Visual System Dysfunction Part 2 Handout PDF

DPT 6340 Visual System Dysfunction Part 2 Objectives Identify clinical presentation and pathology of common visual dysfunctions Identify strategies for managing patients with visual impairments Common Diseases/Disorders: Nystagmus-- involving oscillations of eyes Often present at birth or soon after...

DPT 6340 Visual System Dysfunction Part 2 Objectives Identify clinical presentation and pathology of common visual dysfunctions Identify strategies for managing patients with visual impairments Common Diseases/Disorders: Nystagmus-- involving oscillations of eyes Often present at birth or soon after; Unknown cause, but can also indicate neurological damage; Movements may be jerky or slow; may have decreased acuity due to inability to maintain steady fixation. Common Diseases/Disorders: Refractive Errors In a farsighted (hyperopic) eye, the eyeball is too short, and light rays focus behind the fovea of the retina; symptoms may include a lack of interest in reading, rubbing of the eyes, or even headaches, dizziness, or nausea. In a nearsighted (myopic) eye, the eyeball is too long, and light rays come to a focus before they reach the fovea of the retina, symptoms include squinting and frowning. Examples of Hyperopia and Myopia Common Diseases/Disorders: Refractive Errors  Astigmatism is an irregular curvature of the cornea, and may cause visual fatigue, headaches, frowning, and squinting.  In middle age, the lens becomes less flexible and less able to accommodate for nearpoint viewing; this condition is known as presbyopia. Common Diseases/Disorders: Refractive Errors Tend to be inherited, but there is no pattern of inheritance. Size of the eyeball, shape of the cornea, shape of the lens, etc. are all variables in refractive errors. In the absence of disease or other abnormalities, glasses, contacts, or lasik surgery are the only treatment needed for refractive errors. However, the wearing of glasses does not "strengthen" or "weaken" eyes, or affect the degree and progress of myopia. Eye exercises are of no benefit in improving refractive errors, since they cannot alter the size of the eyeball or the refractive power of the lens. Common Diseases/Disorders: Retinitis pigmentosa-- an often hereditary, progressive retinal deterioration; slow progressive field loss; Peripheral to total blindness or tunnel vision; Symptom is night blindness since affects rods first; Problems with mobility and adjusting to light change; No effective treatment. Example of Retinitis Pigmentosa This condition results in tunnel vision. Common Diseases/Disorders: Retinopathy of prematurity (ROP) [older term was Retrolental fibroplasia (RLF)]-- occurs mainly in preemies that get high/prolonged oxygen; A proliferation of blood vessels and fibrous tissue through the retina and vitreous stretches the retina and causes retinal detachment; Visual damage is moderate to total; can have scattered areas of intact retina, so may have some scattered vision. Common Diseases/Disorders:  Strabismus-- deviation in position of one or both eyes due to muscle imbalance;  May occur only at certain distances or times (tired);  may have vision suppressed from involved eye (amblyopia or ‘lazy eye’);  Can be corrected with surgery, visual training (patching or eye exercises), or inject paralyzing drugs into muscles involved;  Should be identified and treated ASAP, preferably before age 2; it is not "outgrown"; ability to correct decreases with age.  Appears to run in families, though not a clear-cut hereditary pattern. Common Diseases/Disorders: Strabismus: Esotropia is the deviation of one eye toward the nose and is the most common form. Exotropia is the deviation of one eye outward and is less common. Hypertropia is the deviation of one eye upward and is the least common. Deviations may occur with either eye, alternately, or may be always the same. Examples of Strabismus Esotropia Exotropia Hypertropia In closing…. There are a variety of visual impairments that range from mild dysfunction to blindness. VI may impact many of our patients, and our patients with stroke, brain tumor, and TBI may have VI that impacts their recovery. Collaboration with rehab team as well as vision specialists is crucial.