Treatment Options for Adult Strabismus

REVIEW

Treatment options for adult strabismus

David R Stager Sr†, In the past, misaligned eyes were considered to be only a pediatric problem. We now David R Stager Jr realize that it is a common problem in the adult population, affecting as many as 4% over & George R Beauchamp the age of 15 years. There are multiple problems associated with this condition, including †Author for correspondence Department of psychosocial problems, bias and discrimination, communication skills and adverse Ophthalmology, University of vocational opportunities. In addition, these patients may have significant physical Te x as S o u t hwe s t e r n Me di c al handicaps, including double vision, suppression, loss of stereopsis and fusion, abnormal Center, Dallas, TX, USA Tel.: +1 214 369 6434; head posture and abnormal field of vision. Driving skills may also be impaired. There is Fax: +1 214 696 6273; often a long delay in appropriate strabismus correction in these patients due, in part, to E-mail: [email protected] antiquated professional advice. The importance of strabismus treatment in adults and the outlook for successful treatment with modern techniques is the rationale behind this review. The heartfelt overwhelming joy that patients express when told that their years of suffering may be over with modern treatment options is extremely moving.

Misaligned eyes in adults has increasingly referred to as after visual maturation onset become a focus of eye muscle doctors. Manage- (AVM). Misalignment from childhood is usually ment of these problems can be difficult; however, associated with suppression of one eye (no dou- good clinical and functional outcomes are now ble vision). With adult onset, suppression may being reported [1–10]. The American Academy of be impossible with constant double vision. Ophthalmology has recently stated that the sur- Adult strabismus can also be categorized by gical treatment of strabismus in adults is gener- the ability of the patient to control the deviation. ally safe and effective [11]. Furthermore, some The deviation can be constant, intermittent or adults with strabismus can be treated without well controlled but, in many cases, stressful to surgery (e.g., with glasses and/or prisms). Many the patient. reports have indicated that strabismus is associ- It is also divided according to the direction of ated with both functional deficits and psychoso- the deviation. It can be a crossing problem cial problems [4,12–17]. The normal function of (esotropia [ET]) or an outward deviation (also the visual system requires that the eyes be prop- known as wall-eyed), referred to as exotropia erly aligned so that the image can be simultane- (XT). A vertical deviation is referred to as hyper- ously perceived by the occipital cortex. tropia (HT) and, by convention, we refer to the Repositioning the eyes for normal function is eye that is higher. RHT would refer to the right not a cosmetic problem to beautify something eye being higher or the left eye being lower. that is already normal, such as a face lift. Many Likewise, the term hypotropia is used to indi- reports have shown that realigning the eyes does cate the eye that is lower. A cyclotropia refers to have significant success in re-establishing binoc- an eye that is rotated compared with the other ularity as well as returning psychosocial func- eye. This can be excyclotorsion or incyclotor- tioning to a normal realm. The following is a sion. Thus, you can have an intorsion or an review of the problems of eye misalignment as extorsion that is often measured in degrees. ET, well as advantages in correcting those problems. XT and HT are all measured in prism diopters, which are equal to approximately one half of a Types degree of visual angle. Adult strabismus can be categorized according to Keywords: adults, eye the age of onset. Those that occur in early child- Incidence misalignment, ophthalmology, strabismus, hood are referred to as before visual maturation The approximate incidence of strabismus is 4% strabismus surgery onset (BVM) [18]. In BVM cases with amblyopia, in the general population. In a country of strabismus surgery does not improve the ambly- 300 million, of which 240 are adults (16 years part of opia but may improve peripheral fusion. Those of age and older), one could surmise that there that occur after the ages of 9 or 10 years are are almost 10 million adults in the USA with

