AN INTRODUCTION TO VISION TRAINING I'M 50 YEARS OLD...AND I HAVE THE EYESIGHT OF A 25-YEAR-OLD. HOW DID I DO IT? THROUGH VISION TRAINING EXERCISES, WHICH I LEARNED FROM MY OPTOMETRISTS... THIS IS AN INTRODUCTION TO VISION TRAINING, TO GET YOU USED TO THE GENERAL TECHNIQUES, WHAT TO EXPECT, AND SO ON...

CONTENTS:

(1) What Is Vision Training?

(2) Is This A Brain Problem Or An Eye Problem?

(3) What Is The History Of Vision Training? How Long Has It Been Available?

(4) Why Doesn't Everyone Know About Vision Training?

(5) How Can I Tell If I Could Benefit From Vision Training?

(6) How Do You Know That I Can Do It?

(7) How Do You Know About Vision Training? What Is Your Personal History?

(8) What About The Bates Method Of Vision Improvement? Is There Anything Useful In It?

(9) Can You Describe a Typical Vision Therapy Session In Your Doctor's Office?

(10) What Parts Of The Visual Apparatus Are Involved In Vision Training?

(11) How Is It Possible That You Can You See Better, If You Don't Do Well In Your Office Practice Or Home Practice Session?

(12) What Are Some Easy Vision Improvement Practices One Can Do Without Special Equipment?

(13) What Are Some Bates Methods and Observations I Have Found Especially Useful?

(14) What Home Practices Does The Vision Training Provider Prescribe?

(15) What Side Effects May Result From Your Practice of Vision Therapy?

(16) What Is A Typical Day Like For You, In Terms of Practicing Vision Exercises?

(17) Are There Other Factors May Affect Your Vision and Vision Training Practices?

(18) Can I Keep Doing This Forever?

(19) Do I Need To Understand all the Unfamiliar Technical Terms used to Describe Vision and Vision Therapy?

(20) Is Vision Therapy A Scientific, Medically accepted Practice?

(21) WHO Can Benefit From These Exercises?

(22) Are There Any Other Things One Might Do To Improve Vision?

(23) What Books Are On Your List of Suggested Reading About Vision?

