The Skeffington Perspective of the Behavioral Model of Optometric Data Analysis and Vision Care

THE SKEFFINGTON PERSPECTIVE OF THE

BEHAVIORAL MODEL OF

OPTOMETRIC DATA ANALYSIS

AND

VISION CARE

BY

EARL P. SCHMITT, O.D., Ed.D, D.O.S.

© 2010 EARL P. SCHMITT, O.D., Ed.D, D.O.S.. All rights reserved.

No part of this book may be reproduced, stored in a retrieval system, or transmitted by any means without the written permission of the author.

First published by AuthorHouse 7/2/2010

ISBN: 978-1-4520-2792-0 (e)

ISBN: 978-1-4259-1054-9 (sc)

Library of Congress Control Number: 2005911349

Printed in the United States of America

Bloomington, Indiana

This book is printed on acid-free paper.

Dedicated

To the memory of Irv Dunsky – Clinician; Teacher; Gentleman; Friend

And

To my many students and colleagues, who, over the years, have given me

a rich, rewarding, and enjoyable professional life.

Table of Contents

Dedicated

Foreward

Acknowledgments

Chapter I

Chapter II

Chapter III

Chapter IV

Chapter V

Chapter VI

Chapter VII

Chapter VIII

Chapter IX

Chapter X

Chapter XI

Chapter XII

Chapter XIII

Chapter XIV

Chapter XV

Chapter XVI

Chapter XVII

Chapter XVIII

Chapter XIX

Chapter XX

Chapter XXI

Chapter XXII

Chapter XXIII

Chapter XXIV

Suggested Readings

And Selected References

About The Author

Foreward

The practice of clinical health care often is not an exact science.  While licensed providers are professionally, morally, and legally bound to offer their clients and patients the highest level of services available, clinicians are limited by what their respective disciplines have discovered in the way of effective remedies and protocols.  It is understood that practitioners are obligated to keep current on new information.  At the same time, schools, colleges, and research centers that nurture professional specialties  continuously must seek to validate conventional knowledge.  They also are charged to develop new methodologies, expand data bases, and then disseminate these findings to their practitioners and graduates for the benefit of the general public.

Optometry is no exception to these principles.  In particular, there are few absolutes when human visual performance is considered.  Clinical optometric tests can be taken, and the features of the system under investigation can be noted.  But the etiology of much of what is recorded, and the manner by which the vision system operates, is poorly understood.  The hard truth is that, while a great deal of anecdotal evidence is available, the exact causes of many clinically described binocular vision problems are unknown.

A few illustrations may demonstrate this point.  There is, for example, no consensus on exactly what a lateral phoria represents, or where in the central nervous system such a characteristic originates.  Again, while it is known that the interactive potentials and properties that may exist between accommodation and convergence lead to duction blur findings, why vergence ranges shrink or expand is unclear.  Subjective and objective clinical findings will vary, with procedures which ostensibly evaluate the same visual property resulting in conflicting data, all of which may be interpreted differently by the examining practitioner.  Regarding this last point, retinoscopy at distance and the Basic Subjective finding immediately come to mind.

Yet, if the reasons behind much of what occurs within the human vision system remain speculative, how scientific can clinical vision care actually be?  The answer is: no less than that of the practice of clinical medicine.  Medical providers rely heavily on the judicious use of pharmaceuticals to remedy the ailments and dysfunctions which are presented to them.  Still, the exact pharmacomechanics of many drugs and medications used commonly in practice are unknown.  The utilization of various steroids is a cardinal example.  To justify the application of such products, however, the medical profession relies on hypothetical constructs and the anecdotal evidence of what works and what doesn’t.  Field trials, along with ongoing institutional research into the pharmacology of drug products that are believed to be useful, provide medical practitioners with the basic tools of their trade.  It is a model that optometry well might emulate, which could include the preparation of our graduates to become effective clinician-scientists, as described by Epstein.[1]

The optometric profession has made quantum leaps in expanding its scope and sequence of patient care over the last twenty or thirty years.  Intense inter- and intra-disciplinary battles have been waged to enlarge optometry’s professional arena, and are ongoing to this day.  But in the process, much of what constituted the traditional foundation of optometric vision care lately seems to be either taken for granted, or has been de-emphasized during the training of new practitioners.  At the same time, practicing clinicians also may have lost touch with certain underlying principles which undoubtedly they were taught during their student days.  These trends can lead to unintended consequences, such as the doctor conducting his or her practice of optometry at a relatively lower level of sophistication than otherwise might be possible.

As a profession, we seem to have become distracted.  The unrelenting necessity of remaining competitive in a ubiquitous medically oriented, third-party payment health care system must be recognized, of course.  But in the process, optometry unwittingly may be sacrificing its unique heritage of preventative and remedial vision care strategies.  Yolton and Citek[2] spoke directly to this concern when they asked (I)s it time to start (or re-start) a back fire of interest in functional vision and vision enhancement?  Perhaps this text could prove useful in that respect, particulaly in light of the fact that the vast majority of an optometric practitioner’s income seems to be derived from traditional optometric care.[3]

Absent a fund of uncontroversial facts, a well-articulated hypothesis is indispensable to the development, advancement, and practice of a professional body of information.  Around the turn of the last century Pierce[4] noted  that (A) hypothesis is something which looks as if it might be true and were true, and which is capable of verification or refutation by comparison with facts.  He underlined the need to validate a working hypothesis through controlled studies and research.  To Pierce, a likely hypothesis is one that falls within our preconceived ideas of reality.  Scientific inquiry should challenge these abstractions and constructs.  Those that cannot be supported should be cleared away, leaving the field free, as he concluded, for the main struggle.

