Strabismus, recognized from the earliest times because the eyes are readily observable, has changed little in form throughout the years. However, its causes are now well understood, and its treatment undergoes regular revision and refinement. The condition, at first, was considered to be a visitation of an evil spirit and incurable. The earliest physicians suggested treatment with the only available methods-- potions, purification, and diet. In the seventh century, masks designed to redirect the visual axes were described. Curiously, variations of this type of treatment are still advocated by some today in the form of sector occlusion, despite 13 centuries of failure!
The practice of strabismus surgery began inauspiciously in 1739 with the efforts of John Taylor (Figure 1). He is reported to have had “...a considerable amount of sense...,” according to Stewart Duke-Elder, who said Taylor undoubtedly recognized that strabismus was a muscle abnormality that could be treated by dividing the extraocular muscles.* However, Taylor’s surgery was not successful. On the contrary, Taylor is said to have been a showman who may have only snipped the conjunctiva, patched one eye, and left town before the results could be assessed. By patching the unoperated eye and having the operated eye take up fixation, Taylor’s procedure would have given the appearance of being successful since the operated eye would appear to have been ‘straightened.’ John Taylor’s position in history appears to be one of ridicule rather than honor.
Abundant showmanship and fast carriage rather than surgical skills were outstanding attributes of the first strabismus ‘surgeon’ John Taylor (1703-1772), an itinerant healer who is depicted in this eighteenth century drawing.
After Taylor, several surgeons contributed to the body of knowledge that led to successful, scientifically founded strabismus surgery. In 1752, Eschenbach made the comment “each oculist dreams from time to time that it may be possible to dissect completely or partially the offending rectus muscle”. In 1816 Dulspech, an orthopedic surgeon, performed tenotomy of the Achilles tendon as treatment for club foot with a technique not too different from strabismus surgery. Gibson experimented with extraocular muscle transection for treatment of esotropia in 1818 but did not report this until 1841. White, in 1827, made similar attempts without success. Stromeyer performed extraocular muscle tenectomy on a cadaver in 1838, and a year later, Dieffenbach performed successful myotomy of the medial rectus on a 7-year old boy with esotropia. His priority was contested by Cunier, but the honor has been granted to Dieffenbach. The year 1839 is generally considered to be the beginning of modern strabismus surgery. __________________________________________________
*Duke-Elder S and Wybar K: System of ophthalmology, Vol 6, Ocular motility and strabismus, St Louis, 1973, The CV Mosby Co.
†von Noorden GK (ed): History of Strabismology, Belgium 2002, J. P. Wayenborgh
In the nearly century and a half since its beginning with Dieffenbach, strabismus surgery has undergone many refinements, but the basic principles have changed little. The orthopedic principles that were adhered to at the beginning of strabismus surgery remain as the primary guiding factors today. To these have been added new knowledge of the central nervous system influences and psycho-physical factors related to strabismus. Understanding of neural mechanisms combined with knowledge and appreciation of both the dynamic muscle forces and the physiologic and pathologic restrictive aspects of ocular motility make strabismus surgery a science. Improved diagnostic techniques, such as passive duction testing, interpretation of differential intraocular pressure, differential saccadic velocity measurement, electrooculogram testing of nystagmus, and generated muscle force testing, have enabled more accurate diagnosis leading to more accurate surgery.
Improved imaging techniques, especially those using magnetic resonance imaging (MRI), have made possible the noninvasive morphologic study of extraocular muscles. Technical improvements in anesthesia, sutures and needles, implanted materials, antibiotics, corticosteroids, and, most recently, injectable toxins have broadened the scope of strabismus surgery. Recent studies of the origins of the most common strabismus, essential infantile or congenital esotropia, have promoted earlier surgery. Strabismus surgery, frequently done as an office procedure in its early years, is now once again done on an outpatient basis.
Taylor may have only snipped the conjunctiva, patched the eye, and then left town. He is said to have operated twice on Bach, the musician of Leipzig, who later became blind. The antics of Taylor may have been responsible for a 100-year delay in the establishment of strabismus surgery as part of the surgeon’s armamentarium.
