Ординатура / Офтальмология / Английские материалы / Fixing My Gaze_Barry, Sacks_2010

Anisometropia—the condition in which the two eyes have different refractive powers. One eye may be more nearsighted (myopic) or farsighted (hyperopic) than the other. If one eye is more farsighted, then it will be continually out of focus. This condition can lead to amblyopia in the more farsighted eye.

Anomalous correspondence—a condition found in strabismics in which objects seen by the foveas of the fixating and the turned eyes are not interpreted as being located at the same point in space. Instead, objects seen by the fovea of the fixating eye and a nonfoveal region of the misaligned eye are interpreted as being in the same place. In many cases, the images seen by the two foveas are interpreted as being separated in space by the same amount as the angular deviation of the two eyes.

Behavioral optometrist (developmental optometrist)

—an optometrist with a specialty in treating functional vision problems, including difficulties with binocular vision and depth perception, eye movements, visual problems that impact reading and learning, and visual deficits following stroke or brain injuries. These optometrists are skilled in the use of optometric vision therapy.

Bifixate—to aim the fovea of both eyes at a target. Convergence—the turning in of the two eyes when one

looks at a near distance. You converge your eyes to position the image of regard onto the fovea of both retinas.

Convergence insufficiency—a disorder in which the individual does not focus and aim the eyes at the same

place in space, particularly when viewing a near target.

Corresponding retinal regions—the fovea of each retina as well as the regions located equally to the right or equally to the left of them. For people with normal binocular vision, objects that cast their images on corresponding retinal regions are interpreted as being located in the same place in space.

Crossed eyes—a colloquial term for esotropia.

Depth perception—the sense of an object’s distance obtained from both stereopsis and monocular depth cues like perspective, shading, and object occlusion.

Developmental optometrist (behavioral optometrist)

—an optometrist with a specialty in treating functional vision problems, including difficulties with binocular vision and depth perception, eye movements, visual problems that impact reading and learning, and visual deficits following stroke or brain injuries. These optometrists are skilled in the use of optometric vision therapy.

Divergence—the turning out of the two eyes when switching one’s gaze from near to far. You diverge the eyes to position the image of regard onto the fovea of each retina.

Esotropia—a condition in which one eye fixates, or is aimed at, the target, while the other eye turns in. This disorder is colloquially called crossed eyes.

Exotropia—the condition in which one eye fixates, or is aimed at, the target, while the other eye turns out. This condition is colloquially called walleye.

Fixate—to aim the eye at a target so that the image of the target is cast on the retinal fovea.

Fovea—the central region of the retina containing the highest density of light-sensing cells. Images are seen most clearly and in the greatest detail if cast on the fovea.

Infantile esotropia—esotropia that develops within the first six months of life. This condition is also called congenital esotropia, although it is rare for an infant to be born with esotropia.

Lazy eye—a colloquial term for amblyopia.

Normal correspondence—the condition found in normal vision in which objects seen by the two foveas are interpreted as being located in the same place in space.

Panum’s fusional area—the area on the two retinas that corresponds roughly to the plane where one is looking. Objects whose images fall within Panum’s fusional area are seen as single. Objects whose images fall outside of Panum’s fusional area are seen as double. See discussion of the Brock string in chapter 6.

Retina—the tissue located toward the back of the eye that contains the light-sensing rod and cone cells.

Squint—another term for strabismus.

Stereopsis—the ability to use the different viewing perspectives of the two eyes to see in three dimensions.

Strabismus—a misalignment of the visual axes of the two eyes. Esotropia (crossed eyes) and exotropia (walleye) are both types of strabismus.

Walleye—a colloquial term for exotropia.

Wandering eye—a colloquial term for amblyopia.

Resources

College of Optometrists in Vision Development (COVD)

COVD is a nonprofit, international organization whose members include optometrists, optometry students, and vision therapists. The organization was founded in 1971 to standardize optometric vision therapy techniques and provide a rigorous board-certification process for optometrists and vision therapists. Optometrists who complete the board-certification process become fellows of COVD. The COVD publishes the journal Optometry and Vision Development. Information about the COVD can be accessed via their website at www.covd.org.

Optometric Extension Program Foundation (OEP)

Optometrists A. M. Skeffington and E. B. Alexander founded the Optometric Extension Program Foundation in 1928 to provide educational programs and materials for both eye-care professionals and the public. The organization publishes the Journal of Behavioral Optometry. Information about the OEP and useful books about vision therapy can be accessed via their website at www.oepf.org.

