I've used it 5 times and my job requires me to be able to see at night. It's pretty simple: The higher the dose OR the faster you ramp it up, the quicker and harder the vision sides effect you. Your best bet would be to start low (25-40mg ED) and if it doesn't effect your vision after 1-2 weeks, slowly ramp up to 50 mg ED. This way if you start noticing any night vision issues, they'll be very mild and you can back off on the dosage a bit until you adjust to it. Then you can try ramping up again in another week.