3rd… From Out-Thinking … Eyes

2, 3, 4, 6 OPTIC NERVEOCULOMOTOR NERVE, TROCHLEAR NERVE , ABDUCENS NERVE 

  • Cranial Nerve 2 –  “a paired nerve that transmits visual information from the retina to the brain.” 
  • Cranial Nerve 3 – “supplies muscles that enable most movements of the eye and that raise the eyelid and enables the ability to focus on near objects as in reading.”
  • Cranial Nerve 4 – ” a motor nerve that supplies the superior oblique muscle” which controls turning of the eye in the socket, in particular the actions of looking down or towards the nose.
  • Cranial Nerve 6 – “a motor nerve that supplies the lateral rectus muscle of the eye” which controls turning of the eyes outwards, away from the nose.

……………………………….Since my being diagnosed with oblique double vision led me to finally receiving the diagnosis, I found it worthwhile to wade through the voluminous amount of goblty gook/geek speech. What I found fascinating was the reference to visual acuity, because back over 20 years ago I participated in something called applied kinesiology (muscle testing). Then a day came that I could no longer trust the answers I got. Various people came to the same conclusion… my polarity was reversed. Those same people told me how it could be made right. BUT traditional efforts failed to right my polarity. Then a doctor deduced… through muscle testing, that my problem was related to visual acuity. He said, “Whatever that is?” Twenty years later, I found the answer. So, does that mean the disease has been progressing in me for 20 years?

Eye and vision problems abound in Parkinson’s Disease, from dry eyes, involuntary closing of the eye lids, to fixed and unfocused eyes. Visual problems that have been strongly correlated with PD include issues with: visual acuity; contrast sensitivity; color vision; motion perception; visual disturbances and hallucinations. Physical and structural changes to the eye and retina have also been found in people with Parkinson’s, as determined by a number of modern eye examination methods. Therapies which involve injecting small amounts of dopamine into the eyeball have proven successful in PD, and strategies based on this are being developed”

After browsing 14 paragraphs of goblty gook… (from the link above… Eye and vision problems)

“Appreciation of the multiple sites of, for instance, contrast modulation is vital if we are to localize Parkinson’s disease-specific alterations in such processing to the anterior or posterior visual system.”

(and after another 7 large paragraphs of goblty gook) … “In other words, dopamine is a chemical messenger for light adaptation, promoting the flow of information through (neurons in the retina) cone circuits while diminishing that through rod circuits.”

(and after an additional 6 paragraphs of goblty gook) addressing Visual Acuity … “in generating a working hypothesis for the role of dopamine in the retina and the subsequent changes seen in Parkinson’s disease.”

(2 p goblty) “As temporal frequency increases, contrast becomes more difficult to perceive, resulting in flicker fusion, the point at which the stimulus appears not to change at all.”….. “Hence, at least from a retinal perspective, visual acuity and contrast sensitivity will depend not just on ‘optical’ factors … but also on ‘neural’ factors.” 

“There can be little doubt that dopaminergic deficiency plays an important role in retinal function, as seen in Parkinson’s disease.”…

Contrast sensitivity is vital for a range of day-to-day activities and diminished contrast sensitivity has been implicated in falls, difficulties in reading and driving performance, as well as with activities of daily living.” further more “Parkinson’s disease patients with visual hallucinations had significantly worse contrast sensitivity than those without hallucinations, suggesting a putative role for retinal dysfunction in the development of visual complications in Parkinson’s disease.”….

Deficits in colour vision in Parkinson’s disease are also well documented and suggest involvement of different colour-opponent pathways in the disease process.”….

“In addition to changes in visual acuity and contrast sensitivity, perception of motion is also affected in Parkinson’s disease.”…. “However, group differences persisted for measures of visual speed of processing and alternative measures of visual attention, supporting a cortical contribution to such perceptual disturbances as well.”…

In conclusion… “A better appreciation of how structural disease of the eye contributes to disability in Parkinson’s disease is overdue, particularly as effective treatments exist for many of the concomitant ocular disorders that may contribute to visual symptoms in Parkinson’s disease. Successful intervention therefore offers the prospect of improvements in the quality of life of Parkinson’s disease patients and their carers.”