|Year : 2016 | Volume
| Issue : 2 | Page : 229-231
Situational restriction of elevation in adduction relieved by faden on the medial rectus
R Muralidhar1, P Vijayalakshmi1, K Sujatha1, Shashikanth Shetty1, K Malay1, Steve Rosenberg2
1 Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Hospital, Madurai, Tamil Nadu, India
2 Department of Pediatric Ophthalmology and Strabismus, New York Eye and Ear Infirmary, New York, USA
|Date of Web Publication||5-Apr-2016|
Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Hospital, Anna Nagar, Madurai - 625 020, Tamil Nadu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
We describe a patient with situational restriction of elevation in adduction in his left eye. Clinical examination pointed to instability of the left medial rectus pulley. This was corrected by Faden on the medial rectus. The importance of this relatively new concept in identifying and treating orbital pulley instability is discussed.
Keywords: Extraocular Muscle Pulley Instability, Medial Rectus Faden, Situational Restriction
|How to cite this article:|
Muralidhar R, Vijayalakshmi P, Sujatha K, Shetty S, Malay K, Rosenberg S. Situational restriction of elevation in adduction relieved by faden on the medial rectus. Middle East Afr J Ophthalmol 2016;23:229-31
|How to cite this URL:|
Muralidhar R, Vijayalakshmi P, Sujatha K, Shetty S, Malay K, Rosenberg S. Situational restriction of elevation in adduction relieved by faden on the medial rectus. Middle East Afr J Ophthalmol [serial online] 2016 [cited 2019 Dec 15];23:229-31. Available from: http://www.meajo.org/text.asp?2016/23/2/229/175883
| Introduction|| |
While investigating the cause for an eye movement disorder, it is important to undertake detailed testing to elucidate the cause for restricted extraocular motility that could be due to a restriction or a paralysis. Restrictions are suggested by a positive forced duction test and good saccadic velocities with a tethered stop while paralysis is suggested by slow saccadic velocities with a weak tug on forced generation test.
In addition to restriction and paralysis of an extraocular muscle, situational restriction can also impair eye movements. This is a relatively new concept and occurs when the order of rotational movement affects the apparent limitation of movement. To understand this, we need to understand the concept of commutativity. Commutativity from algebraic logic implies that the order of operation makes no difference to the final result, e.g. addition (a + b = b + a). On the other hand, subtraction is noncommutative, i.e. a − b ≠ b − a. Here, the order of operations affects the final result. Versions and ductions are normally commutative. This is so even if there is a muscle restriction or paresis. The eye is constrained by Listing's law (when the head is upright and held immobile): The torsion of the eye in any gaze direction is that which it would have if it had reached that gaze direction by a single rotation from the primary eye position about an axis lying in a plane. Listing's law is obeyed because the orbital pulleys confirm to the half angle rule as described by Demer, i.e., the ocular axis for subsequent rotation shifts by exactly half of shift in ocular duction. He also suggested that defects in the pulley system could make ocular movements noncommutative. Rosenberg and Shippman described situational restriction as a noncommutative eye movement that would point a defect in the pulley system and would be a useful clinical tool when dynamic magnetic resonance imaging (MRI) is not available. In situational restriction, the versions and ductions are noncommutative. This means that the final position of the eye will depend on the order of rotation of the eye. With a different order of rotation, the eye may end up in a different position. ,, We report a patient who presented to us with restriction of elevation in adduction, and examination of ocular motility was suggestive of situational restriction. This was corrected by scleral posterior fixation on the medial rectus that possibly rectified the pulley instability.
| Case report|| |
An 11-year-old male patient presented to us with crossed eyes since birth. His perinatal period was uneventful, and the developmental milestones were normal. The patient had no history of systemic illness. On examination, he was noted to have an uncorrected vision of 6/6 OU. He had an esotropia of 50 prism diopters for distance in the primary position which increased to 62 prism diopters on looking straight down and decreased to 45 prism diopters on looking up [Figure 1]. The ocular motility showed a situational restriction: There was a limitation to supraduction OS when the eye first adducted, then attempted to elevate, a limitation that was relieved when the eye first supraducted, then adducted [Video 1]. No similar motility pattern was observed in any other eccentric gaze for either eye. There was no significant refractive error on cycloplegic refraction. He had alternate suppression on a Worth Four Dot test. Examination of his anterior and posterior segments was within normal limits. No torsion was noted on fundus examination in either eye.