strabismus. This is certainly a very common dis- • Straightening the eyes will cause double vision order that may be seen in relatives, friends and • Straightening the eyes is only cosmetic in the public at large. • The problem will always come back • The eye surgery is very risky Importance of strabismus • Eye muscle surgery is not very successful One of the most common forms of nonverbal • This surgery is very painful communication is eye contact. We all maintain eye contact when communicating with others. When • Many patients are too old to have this done there is a misalignment of one’s eyes, it can lead to • Patients should just get used to this handicap quite serious psychosocial problems [15–17,19,20]. • Eye-alignment surgery requires extensive hos- People with this condition will often avoid eye pitalization and long-term curtailment of contact. Studies have shown that people with stra- normal activities bismus report difficulty with self-image [12], secur- • Eye-alignment surgery involves removing the ing employment [14], interpersonal relationships, eye, adjusting it and putting it back in the school, work and sports [15]. These problems do socket not go away after childhood but continue into the teenage and adult years. Subjects have dem- Patient comments regarding their onstrated higher levels of distress on the Hopkins misaligned eyes Symptom Checklist compared with controls [17]. Patient comments regarding their misaligned Strabismus creates a significant negative social eyes include: prejudice and can have a detrimental impact on • Who would want to hire someone with an socialization and employability. Drivers with obvious and distracting disfigurement? esotropia have limited temporal peripheral vision. • At a grocery store checkout line, a six-year-old Traffic accidents and conviction rates are twice as boy points at you and, in a loud voice, says high in these patients as in those of age- and “Mommy, what’s wrong with that lady? Her sex-matched controls [21]. eyes are crossed” In addition to the above areas of concern, • I cannot bear to look at myself in the mirror there have recently been a number of quality-of- • Are you looking at me or that wall? life (QoL) studies to determine the importance • People think I’m dumb of good eye alignment to the QoL of the patient. The average adult strabismus patient undergo- • Why didn’t somebody tell me this could be ing surgery would give up 10% of his remaining fixed life expectancy to be rid of his strabismus prob- • I was told nothing could be done. That makes lem. The level of importance of this condition me angry to patients is comparable with that of a mild • My crossing has prevented me from getting an stroke. The improvement in the quality- advancement in my job adjusted life years (QALYs) comes at a cost of • At business meetings, I find it very difficult to approximately US$3000–6000 per surgery. look people in the eye With a mean life expectancy in these patients of 36 years, the cost per QALY (3.6 years) is New attitudes approximately US$1632 [22]. In the USA, treat- Over the past 10–15 years, there have been ments with an associated incremental cost utility extensive studies published regarding adult stra- of US$50,000 per QALY or less are generally bismus. In patients with misalignment but no considered ‘very cost effective’. Thus, adult stra- double vision before surgery, persistent double bismus is a very significant problem for these vision occurs in less than 1%. None of the patients and is cost effective to correct. patients developed double vision after surgery if no double vision occurred with corrective prism Past attitudes before surgery [23]. According to one study, 86% Old attitudes have persisted despite extensive of patients will regain binocularity following research and advancement in the treatment of strabismus surgery; even those with amblyopia adult strabismus. have binocularity in 68% [6]. Improved field of Such misguided impressions have been: binocularity occurs in esotropic patients [5,10]. Those with abnormal head tilting or turning • Nothing can be done about misaligned eyes clear in the majority of cases. There is improved after a certain age psychosocial functioning and better opportunity

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for employment and economic success [12,14,24]. several millimeters from its attachment to the A significant improvement of alignment occurs globe and, after resecting the terminal portion in more than 80% of this age group [2,18,25]. of the muscle, the suture is reattached to the In a joint statement of the American Associa- original insertion site, thus strengthening the tion for Pediatric Ophthalmology and Strabis- muscle. Muscles can also be transposed to dif- mus (AAPOS) and the American Academy of ferent parts of the globe or even to the bony Ophthalmology, strabismus was defined as an orbit in rare cases. abnormal condition. Strabismus surgery seeks to restore or reconstruct normal ocular alignment Advances in surgical treatment and is not a surgical enhancement for cosmesis. Over the last 15 years, there have been many Indications for strabismus surgery include advances in the treatment available and in the diplopia, which can occur particularly in adults understanding of the results of strabismus sur- with misalignment developing after visual matu- gery. Patients can be put to sleep for a brief ration. This is particularly the case in medical or period, usually less than 1 h in most cases. This neurologic conditions, such as diabetes, Graves procedure can also be carried out under a local disease, brain tumor, head trauma or stroke. The anesthetic, where the patient is kept semi-awake surgeon strives to align the eyes and eliminate but the eye is deadened with an anesthetic. These diplopia in the primary position and into the patients do not see or feel any aspect of the surgi- periphery as much as possible. Many patients cal procedure. We now know the importance of a can still find a corner of their vision where diplo- good preoperative health check to be sure pia may persist. Another concern is newly devel- patients can tolerate the procedure or modify oped strabismus in adults, which may represent appropriately. Adjustable sutures are being used an emergency. where the suture controlling the position of the eye is adjusted sometime during the postopera- Goals of treatment tive period before the muscle becomes scarred Goals of strabismus treatment include: back firmly to the eye. Most surgeons perform this in the operating room at the time of surgery, • Elimination or reduction of any constant or in the recovery room after surgery or in the doc- intermittent misalignment of the eyes tor’s office a day or two later. Some have adjusted • Elimination of visual confusion, defined as a muscle 3–7 days postoperatively by returning having two different images superimposed to the operating room in the rare situation (inci- onto the same space, which is particularly a dence <5%) where there is a significantly unex- problem for driving, especially at night pected result. This may cause less discomfort • Restoration of binocular vision occurs in the than adjustment in the office but may be less majority of patients, giving some depth precise. Most patients are pleased to know that perception there are two chances to make the adjustment as • Elimination of preoperative diplopia accurate as possible. Still, changes can occur as • To eliminate intolerance of prism glasses or the eye heals over a period of months, necessitat- patching ing further correction. • Restoration of the field of vision, particularly Another new development is the introduction for esotropic patients of minimally invasive muscle surgery. A better • Elimination of abnormal head posture, partic- understanding of the ultimate outcome of stra- ularly in patients with adult onset strabismus bismus surgery is being enhanced using compu- associated with a compensatory head posture, ter-based outcome studies. The strabismus such as a face turn or a head tilt surgeon now has many new techniques available • Improve psychosocial and vocational status to modify his surgical approach, such as marginal disinsertion and posterior fixation sutures. Types of treatment There are several ways of improving strabismus Prognosis in adults, including the use of glasses, prisms, Most patients obtain significant improvement botox injections, patching and surgery. Surgery from adult strabismus therapy [2,18,25]. How- involves weakening an eye muscle, usually by ever, each case has its unique characteristics and detaching the muscle at its insertion and reat- therapy must be individualized. Most patients taching it closer to its origin. The muscle can can get back to their normal activity within be resected or tightened by placing a suture 2–3 days. In 2–3 weeks, the majority of the futurefuture sciencescience groupgroup www.futuremedicine.com 309 REVIEW – Stager, Stager & Beauchamp

