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Strabismus Surgery (Eye Muscle Surgery)

The surgeon told us, "There is nothing wrong with your child's eye muscles, but that's how we fix it." Anonymous Parents, after a strabismus surgery consult for their coss-eyed child

Strabismus (sometimes called "lazy eye") is the condition where the eyes are not properly aligned relative to each other.  That is, they are not pointing at the same thing at the same time. The most common version of this condition is known as crossed eyes (convergent strabismus or esotropia), where one or both eyes turn in towards each other. One or both eyes can also turn outward (divergent strabismus or exotropia). Although it is less common there can be a vertical alignment problem. All of these conditions are often treated with strabismus surgery  when they are cosmetically noticeable. There are actually many instances of strabismus where the eyes look straight to the untrained eye. Very few cases of strabismus actually involve damaged eye muscles.

The results of strabismus surgery (eye muscle surgery) are unpredictable and often cause serious secondary problems of their own.  Sometimes eye muscle surgery results eyes that appear straight but are not really working well as a team. Many, if not most, cases of strabismus are caused by the inability of the brain to use the eyes together. There is rarely an actual eye muscle problem; it is usually a brain issue. Eye muscle surgery often creates confusion in the brain and makes eye teaming even more difficult unless vision therapy is done.

People are not always adequately informed when consulting surgeons about their condition and the possible long-term consequences of strabismus surgery. Surgeons generally believe that strabismus surgery is the only approach to treating strabismus. This is profoundly untrue. Surgeons tell parents that there is nothing wrong with their child's eye muscles but that eye muscle surgery is still the way to treat the problem. Behavioral optometry offers safe, non-invasive alternatives to strabismus surgery – vision therapy and therapeutic lenses - for people with every type of strabismus. Nothing works all the time, including strabismus surgery. In fact, at least half of those who have strabismus surgery need more than one operation.

Strabismus Surgery

Steve Gallop, O.D., F.C.O.V.D.  (unpublished manuscript written in 1999)

Over the past ten years I have had the good fortune to work with many adults who have had strabismus surgery or surgeries at some point in their lives.  All of these people had first undergone strabismus surgery as young children with varying periods of relative postoperative calm.  Some had no clear notion that any difficulties might be associated with the surgery, some experienced no apparent difficulties for a period of time followed by growing discomfort, and others could pinpoint to the day when the surgery “wore off.”  The presenting complaints have varied although there has been a general consensus that visual performance is labored at best and wildly variable at worst.

Standard wisdom holds that there is no way to improve comfort and performance for these people. Many have had multiple surgeries to attempt to bring about relief or improvement, almost always without success. Imagine my surprise when the impossible happened. These people were experiencing increases comfort and improved performance through visual training and therapeutic lenses. As a result of this success I have decided to attempt putting together something of a manual for prospective candidates for strabismus surgery as well as for those who have undergone strabismus surgery. My goal is to provide accurate, comprehensive, up-to-date information on what to expect as well as possible alternatives and/or adjunct treatment modalities for these individuals. Strabismus is one of the most common visual problems in children affecting 2-5% of newborns to children four years of age.1  Considering the frequency with which these procedures are performed it could be very useful for the general public to have such materials readily available.

Strabismus surgery is the second most frequently performed ophthalmologic procedure after cataract surgery.2,3  According to one author, one of the great values of this procedure is its relatively low cost compared to other surgical procedures. “That strabismus surgery is compensated at a lower rate, than for example, cataract surgery, suggests that strabismus surgery is an excellent value.”2  So, if you’re in the mood for surgery and don’t have a lot of money, this is the procedure for you.  Otherwise, you had best be very wary.  It is well accepted that by performing the exact same procedure on two individuals one should not expect identical results.4,5,6,7  My recent search of the literature shows that the standard for a successful outcome is 10 prism diopters either side of orthophoria as measured at four weeks to six months postoperatively.3,4,5,8,9

Some authors have begun to realize that this follow-up period is inadequate due to the frequency of deterioration of ocular alignment over time3 and that these patients should be reevaluated after four years to get a more accurate picture of the efficacy of these procedures.8,10 As many of us know, even four years is probably insufficient. If there is any meaningful cut-off time for the staying power of strabismus surgery it would be no less than five years.