(1) WHAT IS VISION TRAINING? (also known as vision therapy, visual training, behavioral optometry, developmental optometry ) It is a kind of physical therapy, or rehabilitative therapy for the brain and eyes. It is a progressive program, meaning that the beginning exercises are the easiest, gradually becoming more difficult, so that the flexibility and coordination of the eye muscles is improved. Students of vision training learn to control their eye muscles and are able to overcome many kinds of vision impairment which involve the muscles of the eyes. It involves improving visual skills such as eye teaming, depth perception, tracking, and vision-body (eye-hand) coordination.(See also orthoptics) Most people who visit an optometrist know that any eye health problems will be detected and managed and that glasses or contact lenses will be prescribed if indicated. However, there are visual conditions that are best managed by optometric vision therapy. Some of these conditions are weaknesses that a person is born with. Others are caused by accident or trauma. And of course the eye muscles and other parts of the eye will gradually weaken as a natural consequence of the aging process.This therapy enables an individual to learn more efficient ways to perform visually. It is a valuable adjunct to the prescription of eye glasses, contact lenses and the treatment of eye disease. (2) IS THIS A BRAIN PROBLEM OR AN EYE PROBLEM? It is both, because the visual system involves the brain as well as the eyes. The eyes are literally physical extensions of the brain. Binocular vision problems may involve difficulties with how the brain processes visual info coming through both of the eyes. (3) WHAT IS THE HISTORY OF VISION TRAINING? How Long Has it Been Available? Vision therapy is not new. Physicians in the mid-1800s originally introduced many of the techniques that are used today. Modern Optometric Vision Therapy was introduced in the United States in 1928. Throughout the years, vision therapy has been called various names such as visual training, orthoptics, or eye exercises. (4) WHY DOESN'T EVERYONE KNOW ABOUT VISION TRAINING? First of all, Vision Training is well-known in many parts of the world, but is best known with respect to vision problems in children. We have all seen children with strabismus, where the eyes are crossed. The daughter of one of my best friends had this condition, and it was corrected through the use of vision training. Children with attention deficit disorder often have difficulty with eye muscle coordination. The benefits for adults are well documented, but are simply not well-known yet by the general population. But everyone knows the value of exercise in general. The practice of yoga, for instance, is well known to produce benefits in muscle flexibility and coordination. If practiced consistently, it helps to slow down the deterioration of one's muscles which is a natural consequence of the aging process. Vision Training will have this effect as well, but it targets the visual system. It requires persistence, more than anyting else, but the benefits are absolutely enormous. (5) HOW CAN I TELL IF I COULD BENEFIT FROM VISION TRAINING? First of all, you know your eyes better than anyone does. Think for a minute about the variability of your vision. Do you see better at some times than at other times? This suggests right away that whatever is imperfect about your vision is not a fixed thing. If you recognize this, there exists the possiblity that muscle weakness, fatigue, and coordination problems may be at least part of your problem. Get a comprehensive eye exam, so you know if there is anything else afoot. There are eye conditions that there is no remedy for, and you will want to rule these out. If you hear the good news from your eye doctor that you do not have one of those conditions, like cataracts, glaucoma, or retinopathy, it is likely that you can benefit from vision exercises. Even if the doctor says that you are aging, and your lenses are less flexible now, there is hope that you can improve your vision. (6) HOW DO YOU KNOW THAT I CAN DO IT? I think you can do it because I was able to do it, and at an age when I was told that it probably was too difficult for me; I was too old. But I am a jewellery modelmaker, and I needed my eyesight to be very good for my work, and I needed my eyes to be strong so that I didn't suffer when I was using all that magnification equipment. I saw that my eyesight was getting worse and worse, for both close work and distance vision. I needed glasses to read, even if I hadn't been using my eyes much, and when I wasn't even tired. I was kind of desperate, actually. So I decided that it was worth the effort involved. ** Please remember that it is absolutely essential that you have a comprehensive eye exam before you seriously undertake vision therapy exercises. I cannot stress this enough. There is always the possiblity that you may have an underlying condition that cannot be improved through vision training, and this first has to be ruled out. (7) HOW DID YOU KNOW ABOUT VISION TRAINING? WHAT IS YOUR PERSONAL HISTORY? I had known about it for years, because my family optometrists, Dr Evans and Dr Stein, are people I have known for my entire life. I would sometimes be in the optometrist's chair, and Dr Evans would entertain me with stories of baseball leagues who sent some of their players to him to see if they could benefit from vision training. It seems that some of them were having trouble in the outfield, etc. He told me that on testing them, he could tell if their problems could be remedied through vision training. I never thought about having vision training myself, because I was lucky enough to be born blessed with very superior eyesight, much better than 20/20. I could see well at almost any distance, in dim and bright light. Some people are fortunate like this