You would think but this is what I got off of a Marine and Coast Guard website. A good friend of mine flys for the Coast Guard and confirmed that they only require 20/50. As far as the Marines I am going off what they have posted.

Marine Corps Officer Selection Office Dallas

OCC AVIATION ADDITIONAL REQUIREMENTS
-No more than 27.5 years when commissioned a Second Lieutenant
-Pass the Navy/Marine Corps Aviation Selection Test Battery (ASTB)
-Be found medically qualified for flight training
-Minimum vision requirements are 20/40 -- correctable to 20/20

UNITED STATES COAST GUARD: FAQS

What are qualifications for Coast Guard pilots?
A qualification for flight school includes passing a Class 1 Flight Physical. Two big issues, aside from being in good physical health, are dental and vision requirements. The dental exam will check for cavities and other problems with teeth and gums that may be affected by changes in air pressure while engaged in flight. Basically, you will be required to have no dental problems and no cavities. Vision requirements are also very stringent. Eyesight should be 20/20. If not, it must be correctable to 20/20, no exceptions. Uncorrected visual acuity must be better than 20/50 in either eye. There are other limitations imposed, based on the type and strength of the lens prescription. In addition, normal color perception, depth perception, and field of vision are also required.