The realization that much of what is done clinically during an optometric examination is predicated on a body of hypothetical knowledge might disturb some, but nonetheless, it is true.  The results of many tests are taken for granted.  Once obtained, such information may then be applied somewhat mechanically, and without much insight, to therapeutic regimens.  Yet, in turn, these regimens themselves often times also are founded on abstract tenets.  Absolutes notwithstanding, that this can be a successful approach to patient care is substantiated by the popularity and acceptance of optometry by the general public.  Missing, however, is the insight and understanding on the part of the clinician of what is being tested, the reasons how and why the patient is responding, the mechanisms that result in the data being generated, and the logic behind the therapeutic options and choices available to remedy the problem at hand.  A bevy of hypothetical constructs exists to justify each clinical procedure undertaken by an optometric examiner.  As a complement to these assumptions, the manner by which clinical data is generated during an examination is governed by what the practitioner intuitively holds to be true and reliable when evaluating the performance of human vision.  Ultimately, interpretation of these findings depends on what the clinician believes are the mechanisms and reasons underlying how the patient responds to various clinical probes.  The manner in which all this information then can be applied in the best interests of the patient is the ultimate expression of the doctor’s operational understanding of our human vision system, and what works to rectify the problem at hand.  And yet, how many optometric practitioners – or students – or teachers of optometric clinic science, for that matter – could define the principles which underlie the model of vision care which they or their institutions espouse?  At this point, the question is rhetorical.

This text presents the Behavioral Model of optometric data analysis.  The descriptions given in the following chapters include how phorometric tests are taken, and the manner by which the resulting numerical information is processed.  Behavioral Analysis originated with  Dr. A. M. Skeffington in the early 1930’s.  He was convinced that concepts then in vogue of how  human vision functioned were inadequate to explain the dynamics he observed as a practitioner.  Dr. Skeffington came to realize that the principles of bench optics were insufficient to explain the act of accommodation, and that binocular convergence reactions represented more than simple muscular responses to fusional demands.  It became evident to him that interaction potentials between the subsystems of accommodation and convergence were not immutable, and varied over time as the individual was subjected to ongoing and continuous near point vision demands. Moreover, as these interaction potentials could be quantified, the data then could be clustered systematically, presenting specific modes of change as they occurred for each patient. It was the classification of clinical case types that represented Dr. Skeffington’s first great insight into the principles of Behavioral analysis.  From this inspiration developed the concept of case deterioration, as the relationship between adaptation to environmental stresses and adaptation of the vision system became more evident.

Over the years, Behavioral analysis has attracted the attention of numerous distinguished clinicians, scholars, and writers, many of whom are cited in this present work.  Their contributions have enhanced our understanding of how the human vision system operates, how it can be measured and quantified, and how it can be treated when dysfunctions are detected.  However, during the past few decades, little has appeared in print that would serve to explain the fundamentals of Dr. Skeffington’s model of data analysis.  There have been no discussions regarding the clinical procedures that are appropriate to the Behavioral model, or to what the tests ostensibly measure when performed as part of an examination routine.  Unfortunately, the challenges of creative syntax often become an impediment to Dr. Skeffington as he tried to describe his emerging concepts, and as he attempted to identify newly identified directions of thinking during his teaching career.[5],[6],[7],[8]  For the modern optometrist, this sometimes makes for difficult reading[9], which in turn may shroud the beauty of the Behavioral model to the impatient reader.  Hence, a basic purpose of this text is to outline the intricacies and nuances of the Behavioral Model of optometric data analysis in terms that are easily grasped and readily understood.  The Model itself is left intact, with but minor didactic changes which are meant to clarify the interpretation of certain findings and the underlying reasons for specific modes of adaptation.  These are discussed in Chapter XII, all with the fundamental intent of bringing Twenty-first Century understanding to what now should be recognized as a timeless model of human behavior.

A second objective of this work is to state the hypotheses upon which the  Behavioral Model is built, and to identify those assumptions and hypothetical constructs which underlie many of the clinical tests which are performed routinely.  Every health practitioner operates under the aegis of a professional model.  In order to be effective, and to continue his or her career as licensed provider, a clinician must have a set of rules, guidelines, and parameters which essentially define who he or she is, and what he or she can do.  At times, however, as well intended as they may be, these guidelines are based on hypothetical assumptions.  In turn, clinicians may take such assumptions for granted, never giving much attention to the presumed truths that must be held by the doctor before a procedure is performed or a therapy undertaken.

For every routine optometric clinical test covered in this book, a set of assumptions is listed that is intended to corroborate the particular procedure being discussed.  Naturally, these presumed truths are structured in a manner as to be applicable to the Behavioral Model.  But the approach could be used to construct supporting arguments for any other clinical model of data analysis.  This format has not been attempted previously for the Behavioral Model of optometric practice, and it has been an interesting exercise, to say the least.  But as a teaching and learning format, perhaps it should be applied to other philosophies of clinical care.  This issue is raised early in Chapter I, and is worthy of continued debate.

If well stated hypothetical constructs govern what is done during the delivery of many health care services, it is evident that some serious research needs to be done to validate our body of professional assumptions.  Basic investigation is needed into how and why clinical findings reflect what is going on within the vision system.  We need to know what our clinical tests really signify.  Many of the hypotheses made in support of various procedures and points of view in this text need to be ratified.  Undoubtedly there will be honest disagreement with a number of the assumptions that are made throughout this work.  Thoughtful critiques are useful and necessary, but more important, viable alternatives need to be stated.  Those who would deny the modular constructs that are described here are, in turn, obligated to present equally cogent hypothetical constructs to justify another argument.  Well designed investigations then should be initiated to determine which of the several clinical philosophies seems most defensible.  Innovative investigations are underway[10], and should be encouraged.  The basic elements of clinical optometric care are prime candidates for scientific inquiry.  Dr. Skeffington[11] made this point years ago when he wrote that (W)e are not organized in anatomical segments but in movement patterns ... , which would make vision a legitimate field for research to a greater extent than if the only thing of importance was correcting a refractive error.  Hence, if this text raises intraprofessional debates to a higher plateau than has been the case in the past, a major step forward will have been taken.

