Developmental Behavioral Optometry

Developmental/Behavioral Optometry

Behavioral optometrists are primarily concerned with visual development and visual performance. We understand that a thorough evaluation of the visual process (how well developed eye movements, eye teaming, focusing, peripheral awareness and visual acuity are and how a person uses these skills to process visual information) tells a great deal about how a person does many things. Understanding how a person uses the enormous potential of the visual process to meet their daily needs helps behavioral optometrists enhance the visual abilities of many people with a wide variety of visual deficits with vision therapy and the strategic use of lenses. Most eye care professionals place little or no emphasis on the issues that are most important to behavioral optometrists. The vast majority of eye care practitioners therefore will not offer vision therapy or therapeutic lens options. In fact they will generally ignore or deny the existence of the kinds of problems requiring treatments they either do not provide or do not believe in. This is not done with malice, it just seems that it’s easier for them to avoid the issue than to dig deeper in these situations. It need not be this way. Ophthalmologists willingly and consistently avoid any consideration of visual development or any serious connection between the visual process and the learning process. Standard medical education makes no substantive mention of visual development, vision therapy or behavioral optometry in general. Ophthalmologists continue to wallow in the anti-vision therapy mythology they themselves created. So it is no surprise that they continue to deny the mounting scientific evidence supporting the concepts and practices of behavioral optometry.

On the other hand, all optometry students and therefore all optometric practitioners are exposed to the concepts at the core of behavioral optometry and developmental vision care. Unfortunately even most optometrists choose not to apply this information in practice. This means that they are unable to solve many people’s problems. And because they themselves are unable to solve the puzzle, they tend to avoid making appropriate referrals. This means that many people end up living with reduced comfort and reduced efficiency in work, school or sports because their issues were not thoughtfully and thoroughly addressed by the doctor. It would not be difficult for all optometrists to think in behavioral terms when confronted with problems that standard approaches are unable to recognize or solve. This piece was written as an appeal to all optometrists, and in fact to all eye care providers, to consider the importance of behavioral/developmental thinking as well as the ease with which this could be incorporated into every practice.

Please feel free to contact Dr. Gallop if you have any questions.  Call 610-356-7425 and speak with Dr. Gallop personally.

Behavioral Optometry:
Why All Optometrists Should Think Developmentally

by Steve Gallop, O.D.

Vision therapy has a long, clinically successful history within optometry. Beginning in the early 1930s, under the guidance of A.M. Skeffington, and others, optometrists began using lenses to prevent visual problems and to enhance visual performance. In the 1940s Skeffington, along with G. N. Getman, began an association with Arnold Gessell, M. D., the father of child development in America, at the Institute for Child Development at Yale University. This broadened the understanding of visual development in the infant and child and helped further the impact optometry would have working with many types of visual problems that interfere with development, learning and all areas of visual performance.


As optometrists are faced with the increasing ability to use therapeutic drugs and new technologies, along with the demands of a changing health care environment, we are receiving more and more education about structural pathology, and less and less about functional pathology. Usually pathology is thought of as a breakdown of the physical structures of the human body. I have coined the phrase functional pathology to indicate a non-physical disturbance of function. Functional pathology includes visual-motor deficiencies, accommodative (focusing) and/or convergence (eye teaming) problems, and most forms of strabismus (misaligned eyes). As a profession, we have lost sight of the fact that we affect functional performance whenever we prescribe lenses, whether we intend it or not.

It has been proposed that artificially creating 20/20 acuity can interfere with overall visual performance.1,2 I have seen this happen in numerous cases over the years including my own personal history. However, like many other conditions, it is much easier to recognize something when you know what it looks like. All lenses and prisms cause changes in spatial perception. Just look through a minus lens and notice how it compresses not only the object of regard, but also the entire volume of space seen through the lens.

