Adult Strabismus Preferred Practice Pattern®

AMERICAN ACADEMY OF OPHTHALMOLOGY® Protecting Sight. Empowering Lives.® © 2019 by the American Academy of Ophthalmology Published by Elsevier Inc. http://dx.doi.org/10.1016/j.ophtha.2019.09.023 ISSN 0161-6420/19 Secretary for Quality of Care Timothy W. Olsen, MD Academy Staff Ali Al-Rajhi, PhD, MPH Andre Ambrus, MLIS Meghan Daly Flora C. Lum, MD Doris Mizuiri Medical Editor: Susan Garratt Approved by: Board of Trustees September 7, 2019 © 2019 American Academy of Ophthalmology® All rights reserved AMERICAN ACADEMY OF OPHTHALMOLOGY and PREFERRED PRACTICE PATTERN are registered trademarks of the American Academy of Ophthalmology. All other trademarks are the property of their respective owners. Preferred Practice Pattern® guidelines are developed by the Academy's H. Dunbar Hoskins Jr., M.D. Center for Quality Eye Care without any external financial support. Authors and reviewers of the guidelines are volunteers and do not receive any financial compensation for their contributions to the documents. The guidelines are externally reviewed by experts and stakeholders before publication. American Academy of Ophthalmology® P. O. Box 7424 San Francisco, CA 94120-7424 415.561.8500 The Pediatric Ophthalmology/Adult Strabismus Preferred Practice Pattern® Panel of the American Association for Pediatric Ophthalmology and Strabismus Adult Strabismus Task Force members wrote the Adult Strabismus Preferred Practice Pattern® guidelines (“PPP”). The PPP Panel members discussed and reviewed successive drafts of the document, meeting in person and conducting other review by e-mail discussion, to develop a consensus over the final version of the document. Pediatric Ophthalmology/Adult Strabismus Preferred Practice Pattern Panel of the American Association of Pediatric Ophthalmology and Strabismus 2017–2019 Chair Linda R. Dagi, MD Vice Chair: Federico G. Velez, MD Jonathan M. Holmes, MD Steven M. Archer, MD Stacy L. Pineles, MD Mitchell B. Strominger, MD Matthew Simon Pihlblad, MD Evelyn A. Paysse, MD David Stager Jr, MD David R. Stager Sr, MD Hatice Tuba Atalay, MD Hilda Capo, MD Natalie C. Kerr, MD Burton J. Kushner, MD Sarah E. MacKinnon, CO, COMT Brian N. Campolattaro, MD Jason H. Peragallo, MD Reecha S. Bahl, MD The Preferred Practice Patterns Committee members reviewed and discussed the document during a series of meetings spanning 2017-2019. The document was edited in response to the discussion and comments. Preferred Practice Patterns Committee 2019 Robert S. Feder, MD, Chair Roy S. Chuck, MD, PhD Steven P. Dunn, MD Christina J. Flaxel, MD Steven J. Gedde, MD Francis S. Mah, MD Randall J. Olson, MD David K. Wallace, MD, MPH David C. Musch, PhD, MPH, Methodologist The Adult Strabismus PPP was then sent for review to additional internal and external groups and individuals in August 2019. All those returning comments were required to provide disclosure of relevant relationships with industry to have their comments considered. Members of the Pediatric Ophthalmology/Strabismus Preferred Practice Pattern Panel reviewed and discussed these comments and determined revisions to the document. The following organizations and individuals returned comments. In compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies (available at www.cmss.org/codeforinteractions.aspx), relevant relationships with industry are listed. The Academy has Relationship with Industry Procedures to comply with the Code (available at www.aao.org/about-preferred-practice-patterns). A majority (75%) of the members of the Adult Strabismus Preferred Practice Pattern Panel 2017–2019 had no financial relationship to disclose. Adult Strabismus Preferred Practice Pattern Panel 2017–2019 Steven M. Archer, MD: No financial relationships to disclose Hatice Tuba Atalay, MD: No financial relationships to disclose Reecha S. Bahl, MD: Brian N. Campolattaro, MD: No financial relationships to disclose Hilda Capo, MD: No financial relationships to disclose Linda R. Dagi, MD: Boston Neurosciences Jonathan M. Holmes, MD: Grant support from National Institutes of Health and Research to Prevent Blindness Natalie C. Kerr, MD: