I'm very interested to see how this turns out for you. I have a feeling I will be in the same boat as you when I graduate school and begin looking for a job.
I am also color "blind" in the red/green spectrum, at least according to the Ishihara test. On most of the plates I can see the outline of the numbers but might confuse a 1 for a 7 or a 5 for a 6. On some of the plates I fail to recognize the number but can look at individual tiny dots on the plates and tell you their exact colors. So inevitably I fail these tests too. I think it is partially my perception of color and partially a brain processing issue. In other words, my brain will not process the number pattern.
If someone can please point to an example in their nursing experiences where they are required to distinguish a number from a group of multicolored dots? I doubt you'll ever see that in practice. So, if you can distinguish skin abnormalities/changes, read test strips, and see color coded labels/tubes then I don't see why you should ever have a problem. If you ever question your ability to perceive a color then I'm sure there will be someone around to verify. There are many legally blind, hearing impaired, and other nurses with disabilities. There are also pilots, police officers, surgeons and a multitude of of people in other professions who are color deficient.
My cousin is color "blind" and he has no problem working as an ICU nurse.
Let's take a hypothetical example of a nurse who is visually impaired but has corrective lenses that only corrects his or her vision to 20/25. Do you think he or she should be denied a job because of this? Let's take another example of a nurse who has back problems and can't lift patients. This nurse needs assistance for lifting/turning most every patient. The employer accommodates the nurse without question and the nurse can always ask for assistance. Just as you can ask for assistance in differentiating a color if you are unsure.
I would also be interested if the ADA would apply to your situation. Is it discrimination to deny you a job because you can't pick out number patterns on a multicolored dotted plate? Unless you truly can't differentiate any color then I don't see this "disability" holding you back. I would ask for a different type of test.