hello in this video we're going to look at the pathway vision and we also will look at what happens when there are lesions that occur along this pathway and how it affects our vision so here is the occipital lobe the eyeball optic nerve optic chiasm lateral geniculate body and optic tract also known as a Jenica Techtron tract here are our visual fields we are looking at this whole visual pathway you know from the top so the blue nerve on the left side here will pick up the left nasal field and will carry this visual information to the lateral geniculate body where it will synapse with another nerve and this will this other nerve will and carry this information to the occipital lobe the blue nerve on the right eyeball here will capture images from the right temporal field and will carry this information down the optic nerve and will cross over at the optic chiasm and sign ups with the neurons of the left lateral geniculate body the nerves will then carry the information to the occipital lobe this orange optic nerve on the left eyeball here will capture images from the left temporal visual field and cross over at the optic chiasm and synapse at the right lateral geniculate body where it will relay the information to the occipital to the optic tract which then will bring it to the occipital lobe now similarly the orange optic nerve of the right eye will capture the image from the right nasal visual field it will not cross over but will remain well we'll relay this information you know down to the lateral geniculate body and then it will synapse with other nerves along the optic tract and then down to the occipital lobe I hope this pathway makes sense now now that we have an overview or an understanding of the visual pathway what happens to our vision if we have lesions occurring you know along these different parts so let us have a look and compare normal two defects in visual fields if a lesion were to occur on the Left optic nerve a what happens is that the orange and blue optic nerve on the left side cannot even bring the information down and so we get blindness in the left eye this is called the left in opium if a lesion occurs along the optic chiasm here in b and this can be due to a pituitary tumor while the nerves that crossover that normally captures images on the temporal visual fields cannot you know send this information and so we get blindness in the temporal visual field from both right and left and this is called a temporal Inman Opia if a lesion occurs here after the optic chiasm we get loss of the visual field that these blue nerves carried and which means we get loss of vision on the left nasal field and the right temporal field this is called right homonymous hemianopia and lastly d if a lesion occurs on one of these nerve tracts nerve tract bundles it will cause what is called right phenomenas superior quadrant - no pia finally there can be other visual field problems that can occur due to an underlying eye condition let us cut a cross-section of the eyeball and learn some important structures so here is the optic disc where the optic nerve and vessels of the eye will pass through here is an area within the eyeball at the very back called the macula now the macula contains what's known as a phobia which is an area where a lot of where a lot of pigmented cells are called cones and these pigmented cells of the retina these guys allow for high resolution so when we damage the macula we get loss of central vision we get loss of that high-quality vision so drawing out normal to abnormal here is normal and this central visual field is the macula in a condition known as central schemata or macular degeneration you get loss of this central visual vision because of the damaged macula if everything else is lost but the macula is preserved this is called constricted visual fields this is what we see in glaucoma and Retin and retinal pigmentosa the macula is spared as a result the patient has tunnel vision now just to finish this diagram off here is the midbrain an area where the optic nerve also brings information to this area is primarily involved in reflexes to do with the eye such as the blink and light reflex