when they are young; others are not. When I was about 33 years old, I suffered an eye injury on the job. I was working in a jewellery factory, without any glasses or goggles on to protect me, and a piece of metal broke off of what I was working on. It hit me in the right eye. It damaged my cornea, which is the clear covering over the front of the eyeball. I had to have emergency surgery to remove bits of metal from my eye, and I had a bandage on for awhile. After that my vision wasn't as good, but I really didn't want to think about it too much. Some time later, Dr Evans examined me and informed me that my eyes were not working in concert with each other. He said that my ciliary muscles which are used to focus the lens of the eye were in spasm, too, from the shock of the accident. He frankly didn't know how I was even able to do my work with that problem, and recommended vision therapy. When I started my therapy, I was forced to confront the inadequacies of my eyesight, and it was very upsetting to me, emotionally. I was given various procedures to practice in the doctor's office, and lenses to practice with at home. I found everything very difficult, and I was also forced to notice exactly how long it took me to focus the eye that had been damaged. There was a lapse of about 5 seconds in focusing, and when I finally did manage to focus, the image that I saw with my right eye was considerably smaller than the one I saw with my left eye. Mercifully, I did not suffer any permanent scarring of the cornea, since I somehow absorb scar tissue. Another bit of luck. This time I really needed it. I continued with my therapy for some time, but frankly I was not too dedicated. I was able to improve my focusing ability and the ability to use my eyes in tandem with each other. The next time I underwent therapy, I was much more determined. I was 45 years old, and both my near vision and distance vision were getting progressively worse. I didn't want to go to see Dr Evans, because each time I went I needed a stronger prescription, just to read the newspaper. I kept using more and more magnification for my modelmaking work, and my eyes just felt so uncomfortable after doing this. I decided to try vision therapy again, although I was told that it would probably be too difficult for me since the flexibility of the lens was no doubt affected, due to the aging process. When I started my exercises I once again had a great deal of trouble, but somehow this made me more persistent and creative in my approach to it. I had difficulty with even the easiest lenses, so I tried doing things a different way than suggested. For example, instead of using a lens with a small reducing factor, I held the newspaper closer and closer to my eyes. This helped to "coax" my eyes into improvement. Soon I was able to use the practice lenses.There were many other things I tried, but most of all I decided to take notice of every single detail in my practices. I realized that being hyper-aware of what my eyes were doing was of utmost importance, especially when I found something that worked. I will give many details of my vision therapy practices in the pages that follow. Most of these were homework ordered by Dr Evans and his partner, Dr Stein. Others are culled from the writings of other people who have had vision problems, and of course I came up with a few useful ideas myself. The result of all this? I practice vision exercises every day of my life, and I have been told that I now have the eyes of a 25-year-old. I have heard many anecdotes of successful vision therapy in other people, too. I am not the exception. And I think that you all could succeed at it, too. The benefits are too great for you not to give it a chance. HERE'S ANOTHER THING TO CONSIDER: Experts of all kinds like to toss around language that you can?t understand. It makes a person feel kind of ignorant. I happen to think that people do this on purpose, for reasons of their own. For instance, before I got a computer, people made me feel very small when they used computer terminology. Which turned out not to be all that difficult to understand, by the way. Well, with this essay and its accompanying glossary about vision, you will feel empowered with understanding about the workings of your eyes! Trust me; you?ll feel alot better knowing this stuff... 20) Is Vision Therapy A Scientific, Medically accepted Practice? Vision therapy is not voodoo or a magic act, but a very well-documented practice. See Scientific studies on vision therapy, at the Indiana University School of Optometry web site, and Vision Therapy References for other publications. See also Appendix B. It is akin to other types of physical therapy, and is most widely-known as an aid for children with vision problems. Many opthamologists think that vision therapy doesn?t work., but they are primarily concerned with diseases of the eye, and with surgery. They are not required to learn about physical therapies for vision improvement, as optometrists are, during their training. Similarly, in the USA, medical doctors have no required.training in herbal medicine or nutrition, and few of them consider learning about it to be worthwhile. So there is a rivalry between herbalists and medical doctors. Herbal medicine is very well-respected and researched in Europe, China, and India. MDs are ignorant of herbal medicine; opthamologists are ignorant of vision therapy. The problem is merely their lack of knowledge, and many professionals are loath to admit this. My answer to either situation is: Try it! You may be quite suprised and pleased. 