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The Scientific Basis for and Efficacy of Optometric Vision Therapy in Nonstrabismic Accommodative and Vergence Disorders

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The Scientific Basis for and Efficacy of Optometric Vision Therapy in Nonstrabismic Accommodative and Vergence Disorders ISSUE HIGHLIGHT The scientific basis for and efficacy of optometric vision therapy in nonstrabismic accommodative and vergence disorders Kenneth J. Ciuffreda, O.D., Ph.D. State University of New York, State College of Optometry, Department of Vision Sciences, New York, New York Background: For nearly 75 years, optometric vision therapy has ptometric vision therapy for nonstrabismic accom- been an important mode of therapy for both children and modative and vergence disorders involves highly spe- adults who manifested a range of nonstrabismic accom- cific, sequential, sensory-motor-perceptual stimulation modative and vergence disorders. O paradigms and regimens. It incorporates purposeful, con- Methods: In this article, the scientific basis for, and efficacy of, optometric vision therapy in such patients will be discussed. trolled, and scientifically based manipulations of target blur, Using bio-engineering models of the oculomotor system as disparity, and proximity, with the aim of normalizing the the conceptual framework, emphasis will be focused on stud- accommodative system, the vergence system, and their ies that used objective recording techniques to directly mutual interactions.1-3 In addition, other sources of sensory assess therapeutically related changes in oculomotor information, such as kinesthesia4 (e.g., touching the near test responsivity. object) and audition5,6 (e.g., oculomotor auditory biofeedback) Results and Conclusions: The findings clearly support the correlated to the accommodative and vergence states (e.g., validity of optometric vision therapy. Furthermore, the results are consistent with the tenets of general motor learning. position, innervation, effort, etc.) can provide cue rein- forcement. Inclusion of related behavioral modification par- Key Words: Accommodation, behavior modification, motor learn- 7-9 5 10,11 ing, oculomotor plasticity, oculomotor responsivity, vergence, adigms, such as general relaxation, visual imagery, 12 vision therapy (e.g., “think far or near”), and attentional shaping may help one learn to initiate (i.e., provide a “trigger” mechanism) and/or enhance the appropriate motor responses. However, the ultimate goal of optometric vision therapy is not simply to impact positively on various aspects of the oculomotor sys- tem per se, in isolation, but to attain clear and comfortable binocular vision at all times. It involves oculomotor inte- gration with the head (i.e., eye-head coordination),13 neck (i.e., proprioceptive information),14 limbs,15 and overall body,16,17 with information from the other sensory modal- ities, producing temporally efficient, coordinated behavior18,19 within a context of harmonious spatial sense16,17,20 under a variety of external and internal conditions and states. Prevalence of nonstrabismic accommodative and vergence disorders Nonstrabismic accommodative and vergence disorders of a non-organic, nonpathological nature (i.e., “functional” in Ciuffreda KJ. The scientific basis for and efficacy of optomet- ric vision therapy in nonstrabismic accommodative and ver- origin) are the most-common ophthalmic vision conditions gence disorders. Optometry 2002;73:735-62. (other than refractive error) that present in the general opto- 735 VOLUME 73/NUMBER 12/DECEMBER 2002 OPTOMETRY ISSUE HIGHLIGHT metric clinical practice. The specifically related Cure rates in patients who manifest nonstrabismic signs and symptoms may also initially be accommodative and vergence disorders reported to, or uncovered by, the orthoptist, oph- thalmologist, neurologist, internist, or general pri- The cure rates in symptomatic patients who man- mary care medical practitioner, as well as others ifest nonstrabismic accommodative and fusional in the allied health and educational professions vergence disorders are very high (also see (e.g., school nurses, remedial reading teachers, ‘Accommodative Therapy’ and ‘Vergence Ther- etc.). Failure to detect and diagnose these prob- apy’ sections). Cure rates for accommodative dis- lems may have grave consequences to some orders generally ranged from 80% to 100%,26 and patients and, hence, legal consequences.21 cure rates for vergence disorders generally ranged from 70% to 100%.26 Thus, both the In symptomatic, nonpresbyopic clinic patients, the accommodative and vergence systems are remark- prevalence of accommodative dysfunction and ably remediable and exhibit considerable oculomo- correlated symptoms is estimated at: accom- tor plasticity, with concurrent marked reduction of modative insufficiency, 9.2%; accommodative symptoms. infacility, 5.1%; and accommodative spasm, 2.5%.22 However, as