1. Go to Madinat Khalifa traffic department
2. Documents to take: Your Dubai license, copy of passport, copy of RP, Driving license NOC from your company, 250 riyals.
3. Get your number, they will send you to the clinic (in the same compound) for eye-testing.
4. Khallas....

takes about an hour...

Go at 8:00 AM on a saturday...

Best of luck...