21) WHO Can Benefit From These Exercises? Anyone whose vision problems are related to muscle weakness or lack of coordination. The exercises take time, patience, and persistence. People whose work is especially stressful to their eyes, such as jewellers, designers, photographers, and computer users will find them especially valuable. Below are some tips for certain professions: JEWELLERS, DESIGNERS, ETC: a) Have a comprehensive eye exam. Having the proper glasses will prevent further stress on your eyes, since they will correct whatever is your particular weakness. b) If your vision does not need correction, wear glasses with non-corrective lenses. You will need to protect your eyes from damage due to possible accidents on the job. c) If your work requires better than 20/20 vision, have your eye doctor prescribe magnification lenses in your particular prescription. d) Frequently change the magnification you are using. This helps to prevent the lenses from losing their flexibility at varying distances. e) You may find it useful to use your prescription magnification glasses with optivisors, etc for additional magnification. Many people experience eye pain or discomfort when using non-prescription magnifiers. The use of BOTH often remedies this. f) Make sure that you have adequate lighting for your work, whatever is comfortable for you. g) Take frequent breaks if your schedule permits, to practice vision training exercises of all kinds. COMPUTER USERS: a) Have the monitor from 16 to 24 inches away from you. Excessively close computer work is a strain on one?s eyes. b) Frequently take a break from looking at the monitor, at least every 15 minutes. Look far away, at varying distances. c) Use the largest monitor possible, with screen contrast, etc. so that resolution is maximized. d) Location of Monitor: The center of the computer screen should be 4 - 9 inches below your eyes. Your eyes work best with a slight downward gaze. If the computer screen is higher or lower than this, it causes an awkward posture that contributes to sore neck, back, or shoulder, and may also produce headaches. Also, your computer screen and other work should be located straight in front of you so that you don't have to look sideways or twist your body or neck to see them. e) Lighting: Bright lights or other bright objects in your peripheral vision can be uncomfortable. Use a relatively low-wattage bulb in your desk lamp if possible. Drapes can be used to shield one?s eyes from daylight if necessary. f) Look for anti-reflection screens that have been approved by the American (or other)Optometric Association. g) Experiment: Try varying the size and kind of fonts you use in your browser, word processing application, and other programs during the course of the day. This serves as a kind of vision exercise itself. h) Do vision training exercises as often as your work schedule permits. Try doing some of the stereograms you find online as well. i) Blink on a regular basis; do not stare at the monitor. This sounds obvious, but people sometimes don?t realize that they are staring. Blinking helps one to refocus the eye, and is also relaxing. j) This may sound obvious, but an easy way to rest your eyes from computer use is to just throw them out of focus. Try it, and see how you feel... NUTRITIONALLY SPEAKING... 22) Are There Any Other Things One Might Do To Improve Vision? Do whatever you can to remain in good health. It has been suggested that certain herbs and nutrients might promote the health of the visual apparatus. These include bioflavonoids such as quercetin and lutein, vitamins E, A, and C, and herbs such as bilberry. CoEnzyme Q10 is another. Any nutrient that has the reputation of having Antioxidant properties would be a good idea. Of course nutritional supplements of any kind are an added expense. The most important thing is to eat a balanced diet containing all the essential food groups. Essential fatty acids (oils) which are polyunsaturated or monounsaturated help especially the nervous system and hormonal systems. Many people try to eat a very lowfat diet to keep their weight down, but if you eliminate too many beneficial fatty acids, your health will suffer. Of course try to get enough rest and do whatever is your favorite method of relieving stress. And what one doesn?t do can often have more of a good effect than anything else. Smoking and drinking are well known to promote rapid aging, as do recreational drugs (Sorry!) so they are also not a good idea. Try to live a life of moderation, in terms of eating well and exercising regularly, in general. If you know that you have a medical condition, like diabetes, make sure that you keep your sugar level under control. Vision problems related to blood vessel problems are related to this disease, among other things. And no one lives a perfect life, healthwise, but most of us know what is actually really bad for us... 23) Suggested READING: THE ART OF SEEING by Aldous Huxley STEREOGRAM by Cadence Books This book is a very good start for practicing Base In (distance) Exercises. Seeing Stererograms is much easier than regular training. It is also alot of fun! (See stereogram links) APPENDIX A: A GLOSSARY OF USEFUL TERMS Accommodation- (eye focusing) the eye's ability to adjust its focus by the action of the ciliary muscle, which increases the lens focusing power. When this accommodation skill is working properly, the eye can focus and refocus quickly and effortlessly, which is similar to an automatic focus feature on a camera. The ciliary muscles must contract to adjust for near vision, which causes the eye?s crystalline lens, which is flexible, to be squashed. For distant vision, the ciliary muscle must relax and the eye?s crystalline lens is stretched out. The ability of the eye to accommodate does decrease with age due to the crystalline lens becoming less flexible causing a condition called presbyopia. (See Presbyopia) Accommodative Fatigue- This clinical condition is also called Ill-Sustained Accommodation. It is the inability of the eye to adequately sustain sufficient focusing over an extended time period. The most common sign or symptom is blurred vision after prolonged near work such