The Behavioral Model recognizes a broad scope of adaptive behaviors which are not articulated in other modes of professional vision care.  The exact pathways presently are obscure as to how the human vision system organizes itself to cope with otherwise unacceptable, environmentally imposed stresses.  The hypothetical bases of adaptive changes on the part of human vision are neither recognized nor acknowledged by a number of our optometric colleagues, and largely are given short shrift by representatives of other health care professions.  Yet because these concepts seem to be substantial, viable, and rational, it is not inconceivable that the substance of Behavioral Optometry could be re-discovered by another discipline.  These constructs then would be seized upon by others as representing a new and enlightened approach to a critical aspect of human behavior – that is, vision – and claimed as their own creation.  With appropriate modifications and a modicum of research, the elements of Behavioral Optometry thereby could be lost to another coterie of health care providers.  In the process, optometry quite likely would receive little or no credit for its pioneering efforts, and for its original, innovative thinking.  If it achieves nothing else, therefore, this text can keep the creative inspiration of Dr. Skeffington and his cohorts in proper, historical perspective.

The present work may be used as a reference, or as a teaching text.  Various chapters could be reviewed independently, or they could be utilized in serial fashion, depending on the instructor’s preference.  Certain constraints may limit formal class time.  If so, selected discussions or sections could be deferred, such as the first three chapters which deal with historical and philosophical concepts.  For those already familiar with the Behavioral model, individual chapters can be referenced without the need to review earlier sections.

Finally, while the general tenor is meant to reflect the elements of data analysis, as promulgated by the Behavioral Model of Optometric Data Analysis, the substance and content of this work are the responsibility of the author.  Data analysis is but one facet of the entire Model.  The present discussion is intended to highlight the manipulation of clinical data, as this information is derived from a standard optometric vision examination, and after having been obtained by following the protocols advocated in publications by the Optometric Extension Program Foundation, Inc.  These writings are referenced appropriately throughout the text, with a few key works included at the end of the volume  under the heading of  Suggested Readings.  Also given are additional sources, which cover aspects of the Behavioral Model that could not be dealt with in this book.  

Acknowledgments

Each of us has known individuals in the past who have served as inspirational icons  during our professional lives.  The faculty who nurtured me at the Pacific University College of Optometry between the years of 1958 to 1961 left lasting impressions.  I have tried to perform, as a practitioner and as an instructor, in a manner and with the decorum they would have expected.  In particular, Dr. Charles Margach, Dr. Harold Haines, and Dr. Detleff  Jans remain forever prominent in my memory.  Dr. James Wahl, one of the early deans of the College at Pacific University, also was an inspiration.

During my career I have had the good fortune to serve on the teaching faculties of two prominent institutions.  For fifteen years, starting in 1968, I was associated with the Southern College of Optometry, located in Memphis, Tennessee.  At Southern College I filled several teaching positions, was Director of Clinics for four years, and held the office of Dean of Students for another four years.  During my tenure there I was able to complete a graduate doctoral program at Memphis State University.  Taking the opportunity to join an emerging professional school, in 1982 I relocated to Tahlequah, Oklahoma, and spent an additional fifteen years on the faculty at Northeastern State University College of Optometry.  My teaching emphasis at Northeastern was in the area of clinical methods and data analysis, which allowed me to refine my own skills to higher levels.  I also served five years at Northeastern as Director of Clinics, which kept me in close contact with all aspects of patient care.  The administrators of these institutions were generous, supportive, and considerate of my professional objectives.  To them I am deeply indebted.

One does not develop an area of clinical expertise in isolation.  Conversation with professional colleagues is invaluable when trying to organize a body of hypothetical constructs into a logical system of thought.  Ongoing communication with fellow clinicians is invaluable when working to translate that philosophy and its accompanying tenets into an array of practical clinical activities.  But such has been my good fortune for over forty years, and I am grateful to my colleagues, associates, and the army of students with whom I have marched with down various academic halls for these memorable decades.

Several individuals have been especially helpful and supportive in the preparation of this text.  Mr. Bob Williams, Executive Director of the Optometric Extension Program Foundation, Inc., granted me unlimited access to the OEP archives in Santa Ana, California, for one week during the summer of 2001.  He was a gracious host, and was helpful in locating historical documents and publications from the early Skeffington days.  Before my visit, the late Dr. James Gregg had spent considerable time in bringing some semblance of order to the Foundation’s holdings.  His selfless efforts should not go unrecognized.  The Foundation’s administrative staff, under the able direction of Editor in Chief,  Dr. Anne Barber, also were helpful, and made valuable suggestions.

While in California it was my extreme good fortune to meet – quite by accident – Dr. Leonard Emery, as he paid a visit to the Foundation’s library.  We spoke about my proposed project, and Dr. Emery voluntarily offered to read the chapter drafts, and to provide constructive commentary.  Before his retirement, Dr. Emery wrote many articles for the OEP Papers.  I could not have asked for a more astute review of my original copies than that which was provided by this experienced author and clinician.  For his insights, critiques, and professional encouragement, I remain eternally grateful.

Archive librarians at the John Vaughn Library, on the campus of Northeastern State University, were ever able to provide me with articles, books, and other reference materials through their interlibrary loan services.  Without their help, much of the early Twentieth Century historical information that this work contains would not be included.  Ms. Sara B. Archer, Mr. Garry Cheatham, and Ms. Sandra Martin were particularly helpful.  The assistance of Mr. Glenn Larrison also is gratefully acknowledged for his help in compiling the final manuscript.

Fellow faculty members at the NSU College of Optometry supplied me with citations and various articles which were extremely useful.  Prominent among these individuals were Dr. W. C. Maples, Dr. Wes DeRosier, Dr. Lynn Cyert, and Dr. Doug Penisten.

I have been accused, on occasion, of being syntactically challenged.  It was not so much that subject and verb did not agree, but that tense and grammar needed a bit more attention than I was providing.  Shielding me from the wrath of irate grammarians, my wife Dicksie read every page of the first drafts, before I sent them on to Dr. Emery for his further commentary.  For her gentle but inevitably correct admonitions, all of which resulted in a much more coherent presentation of what, admittedly, is a complex subject, I extend my love, respect, and gratitude.  Her critical eye, combined with the patience  demonstrated during the many hours I spent with the word processor rather than in her company, deserves more tributes than I will ever be able to bestow.

