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Thread: Hemianophia

  1. #1
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    Hemianophia

    Just got asked about this today and I have no idea how to even approach fixing this with glasses. Quick search through here mentions using prism to bring vision back into the field of view. Should I find out where the blindness is occuring and then order prism base in the opposite direction?
    **hemianopia
    Last edited by Oscar; 07-26-2019 at 10:35 AM.

  2. #2
    One eye sees, the other feels OptiBoard Silver Supporter
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    Quote Originally Posted by Oscar View Post
    Just got asked about this today and I have no idea how to even approach fixing this with glasses. Quick search through here mentions using prism to bring vision back into the field of view. Should I find out where the blindness is occuring and then order prism base in the opposite direction?
    **hemianopia
    Optical24/7's ABOM topic was on Hemianopia.

    Hope this helps,

    Robert Martellaro
    Science is a way of trying not to fool yourself. - Richard P. Feynman

    Experience is the hardest teacher. She gives the test before the lesson.



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    Master OptiBoarder optical24/7's Avatar
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    Hi Oscar. My 1st question would be how long has the patient had the condition? If recent, most patient have "spontaneous recovery", where the brain re-wires and the hemianopia goes away. Always wait at least 6 month before attempting any visual aid treatment. If they have suffered with it for many years, they probably have adjusted how they use the vision they have left and probably won't take to a prismatic visual aid. Hemianopia can be a deep study dependent on cause and quadrant(s) of loss. I was asked a number of years ago to condense the subject down for an Optician publication, I'll paste it below. If you have any questions let me know if I can help...

    Hemianopia: Spectacle Vision Aids

    Hemianopia can be a serious and bothersome visual impairment. It involves the loss of usually fifty percent of the visual field in one eye. It can be binasal (loss is nasally oriented) but is usually bitemporal ( loss is towards the temple side). The usual causes are stroke or brain trauma. If the loss is in both eyes it is considered homonymous. With homonymous hemianopia the loss will be to the same side in both eyes. In other words a right side brain injury may cause the loss of visual field to the left side of both eyes.

    For many years the fabrication of hemianopic spectacles involved mounting a small mirror to the frame (usually on the nasal portion). This enabled the patient to “see” towards the peripheral loss area so they may navigate better around objects. But these mirrors were very difficult for many to adjust to. During the last 20 years or so the deployment of special, specific prisms have been the preferred treatment. One system (Peli) uses Fresnel type lens inserts of 40 diopters of prism. These inserts (8x22mm) are placed 6mm above the patient’s pupil and 6mm below (think occupational seg) so the patient may pick-up object peripherally up to 20 degrees.

    Another system ( Gottlieb ) uses a 30 diopter prism “button” cemented to the patient’s lens. (Base of prism is placed towards the lost field since objects are displaced towards the apex). These prisms are placed off-set from center so as not to interfere with central vision. This type of treatment yields approx. 15 degrees of added field for the patient. There are Fresnel stick-on prisms available in both 30 and 40 diopters to see which type of treatment best suits the patient. Experimentation on placement, type and amount will vary patient to patient. Also keep in mind that any prism has inherent distortions. These treatments are made for greater mobility and will not bring back clear peripheral vision for these patients.

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    Thanks for your help Robert and Optical 24/7. Very detailed and to the point. I will get more information from the patient first regarding this. I had already considerd getting tester fresnel prisms but wasn't sure what power to start. I will have to experiement and see. Thanks again.

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    Just an update. I had another patient with the same issue. This patient had no vision on the right side bilaterally. Fit 20D base out fresnel prism on the right half of the lens and they noticed a wider field of view right away! had to play around with the exact placement but it seemed to have worked out

  6. #6
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    A controversial option that you should check.
    Visual fields may vary depending on colour innervation. Sometimes by using complete attenuation of a band corresponding to the responses of lms pathways will result in restoration of field immediately. It is idiosyncratic and will not work for everyone - in fact it probably only works for a subgroup in which processing is impaired due to colour pathways. It can be the cause of strabismus and reading problems in children too.

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