In these days of blurring distinctions between optometry and ophthalmology, functional/developmental vision care is truly a unique service, one that is not offered by any other group of health care professionals. No other profession has the academic background available to optometry students as far as understanding the visual process on many levels. Statistics continue to show that there are many more people with manageable functional pathologies than with all types of structural pathologies combined. Whereas many cases involving physical pathology still need to be referred out of our profession, those of a functional nature can be treated in our offices or in those of our colleagues.

Functional pathology impedes people in many daily activities that rely upon accurate eye movements, efficient focusing, binocular coordination, spatial perception, balance and mobility. Job performance, athletic performance, driving, reading and general academic performance, are all activities which require good visual function. People will present with a wide variety of symptoms such as headaches, asthenopia, visual and visually related fatigue, late-onset myopia, diplopia, reading difficulties, etc. Vision therapy is a safe and effective means of providing symptomatic relief as well as significant functional improvement in all areas mentioned above.

Many people are able to function in spite of double vision (or suppression of binocular vision), or other forms of functional pathology. There are many other visually related complaints that go unnoticed, unreported or thought to be unimportant until they are properly questioned and/or evaluated. This holds true for adults as well as children, although it is much more common for such things to go unreported by children. Once it has been determined that there is a functional problem, it is important to determine several things: When was the problem first noticed? How often does it occur? Has the frequency increased over time? Is it related to viewing distance? Is it variable relative to position of gaze? Are there specific activities or situations that seem to initiate or exacerbate the visual difficulty or symptoms? This information begins to provide clues to treatment possibilities as well as prognosis.

A written questionnaire can be helpful in bringing these issues to light. A properly worded questionnaire provides a world of information about an individual’s overall visual performance in a short period of time. It also begins to educate the individual about the larger picture of visually-related issues.(Fig. 1) People are frequently surprised to learn that various symptoms such as headaches, fatigue, poor coordination, motion sickness, etc., can often be related to visual function.


I often examine people within weeks of an eye exam because there is a sense of dissatisfaction with the outcome of the previous exam. In many cases these are children with learning problems whose parents heard about behavioral optometry through a non-optometric source. Almost as often, they are adults suffering with some significant symptoms that were not addressed by the previous doctor. At the previous exam all of these people were told that nothing was wrong with their eyes, or that there was nothing that could be done to improve the situation. Sometimes it is just a matter of how you view patients and how you think about findings. A more behaviorally oriented philosophy will enhance optometrists’ ability to take care of patients’ needs by giving us more ways to help more people.

Several quick and easy tests can help provide a more complete picture of an individual’s functional/developmental status. These additional probes into the visual process should not be considered sufficient to fully understand the problem. They will provide more information than an exam done without them, but these findings can only be counted on as a kind of screening since they are taken essentially out of the context of a thorough functional/developmental evaluation. The most important “test” is for the optometrist to be on the lookout for functional pathology in relation to the presenting complaints. It is important to listen to a person’s various issues and reasons for coming to your office with more functional ears. It may not even be necessary to do additional testing if we can look into the testing we already perform with a more behaviorally oriented mindset. If we make ourselves aware of functional and developmental issues and the relationships between physical signs/symptoms and functional difficulties, we will improve our chances of providing relief to people in these situations. Often the simplest solution combined with the safest treatment can work wonders. This doesn’t mean we must stop looking at things the way we already do. It just means we should allow ourselves more than one point of view, especially when our usual assumptions are not meeting a particular patient’s needs.

An example would be a person presenting with recent onset headaches. Our first concern with headaches is to rule out dire physical pathology. Many causes can be ruled out during the history taking process and basic exam. If you feel safe in the knowledge that the headaches are not related to structural pathology, or if subsequent testing rules out structural problems, start to think functionally. It is common for headaches to result from accommodative and/or binocular dysfunction. While it may not be possible to eliminate the symptoms in the average office, optometrists are experts in diagnosing and referring patients for a vast array of pathologies. Functional pathologies should be among them.


