|Year : 2018 | Volume
| Issue : 3 | Page : 160-161
Strabismus: Widening horizons
Department of Ophthalmology, Little Flower Institute of Ophthalmology, Angamaly, Kerala, India
|Date of Web Publication||17-Dec-2018|
Department of Ophthalmology, Little Flower Institute of Ophthalmology, Angamaly, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Joseph E. Strabismus: Widening horizons. Kerala J Ophthalmol 2018;30:160-1
As ophthalmologists, we are guardians and caregivers of those organs that not only receive visual stimuli but also reflect the intelligence of thought and warmth of personality. Normal eye contact is the hallmark of human race, and it is an asset to have normal alignment of the two eyes. The advantages of binocular vision cannot be overemphasized and should not be taken for granted. It becomes a liability when the binocular vision is lost. All ophthalmologists are committed to give or restore vision but a strabismologist works to restore or preserve binocular vision. We can do perfect microscopic ophthalmic surgery only if we have good binocular vision and stereopsis. Moreover, strabismus is the single most important cause of loss of binocular vision. As strabismologist, the ultimate aim is not only to give straight eyes to the patients but also to give perfect binocular vision to enjoy the beauty of this world throughout the lifetime.
Diagnosis and management of strabismus has gone through revolutionary changes in the last few decades. In this short write up, I am trying to give an insight into the current thinking and advances in the field of strabismus. One of the most important concepts is about early surgery, as early as 6–8 months of life in infantile strabismus. If precious time is wasted before fixing the eyes, and if surgery is postponed beyond 2 years the chance of restoring binocular vision falls to almost nil. In intermittent squints of infancy, we have some more time, probably up to 4 years. The concepts regarding the management of amblyopia also are going through revolutionary changes. Treatment tools extend beyond patching to binocular integrative activities. Recent advances include computerized therapy including iPad games. Activities involving perceptual learning are advantageous, for example, the I–Bit game [Figure 1] and the Tetris game. Amblyopic eye gets high contrast, and normal eye gets low contrast. The contrast level of both eyes equalizes when suppression is abolished. Recent evidence suggests that transcranial stimulation can reduce GABA-mediated suppressive interactions within the human cortex.
|Figure 1: I Bit system in which children play interactive computer games|
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In adult strabismus surgery, peribulbar block is avoided, and no injection techniques of topical anesthesia or sub-Tenon's infiltration are resorted to. Topical anesthesia with 0.5% bupivacaine 15 min before surgery allows strabismus surgery with intraoperative adjustment to yield a perfect correction, in cooperative patients. Sub-Tenon's infiltration of 3–4 cc of xylocaine into the muscle cone after opening the Tenon's capsule will make strabismus surgery painless and can be done without any injections even in very nervous patients.
The works of Demer and others with the use of high-resolution MRI scans has shed light on the significance of muscle pulleys. Heterotopic pulleys account for many types of incomitant squint and pattern strabismus. Sagging eye syndrome, the most common cause of adult divergence insufficiency is due to acquired lateral rectus (LR) pulley heterotopy. So also heavy eye syndrome of high myopia is due to pulley dysfunction. Pulley displacements can be diagnosed radiologically.
Loop myopexies and pulley posterior fixation are new surgeries based on the concept of muscle pulleys. Pulley posterior fixation sutures on the recessed medial rectus muscles reduce distance-near incomitance in accommodative esotropia with high accommodative convergence/accommodation ratio and reduce the need for bifocals.
Myopic strabismus fixus gives good results with looping superior and LR muscles with a silicone band.
Small deviations of 8–10 prism diopters are now addressed with mini-tenotomy popularized by Wright and partial tenotomy described by van der Meulen-Schot. The success of these procedures depends on perfect patient selection. Both mini-tenotomy and partial tenotomy are done under topical anesthesia, and intraoperative cover tests are done to fine-tune the correction.
Nishida's procedure of muscle transfer without splitting or dis inserting the muscle is effective in muscle aplasia and restrictive or paralytic absent extraocular muscle movement. Here, nonabsorbable sutures are passed through superior rectus and inferior rectus and pulled medially in, medial rectus aplasia and laterally in abduction deficit in Duane's or LR palsy [Figure 2]. The risk of anterior segment ischemia is avoided; at the same time, the direction of muscle pull is changed as we want to create a new adduction force or abduction force.
|Figure 2: Nishida's technique for eso Duane's with abduction deficit - Nonabsorbable suture passed through superior rectus and inferior rectus 8 mm behind the insertion and brought and sutured to sclera near lateral rectus insertion|
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Oblique muscles were once on time considered as touch me nots-due to the challenges involved with the triple actions of the obliques. However, now many surgeries of the obliques are routinely done with great success. Injection Botulinum toxin 2.5 units to 15 units into the antagonist in acute muscle palsies will make the eyes straight in 1-week time in conditions such as acute LR palsy. Injection bupivacaine to the paretic muscle and Botulinum toxin to the antagonist will allow the paretic muscle to recover fast without the opposing resistance from the antagonist.
To conclude, I would say that we have now less cumbersome procedures, more effective treatments, better surgical outcome, and we are able to address more problems than in the past. There are constant improvements, and many new developments are happening, and it is truly exciting to be part of this great fraternity.
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.
| References|| |
Mitchell L, Kowal L. Medial rectus muscle pulley posterior fixation sutures in accommodative and partially accommodative esotropia with convergence excess. J AAPOS 2012;16:125-30.
Muraki S, Nishida Y, Ohji M. Surgical results of a muscle transposition procedure for abducens palsy without tenotomy and muscle splitting. Am J Ophthalmol 2013;156:819-24.
Wright KW. Mini-tenotomy procedure to correct diplopia associated with small-angle strabismus. Trans Am Ophthalmol Soc 2009;107:97-102.
van der Meulen-Schot HM, van der Meulen SB, Simonsz HJ. Caudal or cranial partial tenotomy of the horizontal rectus muscles in A and V pattern strabismus. Br J Ophthalmol 2008;92:245-51.
[Figure 1], [Figure 2]