Chapter I

The Use of Models in Clinical Health Care

Models as Applied to Human Behavior

The behavior of a human being at any given moment is the summation of many sub-patterns of activity.  One’s modes of performance in turn result from the complex interactions of both learned and innate responses, combined with  adaptations that are within the individual’s capacity to induce and which are made to environmental demands. In an attempt to comprehend some aspect of human function it often is useful to construct a hypothetical model. A model of human behavior may be defined as a set of principles or expecteds which govern individual or group action under specified conditions.1  This suggests that a model or set of general parameters may be assumed to underlie any deliberate or conscious act performed by an individual or social body of individuals.2  Therefore, everything from human cognitive functions3 to corporate organizational management4 generally might be described in terms of certain reasonable and anticipated activities.  Man’s every rational function is a fabric that can be categorized by identifiable rules.  Such action sets or parameters then collectively define a behavioral model.  Concerning government, for example, in the United States our social and legal behaviors are predicated upon the Constitution, which permits and encourages maximum individual freedom and initiative so long as, at the same time, the comparable rights and privileges of our fellow citizens are not compromised.  Our model of government, in other words, recognizes the dignity and respects the privacy of its constituents.  By contrast, certain other national governmental models are and have been less permissive and more authoritarian.5  Historical perspective will be the ultimate judge as to which one of these various models of government is the most beneficial to society at large.

Anyone who engages in professional duties and responsibilities also finds his or her vocational decisions governed by models.6  While the term sometimes is used rather glibly to describe a variety of jobs and occupations, a profession has several attributes which set it apart from other, more generic occupations.  While not enumerating them specifically, Flexner7 implied the elements of a profession throughout his report to the Carnegie Foundation concerning the status of medical education as it existed in the United States and Canada at the start of the twentieth century.  Among other things, Flexner intimated that a profession trains its members to accept individual responsibility and accountability for critical decision-making within his or her realm of expertise.  A professional person vocationally limits himself or herself specifically to a particular field of activity. Defining this realm of knowledge is a battery of skills and background of information which provides the professional with attributes and capabilities not necessarily shared by the general population.  Moreover, the training necessary to acquire the professional expertise under consideration must be imparted through a systematic, well-prescribed curriculum that is offered at an accredited, post-secondary institution of higher learning, and conducted by a faculty who are acknowledged experts in their respective fields.  Applicants for professional training are selected on the basis of demonstrable ability, merit, and a predicted capability to succeed.  Such candidates are chosen from a qualified applicant pool by representatives from the professional field itself. In other words, the profession that is conducting its training program is self-regulating, and establishes its own standards of excellence which are consistent with its mission statements.  A profession is subject to regular and ongoing internal and peer reviews.  A profession  purports to produce competent individuals who can fulfill a specialized role in society, and who at the same time can provide a vital and often a unique service to the community. This theme generally has been reinforced in the literature.8  Similar definitions of a profession have been proposed by other authors.9, 10,11

As a professional person is required to function within a prescribed set of parameters, it follows that a body of rules and regulations inevitably will exist which serve to identify and limit his or her decision-making capabilities.  These restrictions often are codified in the form of state laws.  Regarding optometry, pertinent examples of jurisdictional regulations may be found in any current edition of the Optometric Blue Book.12

When a pattern of human activity legally is established, defined, and circumscribed by an agreed upon set of assumptions, rules, and guidelines, such a formalized canon of behavior globally can be referred to as a model.  As applied to a particular enterprise, a given model will be both prescriptive and proscriptive of human behavior.  For most observers, a professional title and a model of professional behavior will be synonymous.  How solid a grasp one has of an individual’s scope of responsibilities, however, will depend on how well informed the observer is about the occupation being  considered.

Perspectives in Model Construction

For sake of discussion it will be assumed that various aspects of human social behavior and interaction, as well as physiological functioning, may be described in terms of modular constructs. It is logical to suggest, therefore, that the more intricate and involved the activity or function under consideration becomes, the more precise and specific are the tenets which establish the behavioral parameters of that activity.  This is particularly true in the socioeconomic world of work.  In fact, the more narrowly one’s job-related duties are defined by law, the more critical and restrictive appears to be the model by which the expert may operate.

Indeed, to increasingly delimit a professional’s realm of responsibility is to restrict more narrowly the area of expertise within which he or she can make decisions.  This means that the higher the level of training achieved by a professional, the more refined and delimiting the applicable operational models tend to become.

For health providers this is particularly evident. The diplomate must limit his or her practice to a defined field of specialization.  It is unethical to encroach into a fellow practitioner’s field of expertise, or to function at another level of care  within one’s personal discipline. In addition, certain specialists reach a point where the operational models used to analyze patients’ behavior become laced with ever more esoteric guidelines and corollaries.  At this point many of the professional’s clinical operatives and assumptions are predicated upon certain theoretical constructs which are largely hypothetical in nature.  That is, instead of absolutes and uncontroversial statements of fact, higher levels of professional activities and decisions may be dictated more by selected assumptions and presumed truths than by unequivocal certainties.  Such is the case in the professional delivery of optometric vision care when performance data is to be evaluated.  It is the purpose of this text to discuss specific aspects of optometric data collection and analysis, and to illustrate how modular constructs can be used to diagnose certain visual dysfunctions prevalent within a clinic population.

Optometry historically has identified  physiological optics as its academic  home,13,14 although Margach15 takes some exception to this idea.  However, optometry also has legitimate ties to psychology, education, biology, physiology, physics, and chemistry.  More recently, as the scope and sequence of the profession have expanded (that is, as the model of clinical optometric practice has grown and matured) optometry has assumed stronger links to pharmacology and to selected areas of medicine.  In these respects, many aspects of optometric practice and concern are bounded by well-defined scientific principles.  Nonetheless, it should be emphasized that not all medical tenets are definitive or final.  In so key an area as  Pharmacology the circumstances surrounding the development of some drug interactions are complex and poorly understood.16  A considerable number of unanswered questions concerning pharmacodynamics persist, yet drug regimens routinely are incorporated into many health care practices.  The entire subject of corticosteroid anti-inflammatory therapy may be cited as an example.  The benefits accrued through the prudent use of these particular pharmaceutical agents must be weighed against the fact that science still does not understand thoroughly the mechanisms by which these drugs function.17, 18, 19

The Elements of Model Construction

Within the matrix of models which profess to describe human activity and behavior, inevitably there will be found certain theoretical constructs and ideas.  Yet as Schmidt20 notes, a model and a theory are two different entities.  A model, he writes, describes a theory, and tries to provide a basis by which the details of a theory may be visualized more clearly.  Moreover, a well constructed model provides a solid foundation for teaching how a particular theory can be applied toward the understanding of human behavior.

