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Vision changes are common, some are reversible.
Lori Ann Bravi, MS, OTR/L Mar 05, 2010
Vision impairment after stroke is common and can be alarming and even hazardous to the survivor. Depending on the areas of the brain affected by stroke, these changes can range from blurry vision when reading to gaps in vision — called visual field cuts — that impair sight on a more severe level. The location and severity of a stroke will determine the changes a person experiences. Some changes might improve with time and exercise while other changes might require surgery and or be permanent.
Our eyes are controlled by seven tiny pairs of muscles that receive signals from specific nerves in our brain. If those nerves are affected by swelling or bleeding, the messages from the nerves to the muscles will be weakened and vision can change as a result.
Blurred Vision: Decreased acuity can occur if the oculomotor nerve is affected. This nerve is responsible for moving the eye muscles we use to see reading material. These muscles might strengthen within several weeks after your stroke or your doctor might recommend reading glasses. The oculomotor nerve is also responsible for moving the eye upward and for keeping the eyelid open.
Drooped Eyelid: If a person’s eyelid is drooping after a stroke it is called ptosis. Ptosis can improve if you force the use of the affected eye for a few minutes each hour, gradually building up the muscles tolerance.
If exercises do not work, your doctor might treat the ptosis with surgery. In addition, ptosis often is caused as part of the Horner’s syndrome, which results from dysfunction of a portion of the oculomotor nerve. This can result in double vision, in which case your doctor or therapist might suggest patching — putting a patch over one eye at a time for a period of time — of the eyes.
Seeing Double: Diplopia, or double vision, is another common visual problem after stroke. Diplopia is the result of the weaker eye moving at a slower pace than the stronger eye. Since diplopia is a result of muscle weakness, the best treatment is to perform exercises that encourage your eyes to work together. But if diplopia is persistent and troublesome, alternate patching might help to decrease diplopia. Prism glasses or surgery might also be required.
Vision Gaps: Vision field cuts are a more limiting visual change after stroke. These changes occur when the optic nerve is affected and there is partial vision loss in the left, right or both visual fields in one or both eyes. The most common type of visual field cut is called homonymous hemianopsia and this affects the same side of each eye. This can involve either the right or left halves of each eye.
Field cuts are frustrating for the patient because they don’t perceive the field cut as a blacked-out portion of their visual field. Rather, their visual field looks normal to them and they often are not aware that they are missing visual information. The number 8 might be read as a 3 or the patient can trip on an object while walking through the house if it was in the part of the visual field that is not processing information. Your brain might compensate for a smaller visual field cut by using perceptual completion. Frequent head turns and compensatory strategies are the best interventions for this type of vision change. In some cases, prism glasses can be helpful.
If you or someone you know experiences visual changes after stroke, it is important that you communicate these changes to your therapist and doctor.
Visit stroke.org/shop or call 800-STROKES to order a brochure on Vision Loss and Stroke.
Lori Ann Bravi, MS, OTR/L, works at the Rehabilitation Institute of Chicago. She can be reached at email@example.com.
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