Adult Strabismus: it’s never too late

In his Costenbader lecture “Adult Strabismus,” presented 20 years ago this month, William E. Scott reported his results on the surgical outcomes of 892 adult patients who underwent strabismus surgery and concluded, “It is clear that adult strabismus is more than just a cosmetic problem and treatment is worthwhile.”1 The ensuing two decades have witnessed explosive progress on adult strabismus by AAPOS members and others.

But are we doing enough?

Abstracts referencing “adult strabismus” in this journal have more than doubled in the last 5 years. The AAPOS website lists “adult strabismus” as one of the most common search terms and now provides three educational videos, an updated policy statement,2 and several pages of information under “Frequently Asked Questions.” The Adult Strabismus Workshop enters its 16th year at the annual AAPOS meeting as one of the most highly attended workshops. Efforts have also extended beyond our organization to reach primary care physicians and other eye care professionals with more accurate information about misaligned eyes in the adults. Two of our members, David Stager Sr and Jonathan Holmes, recently participated in the first joint workshop on adult strabismus at the 2013 American Optometric Association meeting. Burt Kushner’s recent “The efficacy of strabismus surgery in adults: a review for primary care physicians”3 and his forthcoming “The benefits, risks, and efficacy of strabismus surgery in adults”4, which will appear in an optometric journal, also clearly indicate how much committed individuals are working toward a greater appreciation for the work at hand. Are we prepared to meet the potential demand?

Consider the magnitude of the problem. Estimates on the prevalence of adult strabismus center on 4% but may run as high as 5.6%.5,6 Assuming 4% prevalence, 9.68 million adults in this country are likely affected. This means roughly 11,500 adults with misaligned eyes for each current AAPOS member. If we captured only a tenth of these patients, that would still yield almost 100 new adult patients per member per month. These numbers are staggering and likely unmanageable, especially considering, according to census data, that there will be an additional 32 million adults in the United States in 15 years and 65 million more by 2050.

Despite these impressive estimates, the vast majority of adult strabismus is undiagnosed, and even fewer cases ultimately receive surgical correction. Repka and colleagues5 found that only 0.68% of Medicare beneficiaries (age 65 years and older) in 2010 were diagnosed with strabismus. Of greater concern, only 2.6% of those diagnosed underwent surgical correction. What accounts for this disparity?

Myriad obstacles have prevented adults from not only seeking care but also undergoing surgical correction when indicated. Primary among them is the misinformation that exists among patients and referral sources. Kushner3,4 identified the four most common reasons adult patients give for not seeking help: (1) nothing can be done for adults with strabismus; (2) strabismus surgery in adults is not effective; (3) surgery is “cosmetic” and does not improve binocular function; and (4) there is a high risk associated with strabismus surgery, including a substantial risk of intractable postoperative diplopia. Similar reasons were reported by patients who ultimately did decide to seek care and who underwent surgery long after the onset of their ocular misalignment.7

A volume of research has shown adult strabismus surgery to be successful, long lasting, with relatively few risks.1,8-10 Kushner has reported the incidence of permanent postoperative diplopia to be <1% in patients with longstanding strabismus and nonexistent in patients who showed no diplopia on preoperative prism testing.11 In addition, the benefits are significant both in functional as well as psychosocial parameters. Specifically, the improvements in self-esteem and psychological health are often underestimated.12 In his 1999 editorial on adult strabismus, Rosenbaum argued that “we should begin to view our adult patients with strabismus as having a disability that requires compassion from both physicians and the general public.. As part of our expanding compassion, we should be aware that patients may require socialization, rehabilitation, occupational counseling and psychotherapy.”13 underscoring Hippocrates’ admonition, “It is far more important to know what person the disease has than what disease the person has.”