No financial relationships to disclose Burton J. Kushner, MD: NovaSight – Scientific Advisory Board member Sarah E. MacKinnon, CO, COMT: No financial relationships to disclose Evelyn A. Paysse, MD: No financial relationships to disclose Jason H. Pergallo, MD: No financial relationships to disclose Matthew Simon Pihlblad, MD: No financial relationships to disclose Stacy L. Pineles, MD: No financial relationships to disclose Mitchell B. Strominger, MD: No financial relationships to disclose David R. Stager Sr, MD: No financial relationships to disclose David Stager Jr, MD: No financial relationships to disclose Federico G. Velez, MD: Grant support from Omeros, Bausch+Lomb, Retrophin, Research to Prevent Blindness Pediatric Ophthalmology/Strabismus Preferred Practice Patterns Committee 2019 David K. Wallace, MD, PhD: No financial relationships to disclose Stephen P. Christiansen, MD: No financial relationships to disclose Katherine A. Lee, MD, PhD: No financial relationships to disclose Christie L. Morse, MD: Grant Support from Luminopia Michael X. Repka, MD, MBA: No financial relationships to disclose Derek T. Sprunger, MD: No financial relationships to disclose Michele Melia, ScM: No financial relationships to disclose Preferred Practice Patterns Committee 2019 Roy S. Chuck, MD, PhD: No financial relationships to disclose Steven P. Dunn, MD: No financial relationships to disclose Robert S. Feder, MD: No financial relationships to disclose Christina J. Flaxel, MD: No financial relationships to disclose Steven J. Gedde, MD: No financial relationships to disclose Francis S. Mah, MD: No financial relationships to disclose Randall J. Olson, MD: No financial relationships to disclose David K. Wallace, MD, MPH: No financial relationships to disclose David C. Musch, PhD, MPH: No financial relationships to disclose Secretary for Quality of Care Timothy W. Olsen, MD: No financial relationships to disclose Academy Staff Ali Al-Rajhi, PhD, MPH: No financial relationships to disclose Andre Ambrus, MLIS: No financial relationships to disclose Susan Garratt, Medical Editor: No financial relationships to disclose Meghan Daly: No financial relationships to disclose Flora C. Lum, MD: No financial relationships to disclose Doris Mizuiri: No financial relationships to disclose The disclosures of relevant relationships to industry of other reviewers of the document from January to October 2019 are available online at www.aao.org/ppp OBJECTIVES OF PREFERRED PRACTICE PATTERN GUIDELINES P332METHODS AND KEY TO RATINGS P333HIGHLIGHTED FINDINGS & RECOMMENDATIONS FOR CARE P334SECTION I. ADULT STRABISMUS OVERVIEWINTRODUCTION P335Disease Definition P336Patient Population P336Clinical Objectives P336BACKGROUND P336Prevalence P336Rationale for Treatment P336SECTION II. COMMON AND CLINICALLY IMPORTANT MANIFESTATIONS OF ADULT STRABISMUSSECTION IIa. PERSISTENT OR RECURRENT CHILDHOOD STRABISMUSINTRODUCTION P339Disease Definition P339Patient Population P339Clinical Objectives P340BACKGROUND P340Prevalence P340Natural History P340Rationale for Treatment P340CARE PROCESS P341Patient Outcome Criteria P341Diagnosis P341History P341Examination P341Management P343Monitor/Observe P343Nonsurgical P343Surgical P343Provider and Setting P343Counseling and Referral P343SECTION IIb. SENSORY STRABISMUSINTRODUCTION P344Disease Definition P344Patient Population P344Clinical Objectives P344BACKGROUND P344Prevalence P344Natural History P344Rationale for Treatment P345CARE PROCESS P345Patient Outcome Criteria P345Diagnosis P345History P345Examination P345Management P346Monitor/Observe P346Nonsurgical P346Surgical P346Provider and Setting P346Counseling and Referral P346SECTION IIc. CONVERGENCE INSUFFICIENCYINTRODUCTION P347Disease Definition P347Patient Population P347Clinical Objectives P347BACKGROUND P347Incidence P347Risk Factors P347Natural History P347Rationale for Treatment P348CARE PROCESS P348Patient Outcome Criteria P348Diagnosis P348History P348Examination P348Management P349Monitor/Observe P349Nonsurgical P349Surgical P349Provider and Setting P349Counseling and Referral P349SECTION IId ACQUIRED STRABISMUS RELATED TO AGING AND