The prevalence of reoperations is so great that most of the literature mentions the need for multiple surgeries very matter of factly1,2,4,5,11 and I lost count of the number of articles with the word “reoperation” in the title. Apparently it is not really considered a negative factor if an individual should need multiple procedures.5,10,11  “Looked at another way, if the eyes are straight at any time after strabismus surgery, the surgery itself has been effective.  Moreover, strabismus surgery that is done carefully can be repeated effectively and without compromise to the patient.”2

Proof of the prevalence of this way of thinking is demonstrated by one of the most significant advances in these procedures, the principles of which “have remained essentially unchanged since the mid-18th century, when this surgery was first done”2 – adjustable sutures.4,12 This technique so blatantly admits the uncertainty surrounding strabismus surgery as to beyond the obvious, verging on the ridiculous. Other exciting innovations which appeared around the same time (the late 1970s) were the posterior fixation suture, which creates a permanent union between rectus muscle and sclera at a point posterior to the equator of the globe, and botulinum toxin injection, used to weaken extraocular muscles.12 These two innovations have not achieved the popularity they had hoped for but adjustable suturing remains staggeringly popular.

This is not to say that strabismus surgery should never be done, although it is probably safe to say that it should never be done in the absence of pre and post-operative therapy.  Having had recent experience with surgery aimed at providing a close to normal functional outcome, it is obvious to me that follow-up therapy is essential to the achievement of such a goal.  I do not believe the fact that the predicted, desired result was nothing like the actuality was in any way the fault of the therapy regimen of the therapist and I can assure you that it was not a problem of patient compliance.

It seems only a matter of common sense that any insult to functional tissue, be it accidental or otherwise, whether or not there is surgical intervention, should be followed by a functionally oriented therapeutic regimen. If a muscle is strained or sprained it is first rested and then exercised. If a muscle is damaged and repaired, the protocol is the same. Even if we consider eye muscles to be at fault in the majority of strabismic cases,1 which is of course akin to using the measure of visual acuity as the determining factor in overall visual performance, the almost total lack of active follow-up care is mind boggling. It is fairly well accepted that there is more to sensory fusion, which is mentioned frequently throughout the literature (sensory fusion that is) than ocular alignment. Why then is there no attempt made to maximize the possibility of achieving this goal?

The cause of strabismus would seem to be and important issue in determining a course of treatment. In my search of the literature, etiology is typically mentioned only when describing those cases excluded from a retrospective study. Etiology was also mentioned when describing the fact that the origins of strabismus are still a point of disagreement as has been the case since the beginning of the Worth/Chavasse debate, one stating that sensory fusion was at the root of the problem and the other claiming it to be a motor defect.12,13 There also continues to be complete disagreement on when to perform these surgeries.10,15 It has recently been suggested that there is a significant difference in results and surgical effects among developmentally delayed children including those with cerebral palsy, hydrocephalus, seizure disorder, and Down Syndrome.14

Another issue which I did not see mentioned even once was the effect such surgeries have on an individual’s performance, behavior and psyche. The closest thing I saw was mention of changes in spatial perception post-operatively.  I have witnessed various effects which are directly attributable to the surgery and many that are very likely to be the result.  One patient spent years battling with her surgeon over her complaints of severe discomfort whenever trying to use her eyes; she was told that it was all in her head and was summarily dismissed as a nuisance.  Another patient came into my office with a severe eye and head twitch, severe in both magnitude and frequency – I am amazed that he has not sustained a neck injury. A six year old with whom I have recently begun working had surgery within the past year and reported that he eyes “feel like they’re melting.”

