The federal CDL vision standard requires distant visual acuity of at least 20/40 (corrected, with or without lenses) in each eye and binocularly, plus a horizontal field of view of at least 70 degrees in each eye, plus the ability to recognize the colors of standard traffic signals. The standard is checked at every DOT physical.
What 20/40 means
20/40 vision means you can read at 20 feet what a normal-vision person can read at 40 feet. It's roughly two lines below "perfect" 20/20 vision on a standard Snellen eye chart. Most adults achieve 20/40 with prescription glasses or contact lenses; if you don't currently meet 20/40 corrected, see an optometrist before scheduling your DOT physical.
Monocular drivers
Drivers with vision in only one eye (monocular) historically could not hold an interstate CDL. The FMCSA Vision Exemption Program now allows monocular drivers to operate interstate provided they: have at least 3 years of recent CMV driving experience (intrastate or military); meet the standard in the seeing eye; and pass an annual ophthalmologic exam. Application is to the FMCSA directly; turnaround is typically 6 to 8 months.
Color blindness
The standard requires recognition of red, green, and amber traffic signals. Most color-deficient drivers can recognize signals by position (top is red, bottom is green) and pass the DOT exam without issue. Severe red-green deficiency (rare) may require an exemption.
Cataracts and post-surgical vision
Drivers who undergo cataract surgery, LASIK, PRK, or other refractive procedures may need to wait until vision stabilizes and obtain a written statement from the surgeon clearing them for commercial driving. Many examiners require a 30- to 90-day post-surgical waiting period before issuing a new card.
Loss of vision while certified
If your vision deteriorates during a certification cycle, federal rules require you to notify your carrier and be re-evaluated. Driving with vision below the federal standard is itself an out-of-service violation regardless of when you last passed the DOT physical.