A Myectomy of the medial rectus for esotropia, as performed by Dieffenbach in 1839, often produced a large exotropia and unsightly medial displacement of the caruncle. The so-called cure may have been only a slight improvement over the malady.
B Simple tenotomy carried out nearer the insertion reduced the number and severity of overcorrections and lessened caruncle displacement.
Strabismus surgery began with weakening procedures of the medial rectus. These procedures were first performed by transecting the muscle and often produced disastrous results (Figure 2). Shifting surgery from the belly of the muscle to the tendon reduced the number of overcorrections (Figure 3). Tendon weakening or lengthening, which avoided cutting across the full width of the tendon, was subsequently carried out using a variety of ingenious techniques. The earliest of these were performed without placing a needle and suture through the tendon. Instead, one or more incisions were made in the muscle or tendon, usually at right angles to the long axis of the muscle and crossing the midline. Later, tendon lengthening procedures used sutures. (Figure 4 & 5).
A wide variety of tendon lengthening procedures provided a safeguard against overcorrection and could also be carried out without sutures, The simple Z tenotomy (Blaskovics, 1912) is still used today for weakening an already maximally recessed muscle (Chapter 4).
A O’Connor E Abadie
B Bishop-Harmon F Verhoeff
C Blaskovics G Terrien
D von Graefe
Some modern surgeons are reporting satisfactory clinical results from tenotomy which does not cut across all fibers, but more or less nicks the muscle. Biglan reports success treating small vertical deviations by doing incomplete tenotomy of the superior rectus.
The use of sutures added to the complexity and safety, if not the effectiveness, of tenotomy. Again, the principle was that a lengthened tendon-muscle would result in reduced muscle pull and therefore produce a change in alignment, shifting the globe ‘away’ from the weakened muscle.
Late in the nineteenth century, measured recession with reattachment of the muscle to the sclera was carried out. Tendon and muscle tucking or plication; muscle advancement procedures; and, later, resection and advancement procedures were also performed (Figure 6).
A Sutures were also used to reapproximate myotomized muscles to avoid producing more than the intended result. The sutures were not placed in the sclera. They were placed only in the cut ends of the muscle and tendon. The initial use of sutures apparently was for overcorrected and not primary cases.
B Prince (1887) was credited with describing recession with the tendon actually sutured to the sclera. This procedure was the forerunner of more accurate and reproducible surgery.
C Worth (1904) described resection using sutures. This muscle shortening was accomplished with or without recession of the antagonist muscle.
Surgery of the oblique muscles began when inferior oblique weakening was carried out to treat myopia and asthenopia, not surprisingly without success. The superior oblique muscle was considered by some noli me tangere, loosely translated today as ‘off limits,’ in the early twentieth century. However, all types of oblique surgery had been described by the middle part of the twentieth century. Fink, in 1951, said "up to a few years ago, all corrective surgical measures for the obliques were not considered feasible because of anatomical difficulty.”*
Along with oblique muscle surgery and vertical rectus muscle recession and resection, extraocular muscle transfer procedures were used for strabismus caused by muscle paralysis. Although, at first, the improved alignment after eye muscle transfer procedures was thought to be due to postoperative neurologic reorientation, it became apparent from electromyographic studies that the effect of an extraocular muscle transfer procedure was mediated through mechanical factors.
Technical advances in strabismus surgery have occurred along with, and in some ways because of, advances in anesthesia. A glass of wine and a good lunch followed by a head lock and a quick surgeon were early ‘anesthesia.’ This was replaced by pontocaine, cocaine, and ether for general anesthesia, and later, a wide variety of modern agents were used.
Supporting modern anesthetic agents are the extensive and detailed monitoring devices that provide instantaneous, real-time recordings of temperature, respiration, electrocardiographic data, and oxygen saturation.
Highlights of the history of strabismus surgery from its earliest beginnings in 1739 to the present are depicted in the following drawings. They describe a wide variety of manipulations that surgeons employed to straighten the eyes by altering the state of the extraocular muscle (Figures 7-24). The statement has been made, “Those who do not learn from history are destined to repeat it.” Thus, some surgical procedures have a tendency to be rediscovered every generation or so by surgeons who may have overlooked an earlier description. Nonetheless, strabismus surgery has followed a steady progression, with improvement through innovations in the surgical technique, combined with better instruments, more reliable sutures, safer anesthesia, and a better appreciation on the part of the surgeon of neural, sensory, and mechanical factors.