MYOPIAINTRODUCTION P350Disease Definition P350Divergence Insufficiency P350Sagging Eye Syndrome P350Strabismus fixus (“Heavy Eye Syndrome”) P351Patient Population P351Clinical Objectives P351BACKGROUND P351Prevalence and Risk Factors P351Divergence Insufficiency P351Sagging Eye Syndrome P351Strabismus fixus or “Heavy Eye” P352Natural History P352Rationale for Treatment P352CARE PROCESS P352Patient Outcome Criteria P352Diagnosis P352History P352Examination P353Management P354Divergence Insufficiency P354Sagging Eye Syndrome P355Strabismus fixus P355Provider and Setting P356Counseling and Referral P356Divergence Insufficiency/Sagging Eye Syndrome P356Strabismus fixus P356SECTION IIe. THYROID EYE DISEASEINTRODUCTION P358Disease Definition P358Patient Population P358Clinical Objectives P358BACKGROUND P358Incidence P358Risk Factors P358Natural History P359Rationale for Treatment P359CARE PROCESS P359Patient Outcome Criteria P359Diagnosis P359History P359Examination P359Management P360Observation P361Nonsurgical P361Surgical P361Provider and Setting P363Counseling and Referral P363SECTION IIf. STRABISMUS AFTER ORBITAL TRAUMAINTRODUCTION P364Disease Definition P364Patient Population P364Clinical Objectives P364BACKGROUND P365Prevalence and Risk Factors P365Natural History P365Rationale for Treatment P365CARE PROCESS P365Diagnosis P365History P365Examination P365Management P366General Guidelines P366Guidelines for Treating Strabismus P367Provider and Setting P368Counseling and Referral P368SECTION IIg. STRABISMUS ASSOCIATED WITH OTHER OPHTHALMIC SURGERYINTRODUCTION P369Disease DefinitionCataract Extraction or Keratoplasty P369Glaucoma Filtering Procedures (including trabeculectomy and glaucoma plate reservoir surgery) P370Scleral Buckling Procedures P370Pterygium Surgery P370Blepharoplasty and Eyelid Procedures P370Patient Population P371Clinical Objectives P371BACKGROUND P371Cataract Extraction P371Glaucoma Filtering Procedures P371Scleral Buckling Procedures P372Blepharoplasty and Eyelid Procedures P372Natural History P372Rationale for Treatment P372CARE PROCESS P373Patient Outcome Criteria P373Diagnosis P373History P373Examination P373Management P374Monitor/Observe P374Nonsurgical P374Surgical P374Provider and Setting P375Counseling and Referral P375SECTION IIh. SUPERIOR OBLIQUE PALSYINTRODUCTION P376Disease Definition P376Patient Population P376Clinical Objectives P376BACKGROUND P377Incidence P377Risk Factors P377Natural History P377Rationale for Treatment P377CARE PROCESS P377Patient Outcome Criteria P377Diagnosis P377History P377Examination P378Management P378Monitor/Observe P378Nonsurgical P378Surgical P378Provider and Setting P379Counseling and Referral P379SECTION IIi. SKEW DEVIATIONINTRODUCTION P380Disease Definition P380Patient Population P381Clinical Objectives P381BACKGROUND P381Prevalence P381Risk Factors P381Natural History P381Rationale for Treatment P381CARE PROCESS P381Patient Outcome Criteria P381Diagnosis P382History P382Examination P382Management P383Provider and Setting P383Counseling and Referral P383SECTION IIj. ABDUCENS PALSYINTRODUCTION P384Disease Definition P384Patient Population P385Clinical Objectives P385BACKGROUND P385Incidence P385Risk Factors P385Rationale for Treatment P385CARE PROCESS P385Patient Outcome Criteria P385Diagnosis P385History P386Examination P386Ancillary Testing P386Management P387Monitor/Observe P387Nonsurgical P387Surgical P387Provider and Setting P388Counseling and Referral P388SECTION IIk. OCULOMOTOR PALSYINTRODUCTION P389Disease Definition P389Patient Population P389Clinical Objectives P389BACKGROUND P389Incidence P389Risk Factors P389Rationale for Treatment P390CARE PROCESS P390Patient Outcome Criteria P390Diagnosis P390History P391Examination P391Management P392Monitor/Observe P392Nonsurgical P392Surgical P392Provider and Setting P393Counseling and Referral P393SECTION IIl. MYASTHENIA GRAVISINTRODUCTION P394Disease Definition P394Patient Population P394Clinical Objectives P394BACKGROUND P395Prevalence P395Risk Factors P395Natural History P395Rationale for Treatment P395CARE PROCESS P395Patient Outcome Criteria P395Diagnosis P395History P396Examination