We are constantly required to defend our method of treatment based on medical necessity. One article cited “Compromised Appearance (Poor Self Image)” under the heading “Indications” for surgery this was listed after diplopia and deficient motor fusion and prior to abnormal head posture and nystagmus.2(p.312) It was also surprising to realize that as new procedures are developed, they are tried out on human guinea pigs as seemingly routine events.16 Of course, my perspective, most strabismus surgery seems fairly experimental and my search of the literature has done nothing but reinforce this perception. There is frequent criticism that our concepts and methods are not grounded in scientific proof. Where is the scientific proof of the efficacy of strabismus surgery? The causes of the conditions are poorly understood, the procedures have an effectiveness that varies wildly, there is no way to predict the amount of change in eye alignment per amount of surgery. The answer to this problem is adjustable sutures, a procedure which is now skewing the data since these adjustments are not considered reoperations. There is no guarantee nor any way of predicting whether or not the immediate postoperative realignment of the eyes will remain intact or for what length of time. There is little data on the effects these procedures have on binocular integration; what data there is in this regard is as inconclusive as all the other data. Actually, calling this data inconclusive is a little unfair. There is a fairly consistent pattern in all this literature. The concepts, procedures and results of strabismus surgery in general are extremely weak from the ground up. Perhaps another 100 years of trial and error will shed more light on all aspects of strabismus surgery. In the meantime optometric vision training continues to achieve better results in at least as many cases with none of the drawbacks of surgical intervention.

It has even been found that there was no significant difference in the outcomes of surgeries performed by specialists as compared to those performed by generalists.3  While this finding was quite unnerving to me, the authors found it to be “reassuring.”

 Further reading on strabismus and strabismus surgery:

Groundbreaking Research! Treatment After Age 7…
New Scientific Research Contradicts Popular Beliefs and Medical Theories Regarding Age Limits for Successful Treatment of Lazy Eye by Susan R. Barry, Ph.D. and Rachel Cooper
 

Age is Not a Limiting Factor in Fixing Lazy Eye or Amblyopia by Rachel Cooper

Why Are Older Children, Teenagers and Adults with Lazy Eye Still Being Told That Nothing Can Be Done for Them? by neurobiologist Susan R. Barry, Ph.D. and Rachel Cooper
 

References

1. Nelson LB. Calhoun JH. Harley RD. eds, Pediatric Ophthalmology, third ed. Philadelphia. WB Saunders Co. 1991.

2. Helveston EM. The value of strabismus surgery. Ophthalmic Surgery, 1990 May: 21(5):311-317.

3. Lipton JR. Willshaw HE. Prospective multicentre study of the accuracy of surgery for horizontal strabismus. Brit J Ophthalmol. 1995; 79:10-11.

4. Wisnicki HJ, et al. Reoperation rate in adjustable strabismus surgery. J Ped Ophthalmol and Strab. 1988; 25(3):112-114.

5. King RA, et al. Reoperations for esotropia. J Ped Ophthalmol and Strab. 1987; 24(3):136-140.

6. Mims, et al. Variability of strabismus surgery for acquired esotropia. Arch Ophthalmol. 1986; 104:1780-1782.

7. Kennedy R. McCarthy J. Surgical treatment of esotropia. Am J Ophthalmol. 1959; 47:508-519.

8. Maruo T. Nobue K. Iwashige H. Kamiya Y. Long-term results after strabismus surgery. Graefe’s Arch Clin Exp Ophthalmol. 1988; 226:414-417.

9. Beneish R. Flanders M. The role of stereopsis and early postoperative alignment in long-term surgical results of intermittent exotropia. Can J Ophthalmol. 1994; 29(3):119-124.

10. Teller J. Savir H. Yelin N. Cohen R. Leviav A. Elstin R. Late results of surgery for congenital esotropia. Metabol Ped Syustem Ophthalmol. 1988; 11:115-118

11. Kittleman WT. Mazow ML. Reoperations in esotropia surgery. Ann Ophthalmol. 1986; May:18:174-177.

12. Greenwald MJ. Amblyopia and Strabismus. Ophthalmol. 1987 June 94(6):731-735.

13. von Noorden GK. A reassessment of infantile esotropia. Am J Ophthalmol. 1988 Jan:105(1):1-10

14. Spierer A. Binocular function after surgical alignment of infantile esotropia. Metabol Ped Syst Ophthalmol. 1988; 11:35-36.

15. Pickering JD. Simon JW. Lininger LL. Melsopp KB. Pinto GL. Exaggerated effect of bilateral medial rectus recession in developmentally delayed children. J Ped Ophthalmol Strab. 1994 Nov/Dec: 31(6):374-377.

16. Capo H. Repka MX. Guyton DL. Hang-back lateral rectus recessions for exotropia. J Ped Ophthalmol and Strab. 1989 Jan/Feb:2 6(1):31-34.