redness will be gone and, within 2–3 months, different techniques. Also, most studies report most cases will be completely healed. There are process rather than outcome variables, which probably 25% of strabismus patients who will are most relevant for our patients. Therefore, a need some further treatment sometime during more patient value-oriented measurement of the rest of their lives; however, this further outcomes would be welcome. One advance- treatment is usually possible. In general, stra- ment is the introduction of the Amblyopia and bismus surgery is safe and has a low rate of Strabismus Questionnaire [26,27]. complications. In addition to the risks associ- Another promising development is in the ated with anesthesia, persistent double vision evolution of chemodenervation agents [28,29], occurs in less than 1% of patients who did not such as ricin, which has a longer effect have double vision before surgery. (>2 years) than botox and which may be titrated, or chemoconstriction agents. Availability of care There are currently approximately 1000 stra- Conclusion bismus specialists in the USA, most of whom Medicine has and continues to change dramati- are interested in helping adults with strabis- cally. Life expectancy was 47 years of age no less mus problems. For further information about than 100 years ago. As recently as 25 years ago, an adult strabismus specialist in your area, the accepted attitude was that nothing can or please contact your own eye doctor. They will should be done about adults with misaligned know who is specializing in this specific area. eyes. Over the past 17 years, there has been a You can also get further information from the plethora of enlightening articles on the possi- American Association for Pediatric Ophthal- bilities, techniques, outcomes and benefits of mology and Strabismus website [101]. They correcting misaligned eyes in adults. This area have a directory as well as a section devoted to of medicine has kept up with the advances in adult strabismus. other areas of medicine. Educating ourselves and the public will help end this scourge in the Future research lives of these patients. Further information, This is one area where there is a great deal of including a bibliography on this topic, can be research and advancement ongoing. Ophthal- found on the Adult Strabismus section of the mologists recognize the importance of this field AAPOS website [101]. and the tremendous cost benefit of resolving these problems for their patients. There is still a Future perspective lack of randomized, controlled trials comparing Up-to-date medical information seems to travel slowly in many corners of medicine. However, I Executive summary would predict that the next 10–15 years will see • Misaligned eyes in adults can be treated at any age. a major shift in the attitudes of the public from an appearance-only benefit to a functional bene- • Misaligned eyes in adults can be long-standing from a childhood problem fit in the treatment of adult misaligned eyes. or of recent onset due to a medical problem. There will be a great deal of research into the • Good eye alignment facilitates both good vision and binocular vision. genetic basis of strabismus as well as manipula- tions of the muscle myofibrils to alter the course • Eye misalignment often impairs the patient’s self-image and social of strabismus. One major advancement has been confidence due to poor eye contact. the better understanding of the use of muscle • Strabismus creates a significant negative social prejudice impacting pulleys, which may lead to a better surgical socialization and employability. This problem is magnified in approach [30,31]. This should lead to an advance- third-world countries. ment of surgical techniques to more accurately • Improved alignment postoperatively occurs in more than 80% of correct the huge variety of strabismus patterns these patients. that occur. Our results will be further enhanced when a computerized database of evidence- • In patients who have no preoperative double vision, intractable based outcomes becomes available. There will postoperative double vision is a very rare complication. be a marked increase in the number of pediatric • Treatment options include glasses, prisms, botox, surgery and patching. strabismus specialists who also care for the adult population. We anticipate there will be as many • There is a tremendous need to educate the medical community and the advances in this field over the next 17 years as lay public that adults with strabismus can be treated. there has been over the past 17.

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