P396Management P397Provider and Setting P397Counseling and Referral P397SECTION IIm. FIXATION SWITCH DIPLOPIAINTRODUCTION P398Disease Definition P398Patient Population P398Clinical Objectives P398BACKGROUND P398Prevalence and Risk Factors P398Natural History P399Rationale for Treatment P399CARE PROCESS P399Patient Outcome Criteria P399Diagnosis P399History P399Examination P400Management P400Monitor/Observe P400Nonsurgical P400Surgical P400Provider and Setting P400Counseling and Referral P401SECTION IIn. RETINAL MISREGISTRATION (BINOCULAR RETINAL DIPLOPIA)INTRODUCTION P402Disease Definition P402Patient Population P402Clinical Objectives P402BACKGROUND P402Prevalence and Risk Factors P402Natural History P402Rationale for Treatment P403CARE PROCESS P403Patient Outcome Criteria P403Diagnosis P403History P403Examination P403Management P404Monitor/Observe P404Nonsurgical P404Surgical P404Provider and Setting P405Counseling and Referral P405SECTION III. COMPLICATIONS OF PERFORMING ADULT STRABISMUS SURGERYINTRODUCTION P406BACKGROUND P406Prevalence and Risk Factors P406CARE PROCESS P406Postoperative Concerns P406Mild Concerns P406Moderate Concerns P407Major Concerns P407Provider and Setting P408Counseling and Referral P408SECTION IV. TECHNICAL CONSIDERATIONS WHEN PERFORMING ADULT STRABISMUS SURGERYINTRODUCTION P409CARE PROCESS P409Surgical Planning and Management P409Anticoagulants P409Adjustable Sutures P409Microtropias P410Chemodenervation P410Anesthesia P410Complex Strabismus P410Intraoperative Issues P411Provider and Setting P411Counseling and Referral P411APPENDIX 1. GLOSSARY OR TERMS P412APPENDIX 2. ALGORITHM FOR APPROACHING ADULT STRABISMUS BASED ON PRESENTATION OF DEVIATION P413APPENDIX 3. LITERATURE SEARCHES FOR THIS PPP P414APPENDIX 4. RELATED ACADEMY MATERIALS P415REFERENCES P416 Background: Strabismus has an estimated incidence of 4% in the adult population. Commonest causes include unresolved or recurrent childhood strabismus, sensory strabismus, divergence insufficiency or sagging eye syndrome, Graves orbitopathy, 4th and 6th cranial nerve palsies and convergence insufficiency. Other notable causes include orbital trauma, third nerve palsy, myasthenia gravis, myopic strabismus fixus, skew deviation, retinal misregistration (“dragged-fovea diplopia”) and strabismus occurring after other ophthalmic procedures. This Preferred Practice Pattern (PPP) details evaluation and management of all these disorders, surgical considerations unique to adults with strabismus, and improvements in quality of life often experienced by those successfully treated. The PPP recommendations are based on Cochrane-identified reliable systematic reviews. Rationale for treatment: Treating adult strabismus can improve binocular function including stereoacuity and binocular fields and can reduce binocular inhibition, diplopia and confusion, associated compensatory head posture, and asthenopia. Successful treatment yields psychosocial benefits due to restoration of normal eye alignment and eye contact. Care Process: Pre-existing suppression increases risk for the development of fixation switch diplopia, which can occur when the previously nondominant eye becomes the dominant eye as a result of monovision or optical changes associated with cataract surgery. Fixation switch diplopia may also occur if vision loss from diseases such as macular degeneration or diabetic retinopathy leaves the previously nondominant eye with better acuity. The risk of new-onset diplopia after strabismus surgery in adults undergoing treatment for unresolved childhood strabismus without previous diplopia is under 1%, and the risk of serious sight-threatening complications is exceedingly rare. Marked improvement in health-related quality of life after successful strabismus surgery is reported in both diplopic and nondiplopic patients, including improvements in general function, reading, self-perception and social interactions. As a service to its members and the public, the American Academy of Ophthalmology has developed a series of Preferred Practice Pattern® guidelines that identify characteristics and components of quality eye care. Appendix 