Neuro-Optometric Rehabilitation Association (NORA)

NORA includes a group of diverse professionals interested in the rehabilitation of individuals suffering from visual-motor, visual-perceptual, and visual-information- processing dysfunctions. More information can be accessed via their website at www.nora.cc.

Find a Doctor

The above three organizations (COVD, OEP, and NORA) provide directories for optometrists conversant in optometric vision therapy.

InfantSEE

InfantSEE is a public health program designed to provide comprehensive vision assessments to children in the first year of life. Optometrist members of the InfantSEE program provide vision evaluations free of charge as a public health service. More information can be obtained via their website at www.infantsee.org.

Useful Websites

Optometrists Network provides a wealth of information at the following linked websites:

optometrists.org strabismus.org

lazyeye.org convergenceinsufficiency.org children-special-needs.org braininjuries.org learningdisabilities.net vision3d.com visionstories.com

visiontherapy.com, visiontherapy.org

These highly informative and recommended websites contain no ads and were created by Rachel Cooper, an individual who suffered from poor binocular vision until she received optometric vision therapy in her mid-thirties.

Parent Organizations

Parents Active for Vision Education (PAVE)

Founded by concerned parents, PAVE is dedicated to helping children who struggle in school as a result of visual disorders. More information can be accessed at their website at www.pavevision.org.

Vision First Foundation

The Vision First Foundation was founded by Janet Hughes whose mission is to make others aware that school vision screenings are not sufficient to uncover and diagnose many vision problems that impede a child’s progress through school. Ms. Hughes was active in the

passage of an Illinois law requiring written notification before a vision screening that states, “Vision screening is not a substitute for a complete eye and vision evaluation by an eye doctor.” More information can be obtained via the foundation’s website at www.visionfirstfoundation.org.

Books

Numerous books about vision therapy are available via the OEP website at oep.excerpo.com. COVD fellow optometrist David Cook has published two helpful books concerning vision and vision therapy: Visual Fitness (2004) and When Your Child Struggles (1992).

Notes

Chapter 1: Stereoblind

1 He was describing the development of the visual system, highlighting experiments done on walleyed and cross-eyed kittens.

Hubel DH, Wiesel TN. Binocular interaction in striate cortex of kittens reared with artificial squint. Journal of Neurophysiology 28 (1965): 1041-59.

Hubel DH, Wiesel TN. Brain and Visual Perception: The Story of a 25-Year Collaboration. Oxford: Oxford University Press, 2005.

2 We have two eyes, he said, but only one view of the world.

An excellent review of stereovision is found in Hubel DH. Eye, Brain, and Vision. New York: Scientific American Library, 1995. Also available online at http://hubel.med.harvard.edu/bcontex.htm.

3 The classroom didn’t seem entirely flat to me.

See chapter 7 for a more detailed discussion of nonstereoscopic cues to depth.

4 Many of the great students of optics, including Euclid, Archimedes, da Vinci, Newton, and Goethe, never figured out how we see in stereoscopic depth

For a fascinating review of the history of our knowledge of binocular vision, see

Howard IP, Rogers BJ. Seeing in Depth. Ontario: I. Porteus, 2002, vol. 1, ch. 2.

Crone RA. Seeing Space. Exton, PA: Swets and Zeitlinger Pubs., 2003.

6 The teddy bear located to your left casts its image on corresponding points on the right side of both your retinas, while the rattle, to the right, casts its image on corresponding points on the left side of both retinas.

In figure 1.3, the block is located at the fixation point. The bear, block, and rattle all fall on a line called the horopter, or, more specifically, the apparent frontoparallel plane horopter. Although this line is slightly curved, we interpret the bear, the rattle, and all other objects along this horopter as located in the same plane as the block. See, for example,

Steinman SB, Steinman BA, Garzia FP. Foundations of Binocular Vision: A Clinical Perspective. New York: McGraw-Hill Cos., 2000, ch. 4.

6 In 1838, Wheatstone explained how the relative position of the images on the two retinas allows us to see in 3D.

Wheatstone C. Contributions to the Physiology of Vision. —Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision.

Philosophical Transactions of the Royal Society of London 128 (1838): 371-94.

10 I thought about people who were totally colorblind.

Individuals with a hereditary form of total colorblindness are described in

Sacks O. The Island of the Colorblind. New York: Alfred A. Knopf, 1996.

10 With this knowledge, could they see in their mind’s