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Strabismus SPE 516 Trimm, Garmon, Morrison, Baldwin Strabismus Strabismus-- is a functional visual defect, affecting 2-3% of the population (Goldberg), in which the eyes do not align normally with each other due to muscle imbalance, genetic disorders, problems with brain development, injuries to the nerves, or trauma. This can cause either one or both eyes to turn: inward (esotropia) outward (exotropia) vertical (up- hypertropia or down- hypotropia) **Most cases of strabismus are due to problems in brain function and not in the actual muscles themselves (Cooper&Cooper). Three Main Types: Esotropia Exotropia Vertical (CNIB) Esotropia, or 'crossed eye' One eye is turned inward, toward the nose. A child may be born with this condition, or it may develop a few months after birth or around age two to three (CNIB) Exotropia One eye is turned outward, away from the nose. A child is rarely born with this condition. More often, it develops later. (CNIB) Vertical strabismus The eyes are out of alignment vertically (CNIB). How Does Strabismus Effect Vision NORMAL VISION With normal vision, the eyes are straight so that the brain receives two only slightly different visual images. This is called binocular vision which the brain then combines into a single three-dimensional picture. It is this 3-D vision that allows us to judge depth (CNIB). How Does Strabismus Effect Vision Vision With Strabismus When the eyes are not aligned there are several things that occur. Vision will be blurred or doubled because of the different focal points. If left untreated the brain may ignore the visual information from the weaker eye and in a sense “turn off” the eye to avoid the double vision. This is called suppression (ON). Occasionally in young children the brain will develop a fusion in vision between each eye called anomalous retinal correspondence (ON) or in other words the brain self corrects the non-aligned images. *Image (Radiant). Early Detection is the Key According to the American Optometric Association and the American Ophthalmological Association, all children should have their eyes examined before 9 months. The ability to see 20/20, focus, have eye muscle coordination and stereopsis are all developed by 6 months of age and by 9 months the system is in place (Optometrists Network). Vision Check List Early Warning Signs eyes drift in different directions tilts head often to see covers or closes one eye excessive blinking poor hand-eye coordination holds texts and objects close uses fingers to read rubs eyes frequently headaches dizziness and nausea DOUBLE VISION (The Optometrist's Network Website) OK...SO WHAT? What does all this mean for a person with strabismus? A student with strabismus will have trouble with any activity involving depth perception. Catching a ball, learning to drive a car, navigating busy hallways, reaching for objects and up-close tasks like threading a needle or stringing beads would all be extremely difficult and frustrating for them. Tips for Classroom Setting Lemer recommends the following classroom interventions: Assure quality lighting Decrease “busyness” of room and written work Add touch & movement to activities Offer a variety of seating, standing, kneeling options Include breaks during the activities Add extras: grips, paper, fidgets, slant boards, cushions Work with occupational therapist and physical education Can Strabismus be treated? Treatment Options Orthoptics Vision Therapy Surgery Botox Injections It is key to remember that the treatment option is entirely dependent on the type, cause, and age of the individual. In children early detection is vital to prevent vision loss due to suppression or disuse of the weaker eye (Goldberg). Adults who develop strabismus will not develop suppression of an eye but will have double vision for the remainder of their life (Goldberg). Orthoptics vs. Vision Therapy Orthoptics : Vision Therapy: Involves Eye Muscle Training Addresses Acuity Only Provided by an Orthoptist or Optometrist Views Strabismus as a focus is on brains ability to control eye alignment, teaming, focusing and movement. is individualized to whole visual system of an individual includes some orthoptics utilizes therapeutic lenses, prisms, and filters “muscle problem” Eye patching is used to strengthen the weaker eye ESOTROPIA WITH CORRECTIVE GLASSES (Photos from Optometrists Network) Eye Muscle Surgery Photo/Diagram by: International Medical Center In more difficult cases, surgery is performed on the muscles causing the misalignment. The more muscles involved the more complex the procedure (CHB). Botox Injections Not widely available as a treatment option yet, Botox can sometimes be used in lieu of surgery or in cases where the surgery did not correct the alignment (CHB). References 1. Goldberg, Stephen M.D. (1993) Ophthalmology Made Ridiculously Simple. (10th Printing) Miami, Florida: MedMaster, Inc. 2. Cassin, Barbara & Solomon, Sheila A.B. (1997). Dictionary of Eye Terminology. (Third Edition) Gainesville, Florida: Triad Publishing Company. 3. Lueck. Amanda H. (2004). Functional Vision: A Practitioner’s Guide to Evaluation and Intervention. New York: American Foundation for the Blind Press. 5. CNIB Vision Health Vision Hope: Turned Eyes (Strabismus). Retrieved July 27, 2009 from web site: http://www.cnib.ca/en/your-eyes/eye-conditions/turnedeyes/Default.aspx 6. Optometrists Network. Dr. Jeffrey Cooper & Rachel Cooper 2001-2009 All About Strabismus. Retrieved July 27th, 2009 from web site: www.strabismus.org/all_about_strabismus.html 7. International Medical Centre: Pediatrics and Ocular Motility. Retrieved July 28, 2009 from website:www.internationalmedicalcentre.com 8. Radiant. About Lazy Eyes. Retrieved July 28,2009 from website: http://www.radianthk.com 9. Children’s Hospital Boston. How We Treat Strabismus in Children. Retrieved July 30, 2009 from website :http://www.childrenshospital.org/clinicalservices 10. Lemer, P., M. Ed., NCC The Role of Vision in Autism Spectrum Disorders:. Retrieved August 1, 2009, from Total Learning and Therapy Center Web site: http://www.tltc.org/pdf/Vision_in_Autism_Spectrum_Disorders.pdf 11. (1996-2008) Binocular vision impairments affect at least 12 out of every 100 children. Retrieved August 4, 2009 from The Optometrist’s Network Website: http://www.children-specialneeds.org/parenting/preschool/children_eye_exams.html.