*Fink WH: Surgery of the oblique muscles of the eye, St Louis, 1951, The CV Mosby Co.
Most early recession procedures involved sutures entering and exiting the conjunctiva for added security and to facilitate removal of silk sutures. Tenon’s capsule and the muscle capsule were incorporated in recessions and resections. The muscle is cut between bites of the preplaced suture to avoid ‘loss’ of the disconnected proximal muscle end. Externally placed buttons or bolsters added additional support to the recessed muscle, facilitated suture adjustment, and made suture removal easier.
Jameson’s technique for recession included several sutures anchoring the muscle to the sclera. The external sutures could be removed and loosened or tightened postoperatively if a significant overcorrection or undercorrection was produced.
A Early needles were round; had eyes for threading the suture; and in most cases, had a wire diameter greater than the thickness of the sclera. These factors made the ophthalmic needle a ‘formidable weapon.’
B Jameson admonished surgeons to keep the needle in view while passing it through the sclera, to avoid entering the globe and creating what he described as panophthalmia.
Peter’s whip stitch for securing the cut end of the muscle during recession of a rectus muscle is a sound technique that is still used today.
A A simple tuck for muscle-tendon shortening (‘strengthening’) avoided the need for placing a needle through the sclera and produced a shortened muscle without removing a piece.
B When performed near the limbus, tucking tended to produce unsightly bulk that could be cosmetically disfiguring.
Pragnen used gold buttons as bolsters to eliminate ‘cheese wiring’ of the externalized suture when carrying out resection of a rectus muscle. This technique allowed postoperative adjustment of the length of the muscle.
Peter’s modification of the Bishop tucking instrument was one of several elegant instruments that were designed to facilitate the tucking procedure. Tucking of the extraocular muscles was an early favorite muscle shortening ‘strengthening’ procedure.
An ingenious technique, the O’Connor cinch, produced minimal shortening of a rectus muscle. A large, dull needle was used to weave a multiple-strand suture through slips of the tendon or muscle. The greater the number of threads, producing a bulkier suture and a greater diameter of thread, the more shortening of the muscle is produced.
A Peter suggested fracturing the trochlea and then shifting and attaching the superior oblique muscle to a point near the medial rectus insertion. This procedure was combined with lateral rectus tenotomy or recession for treatment of third cranial nerve palsy.
B The lateral rectus was shifted for treatment of congenital absence of the inferior rectus.
A transcutaneous approach to the superior oblique tendon afforded exposure for tenectomy or tucking. Skin incisions were commonly used for exposure of both superior and inferior oblique muscles in the early twentieth century.
A1 Wheeler exposed the inferior oblique muscle nasal to the inferior rectus through a skin incision.
A2 The inferior oblique muscle was then engaged with a muscle hook.
B From that exposure the muscle could be weakened by myotomy.
C The muscle also could be shortened by a tuck.
D A curious inferior oblique ‘strengthening’ procedure performed by Wheeler was disinsertion of the muscle followed by reinsertion of the cut end into the inferior orbital rim periosteum.
E Wheeler strengthened the superior oblique muscle by advancing the central portion of the tendon. He recognized that this procedure produced decreased elevation in adduction. In addition, he recognized that shifting the tendon anteriorly produced intorsion and that posterior fibers influenced depression of the globe, a concept later credited to Harada and Ito (Jpn J Ophthalmol 8:88, 1964).
Hughes and Bogart exposed the trochlea subperiosteally, freed it, and pushed it backward several millimeters to weaken the superior oblique. This formidable procedure was accomplished with a transcutaneous approach. No reports of series of patients having this procedure performed on them were described. It is unlikely that his procedure was done widely; it indicates the imagination and ingenuity of the early strabismus surgeon. This procedure, when performed inadvertently after use of the Lynch incision for exposure of the ethmoid sinus, can produce superior oblique underaction, creating the clinical picture of superior oblique palsy which, in turn, results in diplopia for the unlucky patient.