1 describes the core criteria of quality eye care. The Preferred Practice Pattern® guidelines are based on the best available scientific data as interpreted by panels of knowledgeable health professionals. In some instances, such as when results of carefully conducted clinical trials are available, the data are particularly persuasive and provide clear guidance. In other instances, the panels have to rely on their collective judgment and evaluation of available evidence. These documents provide guidance for the pattern of practice, not for the care of a particular individual. While they should generally meet the needs of most patients, they cannot possibly best meet the needs of all patients. Adherence to these PPPs will not ensure a successful outcome in every situation. These practice patterns should not be deemed inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the best results. It may be necessary to approach different patients' needs in different ways. The physician must make the ultimate judgment about the propriety of the care of a particular patient in light of all of the circumstances presented by that patient. The American Academy of Ophthalmology is available to assist members in resolving ethical dilemmas that arise in the course of ophthalmic practice. Preferred Practice Pattern® guidelines are not medical standards to be adhered to in all individual situations. The Academy specifically disclaims any and all liability for injury or other damages of any kind, from negligence or otherwise, for any and all claims that may arise out of the use of any recommendations or other information contained herein. References to certain drugs, instruments, and other products are made for illustrative purposes only and are not intended to constitute an endorsement of such. Such material may include information on applications that are not considered community standard, that reflect indications not included in approved U.S. Food and Drug Administration (FDA) labeling, or that are approved for use only in restricted research settings. The FDA has stated that it is the responsibility of the physician to determine the FDA status of each drug or device he or she wishes to use, and to use them with appropriate patient consent in compliance with applicable law. Innovation in medicine is essential to ensure the future health of the American public, and the Academy encourages the development of new diagnostic and therapeutic methods that will improve eye care. It is essential to recognize that true medical excellence is achieved only when the patients' needs are the foremost consideration. All Preferred Practice Pattern® guidelines are reviewed by their parent panel annually or earlier if developments warrant and updated accordingly. To ensure that all PPPs are current, each is valid for 5 years from the “approved by” date unless superseded by a revision. Preferred Practice Pattern guidelines are funded by the Academy without commercial support. Authors and reviewers of PPPs are volunteers and do not receive any financial compensation for their contributions to the documents. The PPPs are externally reviewed by experts and stakeholders, including consumer representatives, before publication. The PPPs are developed in compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies. The Academy has Relationship with Industry Procedures (available at www.aao.org/about-preferred-practice-patterns) to comply with the Code. Appendix 2 contains the International Statistical Classification of Diseases and Related Health Problems (ICD) codes for the disease entities that this PPP covers. The intended users of the Esotropia and Exotropia PPP are ophthalmologists. Preferred Practice Pattern® guidelines should be clinically relevant and specific enough to provide useful information to practitioners. Where evidence exists to support a recommendation for care, the recommendation should be given an explicit rating that shows the strength of evidence. To accomplish these aims, methods from the Scottish Intercollegiate Guideline Network1Bagolini B Sensorial anomalies in strabismus. (suppression, anomalous correspondence, amblyopia).Documenta ophthalmologica Advances in ophthalmology. 