OCULAR SURGERY NEWS U.S. EDITION May 25, 2009
Woman referred for gradually progressive esotropia
by Matthew Swanic, MD; Mitchell B Strominger, MD
| |
Jeffrey Chang |
Vivek Chaturvedi |
A 56-year-old woman was referred to the pediatric ophthalmology and
strabismus service at the New England Eye Center for gradually progressive left
esotropia with accompanying hypotropia.
The patient stated that the condition began approximately 3 years prior
to presentation and that she had never had any problems with eye misalignment
earlier in her life. The patient denied any pain or ocular swelling at any time
during the course of the progression. She denied any diplopia but has had poor
vision for years secondary to very high myopia in both eyes.
Ocular history was significant for pathologic myopia in both eyes and
dense nuclear sclerotic cataract in the left eye. The patient had no history of
thyroid abnormalities, and medical history was significant only for
hypertension and osteoporosis. She denied prior head or ocular trauma. She had
no family history of strabismus or amblyopia. The patient’s review of
systems was unremarkable.
Examination revealed visual acuity of 20/400 in the right eye and hand
motions in the left eye. Current glasses prescription was –16.00 +2.50
× 180 in the right eye and –15.00 +4.00 × 180 in the left eye.
IOPs were 16 mm Hg in both eyes, and pupil exam showed no afferent pupillary
defect.
Anterior segment exam was unremarkable except for the presence of a
densely brunescent cataract in the left eye that prevented visualization of the
fundus. Motility exam revealed a left eye that was fixed in esotropia and
hypotropia in all fields of gaze (Figure 1). Forced ductions were performed in
the office and revealed restriction of ocular motility in the left eye. Fundus
exam of the right eye showed a myopic fundus (Figure 2). An MRI scan was
obtained and showed no extraocular muscle thickening, but it did show abnormal
muscle pathways of the superior and lateral rectus muscles. The superior rectus
was shifted nasally while the lateral rectus had shifted inferiorly (Figure 3).
Both globes were markedly enlarged, most likely secondary to myopia. Additional
MRI sections revealed superotemporal prolapse of the left globe.
What is your diagnosis?
Motility disturbances
Evaluation of a patient with motility disturbances should include a
determination as to whether the problem is restrictive or paralytic. This was
attempted with forced ductions, which revealed the restrictive nature of the
patient’s disease. After this determination was made, the MRI was ordered,
and it revealed abnormal locations of the superior and lateral rectus muscles.
These findings coupled with a long-standing history of pathologic myopia made
the diagnosis apparent.
Diagnosis
The patient was diagnosed with convergent strabismus fixus secondary to
high myopia. This is a rare disorder that commonly presents as a gradually
progressive esotropia. Over time, without intervention, patients progress to
having an eye that is fixed in adduction and is also noted to have substantial
restriction of elevation. This final fixed position of the eye gives it the
name strabismus fixus. Many patients will subsequently go on to develop the
condition in the opposite eye. Sturm et al presented a case of a patient
functionally blind due to this extreme eso/hypo deviation in both eyes that
completely hid both of his corneas.
Discussion
Myopic strabismus fixus is thought to be secondary to prolapse of the
globe out of the muscle cone. This prolapse has been postulated to be secondary
to the enlargement of the eye seen in very high myopia. This prolapse of the
globe leads to a shift in the muscle pathways of the superior and lateral
rectus muscles, nasally and inferiorly, respectively. It is important to note
that the locations of the extraocular muscle insertions are not changed. The
shift of the lateral rectus inferiorly is thought to lead to infraduction and
decreased abduction ability, while the shift of the superior rectus medially
likely causes adduction and decreased elevation ability.
A study by Aoki et al that evaluated 16 patients with acquired esotropia
secondary to high myopia with MRI found similar muscle pathway deviations to
our patient. They evaluated the muscle pathways and level of globe prolapse and
found that patients with greater degrees of prolapse and muscle deviations
showed greater motility abnormalities. They also studied patients with high and
moderate myopia who did not show any ocular motility problems and found that
they had no abnormalities in eye muscle position. Of note, the average axial
length of patients with high myopia in their study was 29.9 mm while the
average axial length of high myopes with motility problems was 33.9 mm. This
suggests that the markedly increased axial lengths may be responsible for the
globe prolapse and motility disturbances seen in myopic strabismus fixus.
Management
The optimal surgical correction of myopic strabismus fixus is not yet
known. Mild cases have been successfully treated with medial rectus recession
with lateral rectus resection. This has not been effective for patients with
severe disease, such as our patient. Yamada et al published a surgical
procedure involving hemi-transpositions of the superior and lateral rectus
muscles with scleral fixation 7 mm from the limbus. They combined this with
medial rectus recession and reported good outcomes. Wong et al subsequently
published their experience with performing a loop myopexy in which the superior
and lateral rectus muscles are looped together in an attempt to restore the
more lateral position of the superior rectus combined with the more superior
position of the lateral rectus. They had to combine this procedure with medial
rectus recession to further improve alignment.
 Figure
4. Lateral rectus heads inferiorly. |
 Figure 5.
Superior rectus heads medially. |
 Figure 6. Improvement in left eye position with remaining
esotropia. |
Because of our prior experience with the procedure, the patient was
scheduled for loop myopexy as described by Wong et al. In the operating room,
the lateral rectus muscle pathway was found to be heading inferiorly (Figure
4). As expected, the superior rectus was noted to be heading medially (Figure
5). Both muscles were isolated and looped together with nonabsorbable suture,
and the conjunctiva was closed.
On postoperative day 1, a marked improvement was noted in the position
of the left eye in primary gaze (Figure 6). The patient was extremely pleased
with her eye position. We will re-evaluate the patient in the coming months and
may perform medial rectus recession to correct the remaining esotropia in
primary position. She will also be evaluated for cataract surgery in the left
eye, as her new eye position will greatly facilitate the removal of her densely
brunescent cataract.
References:
- Aoki Y, Nishida Y, Hayashi O, et al. Magnetic resonance imaging
measurements of extraocular muscle path shift and posterior eyeball prolapse
from the muscle cone in acquired esotropia with high myopia. Am J
Ophthalmol. 2003;136(3):482-489.
- Godeiro KD, Kirsch D, Tabuse MK, Cronemberger M. Yamada’s
surgery for treatment of myopic strabismus fixus. Int Ophthalmol.
2008 June 21. [Epub ahead of print].
- Sturm V, Menke MN, Chaloupka K, Landau K. Surgical treatment of
myopic strabismus fixus: a graded approach. Graefes Arch Clin Exp
Ophthalmol. 2008;246(9):1323-1329.
- Wong I, Leo SW, Khoo BK. Loop myopexy for treatment of myopic
strabismus fixus. J AAPOS. 2005;9(6):589-591.
- Yamada M, Taniguchi S, Muroi T, Satofuka S, Nishina S. Rectus eye
muscle paths after surgical correction of convergent strabismus fixus. Am
J Ophthalmol. 2002;134(4):630-632.
- Matt Swanic, MD, and Mitchell B. Strominger, MD, can be reached at
Tufts Medical Center, 750 Washington St., Box 450, Boston, MA 02111;
617-636-4219; fax: 617-636-4866; Web site:
www.neec.com.
- Edited by Jeffrey Chang, MD, and Vivek Chaturvedi, MD. Drs. Chang
and Chaturvedi can be reached at New England Eye Center, Tufts University
School of Medicine, 750 Washington St., Box 450, Boston, MA 02111;
617-636-4219; fax: 617-636-4866; Web site:
www.neec.com.