|Figure 1: Preoperative photograph of patient showing V pattern and restriction of elevation in adduction OS|
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The forced duction and exaggerated forced duction testing (left superior oblique) for elevation in adduction was found to be negative. Bimedial recession of 5.5 mm with scleral posterior fixation of the medial rectus (Faden) was done. A month after surgery he measured 20 prism diopters esotropia for near and distance with a residual V pattern of 15 prism diopters. The elevation in adduction was full OS [Figure 2].
|Figure 2: (a and b) Preoperative photograph shows restriction of elevation in adduction which improves on following an alternate path. The path followed to reach the tertiary position is depicted by arrows. (c) After surgery, there is no restriction of elevation in adduction|
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| Discussion|| |
A number of pulley abnormalities with potential implications in the etiopathogenesis and treatment of strabismus have been described, e.g. pulley instability, pulley heterotopy, and pulley hindrance. Dynamic MRI is used to identify these abnormalities. ,, The facilities and expertise to perform and interpret dynamic MRI are limited, more so in developing countries.
Situational restriction is a simple clinical tool to identify the presence of pulley abnormalities and infers the presence of the pulley abnormality indirectly by noting noncommutative extraocular movements.  The testing may be performed by asking the patient to look in the direction of apparent restriction by following different paths to reach the same gaze as depicted in Video 1. The apparent restriction of elevation in adduction in our patient was improved by making him look up first and then to the right. A negative forced duction made a mechanical restriction unlikely. However, it does not pinpoint the exact extraocular muscle pulley that may be involved. This may be inferred by indirect evidence.
Our patient was noted to have situational restriction of elevation in adduction OS. The presence of a "V" pattern without oblique dysfunction suggested medial rectus overaction (Urist School of thought).  As we postulated a sag of the medial rectus pulley in adduction (termed "GROPS"),  we did not downshift the medial rectus to correct the V pattern.
Scleral fixation may have corrected the extraocular muscle pulley instability. Direct pulley surgery though ideal is still in its early stages and may also be technically complex.  Scleral posterior fixation sutures on the rectus muscles are known to impact the muscle pulleys. It is useful to remember that the anteroposterior extent of the pulley sleeves encompass the region where the posterior fixation sutures are placed. The forced duction test for adduction has been reported to become positive after placing a Faden suture on the medial rectus. It is postulated that this could be due to the stretch on the connective tissues of the muscle pulley anterior to the posterior fixation suture. It has also been reported that medial rectus pulley posterior fixation is as effective as scleral posterior fixation in patients with acquired esotropia and a high Ac/A ratio. This suggests that scleral posterior fixation does impact the extraocular muscle pulleys. In our patient, it is likely that stabilization of the medial rectus pulley was achieved by Faden, which improved the elevation in adduction and restored commutativity. Faden has been shown to be most effective on medial rectus possibly because of toughness of the medial rectus pulley. , Hence, we cannot say if our results can be reproduced for other extraocular muscles. After surgery, Listing's rule is obeyed. To the best of our knowledge, there are no studies of dynamic MRI/surgical treatment in patients with situational restriction. Our case report appears to suggest that Faden on the medial rectus could correct this presumably by stabilizing the pulley. This assumption is in agreement with the current concepts of anatomy of the extraocular muscle pulleys and also the revised mechanical explanation of the Faden operation. , Further studies with dynamic MRI are needed to confirm this concept.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/ have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
We would like to acknowledge the assistance of Mrs. Sarah Shippman and Dr. Steve Rosenberg who propounded the concept of situational restriction and assisted us with preparing the manuscript.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Rosenberg SE, Shippman S. Situational restriction: Using your physical exam to differentiate pulley abnormalities from other vertical deviations secondary to restrictive conditions. Am Orthopt J 2011;61:13-8.
Demer JL. The anatomy of strabismus. In: Taylor D, Hoyt CS, editors. Pediatric Ophthalmology and Strabismus. New York: Elsevier Saunders; 2005. p. 849-61.
Demer JL. The orbital pulley system: A revolution in concepts of orbital anatomy. Ann N Y Acad Sci 2002;956:17-32.
Sharma P, editor. A-V patterns. In: Strabismus Simplified. New Delhi: Modern Publishers; 1999. p. 105-13.
Clark RA, Isenberg SJ, Rosenbaum AL, Demer JL. Posterior fixation sutures: A revised mechanical explanation for the fadenoperation based on rectus extraocular muscle pulleys. Am J Ophthalmol 1999;128:702-14.
Clark RA, Ariyasu R, Demer JL. Medial rectus pulley posterior fixation is as effective as scleral posterior fixation for acquired esotropia with a high AC/A ratio. Am J Ophthalmol 2004;137:1026-33.
[Figure 1], [Figure 2]