1976; 41: 1-22Crossref PubMed Scopus (51) Google Scholar (SIGN) and the Grading of Recommendations Assessment, Development and Evaluation2Guyatt GH Oxman AD Vist GE et al.GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.Bmj. 2008; 336: 924-926Crossref PubMed Google Scholar (GRADE) group are used. GRADE is a systematic approach to grading the strength of the total body of evidence that is available to support recommendations on a specific clinical management issue. Organizations that have adopted GRADE include SIGN, the World Health Organization, the Agency for Healthcare Research and Policy, and the American College of Physicians.3Buehl W Sacu S Schmidt-Erfurth U Retinal vein occlusions.Dev Ophthalmol. 2010; 46: 54-72Crossref PubMed Scopus (0) Google Scholar ♦All studies used to form a recommendation for care are graded for strength of evidence individually, and that grade is listed with the study citation.♦To rate individual studies, a scale based on SIGN1Bagolini B Sensorial anomalies in strabismus. (suppression, anomalous correspondence, amblyopia).Documenta ophthalmologica Advances in ophthalmology. 1976; 41: 1-22Crossref PubMed Scopus (51) Google Scholar is used. The definitions and levels of evidence to rate individual studies are as follows: Tabled 1I++High-quality meta-analyses, systematic reviews of randomized controlled trials (RCTs), or RCTs with a very low risk of biasI+Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of biasI-Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of biasII++High-quality systematic reviews of case-control or cohort studiesHigh-quality case-control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causalII+Well-conducted case-control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causalII-Case-control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causalIIINonanalytic studies (e.g., case reports, case series) Open table in a new tab ♦Recommendations for care are formed based on the body of the evidence. The body of evidence quality ratings are defined by GRADE2Guyatt GH Oxman AD Vist GE et al.GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.Bmj. 2008; 336: 924-926Crossref PubMed Google Scholar as follows: Tabled 1Good qualityFurther research is very unlikely to change our confidence in the estimate of effectModerate qualityFurther research is likely to have an important impact on our confidence in the estimate of effect and may change the estimateInsufficient qualityFurther research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimateAny estimate of effect is very uncertain Open table in a new tab ♦Key recommendations for care are defined by GRADE2Guyatt GH Oxman AD Vist GE et al.GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.Bmj. 2008; 336: 924-926Crossref PubMed Google Scholar as follows: Tabled 1Strong recommendationUsed when the desirable effects of an intervention clearly outweigh the undesirable effects or clearly do notDiscretionary recommendationUsed when the trade-offs are less certain—either because of low-quality evidence or because evidence suggests that desirable and undesirable effects are closely balanced Open table in a new tab ♦The Highlighted Findings and Recommendations for Care section lists points determined by the PPP Panel to be of particular importance to vision and quality of life outcomes.♦All recommendations for care in this PPP were rated using the system described above. Ratings are embedded throughout the PPP main text in italics.