White plicated the superior oblique tendon medial to the superior rectus using a tucking instrument. He advised placing the tuck nearer the superior rectus and away from the ‘pulley’ of the trochlea to avoid having the superior oblique tendon become hung up in the trochlea.
McLean engaged the superior oblique tendon temporally and brought the redundant loop of tendon temporally. This technique for tucking the superior oblique tendon was said to reduce the incidence of postoperative limitation of elevation in adduction by avoiding the trochlea and by reducing the likelihood of adherence of the redundant loop of tendon to the superior rectus. However, any superior oblique tuck will cause a Brown postoperatively unless the tuck is done in a loose tendon and will result postoperatively in an equal and normal superior oblique traction test (see chapter 9).
Based on a procedure originally suggested by McGuire, Fink described resection of the superior oblique tendon after detaching the superior rectus muscle. Removal of the superior rectus provided improved exposure of the superior oblique tendon.
Fink recessed the inferior oblique muscle using a recession localizer that had a 7 cm handle with 6 mm arms projecting at 90 degrees from each other and a 1 mm tip with a concavity to hold gentian violet for marking. The purpose of the instrument was to allow for an accurate 8.0 mm recession of the inferior oblique muscle. By estimation the recession could be reduced to 6.0 mm or increased to 10.0 mm.
Following the lead of Duane, White and Brown weakened the inferior oblique by disinsertion without reattachment, considering the procedure safe and effective.
Several techniques have been described for extraocular muscle transfer. The underlying principle for each procedure, except superior oblique tendon transfer, is to shift the pull of antagonist muscles to a point on the globe coinciding with the insertion of the rectus muscle lying between. The procedures shown have been described by the following:
B2 Modified O’Connor
*done in the case of an absent medial rectus
A limited number of manipulations can be performed on an extraocular muscle. The muscle can be shortened and then made to stretch, at first under tension, to the original preoperative distance between origin and insertion while presumably being more ‘effective;’ the muscle can be retroplaced with the same length of muscle going between two points closer together than the original origin and insertion; or a ‘longer’ muscle connecting the original origin and insertion can be created with myotomy or tenotomy. The insertion can be shifted to a new place on the globe, retaining the same innervation but having an altered mechanical effect.
Recent innovations in strabismus surgery include change in the arc of contact produced by the Faden operation (retroequatorial myopexy or posterior fixation suture); denervation of the inferior oblique muscle; detachment of the rectus muscles with sparing of the anterior ciliary vessels; and toxin injection at the motor end-plate to weaken a muscle’s function by interference with nerve transmission at the myoneural junction. Thermal disruption of selected eye muscle fibers has been described but has not yet been proven successful.
Early strabismus surgeons had an accurate grasp of muscle function but little appreciation for orbital fascial anatomy. Numerous references to the encountering of fat during strabismus surgery suggest that even the best surgeons found orbital fat on a routine basis. Except for referring to cutting across the conjunctiva, Tenon’s capsule, and the muscle capsule, scarcely a comment on these fascial tissues is found in early literature dealing with strabismus surgery. Modern strabismus surgery differs significantly from early strabismus surgery in its attention to detail in dealing with the orbital fascia and fat. Recent description of the anatomy of the trochlea, the inferior oblique, and especially of the muscle pulleys has provided new insight for strabismus surgeons.
These tissues are thought by some surgeons to be as important as the muscle itself. This book will emphasize the importance of technique in the belief that the surgeon who exercises impeccable care when dealing with all tissues encountered in strabismus surgery will attain better results.
Some operations that have been suggested by older surgeons or a few contemporary surgeons are not mentioned even as an option in either the historical or current sections. These omissions indicate a bias, which I hope will not result in overlooking useful procedures. Only procedures of sufficient historical interest or contemporary procedures that have some rational basis will be described. When appropriate, alternative techniques will be described.
The use of adhesives and plastic sleeves and sheets or caps mentioned in previous editions now are mentioned here only as a part of the history of strabismus surgery. Like many of the procedures shown in this chapter, these techniques sounded good, were tried, but now are relegated mostly to memory.
For a more complete review of the history of strabismology, the reader is advised to consult The History of Strabismology edited by Gunter von Noorden (J. P. Wayenborgh, Belgium, 2002).