The dynamic use of lenses and prisms is an important aspect of the vision therapy process in all cases of functional pathology. This includes the use of low-powered plus lenses3, yoked prisms3,4 and partial occlusion. It is imperative that, given the large number of people of all ages suffering from various forms of functional pathology, we expand our concepts of treatment of these individuals to keep up with the available technology and understanding of sensory plasticity. People of all ages have benefited from therapeutic lenses and visual training over the years.

Lenses might best be thought of and treated as medicine (Medicine n. 1. any substance, drug, or means used to cure disease or improve health.)5 even though they are worn, not taken internally. Like any medicine, they can be used in more than one way. Medicine can be used to compensate for some deficiency, or to stimulate some change in internal processes. The latter approach tends to create fewer undesirable side effects. Lenses can be used as a mere crutch to compensate for a superficial sign of a deeper problem, or as a means of stimulating internal changes that help eliminate the superficial problem by dealing with the actual causes.

Lenses can be used therapeutically to promote changes in behavior, or affect the way one feels. Appropriate near lenses can stimulate positive changes in school performance and work performance as well as overall behavior. These lenses can also bring about changes in a person’s level of comfort by eliminating eyestrain, eye pain, or headaches. While in some cases compensating lenses can be seen to provide some of these same benefits, these changes are typically seen only when the lenses are being worn. This is not unlike some types of internally taken medications. They are effective only during an active phase. And when this phase elapses the symptoms return.

Therapeutic lenses will create more long lasting changes in the majority of cases. In fact, it is generally the case that such changes will become permanent since the primary action of the lenses is to affect internalized changes in behavior and performance. In any case, a compensatory substance or device merely enables a person to ignore their symptoms since they may seem to have disappeared. This can cause a worsening of the overall condition since the root of the problem has not been addressed.

Compensatory prisms are a time-honored method of dealing with binocular dysfunction. They often permit single simultaneous binocular vision while they are being worn. Unfortunately, the phenomenon of prism adaptation can create problems with this approach. Many people can adapt to the prism and end up with the same problem except that the magnitude of the deviation will then be greater than it was initially, necessitating stronger compensating prisms. As previously stated, visual findings tell us something about a person’s visual behavior. Behavior is born out of adaptation, need, learning, and habituation. Compensating treatment modalities, utilizing external devices, do not influence these processes in a dynamic way. It is possible to influence behavior utilizing external devices, but the devices must be carefully selected based on many factors. A compensating device typically causes the person to adapt to the device. This process of adaptation follows previously learned behavior patterns – these are the same behavior patterns that need to be changed if long-term functional improvement is to occur. Active therapeutic intervention, as opposed to compensatory intervention, is aimed at bringing about changes in the internal mechanisms and processes. Active intervention must be pursued in order to modify behavior and improve comfort and performance.

Therapeutic lenses and prisms can be included in this category since they are designed to stimulate internal processing. The goal is to provide just enough change in visual input to cause internal responses that will begin to be different than those previously utilized. This leads to learning new behaviors both on the conscious and unconscious levels. Possible changes include head and body posture, improved eye/hand coordination, increased comfort in reading, computer, and written tasks, improved spatial-perceptual abilities, and generally improved abilities to perform routine daily tasks involving vision. Therapeutic prisms may be yoked or may be a very low-powered version of those prisms found to be of compensatory value. For example, positive changes can be initiated using as little as 2-4 diopters of base in prism for an individual with exotropia measuring 15-20 diopters. Therapeutic low-powered plus lenses can also aid in the rehabilitation of binocular dysfunction. The link between binocular and accommodative function is well established. Low-powered plus lenses can cause changes in visual processing and behavior by creating slight variations in visual input which will stimulate the internal mechanisms and processes to find new solutions leading to improved performance.

The utilization of partial occlusion is another powerful therapeutic approach. The most commonly used is binasal occlusion.6 This consists of placing narrow strips of occlusive material on the lenses on either side of the nose. My preferred material is Scotch brand “magic tape,” but there are other equally effective materials. It is best to start narrow, with neither tape reaching the nasal limbus border, at least in the beginning. I have brought the tape only to the inner canthus in the vast majority of cases. This creates the least amount of conscious disruption while providing considerable improvement in comfort and binocular integration for many individuals. This is a simple intervention that has proven itself useful to this author time and again.