As suggested earlier, individual elements or theoretical assumptions tend to become more abstruse as the complexity of a given behavioral model increases.  Successful models often seem to interweave esoteric assumptions and hypothetical constructs with more traditional, less controversial scientific principles.  This is strikingly so when attempts are made to construct theoretical models of how the human visual system functions.  Behavioral models attempt to describe present events about a particular realm of human activity, but also strive to predict activities in the future, so long as intervening variables are kept under control as much as possible.  Models may also serve to stimulate research, provide a framework for teaching and training new initiates, and to identify more exactly its philosophical propositions.21  It is when some of the hypotheses incorporated within the model themselves are conjectural that the overall model seems vulnerable.

In its least complex dress a hypothesis is a statement of a single phenomenon or occurrence.  This is the context to be used in the present discussion.  A model, therefore, will be defined here as a compilation of hypotheses or assumptions, an approach not inconsistent with Schmidt’s thesis as stated earlier.  In this light and when taken as an integrated whole, a consolidated model can attempt to give meaning and content to a certain aspect of human behavior.

Operational Models in Health Care

Unless operating from within a well defined model no human endeavor properly can claim a professional identity.  Fawcett22 makes this point clearly by stating that (t)he utility of models ... comes from the organization they provide for thinking, for observations, and for interpreting what is seen, ... models also give direction to the search for relevant questions about phenomena, and they point out solutions to practical problems.  Furthermore, they provide general criteria for knowing when a problem has been solved.  Kaplan23 notes that models serve to help the scientist/clinician find the mechanism by which a process occurs, and ... count how often an outcome occurs compared to how often it is sought.  The American Optometric Association has defined doctors of optometry as independent primary health care providers who examine, diagnose, treat and manage diseases and disorders of the visual system, the eye and associated structures as well as diagnose related systemic conditions.24  The modern practice of optometry, particularly in the United States, incorporates more services than those traditionally provided or conventionally described.25  The present discussion will be limited entirely to optometric concerns regarding vision performance and activities, however.  It will be assumed that no clinical morbidity or pathological condition is present which would impact the visual-perceptual mechanisms, these having been resolved or are non-existent at the onset of the examination.26, 27, 28

The most common problems optometrists are likely to encounter in an average clinical population, particularly within the age group of between six months and eighteen years, are those of binocular vision, accommodative dysfunctions, and underlying developmental disorders.29  Regarding other aspects of optometric  services, such as the detection of eye and systemic diseases, references may be found which describe appropriate optometric intervention and professional strategies.30, 31

When considering the complex activity that is called human visual behavior, much that is done in optometric clinical settings is based on hypothetical, that is, theoretical constructs.32  Nonetheless, studied supposition has a legitimate place in scientific inquiry.  Sheard cited Rene Descartes, who wrote that (w)hen it is not within our power to determine what is true, we ought to follow that which is most probable.33  The exact neurophysiological sources of many clinically measured tests remain obscure, so far as vision is concerned.  Therefore, considered speculation is a permissible format, and carefully constructed hypotheses can serve as useful guidelines and parameters for the optometrist when providing professional care.  As Corliss34 notes, direct inquiry into human behavior is hypothesis-driven, with clinical evidence serving either to support a hypothesis or to refute it.   In the exercise of his or her professional responsibilities the vision care specialist performs certain clinical tests and measurements, with data being obtained both by objective and by subjective means.  Decisions then are rendered which ostensibly are directed toward the solution of patients’ problems.  The assimilation and interpretation of optometric vision-related data typically are made as a result of the practitioner’s understanding of what the various bits of clinical information mean.  In short, the model of vision which is espoused by the examining clinician will dictate how he or she initially gathers data, what analytical coding and diagnostic deciphering rules are applied, and how the therapies are derived, options of care considered, and criteria of success are identified and evaluated.

Vision has been held to be a form of human behavior.35,  36  This behavior is investigated during a clinical optometric examination.  The present discussion presumes  that methods used by the examiner to test a patient’s visual status, and the directions which the examination may take, will be governed by the model of vision embraced by the practitioner.

But optometry is not the only health care profession that employs models to direct its operational regimens.  Indeed, anyone who renders care to a patient in a clinical setting more often than not follows a logical sequence of steps which globally can be said to describe a general model of health care delivery.  Such an overall model, interestingly, will show considerable similarities even when applied among different health care disciplines.  While the details of execution will vary, essentially there are six broad categories of activity, or phases, which every health care professional will pursue when exercising his or her primary responsibilities.  These six steps, as detailed in the following section, constitute an overall model of professional clinical health care delivery.  This model is applicable to the most isolated individual practitioner or the largest institutional provider.

It should be appreciated that the generic clinical health care delivery model presented below is both additive and self-generating in its application.  Details involved during the initial approach or first step taken by the practitioner when rendering patient services inevitably will be dictated by the professional’s health care model.  Subsequently, each procedure undertaken by the doctor throughout the model will follow from the one before, expanding upon the information and procedures inherent within the previous step.  In fact the sophistication and intensity of successive investigative stages in the delivery of health care through this modular sequence are at the same time predicated upon and limited by the complexity  and magnitude of the earlier sequence(s).

A General Clinical Health Care Model

Under ideal clinical conditions, whenever a practitioner interfaces with a patient for the purpose of delivering health care, a six-stage model of professional behavior may be postulated.  These six steps, in their order of operation, may be summarized as follows: (1) Data-Gathering; (2) Analysis of Data; (3) Diagnosis; (4) Therapy; (5) Prognosis; and (6) Follow-up.

