{"id":693,"date":"2019-10-09T13:07:45","date_gmt":"2019-10-09T17:07:45","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/jengle\/?post_type=chapter&p=693"},"modified":"2019-10-22T18:40:12","modified_gmt":"2019-10-22T22:40:12","slug":"hemianopia-psychology-assessments","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/jengle\/chapter\/hemianopia-psychology-assessments\/","title":{"raw":"Visual field loss and psychology assessments","rendered":"Visual field loss and psychology assessments"},"content":{"raw":"Definition\/cause:<\/strong>\u00a0<\/span>Loss of vision in part of the field of vision may be due to traumatic brain injury, tumor, surgery, or infarct in the posterior cerebral artery.<\/span>\u00a0Field loss can affect different parts of the field of vision depending on what part of the system is affected.\u00a0<\/span>When the same half of the visual field is affected in both eyes, it is called homonymous hemianopia (HH).\u00a0<\/span>\u00a0Many children with HH will also have weakness or paralysis on the same side of the body as the vision loss.\u00a0<\/span>\r\n\r\nField loss in right HH:[footnote]The original uploader was Nunh-huh at English Wikipedia. - Transferred from en.wikipedia to Commons by Roberta F. using CommonsHelper., CC BY-SA 3.0, https:\/\/commons.wikimedia.org\/w\/index.php?curid=5866899[\/footnote]\r\n\r\n \r\n\r\n\"Rhvf.png\"\r\n\r\nWhat someone with left homonymous hemianopia would see[footnote]By EpagneuldeSaintUsuge.jpg: DanielV27derivative work: Dodo\u00efste (talk) - EpagneuldeSaintUsuge.jpg, Public Domain, https:\/\/commons.wikimedia.org\/w\/index.php?curid=13313467[\/footnote]:\r\n\r\n\"Hemianopsia\r\n\r\nCourse<\/strong>: In some cases, a new field loss can resolve on its own within a few months after the injury. In general, however, it is a permanent loss. It\u00a0is not reversible with therapy.<\/span>\u00a0<\/span>The person with field loss may learn to use special scanning techniques (e.g., when reading). Children who have HH from a young age may not be aware that their vision is different than other children.<\/span>\r\n\r\nFunctional impact on reading<\/strong>:\u00a0 \u00a0When we read, our eyes make rapid eye movements (saccades) between fixations. We are using our central vision to see the small amount of letters which are in focus during the fixation (see image below).\u00a0 The central area is only about 5% of our visual field. When reading a longer word, the child with HH would not see half of the word and would need to scan to see it, creating an extra step.\u00a0<\/span>The area outside central vision is called the parafoveal region. When we are reading, we use this surrounding region to preview what is coming up and see what was previously read. When reading left to right, our perceptual span (how many letters we can see) extends about 4 letters to the left and up to 15 letters to the right.\u00a0 This is like a \"preview\" of upcoming words and helps your eyes plan where to land the next time they move. Thus, with languages which are written from left to right, r<\/span>ight HH has a stronger impact on reading than left HH as the person is not able to preview the upcoming words.\u00a0<\/span>\u00a0<\/span>HH particularly impacts reading beyond the single word stage, and can cause a decrease in reading speed.\u00a0<\/span>Left HH can also impact reading by causing difficulty finding the next line of text and causing reading errors as the first letters of the word may be missed. HH can make reading slow, frustrating, and tiring.\r\n\r\n\"File:EyeFixationsReading.gif\"[footnote]Hans-Werner34 at English Wikipedia [CC BY-SA 3.0 (https:\/\/creativecommons.org\/licenses\/by-sa\/3.0)][\/footnote]\r\n\r\nOther functional impacts:<\/strong>\r\n