SEOUL, June 3 (UPI) -- Researchers in South Korea say long-time use of the 
drug amantadine for Parkinson's may affect vision.
Dr. Won Ryang Wee Seoul National University College of Medicine in Korea 
determined the drug's affect on corneal endothelial cells -- loss of cell 
density in the eye's clear outer surface resulting in edema or swelling and 
vision impairment -- was dependent on the cumulative dose received and/or the 
duration of treatment -- up to eight years.
The study, published in the journal Ophthalmology, suggested the cornea did 
not change quickly and there were two early indicators of this corneal change 
-- deformation of the normal hexagonal cell shape and increase in cell size 
variation.
"Assuming other studies confirm these results, ophthalmologists and 
neurologists should consider evaluating a patient's corneal endothelium at the 
beginning of treatment with amantadine and reassess at regular intervals if 
the drug is used long term," Wee said in a statement.
Wee also advised additional monitoring may be needed for patients on the drug 
who have other eye conditions -- such as cataract surgery, ongoing glaucoma, 
uveitis or Fuch's dystrophy. 
Wee and colleagues compared amantadine-treated patients -- a total of 169 eyes 
-- versus an equal number of matched controls. The average subject age was 59.

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