Data-Gathering

The first step is that of data-gathering.  Here the patient’s chief complaints may be determined during a case history interview,37 the current status of the patient defined by objective and subjective methods, and all pertinent information obtained that will allow the practitioner to appreciate what the patient needs and expects in the way of immediate health care.  In a sense, this first step in clinical health care never terminates, mainly because the case history theoretically is never completed.38

During optometric clinical care, data-gathering includes all aspects of collecting information that describes the visual performance of the patient.  In addition to the case history, this category embraces the recording of entrance or so-called chair skills as well as the results of various in-phoropter tests.  Biomicroscopy, ophthalmoscopy, visual fields, and intraocular pressures also can be involved, along with such auxiliary procedures as obtaining photographic records, conducting electrodiagnostic tests, testing for glare and color sensitivity, and undertaking whatever other procedures might be considered to be necessary in order to develop a visual health and performance profile of the patient.

Analysis of Data

The second step in the general clinical health care delivery model is that of analyzing data.  Now the practitioner evaluates the information that has been obtained and attempts to organize the data into a meaningful syndrome.  In optometric vision care this structuring process will be governed almost entirely by the professional’s understanding of what the individual tests signify, and how they reflect certain aspects of the patient’s visual behavior pattern.  Regarding phorometric data, those tests that are conducted will be  determined by the doctor’s underlying assumptions concerning how vision functions, and how such characteristics can best be clinically scrutinized.

In an optometric setting the clinician takes those findings which he or she believes reflect key visual functions.  These tests probe the patient’s patterns of visual behavior.  In the practitioner’s mind each test  must represent a distinct facet of the whole.  Certain assumptions must be held regarding the significance of a particular test probe, and how the results reflect a discrete aspect of the patient’s visual-perceptual profile.  Detailed discussions of such assumptions constitute a major aspect of the present text.

Optometrists generally regard findings that are taken during a clinical examination as data which have a history behind them, and which convey a context that can be analyzed.39  For example, the attending clinician must have a personal understanding of what a phoria represents, what a set of vergence findings means, as well as what the other test results stand for.  During an examination the optometrist gathers information which supposedly will speak to the problem that the patient has presented with at the clinic.  The practitioner then manipulates the data in a way which will lead logically to the third step in the model.  Obviously there is little merit in taking a test if the resulting datum is not going to be used.  Moreover, it goes without saying that only those data which have been gathered can be analyzed.  When findings are not taken it must be presumed that the clinician did not believe that they would be informative, did not place a diagnostic value on the information that the findings might represent, or simply assumed that the data would be within normal limits for that particular patient.  Hence, the analysis perforce will be limited by the information which was obtained during the investigative phase (step number one), in combination with the clinical assumptions and/or presumptions held by the examiner.

Diagnosis

Following the gathering of pertinent information and the analysis of data the health care professional moves to the third step of clinical care, that of diagnosis.  As Groffman40 states, (t)he complex problem-solving skill of clinical diagnosis is central to effective delivery of health care by practitioners.  Once clinical findings have been grouped by an analytical process into a meaningful syndrome, the condition must be given a name.  The allopathic or homeopathic medical  practitioner would define the malady in terms of a recognized disease or physiological dysfunction, assuming that the analysis completed in the second step of the clinical model was sufficiently unequivocal.  If more information was needed, ancillary tests could be ordered, essentially looping back to step number one if the analysis was inconclusive and the diagnosis still elusive.  Ultimately, however, the condition would be assigned a label, if only tentatively.41  This at least would allow the health care provider to move toward the next step in the model.

The optometrist also will formulate a diagnosis as the third step of his or her general model of clinical health care.  After analyzing the data, a name will be given to the visual condition or problem that is being manifested by the patient.  The term used will, of necessity, reflect the optometrist’s understanding of how the vision system operates, and may refer to one or several of the various pathways by which this complex human behavior can dysfunction.  Quite often the term employed will be descriptive, emphasizing perhaps an area of accommodative or convergence impairment.  It is at this level that will be found the most significant theoretical divergences of opinion among practicing optometrists.  Examples of diverse theoretical constructs will be given in later chapters.  Such diversities of persuasion within a profession should not be disparaged, however.  It must be recognized that much that is clinically measured and tested in the area of visual performance is neither understood completely nor has been subjected to rigorous scientific investigation.42, 43, 44  Such uncertainties are not unique to optometry, as has been stated earlier.

To illustrate this point the etiology of vergence recovery findings might be cited.  While the datum per se represents a reintegration of the accommodative and convergence functions to give a fused image after forced dissociation, exactly why variations occur concerning the range of recovery for individual cases is moot.  Variations in instrumentation and operator techniques have been blamed.45  The resulting impact of visual stress also has been cited.46  In another instance, spontaneous responses made by non-presbyopic patients to the fused and unfused crossed cylinder tests at near point will vary, relative both to the total push-up accommodative range and the net Positive Relative Accommodation range.  The possible causes for such response variances remain elusive, and the issue has not been studied systematically.  Some have  suggested that such accommodative characteristics, as determined through the use of routine near point crossed cylinder tests, are linked to something akin to the dark focus phenomenon.47, 48 Morgan49 speaks to this hypothesis by noting any condition that degrades the stimulus for accommodation results in the passive return of focus toward the natural, equilibrium, or resting state.  Yet other theoretical interpretations have been ascribed to crossed cylinder response data.50  Which is to say that in truth, a great deal of what passes for optometric clinical knowledge actually is empirical.  As mentioned earlier, this probably is true in other health care arenas.  But having stood the test of time and earned professional acceptance, various regimens of clinical vision care and their underlying  clinical decision-making mechanisms may be expected to perpetuate, at least for the present.

Nonetheless, a diagnosis is an educated guess concerning the clinically accumulated data that reflects a patient’s immediate health problem.  The diagnosis is derived directly from the information that was obtained originally during the first step (that is, Data-Gathering) in the generic model of health care delivery.  As that data then is sifted or analyzed according to some algorithm, hopefully to determine a coherent pattern or syndrome, a diagnosis emerges.  

