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VT101 COURSE POWERPOINT TO BE PRESENTED AT COVD ANNUAL MEETING 2012
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VT-101 COVD 42nd Annual Meeting Speaker Disclosure Diana Ludlam and Jennifer Mullen The College of Optometrists in Vision Development in compliance with its Continuing Education (CE) must identify the presence or absence of relevant financial relationships and/or commercial interest that could affect the content of the educational activity/lecture. COVD Directors, Educational Committee, Moderators, Presenters/Authors, Speakers who are in a position to control the content of an educational activity/lecture must disclose all relevant financial relationships and/or commercial interest. Title/Presentation: VT 101 - I have no relevant financial relationships and/or commercial interest. Financial relationships are those relationships in which the individual benefits by receiving a salary, royalty, intellectual property rights, consulting fee, honoraria, ownership interest (e.g., stocks, stock options or other ownership interest, excluding diversified mutual funds), or other financial benefit. Financial benefits are usually associated with roles such as employment, management position, independent contractor (including contracted research), consulting, speaking and teaching, membership on advisory committees or review panels, board membership, and other activities for which remuneration is received or expected. Commercial interest is if the relationship is financial and occurred within the past 12 months, and the individual has the opportunity to affect the content of CE about the products or services of that commercial interest.
VT-101 Diana Eastburn-Ludlam, C.O.V.T. Jennifer Mullen, C.O.V.T. October 16-17, 2012 Fort Worth, Texas
COURSE OUTLINE • WHAT IS VISION THERAPY? • BRIEF ANATOMY, PHYSIOLOGY, AND NEUROLOGY OF THE VISUAL SYSTEM • THE BEHAVIORAL PHILOSOPHY • VISUAL CONDITIONS – WHAT TYPES OF PATIENTS THE OD REFERS TO VT • WHAT THE VISION THERAPIST NEEDS • TOOLS AVAILABLE TO THE VISION THERAPIST • UNDERLYING PRINCIPLES OF VT
WHAT IS VISION THERAPY? “The art of arranging conditions so that the patient becomes aware of new relationships in [his/her] visual world, and through these new relationships learns to utilize processes that allow [him/her] to extract a greater amount of information in a more efficient manner.” Ralph E. Schrock, OD, FCOVD
QUESTION??? Why Is Vision So Important to Humans?
ANSWER We are visual beings!!!
“All men by nature have a desire for knowledge. An indication of this is the joy we take in our perceptions; which we cherish for their own sakes, quite apart from any benefits they may yield us. This is especially true of sight, which we tend to prefer to all the other senses……a preference explained by the greater degree to which sight promotes knowledge by revealing so many differences among things.” Aristotle, The Metaphysics, Book One, Alpha Major, On Philosophical Wisdom, i. The Evolution of Knowledge, Philip Wheelwright translation
“Vision is the brain’s way of touching” Maurice Merleau-Ponty Le Visible et l’Invisible, 1964
FACTS • Vision is pervasive throughout the brain • 70% of all of the sensory nerves in the body come from the 2 eyes • 25 different areas in the brain primarily or totally involved with processing of visual information, plus an additional 7 visual-association areas
FACTS • At least 305 intra-cortical pathways link these visual areas • Every lobe of the cerebral cortex (the part of the brain dedicated to cognitive function) is involved in the processing of visual information • More area of the brain is dedicated to vision than to all of the other sense modalities combined
BRIEF OVERVIEW OF OCULAR ANATOMY
OCULAR ANATOMY ADULT EYE: • diameter: ~ 2.5 cm (1 inch) • weight: ~7 grams (0.25 ounces) • axial length: ~2.5 cm (1 inch) • corneal diameter: ~12 mm (1/2 inch) • corneal power: ~43 D
ANATOMICAL LANDMARKS Cornea • Front transparent part of the outer protective layer • Curvature provides the major refractive power
ANATOMICAL LANDMARKS Sclera • Tough, white, fibrous outer protective layer
ANATOMICAL LANDMARKS Conjunctiva • Clear membrane that covers the sclera and lines the inside of the eyelids • Produces mucus and tears • Helps prevent entrance of bacteria
ANATOMICAL LANDMARKS Iris • Colored portion which surrounds the pupil • Changes determine the amount of light that enters the eye
ANATOMICAL LANDMARKS Pupil • Round hole in the center of the iris through which light passes • Appears black because there is very little light coming from the dark chamber behind it
ANATOMICAL LANDMARKS SIZE OF PUPIL • LIGHT: ~4.0 mm • DARK: ~6.2 mm
ANATOMICAL LANDMARKS Crystalline Lens • Resilient, transparent structure • Focuses light by changing curvature of its front surface • Located directly behind the pupil
ANATOMICAL LANDMARKS Ciliary Muscle • Smooth muscle • Under the direction of the brain controls accommodation by causing the lens to change shape
