the ipsilateral lateral rectus muscle. In patients who have both primary position exotropia and a marked upshoot or downshoot, a lateral rectus recession is usually combined with an additional measure—either a Y-splitting procedure or a posterior fixation suture—to minimize sideslip of the lateral rectus muscle across the globe.
Recession of the lateral rectus is also effective in reducing the upshoot or downshoot during adduction when it is due to sideslip of a tight lateral rectus, particularly if it is combined with recession of the medial rectus. Recession of the lateral rectus muscle alone improves the retraction with adduction somewhat. However, large recessions (10-12 mm) of both the medial and lateral rectus muscles of the ipsilateral eye are effective, particularly when enophthalmos in primary position is a major complaint. As with medial rectus recessions, recessions of the lateral rectus muscles should be decreased when restriction of the lateral rectus muscle is clinically significant.
Y-splitting procedure
Co-contraction of the medial and lateral rectus muscles on attempted adduction can cause a striking upshoot or downshoot of the eye. This effect is attributed to sideslip of a tight lateral rectus over the globe (mechanical factors) in most cases.
The Y-splitting procedure effectively results in a broad lateral rectus insertion that stabilizes its position and prevents it from flipping superiorly or inferiorly over the globe, eliminating or greatly reducing the upshoot or downshoot of the affected eye in attempted adduction. The Y-splitting procedure may be combined with a moderate recession of the lateral rectus muscle, particularly if associated primary position exotropia exists.
Placement of a posterior fixation suture
Placement of a posterior fixation suture on the lateral rectus muscle can effectively prevent slippage of the muscle belly over the globe. This may be used as an alternative procedure to treat upshoots and downshoots. As with the Y-splitting procedure, posterior fixation suturing can be combined with a lateral rectus recession when appropriate.
Procedures to weaken the vertical rectus and inferior oblique muscles
Besides the mechanical factors discussed above, innervational factors, presumably aberrant co-contraction of the vertical rectus or inferior oblique muscles, may contribute to an upshoot or downshoot in some patients with DS. When vertical deviation in primary position is clinically significant, surgery on the horizontal rectus muscle alone generally does not correct the problem adequately, and recession of the appropriate vertical rectus muscle is needed. The upshoot in adduction that often is seen in DS bears some resemblance to inferior oblique overaction, but inferior oblique weakening procedures usually are ineffectual in correcting the problem.
Expected results
Horizontal muscle recession reportedly eliminates the face turn in 79% of patients and substantially reduces the face turn in most of remaining patients. In a patient with esotropic DS, recession of the ipsilateral medial rectus muscle usually provides a modest improvement in abduction if some abduction past the midline was present preoperatively; however, this improvement often comes at the expense of some reduction of adduction. The field of single binocular vision is shifted to include primary position but remains relatively unchanged in size.
On the contrary, if the patient does not have abduction past the midline before surgery, medial rectus recession that is sufficiently large to eliminate the primary position esotropia and face turn substantially limit adduction while providing little or no improvement in abduction.
The size of the field of single binocular vision may be reduced under the circumstances just described, though the addition of a contralateral medial rectus recession, possibly with a Faden procedure, may reduce or eliminate the reduction. Vertical rectus transposition may provide improve abduction and enlarged the field of single binocular vision, particularly in patients with problems with the latter. However, no studies have been conducted to directly compare the efficacy of transposition with that of unilateral or bilateral medial rectus recession.
When they are due to mechanical factors, upshoots and downshoots can usually be satisfactorily reduced or eliminated by performing Y-splitting, posterior fixation, or large recessions of both ipsilateral horizontal rectus muscles. In contrast, when the upshoot or downshoot is due to innervational factors, appropriate recession of a vertical rectus muscle eliminates the vertical deviation in primary position, but some vertical deviation usually remains when the eye is adducted. Large recessions of both horizontal rectus muscles usually provide satisfactory correction of enophthalmos in primary position, but some retraction in adduction remains. FOLLOW-UP Section 7 of 9
Author Information Introduction Clinical Differentials Workup Treatment Follow-up Miscellaneous Bibliography
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