Therapy

When providing health care it does the patient no service simply to give some debilitating condition a name, and then make no attempt to render appropriate care.  The fourth step in the model of delivery of clinical services, therefore, is the design of an adequate therapy.  At those times when a diagnosis can be made only on a tentative basis, the results of an initial  therapeutic regimen subsequently can serve either to substantiate or to invalidate the proposed conclusion determined at the third step of the model.51

Regardless, the therapy selected by the practitioner is expected to follow logically from the diagnosis.  Treatment decisions are dependent upon both the clinician’s perception of the condition or dysfunction, and on his or her insights concerning  the etiology of the patient’s complaint.  These latter concepts again will reflect back heavily on the model that the doctor espouses which describes the ailment under consideration.  

It is at the therapy level that the extent of intervention by the practitioner is determined.  As suggested earlier, if the diagnosis is tentative, a low-risk, conservative approach to the problem might be undertaken.  On the other hand, if the condition is recognized as one being readily controlled and rectified, perhaps a more vigorous and robust attack by the practitioner can be justified.  Professional judgment now is a paramount issue.

Whether or not the practitioner believes that the condition will worsen, can be reversed, eliminated, or simply contained, will depend upon his or her understanding of the probable causes of the patient’s dilemma.  Such understanding, of course, will in turn  be predicated upon the doctor’s model or preconceived ideas regarding the situation at hand.  It is within this realm of decision-making that the fundamental clinical assumptions which are embraced by the health care provider most pointedly come into play.  In following chapters considerable discussion will be given to the structure of such assumptions and how they may impact the several clinical modes of optometric vision management.

To illustrate, distance visual acuity measurements and a patient’s refractive status constitute two major aspects of primary vision care.  If the optometrist is convinced that a far point refractive condition is inherent and immutable, probably the therapy of choice would include the prescribing of lenses which neutralize the refractive error and provide  for the best distance visual acuities.  On the other hand, if the clinician believes that some form of aggressive lens or vision therapy intervention might alter the patient’s measurable refractive status, another approach might be taken such as the application of plus spheres for near use, accommodative facility training, and so forth.  This latter therapy could result from the belief that distance refractive conditions somehow are linked to adaptations a patient might make to near point visual demands.52  Regardless, both attitudes would have their roots in the fundamental modular constructs the clinician would hold regarding the human visual mechanism.

Prognosis

Based on the proposed therapy, the health care clinician next must speculate on the efficacy of his or her care.  This represents the fifth step in a general clinical model, which is the prognosis statement.  Usually a prognosis will in some manner reflect back to the patient’s chief complaint.  The problem the patient brought to the practitioner is what needs to be addressed: The patient will not be satisfied unless he or she is convinced that the debility which required help in the first place is going to be alleviated.

The doctor therefore is obligated to design a therapy that will attempt to relieve the patient’s problem.  The extent to which the problem and symptomatology will be eased or cured will be detailed in the prognosis statement.  A prognosis should try to estimate the time frame within which positive changes will be experienced by the patient.  Also, side effects, possible complications, and other iatrogenic considerations ought to be included.  Secondary benefits should be listed, if anticipated, which would be accrued above and beyond the solution of the patient’s chief complaint.53

A prognosis is a speculation, based on the practitioner’s best estimation of how effective will be the proposed therapy.  The anticipated consequences of therapeutic regimens represent the quintessence of a clinician’s health care model.  Expected benefits to the patient will be delimited by the investigative clinical tools available to and selected by the practitioner; how these techniques are utilized to obtain information; how this information is analyzed and defined; and what interventions then are decided upon.54   At this point the clinician commits totally to his or her fundamental model of human behavior and development.  If the clinician believes that some form of active intervention -- as defined by his or her professional license -- can alter positively certain conditions as observed in the patient, then therapeutic strategies will be devised to permit this dispensing of services, and the expected changes can be verbalized in the form of a prognosis.  Conversely, if the patient’s situation can be but stabilized by means of a therapeutic regimen, with the expectation that further deterioration will not occur yet at the same time no definite remediation or change for the better will result, this also can be defined in the form of a prognosis statement.

It should be obvious that one’s professional activities in each of the preceding four steps of the clinical health care model have been governed by the practitioner’s perception of what is going on regarding the patient’s malady.  These sequential modular phases then are summarized in the form of a prognosis, the fifth step in this logical paradigm.  Such a recapitulation defines the anticipated results that the therapy, which has been rendered consistent with the clinician’s model, will accrue to the patient.  

Follow-Up

Complete execution of a general model of clinical health care requires a provider to take a sixth step during  the delivery of his or her professional services.  Some manner of follow-up evaluation must be performed wherein the effects of a therapeutic regimen that was given are weighed along with any changes that have been brought about.55  It is here that the patient can be reassured that a proper treatment choice was made, and that his or her original complaints have received due consideration.  But more important, it is at this level that the practitioner can reflect on the sequence of procedures which were utilized in addressing the patient’s disorder.  It is now that the doctor can consider whether a sufficient amount of data was gathered during step one to permit a proper analysis of the patient’s initial complaint or dysfunction.  Also, the practitioner can judge whether a suitable diagnosis was reached, based on the collection of information and the ensuing analysis that was made.  The efficacy of the therapy which was recommended or selected ultimately can be estimated by measuring how successfully or unsuccessfully the prognosis predicted realization of desired clinical goals.  In short, the follow-up allows the clinician to look critically at the model which was followed, and to determine if an adequate and appropriate regimen of care was provided.  As the case is monitored over time, adjustments and modifications, both in the level of care and in the model, can be suggested.  As a result, of course, professional wisdom and sophistication should be enhanced as the practitioner gains clinical experience and insight.

Constructs of an Optometric Health Care Model

Throughout this discussion a health care model will be considered as being a quasi-structured set of activities which lead to the solution of a patient’s complaint within the defined arena of a practitioner’s responsibility.  A model can be thought of as representing a composite of  discrete theories encompassing both factual and hypothetical statements, each of which addresses a particular facet or operational aspect of the overall model.