ANATOMICAL LANDMARKS Suspensory Ligaments (Zonules) • Long, thin fibers • Connect the crystalline lens to the ciliary muscle
ANATOMICAL LANDMARKS Right Eye (OD) Retina • Inner lining (tunic) of back of eye • Contains photosensitive receptors
ANATOMICAL LANDMARKS Rods and Cones • Light sensitive receptors • Transform light information into chemical energy
ANATOMICAL LANDMARKS Cones • Found in great abundance at the fovea (macular area) • Responsible for clear central vision, color perception, and bright-light (photopic) seeing
ANATOMICAL LANDMARKS Rods • Found in great abundance in peripheral retina • Dim illumination (scotopic) seeing and motion detection
ANATOMICAL LANDMARKS Fovea Centralis • Small, thinned-out area in the center of the macular area • Due to high cone density information at the fovea sharper than anywhere else on the retina
ANATOMICAL LANDMARKS • Visual acuity sharpest at the fovea - only place 20/20 or better • Visual acuity drops off rapidly as you leave the fovea (even as you leave the very center) • Eyes move to position the images of objects of regard on the fovea, so that they will be seen most clearly
ANATOMICAL LANDMARKS Optic Nerve • Bundle of ganglion nerve fibers • 11 currently known separate branches • Carry messages from the eye to the brain
THE SENSORY PROCESS • Light waves enter through the cornea • cornea bends the light • Iris, a diaphragm, regulating amount of light that enters
THE SENSORY PROCESS • light further bent as it passes through the crystalline lens • which adjusts its shape and power to bring the light waves to focus on the retina
THE SENSORY PROCESS • at the retina, special photoreceptor cells, the rods and cones, convert the radiant energy into chemical energy
THE SENSORY PROCESS • rods and cones synapse with bi-polar cells • chemical energy encoded into electrical impulses • electrical impulses transmitted to ganglion nerve fibers → optic nerve
BEHAVIORAL APPROACH “ Vision is the deriving of meaning and direction of action as triggered by radiant energy.” Robert Kraskin, O.D., FCOVD
BEHAVIORAL APPROACH Sees vision as holistically interrelated with the whole person and his/her behavior
BEHAVIORAL APPROACH • Vision both an input and an output process, involving dual interactions of bottom-up processes and top-down controls traveling in both directions • Visual problems not caused by environmental stresses, but by the individual’s response to these stresses
TOP-DOWN vs BOTTOM-UP • Top-down: processing guided by higher level mental processes as we construct perceptions, drawing on our experiences and expectations (analysis – overview) • Bottom-up: processing guided by input, and proceeds in subsequent stages to larger and more complex systems (synthesis – details)
BEHAVIORAL APPROACH • Evaluation of measurements considered within the framework of the patient’s individual symptoms, needs, abilities, goals • Subjective findings very important
BEHAVIORAL APPROACH • Strong emphasis on the underlying visual processes and integration of all sensory systems • It is not the vision therapy procedure in itself that improves vision • Awareness and the individual making an internal change creates the improvement
BEHAVIORAL APPROACH Vision seen as an organismic process related to: • cognitive-perceptual style • central-peripheral organization • personality and reaction to stress • balance and movement • spatial relations • posture Martin H. Birnbaum, O.D., FCOVD
How do patients get from the OD to us? ANALYTICAL EXAMINATION • Comprehensive optometric exam that probes the functioning of the visual system under varying conditions (the “21 points”) • Findings help the optometrist understand how vision might be helping or interfering in the patient’s performance, comfort, etc.
How do patients get from the OD to us? • OBJECTIVE – test or finding that does not require a patient response • SUBJECTIVE - test or finding based on the patient’s reported personal reaction and ability to respond
How do patients get from the OD to us? • SIGNS – optometric findings or observations resulting from a visual problem or interference, eg elevated IOP, esophoria • SYMPTOMS – patient’s personal and subjective report to perceived departure from “normal,” eg. blurry vision, asthenopia, headaches, losing place when reading
VISUAL ACUITY • Clearness or sharpness of sight • Ability to resolve or discriminate contours and to tell when there is a separation of the contour from its background
VISUAL ACUITY • Usually represented as a fraction, eg. 20/20 • Identifies the size of the smallest letters resolved at the testing distance used • Numerator represents the testing distance used, typically 20 feet • Denominator relates to size of the letter read
VISUAL ACUITY • Visual acuity fraction gives no information as to how much effort is needed to see clearly, or to use both eyes together, or how much meaning is obtained from the visual input
UNDERLYING CAUSES MYOPIA • nearsightedness • light rays come to point focus in front of the retina