as reading and using a computer. In addition, such patients often have asthenopia (eyestrain), general fatigue, headaches and nausea, excess tearing, and an unusual sensitivity to light. Clinical signs include: normal amplitude of accommodation, decreased PRA, and the patient generally fails the +/-2.00 D flipper test. Plus lenses (glasses or contacts) and vision therapy are effective in treating this condition. Accommodative Esotropia- this clinical condition is an excessive inward turning of the eye caused by an overactive convergence response as the eye focuses on an object. More common in farsighted (hyperopic) children. This is treated with plus lenses (glasses or contacts) to decrease the accommodative demand and to straighten the eyes. In some cases, vision therapy and corrective lenses are prescribed. (Please note that Accommodative Esophoria is a condition similar to accommodative esotropia but lesser in extent.) Accommodative Excess (AE)- This clinical condition is also called accommodative spasm. It is an over focusing, over stimulation of the focusing action of the crystalline lens causing an inability to relax the focusing system which may result in blurry vision when focusing at distance objects. Other symptoms include holding near work closer than normal, headaches with near work (such as reading or using a computer), eyestrain associated with near work, and possible double vision. Clinical signs include: patient accepts more minus on accommodative rock but blurs with plus lenses, lower NRA than PRA, dynamic retinoscopy findings indication of over accommodation and/or slow relaxation of accommodation, and reduced or erratic distance visual acuity. Vision therapy is an effective treatment option. Accommodative Infacility- (clinical condition) a difficulty changing eye focus from distance to near. Symptoms include eyestrain associated with near work (such as reading or using a computer), periodic blurring of distance vision especially following sustained near visual work, tendency to hold near work closer than expected, headaches with near work, and possible double vision. Clinical signs include: patient will have difficulty with both the plus and the minus lens (fails +/- 2.00 D flipper test), low PRA and NRA, and poor recoveries on Bell Retinoscopy. Vision therapy is an effective treatment option. Accommodative Insufficiency (AI)- This clinical condition is also called non-presbyopic accommodative insufficiency. It is an under focusing, a lack of focusing ability at a near distance. Symptoms include eyestrain, blurred vision, occasional or constant when doing near work (such as reading or using a computer), occasional unusual sensitivity to light, excess tearing, headaches, and general fatigue. Clinical signs include: patient will have difficulty with a minus lens, low amplitude of accommodation, low PRA and higher NRA. Vision therapy is an effective treatment option. Accommodative Vergence- a convergence response (to turn the eyes inward) which occurs as a direct result of accommodation. (See Vergence and also Amplitude of Accomodation) AC/A Ratio- accommodative convergence / accommodative ratio (measured in prism diopters / diopters). This is the numerical expression for the relationship between the amount both eyes simultaneously turn inward (converge) in response to an increase in optical power of focusing (accommodation) by the eye's lenses. The normal ratio is 4:1. Acuity- sharpness or clearness of eyesight. It is a measure of the finest detail a person can see. The Snellen chart is used to test visual acuity. This chart contains rows of letters, numbers, or symbols in standardized graded sizes, with a designated distance at which each row should be legible to a normal eye. (See "Near Acuity" and "Distance Acuity") After-image- the eye's ability to still see an image during eye blinks and even after the viewed object is no longer present. The most common example is seeing light after the flash of a camera. Alignment- proper fusing (uniting) of images to each eye. Amblyopia- (also called ?lazy eye.?)The unexplainable loss or lack of full development of the vision in one eye. It is not fully correctible with glasses or contact lenses, and has not been traced to any particular eye health problem. Sometimes it is the result of crossed eyes or a great difference in the refractive (light-bending) error between the two eyes. AMD or ARMD (age-related macular degeneration) Disorder characterized by the gradual loss of central vision due to a damaged macula (which is made up of retinal cones necessary for sight). Ametropia- any optical error such as hyperopia, myopia, presbyopia, or astigmatism that can be corrected by glasses or contacts. Also called refractive error Amplitude of Accommodation (AA)- a measurement of the eye?s ability to focus clearly on objects at near distances. This eye focusing range for a child is usually about 2-3 inches. For a young adult, it is 4-6 inches. The focus range for a 45-year-old adult is about 20 inches. For an 80-year-old adult, it is 60 inches. Aniseikonia- unequal retinal image sizes in the two eyes, usually from different refractive errors. (See Iseikonic Lens) Antioxidant - Substance that inhibits oxidation and can guard the body from the damaging effects of free radicals. Molecules with one or more unpaired electrons, free radicals can destroy cells and play a role in many diseases. Antioxidants may help prevent macular degeneration and other serious eye diseases. Aqueous humor - Clear fluid in the eye that both provides nutrients and determines intraocular pressure. Asthenopia- eyestrain, symptoms include excessive tearing, itching, burning, visual fatigue, and headache. May be related to uncorrected refractive error, accommodation (eye focusing) disorder, or binocularity (eye teaming) disorder. Astigmatism- Blurriness of vision at all distances, a common