Optometric health care usually is considered to be an activity that is conducted within a clinical setting.  To reiterate, this particular discussion is limited to concerns about vision and visual performance.  Several philosophical modalities are available to the optometrist when providing such services, each of which may be thought of as representing a pattern of behavior available to be followed by a practitioner.  The global model which directs the clinician’s care of his or her patients, therefore, will in turn be composed of subunits or secondary models.  Ultimately, as reduced to the bare essentials, each  sub-model of clinical behavior can be represented by individual statements or hypotheses that describe discrete and particular aspects of the whole.

If this represents an amenable description of a clinical health care delivery model, then it is proposed that a series of fundamental assumptions or statements of basic assumed truths, when combined subsequently with selected disclaimers, can serve to define each of the subareas within which specific human professional activities will occur.  An individual assumption or theoretical statement must display several aspects if the construct is to be taken seriously.  To start with, a theoretical construct must be plausible.  While sometimes representing an abstract thought, a concept must be believable and within the bounds of reason.  Further, it also must be consistent with the observations of numerous observers.  It should be useful, in that when applied to a particular situation a particular concept tends to further the understanding of specific activities.  This point is underscored by Hawking who writes that a theory represents a rule or ... a set of rules that relate quantities in the model to observations that we make.56  

How useful an individual theoretical statement might be can be determined only after being incorporated into a model, and then the results of applying that dictum evaluated.  The realization that a theoretical construct might not represent an immutable truth should not, ipso facto, preclude its incorporation into a clinical care model.  If effective and helpful in leading to clinical solutions of patient complaints, such a hypothetical construct could find a permanent place in the model toward which it was applied.  If not helpful, the construct subsequently will be either discarded or modified.

This is an important concept when considering the elements of a model; that is, the individual components of the paradigm which here have been referred to as hypothetical constructs.  Specific theories or hypotheses need not represent proven facts.  In truth, once a theoretical concept is proven, it ceases to be an assumption but assumes the dignity and stature of a law.  Of course, indisputable facts are comforting to the professional, but when dealing with human dissimilitudes, such firm data often is a rare commodity.  Again, much of what is done in  health care, particularly in regard to vision, unquestionably reflects the vagaries of the human species.  Simplistic models of clinical care tend to eschew controversial constructs, and will attempt to confine themselves to a minimum of basic principles and guidelines.  On the other hand, more complex models of clinical behavior will contain a goodly number of empirical notions which have been found to be useful and practical, but would not necessarily qualify as facts.

That legitimate clinical health care models might contain theoretical statements which are controversial should not discourage the thoughtful practitioner.  While the cardinal rule in any health care activity is do no harm, innovative approaches to the solution of human behavior problems may have their place if applied with judicious common sense.  To that end Margach wrote that a (t)heory is a structure of metaphors.  As such, theories are neither true or false but only more or less useful, as they are consistent with the clinical experience of the profession.57  Toffler has observed that sometimes it is more important to be imaginative and insightful than to be ‘right.’  Theories do not have to be ‘right’ to be enormously useful.58  A scientific or clinical hypothesis is no more than an educated guess, a prediction.59  Obviously, the acid test for any theoretical construct in a general health delivery paradigm will be found in the sixth step of the clinical care model, when the practitioner conducts a follow-up evaluation of the therapy regimen which was initiated, at least in part, by application of such hypotheses.

Therefore, while a theoretical component of a health care model need not represent a statement which has been proven, those hypotheses which are included should be both reasonable and logical.  Flights of fancy have no place in serious health care schemes.  Moreover, theoretical statements should be internally consistent, supporting not only one another but being compatible with the overall model of which each is a part.  A procedural statement, for instance, should have as its basic objective the enhancement of professional responsibility and patient care.  It should provide the practitioner a means of identifying a realm of action and accountability, and a reasonable scale by which the effectivity of a therapy may be measured.  In short, each clinical construct should allow for the appropriate gathering of data and the ultimate design of a regimen which reflects the patient’s condition and recommends a remedial procedure that is within the patient’s ability and capability to respond.  This theme will be illustrated and expanded upon in the next chapter.

Summary

Unless it is totally random, human behavior may be presumed to adhere to some general pattern when it is task or goal oriented.  Such patterns, or models, may range from a simple group of moral tenets which set limits of performance in their own right, to highly complex archetypes requiring extraordinary skills as exemplified in the flying of jet aircraft or performing neurosurgery.  The more complex the behavior, the more difficult such models are to define.60  Psychologists long have attempted to identify the parameters within which the human individual operates, including the prioritizing of needs which, in turn, motivate a person to perform.61  The behavioral paradigm of Maslow62 may be cited as but one example.

Many optometric clinicians are unable to identify, much less articulate, the elements of the model which governs their professional behavior at a particular time.  Yet in the field of vision health care a practitioner always and unavoidably will operate either overtly or covertly under the aegis of a model.  This is inevitable, for as Margach observes, every professional whether he or she operates in an academic or clinical setting, must be making moment to moment commitments to some standard.  There is no such thing as clinical neutrality.63

It would seem self-evident that optometric clinical data can be neither gathered nor analyzed without some preconceived idea on the part of the doctor as to what might be the underlying causes of a patient’s chief complaint, how that dysfunction came into existence, and what tests can be used to provide meaningful assessments of the patient’s visual condition.  Moreover, all subsequent clinical care which is rendered by a practitioner must follow logically from the dictates of his or her model, or the doctor is left without a basis for deciphering symptoms, devising a strategy for remedial action, and then measuring the resourcefulness of his or her ministrations.  Getman summarizes this thesis,  for as he has noted, (i)t is a well acknowledged fact that every clinician must have a model, or philosophy, with which he can be comfortable enough to provide consistency to his clinical decisions.64  Bartlett made the same point when he wrote that optometric professional behavior has to be guided by well-conceived models because clinically relevant knowledge must be put into a form that is both practical and meaningful so that it becomes useful to the patients our clinical profession serves.65  Suchoff66 has expressed a similar opinion.

A variety of optometric clinical care models currently exist, all of which have their adherents.  The next chapter will examine a few of these prototypes, and will look specifically at the basic assumptions and hypotheses which define these different philosophies.

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