While the functional benefits are well documented in patients who are diplopic or acquire strabismus after visual maturation, many have questioned whether these benefits extend to nondiplopic patients, most of whom developed strabismus before visual maturation. Critics allege that surgery in this group is merely “cosmetic.” In this issue of the Journal of AAPOS, Liebermann and colleagues14 examine this very question in 20 adult nondiplopic patients who underwent strabismus surgery using a patient-derived health-related quality of life (HRQOL) Adult Strabismus 20 (AS-20) questionnaire. Of the 10 function-related items, there was notable improvement postoperatively in 9 including concentration, depth perception, hobbies, strain, reading, stress, and worry. Other studies have also demonstrated binocular and other functional benefits in this subset of patients,9,15 but this is the first to detail specific improvements in a quality-of-life evaluation specifically designed for strabismus. The most intriguing aspect of this and similar studies is what the findings may teach us about deeply ingrained false assumptions regarding these patients. The data show clear and measurable benefits in binocularity and function even in adults with longstanding strabismus who are diplopia free.

I would encourage the authors to explore other questions in their research. Are there measurable aspects of visual function associated with the measured improvements in “functional” HRQOL? Was the subset of patients who also showed improvement in binocularity associated with specific strabismus etiologies? Would those patients, before undergoing surgery, have shown the potential for binocularity had they been tested in prisms?

As we move forward, challenges remain. We must continue to dismantle the misconceptions of the public, patients, and referral sources through education and outreach. We must convince insurance companies and other third-party payers of the functional benefits in these patients so that coverage will be provided. We must continue to explore new treatment modalities and support research to further elucidate the pathophysiology of adult strabismus. But without a doubt our most formidable challenge will be developing new systems and refining existing ones to meet the potential avalanche of patients. Pediatric ophthalmologists are the most appropriate specialists to provide surgical care for these adults. It is incumbent on us to proactively cultivate the desire and skills of our residents, fellows, and colleagues so that an adequate and proficient capacity exists to serve these adult patients.

I am grateful to Drs. Joost Felius and Martin Lederman for their assistance with this editorial.

  1. Scott WE, Kutschke PJ, Lee WR. 20th annual Frank Costenbader Lecture—adult strabismus. J Pediatr Ophthalmol Strabismus 1995;32:348-52.
  2. American Association for Pediatric Ophthalmology and Strabismus. 2012. Policy statement adult strabismus surgery. Accessed February 27, 2014.
  3. Kushner BJ. The efficacy of strabismus surgery in adults: a review for primary care physicians. Postgrad Med J 2011;87:269-73.
  4. Kushner BJ, The benefits, risks, and efficacy of strabismus surgery in adults. Optom Vis Sci. In press.
  5. Repka MX, Yu F, Coleman A. Strabismus among aged fee-for-service Medicare beneficiaries. J AAPOS 2012;16:495-500.
  6. Martinez-Thompson JM, Diehl NN, Holmes JM, Mohney BG. Incidence, types, and lifetime risk of adult-onset strabismus. Ophthalmology Dec 6, 2013. Epub ahead of print.
  7. Coats DK, Stager DR Sr, Beauchamp GR, et al. Reasons for delay of surgical intervention in adult strabismus. Arch Ophthalmol 2005;123:497-9.
  8. Mills MD, Coats DK, Donahue SP,Wheeler DT. American Academy of Ophthalmology. Strabismus surgery for adults: a report by the American Academy of Ophthalmology. Ophthalmology 2004;111:1255-62.
  9. Kushner BJ, Morton GV. Postoperative binocularity in adults with longstanding strabismus. Ophthalmology 1992;99:316-19.
  10. Mets MB, Beauchamp C, Haldi BA. Binocularity following surgical correction of strabismus in adults. Trans Am Ophthalmol Soc 2003;101:201-5. discussion 205-7.
  11. Kushner BJ. Intractable diplopia after strabismus surgery in adults. Arch Ophthalmol 2002;120:1498-504.
  12. Beauchamp GR, Felius J, Stager DR, Beauchamp CL. The utility of strabismus in adults. Trans Am Ophthalmol Soc 2005;103:164-71. discussion 171-2.
  13. Rosenbaum AL. Adult strabismus surgery: the rehabilitation of a disability. J AAPOS 1999;3:193.
  14. Liebermann L, Hatt SR, Leske DA, Holmes JM. Improvement in specific function-related quality of life concerns after strabismus surgery in nondiplopic adults. J AAPOS 2014;18:105-9.
  15. Dickmann A, Aliberti S, Rebecchi MT, et al. Improved sensory status and quality-of-life measures in adult patients after strabismus surgery. J AAPOS 2013;17:25-8.