vision condition which is usually caused by the front surface of the eye having a slight irregularity in shape. Base-Down (BD) Prism- the base (thickest end) of the prism is downward and it causes the eye to move up. Used to measure or treat a binocular dysfunction (eye teaming problem). Sometimes incorporated in glasses. Base-In (BI) Prism- the base (thickest end) of the prism is towards the nose and it causes the eye to diverge (straighten or move out). Used to measure or treat a binocular dysfunction (eye teaming problem). Sometimes incorporated in glasses. Base-Out (BO) Prism- the base (thickest end) of the prism is away from the nose and it causes the eye to converge (turn in). Used to measure or treat a binocular dysfunction (eye teaming problem). Sometimes incorporated in glasses. Base-Up (BU) Prism- the base (thickest end) of the prism is upward and it causes the eye to move down. Used to measure or treat a binocular dysfunction (eye teaming problem). Sometimes incorporated in glasses. Behavioral optometrist- A doctor of optometry who specializes in the practice of vision therapy. Also known as a vision training provider. Bifocal Glasses- eyeglasses that combine two lenses with different refracting powers, one for distant and one for near vision. Often prescribed for people with presbyopia. Binocular- of or involving both eyes at the same time Binocular vision: when both eyes aim at the same target at the same time, working together as a well-coordinated team, equally and accurately (See also stereo vision) Binocular depth perception- the ability to perceive with one?s eyes that space has three dimensions, particularly depth. Also, the ability to judge relative distances between objects Binocular vision impairment- a defect in vision in chich one?s two eyes do not work together as a well-coordinated team. This results in a partial or complete loss of binocular depth perception and stereoscopic vision. At least 12% of the population has some kind of binocular vision impairment. Break Point- measurement, the point at which a person can no longer fuse (unite) two images into one. Cataracts- A condition in which the normally clear lense of the eye becomes cloudy, resulting in clouded and or blurred vision. (Cannot be corrected by the use of vision training) Cataracts may be caused by aging, eye injuries, disease, heredity, or birth defects. Surgery is a treatment option. The affected lens is removed and is replaced with a substitute (implant) lens or with a special type of contact lens. Generally the success rate of cataract surgery is over 90%, if the eye is otherwise healthy. Ciliary Body- a structure directly behind the iris of the eye and contains the ciliary muscle. (See diagram of the eye) Ciliary Muscle- a band of muscle and fibers that are attached to the lens that controls the shape of the lens and allows the lens to accommodate (change focus). Comprehensive eye exam- A comprehensive eye examination should include the testing of the following visual skills which are aspects of normal, healthy vision: (see below) Acuity-Distance: visual acuity (sharpness, clearness) at 20 feet distance. Acuity-Near: visual acuity for short distance (specifically, reading distance). Focusing Skills: the ability of the eyes to maintain clear vision at varying distances. Eye Tracking and Fixation Skills: the ability of the eyes to look at and accurately follow an object; this includes the ability to move the eyes across a sheet of paper while reading, etc. Binocular fusion: the ability to use both eyes together at the same time. Stereopis: binocular depth perception. Convergence and Eye Teaming Skills: the ability of the eyes to aim, move and work as a coordinated team. Hyperopia: a refractive condition that makes it difficult to focus, especially at near viewing distances. Color Vision: the ability to differentiate colors. Reversal Frequency: confusing letters or words (b, d; p, q: saw, was; etc.) Visual Memory: the ability to store and retrieve visual information. Visual Form Discrimination: the ability to determine if two shapes, colors, sizes, positions, or distances are the same or different. Visual Motor Integration: the ability to combine visual input with other sensory input (hand and body movements, balance, hearing, etc.); the ability to transform images from a vertical to a horizontal plane (such as from the blackboard to the desk surface). Computer Vision Syndrome (CVS)- the complex of eye and vision problems related to near work that are experienced during or related to computer use. Its symptoms include eyestrain, dry or burning eyes, blurred vision, headaches, double vision, distorted color vision, and neck and backaches. The condition is caused by various internal and external factors. Treatment options may include prescription glasses and/or vision therapy. Cone- light-sensitive retinal receptor cell that provides sharp visual acuity and color discrimination. (see also Rods) Cornea- is the transparent front-most surface of the eye. Provides most of an eye's optical power. Convergence- the ability to use both eyes as a team and to be able to turn the eyes inward to maintain single vision up close. Depth Perception- the ability to judge relative distances of objects. (See Stereopsis) Diabetic retinopathy - Leaking of retinal blood vessels in advanced or long-term diabetes, affecting the macula or retina. Vision can be seriously distorted or blurred. Diopter (D)- a measurement of the refractive (light bending) power of a lens or a prism (pd). The strength of prescription glasses and contacts are measured in these units. For example a lens that is 0.50 diopter (D) is very weak, where as a lens that is 10.0 diopter (D) is very strong. Eyecare practitioners use it in eyeglass and contact lens prescriptions. A negative number refers to nearsightedness, while a positive number refers to farsightedness. For