There are many situations that call for monocular occlusion to address some functional issue. It is often possible to use a small central occluder in place of full patching in cases of persistent diplopia. This is, in fact, often preferable since it allows peripheral fusion to continue or improve since the added strain of faulty central fusion is removed. Once the proper placement is achieved, it is useful to determine the smallest possible occluder that will eliminate diplopia. Once again, I would use the same tape mentioned above. This can be applied with one end folded onto itself, creating a tab that allows for easy removal. If the acuity and function are similar in the two eyes it may be beneficial to alternate the occlusion.

In certain cases it can be useful to place partial occlusion, or very narrow opaque strips in the temporal area. Some cases require even more creative applications of partial occlusion. It is not always easy to know what may provide meaningful relief for any given individual. It is up to us to try different things in order to see what might work. In the case of partial occlusion it is easy to experiment and takes little time to achieve results in many cases. It is safe to experiment until the most effective approach for a given individual is found since these treatments are non-invasive, free of side effects, and easy to change or eliminate.

The use of therapeutic lenses, prisms, and partial occlusion also requires that a specific wearing schedule of some sort be implemented. This will be a judgment call based on the individual’s lifestyle, their particular needs, and your professional knowledge (not to mention your experience, once you have worked with some cases in this way). It is often useful to attempt to get full-time wear at least for some initial period and then target certain activities or time periods once the person becomes accustomed to the prescription.

It is important, when utilizing these techniques, to do frequent reevaluations to monitor progress. It is often necessary to change the power of the prisms or lenses as well as the wearing schedule at various stages in the process. It may be necessary to change the amount or type of partial occlusion if things are progressing. If you are not seeing the progress you would like or expect this could also mean a change is in order.

Optometry was fortunate throughout its development to have powerful methods of visual analysis and treatment at its disposal. We have the ability to prescribe what may be the most potent tool for the safe, judicious, and gentle manipulation of visual performance, which in turn affects overall behavior – the ophthalmic lens. The ability to utilize lenses for the enhancement of visual performance, or the prevention of visual problems, need not be the exclusive domain of so-called behavioral optometrists.3 In fact it is too important a concept to remain unused by the vast majority of those prescribing lenses on a daily basis.

The accurate diagnosis and subsequent treatment of functional visual disorders through the use of therapeutic lenses7 represents a state-of-the-art technique which should be as much a part of the so-called “standard of care” as procedures like retinal photography, automated visual field testing, and the use of therapeutic pharmacological agents.

This could elevate and differentiate the profession of optometry in many ways. If you are concerned about the economic implications to your practice, the possibility of preventing visual problems, reversing adverse visual adaptations, and guiding developmental processes through the therapeutic use of ophthalmic lenses is a great way to generate income. By educating the public we could start seeing most people at an early age instead of waiting until people reach the age of forty and need reading glasses. If the profession, and then the public, began to understand the benefits of protective plus lenses for school-aged children, we would not have a surplus of eager patients. Besides the fact that everyone should be wearing protective lenses for close work, we could also educate the public regarding the concept that single vision lenses for distance acuity are not sufficient for all activities. This means that people wearing such compensating lenses should have at least one other prescription that would be more appropriate for closer distances.

The goal is to provide the highest possible level of care to the greatest number of people. For some the developmental philosophy includes the concept that everyone who spends time reading, writing, or sitting at a computer should be wearing lenses that help the visual system cope with activities for which they were not designed.7,8,9,10,11, These are the same activities that are causing epidemic visual breakdown in people of all ages. It would be in everyone’s best interest for the public to understand the full scope of optometry better. We will all benefit when the public understands the limitations of single-vision compensating lenses, and embraces the benefits available through a positive, therapeutic approach to using lenses.

