cd
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compression of the optic chiasm often the result of a pitutary tumor or meningoma, result in a loss of peripheral vision in both temporal fields because the crossing fibers from each nasal retina are damaged. The resulting visual field defect is called as bitemporal heteronymous hemianopia.
Can any one explain me, if the nasal retina are damaged, why it is called bitemporal heteronymous hemianopia, instead of biretinal.
i appreciate your inputs.
thanks
cd
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| vallia
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Because of inversion of the optical image, the object seen with the temporal part of eyes are projected to nasal part of retina and these fibers cross to optic chiasm,, all lesions of optic patways are expressed in terms of what part of visual field is lost (not what part of retina is affected), in this case is lost the temporal half of both eyes.
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| cd
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Thanks,so temporal part retinal fiber crosses the optic chiasma but not the nasal retinal fiber rt.
cd
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| vallia
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the nasal retinal fibers, which process image from temopral part of eye, cross at optic chiasm.
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| cd
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so that means, optic chiasm contain mainly temporal retinal fibers and nasal fibers of temporal part. rt.
cd
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| vallia
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yes cd,
see here, optic chiasm contain cross of nasal retina fibers and right and left temporal retina (not crossed)
http://thalamus.wustl.edu/course/basvis.html
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| Dr.Papez
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Cd wrote:
so that means, optic chiasm contain mainly temporal retinal fibers and nasal fibers of temporal part. rt.
cd
cd's terminology is still not right-
Temporal field of vision falls in the nasal part of retina
So you call it as nasal retinal fibers- nasal fibers cross to opposite side
nasal retinal means-temporal field; one doesn't call it as temporal retinal.
Hope it is clear
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| cd
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thanks friends, i appreciate your help.
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