example, someone with -8.00 diopter lenses is very nearsighted, while someone with +0.75 diopter lenses is only slightly farsighted. Diplopia- double vision. Distance Acuity- the eye's ability to distinguish an object's shape and details at a far distance such as 20 Divergence- the ability to use both eyes as a team and be able to turn the eyes out toward a far object. Dominant Eye- the eye that "leads" it partner during eye movements. Humans also have dominant hand, foot, eye, and side of the brain (not necessarily all on the same side). Duction Test- a test of the eye's ability to turn inward or outward while maintaining single, binocular vision with the gradual introduction of progressively stronger base-in or base-out prisms. Dyslexia- a learning disability in which a person has difficulty with letter or word recognition. Children often are of normal or above normal intelligence; however, they have difficulty reading and sometimes naming pictures of objects. This is caused by an inability of the brain's language centers to decode print or phonetically make the connection between the word's written symbols and their appropriate sounds. This is not caused by a vision disorder. Dyslexia cannot be cured and will never be outgrown. Appropriate teaching methods can be taught to help those with dyslexia overcome their weakness by using their strengths. Emmetropia- normal vision, no correction needed Extraocuar Muscles- six muscles that move one eyeball, includes lateral retus, medial retus, superior oblique, inferior oblique, superior rectus, and inferior rectus Eye Hand Coordination- the ability of our eyes to guide our hands, also called visual motor integration. Facility of Accommodation- a measure of the ease and speed of the eye(s) to change focus Floaters Small specks that pass across your field of vision, these are clumps of cells inside the transparent gel filling the eyeball in front of the retina. Focusing skills: the ability of the eyes to maintain clear vision at varying distances Fovea- center of the retina that can produce the sharpest eyesight. Contains a high concentration of cones and no retinal blood vessels. Fusion- the union of images from each eye into a single image. Glaucoma: An eye disease in which the internal pressure of the eyeball increases to the point that the optic nerve can become damaged, resulting in severe vision loss and even blindness (Not correctible by the use of vision training) Hyperopia: (also known as ?farsightedness?) A vision condition in which distant objects are usually seen clearly, but close objects are not able to be brought into proper focus. Iris- the colored part of the eye located between the lens and cornea; it regulates the entrance of light. Iseikonic Lens- eyeglass lens that magnifies or minifies image size. Used for correcting image size difference between the two eyes. Lens - The nearly spherical body in the eye that focuses light rays onto the retina. The lens itself is a multilayered structure (something like an onion). In young people it is normally perfectly clear and quite elastic. As one ages its elasticity is reduced. In fact after the age of about 45 the lens' ability to change in shape is considerably reduced. That is why people over the age of 45 almost always require glasses to read and/or to see distant objects. It is not unusual for people in their 50's and older to wear bi-focal or even tri-focal lenses. Low vision - Also called partial sight. Sight that cannot be satisfactorily corrected with glasses, contacts, or surgery. Low vision usually results from an eye disease such as glaucoma or macular degeneration. Lutein - An antioxidant that is found throughout the body, but is concentrated in the macula. Lutein is believed to help protect the eyes from free radical damage caused by the sun's harmful rays. Macula- the most sensitive part of the retina that is about the size of a pinhead and is where our most detailed vision occurs. Minus (-) Lens- concave lens, stimulates focusing and diverges light. The lens is thinner in the center than the edges. It is used in glasses or contact lenses for people who are nearsighted (myopia). Myopia: (also known as ?nearsightedness?) A common vision condition in which a person can see close objects clearly, but lacks the ability to see distant objects with the same clarity. Near Point of Convergence (NPC)- the closest point at which the two eyes can maintain a single united image. Near Point of Convergence Test- measures the patient?s ability to point the eyes at an approaching object and to keep them fixed on the object as it reaches the patient?s nose. Normal range is 0 to 4 inches away from the nose. Opthalmologist- an MD who specializes in surgery and diseases of the eye. A small number of opthamologists work in conjunction with vision therapists or orthoptists Optician- is a professional in the field of designing, finishing, fitting and dispensing of eyeglasses and contact lenses, based on an eye doctor's prescription. The optician may also dispense colored and specialty lenses for particular needs as well as low-vision aids and artificial eyes. Optic Nerve- is a bundle of nerve fiber that connects each eye to the brain and transmits images from the retina to the brain. It is also the largest sensory nerve of the eye. Optometrist (OD)- a health care professional who is state licensed to provide primary eye care service. These services include comprehensive eye health and vision examinations; diagnosis and treatment of eye disease and vision disorders; the detection of general health problems; the prescribing of glasses, contact lenses, low vision rehabilitation, vision therapy, and medications; the performing of certain surgical procedures; and the counseling of patients regarding their surgical alternatives and vision needs as related to their occupations, avocations and lifestyle. The optometrist has completed