From the HRD Standards:
"Medical conditions listed in the Medical Standards are classified as "Category A" or "Category B" conditions. Category A conditions are considered absolutely disqualifying. For Category B conditions you are required to consider whether the particular examinee's condition would prevent him or her from performing the essential functions of the position...
1. Category A medical conditions shall include:
uncorrected vision worse than 20/100 in either eye
corrected vision worse than 20/20 in the better eye UNLESS - the vision in the good eye alone is at least 20/25 AND the vision with both eyes together is 20/20 or better.
peripheral vision of less than 70 degrees temporally and 45 degrees nasally in either eye AND/OR any history of conditions limiting field of vision will necessitate additional assessment by an eye care professional who will use a Goldmann-type perimeter to determine if the binocular visual field is 140 degrees (at least 70 degrees temporally in each eye) with a III4e isopter.
d. Testing by Ishihara or Richmond pseudo-isochromatic plates is required and if the candidate fails, testing by Farnsworth D-15 is required. Two or more major errors on the Farnsworth is a Category A condition.
2. Category B medical conditions shall include:
a. diseases of the eye such as cataracts, retinal detachment, progressive retinopathy, or optic neuritis,
b. ophthalmological procedures such as radial keratotomy or repair of retinal detachment,
c. any other vision disorder or eye condition that results in an individual not being able to perform the essential functions of a police officer."
In short if you're worse than 20/100 you're out of luck unless it can be corrected surgically. I had to get LASIK in order to pass the exam. It was the best $2500 I ever spent.