one might expect, in clinic The clinical practice of optometric vision ther- patients who are receiving treatment for manifest apy has had nearly 75 years to evolve to its pres- binocular dysfunctions, the prevalence is much ent level within the optometric community.29,30 higher (60% to 80%).22,23 Thus, accommodative dis- Before that, however, its more narrowly focused orders are common in the general optometric clinic counterpart of orthoptics was founded in population. France by the ophthalmologist Javal in the mid- nineteenth century (1858) and is still practiced With respect to the prevalence of fusional ver- widely—especially in Europe and the United gence dysfunction, the most-common type is con- Kingdom—in ophthalmological clinics.3 In 1915, vergence insufficiency. The median prevalence is in the United States, Duane31 reported that 10% 7%, in both children and adults.24 Other relatively of his ophthalmological clinic patients mani- frequent vergence dysfunctions include: conver- fested nonpathological, functional, accom- gence excess, 5.9% to 7.1%;22,25 basic exophoria, modative disorders that he believed could be 2.8%;26 fusional vergence dysfunction, <7%;27 remediated by accommodative “exercises” he and clinically significant vertical phoria, 9%.28 proposed. Both optometrically based vision ther- Thus, as was true for accommodative disorders, ver- apy and ophthalmologically based orthoptics gence disorders are also common in the general opto- have had a long history, and are currently metric clinic population. actively involved in the successful management and treatment of a wide range of oculomotor Symptoms reported in patients who manifest dysfunctions, including those with nonstrabis- mic accommodative and vergence disorders. nonstrabismic accommodative and vergence disorders From this rich background, well-developed There are a wide range of symptoms reported in and scientifically based treatment plans with patients who manifest nonstrabismic accom- common elements have evolved—especially in modative and vergence disorders.26 With respect optometry—to efficiently and cost-effectively to accommodation, these include: blurred vision remediate disorders of both of these oculomo- at distance and/or near during or immediately fol- tor systems26 (see Figures 1 and 2). Clinical lowing nearwork, headaches, poor concentration, guidelines and important conceptual notions and difficulty reading. With respect to vergence, regarding these specific nonstrabismic accom- these include: blurred vision, diplopia, ocular dis- modative and vergence disorders have evolved comfort during or immediately following near- in optometry based on a wide range of labora- work, frontal headaches, nausea, sleepiness, loss tory, clinical, and epidemiologic investigations of concentration, heavy lid sensation, general over the years.26,32-36 All of these factors have fatigue, and “pulling” sensation of the eyes. Of contributed to keen insights and increased interest, the symptom preventing tactic of task understanding of functionally based, nonstra- “avoidance” may be used by some, thus negatively bismic, accommodative and vergence disorders impacting on overall quality of life—especially in clinical practice, resulting in the high success with respect to school and work performance. rates found following therapeutic intervention. 736 OPTOMETRY VOLUME 73/NUMBER 12/DECEMBER 2002 ISSUE HIGHLIGHT Optometric management of the patient with accommodative dysfunction: a brief flowchart (reprinted with permission from the American Opto- Figure 1 metric Association, 1998). The balance of this article will establish the sci- the oculomotor system as the conceptual frame- entific basis for, and efficacy of, optometric vision work, a detailed quantitative overview of various therapy. It will have the following organizational static and dynamic models of accommodation structure. First, using bio-engineering models of and/or vergence having a direct bearing on opto- 737 VOLUME 73/NUMBER 12/DECEMBER 2002 OPTOMETRY ISSUE HIGHLIGHT Optometric management of the patient with vergence dysfunction: a brief flowchart (reprinted with permission from the American Optometric Figure 2 Association, 1998). 738 OPTOMETRY VOLUME 73/NUMBER 12/DECEMBER 2002 ISSUE HIGHLIGHT Figure 3 Simplified, conceptual model of Hung et al., 1996 (reprinted with permission, from Ong and Ciuffreda, 1997). metric vision therapy will be provided. In addi- text of its overall structural framework, especially tion to specifying and describing these direct as the body of knowledge increases. By consid- applications, the importance of models will be fur- ering individual components, one can understand ther developed in subsequent sections. Second, when specific system aspects are abnormal prior selected research studies that provide support for to vision therapy, which aspects normalize sub- the scientific basis for and efficacy
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