pre-professional undergraduate education in a college or university and four years of professional education at a college of optometry, leading to the doctor of optometry (O.D.) degree. Some optometrists complete a residency. Some optometrists are also vision therapy providers. Orthoptics- Literally means ?straightening of the eyes. It dates back to the 1850is but is limited in scope to eye-muscle training and the cosmetic straightening of the eyes. Vision training is an expansion of this. It involves the training of the eye-brain connections involved in vision also, and has progressed in this century as have advancements in the knowledge of neuroscience. Plus (+) Lens- convex lens, relaxes focusing and converges light. The lens is thicker in the center than the edges. It is typically used in glasses or contact lenses for people who are farsighted (hyperopia). Although it may also be prescribed for other visual conditions as well. Polaroid Lens- a lens used in sunglasses which consists of two glass or plastic surfaces with a plastic lamination between the two surfaces, and designed to reduce reflected glare. Presbyopia- A natural part of the aging process, it occurs when the crystalline lens of the eye loses its enough of its flexibility so that the accomodative muscles of the eye can no longer bring close objects into clear focus. Usually, it becomes noticeable when a person reaches their early to mid-forties. Prism- a wedge-shaped piece of glass or plastic that bends light. Used to measure or treat a binocular dysfunction (eye teaming problem). Sometimes incorporated in glasses. (See "Base-Down Prism", ?Base-In Prism?, ?Base-Out Prism?, "Base-Up Prism", "Yoked Prism") Pupil- the opening at the center of the iris of the eye. It contracts in the dark and when the eye is focused on a distant object. It opens and closes to regulate the amount of light the retina receives. Pursuit Test- measures the eyes ability to follow a moving target. Refractive Error- condition in which parallel rays of light are not brought to a focus upon the retina because of a defect in shape of the eyeball or in refracting media of the eye. Also called ametropia. Results in conditions like astigmatism, hyperopia, myopia, or presbyopia. Refractive Power- a lens' ability to bend parallel light rays into focus, as measured by power diopters. In general, the greater the curvature of a lens and the greater the difference between center thickness and edge thickness, the higher the index of refraction and the greater its refractive power. Refractive power can also refer the strength of a person's contact lenses or glasses. Refractive Media- the parts of the eye that light travels through before being focused on the retina includes the cornea, crystalline lens, aqueous, and vitreous. (See diagram of the eye) Retina- the innermost layer of the eye, a neurological tissue, which receives light rays focused on it by the lens. This tissue contains receptor cells (rods and cones) that send electrical impulses to the brain via the optic nerve when the light rays are present. Rod- light-sensitive retinal receptor cell that works at low light levels (night vision). A normal retina contains 150 million rods. Saccades Dysfunction- a condition in which the individual?s ability to scan along a printed page and move his eyes from point to point is inadequate. Symptoms include frequent loss of place while reading, skip or transpose words, and have difficulty comprehending because of an inaccurate eye movement. Vision therapy is an effective treatment option. Sclera- the white protective covering of the eye Stereopsis: The product of good binocular vision, where the separate images from the two eyes are combined successfully into one three-dimensional image. Strabismus: (also known as crossed eyes, wall-eyes, or wandering eyes) A visual defect in which the two eyes point in different directions.In some cases these eye misalignments are not obvious to an untrained observer. One eye may turn either up down, in, or out, while the other points straight ahead. The result of this condition is a partial or total loss of stereo and binocular depth perception. 20/20 -the expression for normal eyesight (or 6/6 in countries where metric measurements are used). This notation is expressed as a fraction. The numerator (1st number) refers to the distance you were from the test chart, which is usually 20 feet. The denominator (2nd number) denotes the distance at which a person with normal eyesight could read the line with the smallest letters that you could correctly read. For example, if your visual acuity is 20/100 that means that the line you correctly read at 20 feet could be read by a person with normal vision at 100 feet. The Snellen chart is used to test visual acuity (sharpness of eyesight). This chart contains rows of letters, numbers, or symbols in standardized graded sizes, with a designated distance at which each row should be legible to a normal eye. The Snellen letter is constructed so as to subtend an angle of 5 minutes of arc (5/60ths of a degree) at a specified distance from the eye. Each portion of the letter subtends an angle of 1 minute of arc (1/60th of a degree). Vergence- to turn the eyes horizontally (convergence- inward or divergence- outward). Accommodative vergence, fusional vergence, proximal vergence, and tonic vergence are needed to maintain single vision. Vergence Facility- a measure of the ease and speed of the eyes to change from a converging to diverging position. Visual Field- the total area that can be seen while looking straight ahead. (See "Tunnel Vision".) (Note: Perimetry is the method of testing an eye's field of vision. Visual-Motor Integration (VMI)- after visual data is gathered, it is processed and combined in the brain with information from movement (eye hand coordination).

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