♦Literature searches to update the PPP were undertaken in March 2016, February 2017, and June 2019 in the PubMed and Cochrane databases. Complete details of the literature searches are available in Appendix 3. Strabismus in adults has profound negative effects on quality of life and many aspects of day-to-day function. Strabismus surgery very often improves quality of life and function, and there are instruments to assess these aspects of evaluation and treatment. Patients with diplopia tend to have greatest improvements in functional domains, and nondiplopic patients tend to have greatest improvements in psychosocial domains. Recessions of the restricted muscles are the mainstay of surgical correction in thyroid eye disease. Resection is generally avoided in restrictive disease out of concern for further reducing ductions and operating on a rectus muscle that would best be spared to provided ciliary artery supply to the anterior segment. However, it can be a useful adjunct in select cases, particularly when extremely large recessions have not fully corrected the alignment. Screening for a history of childhood amblyopia or strabismus, checking spectacles for prism, and performing a cycloplegic refraction and cover testing are recommended for all patients undergoing refractive or cataract surgery, especially for those patients for whom monovision is planned. Patients with a history of childhood strabismus and suppression are particularly at risk for developing fixation switch diplopia. This form of diplopia results when the previously nondominant eye becomes the dominant eye as a result of intended or unintended monovision by refractive manipulation or cataract surgery. A trial of monovision with contact lenses is prudent prior to corneal or lenticular refractive surgery to determine whether surgically induced monovision will result in new-onset diplopia. The development of asymmetric vision loss from other common diseases such as macular degeneration, myopia with axial elongation in the previously dominant eye, or diabetic retinopathy when the nondominant eye is left with better acuity may also result in fixation switch diplopia. SECTION I. ADULT STRABISMUS OVERVIEW Strabismus is misalignment of the eyes and may be congenital or acquired. Although more typically associated with the pediatric population, strabismus is quite common among adults, with an estimated incidence of 4% in this population.4Kushner BJ The benefits, risks, and efficacy of strabismus surgery in adults.Optometry and vision science : official publication of the American Academy of Optometry. 2014; 91: e102-109Crossref PubMed Scopus (7) Google Scholar, 5Hertle RW Clinical characteristics of surgically treated adult strabismus.Journal of pediatric ophthalmology and strabismus. 1998; 35 (quiz 167-138.): 138-145PubMed Google Scholar, 6Nelson BA Gunton KB Lasker JN Nelson LB Drohan LA The psychosocial aspects of strabismus in teenagers and adults and the impact of surgical correction.Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus. 2008; 12 (e71.): 72-76Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar The causes of strabismus in the adult population are numerous, in part because the challenges to ocular alignment common in the pediatric population persist, and because new disorders destabilizing alignment occur secondary to aging, vision loss, myopia, endocrine and neurologic disorders, and iatrogenic and non-iatrogenic trauma to the globe or orbit. Notable causes of strabismus in the adult population include: •Recurrent or unresolved childhood strabismus•Sensory strabismus•Convergence insufficiency•Divergence insufficiency•Sagging eye syndrome•Strabismus associated with high axial myopia•Strabismus fixus•Graves' disease•Orbital trauma•Strabismus associated with other ophthalmic surgery•Fourth nerve palsy•Skew deviation•Sixth nerve palsy•Third nerve palsy•Myasthenia gravis•Fixation switch diplopia•Retinal Misregistration or Binocular Retinal Diplopia Accordingly, accurate diagnosis of the etiology of strabismus in the adult population requires the expertise to recognize associated signs and symptoms and familiarity with studies that may confirm the diagnosis. In addition, the goal(s) of treatment may impact the plan for surgical or nonsurgical intervention. Adult patients often have unique concerns associated with functional vision as well as psychosocial concerns that affect quality of life. In the past, most emphasis was on improving motor alignment, but it is now understood that the goals of treatment should be much broader and include sensory recovery when possible as well as gains in psychosocial and functional domains of vision-related quality of life. Success rates depend on the subpopulati