If optometry could unite on the issue of visual hygiene via proper lens use (and other related precautions such as posture, lighting, nutrition, etc.) and proceed to educate the public, we could find ourselves at a new level of public demand and respect. We need to get the public and the profession to think of vision care as a positive thing. This would also help differentiate our profession at a time when we seem to be melding into the discipline of ophthalmology. We can channel the development, effectiveness, and comfort of visual performance instead of waiting around until people come to us with serious problems. Improved visual performance and reduced visual stress has positive repercussions in all areas of people’s lives. This doesn’t mean we should turn our backs on all the progress our profession has made in recent times. It just means we should keep our real heritage alive and evolving, to the advantage of all concerned.


Vision therapy is a necessary aspect of visual rehabilitation in the majority of cases of functional pathology. While the methods mentioned previously are effective, and in some cases may get the job done, many of these patients require more dynamic treatment. Vision therapy allows for a more dynamic use of various lenses and prisms under controlled circumstances. This provides an environment for closely guided visual performance and more in-depth learning. Optometrists throughout the world are using vision therapy to successfully treat a wide variety of functionally related vision problems. These include:

  • Children whose visual abilities interfere with their ability to learn and perform up to their potential in the school environment.
  • Adults with “recent onset” diplopia or other visual complaints who find that their ability to perform at their jobs has been compromised. (Many of these people have had long standing visual problems that were previously not severe enough to cause symptoms.)
  • People with neurological impairments who are still able to function at a fairly high level. Many such syndromes include binocular problems.
  • People who have suffered traumatic brain injuries.
  • People who have previously undergone strabismus surgery and are no longer visually comfortable
  • People who are considering strabismus surgery for functional or cosmetic reasons

It may not be reasonable to think that all these cases can be effectively handled in all optometric offices. However, it is reasonable to expect that all optometrists are more than capable of effectively evaluating these cases and making appropriate referrals for further treatment as we all do in other cases of pathology.

Have you ever experienced any of the following:

Yes No
Frequent headaches
Eyes frequently red
Double vision
Closing or covering one eye
Eyes tire easily or hurt
Holding reading close
Tilting head while reading
Losing place while reading
Pointing to keep place on page
Words moving on page
Poor reading comprehension
Focus changes while reading
Getting drowsy while reading
Purposely avoiding reading
Difficulty completing work on time
Reversing letters/numbers
Difficulty with spelling
Poor handwriting skills
Short attention span
Blurry vision- far away
Blurry vision-close up
Focusing is slow from near to far (or far to near)
Discomfort during or after computer work
Poor general coordination
Motion sickness
Sensitivity to light
Color vision problems
Wearing an eye patch
Visual therapy

1. Harmon DB. Notes on a Dynamic Theory of Vision. 1958.
2. Gallop, S. Compensating & Therapeutic lenses: Passive vs. dynamic prescribing, an essay. J Behav Optom. 1998;9(5):127-31.
3. Kraskin RA. Lens Power in Action. Santa Ana: OEP, 1982.
4. Press LJ. Applied Concepts in Vision Therapy. St. Louis: Mosby, 1997.
5. Webster’s New World Dictionary, 2nd College Ed. New York: World Publishing Co. , 1970
6. Gallop, S. A variation on the use of binasal occlusion: A case study. J Behav Optom. 1998;9(2): 31-5.
7. Ong E. Ciuffreda K. Accommodation, Nearwork and Myopia. Santa Ana: OEPF, 1997.
8. Kraskin RA. How To Improve Your Vision. North Hollywood: Wilshire Book Co., 1968.
9. Jaques L. Corrective and Preventive Optometry 1950. Los Angeles: Globe Printing Co., 1950.
10. Skeffington AM. Practical Applied Optometry. Optom Extension Prog; Ed by Hendrickson H,1991:83.
11. Birnbaum MH. Optometric Management of Nearpoint Vision Disorders. Boston: Butterworth-Heinemann, 1993. Contact Dr. Gallop for more information about behavioral optometry, vision therapy or developmental lenses.


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