The FALANT (Farnsworth Lantern) and the OPTEC 900 are examples of acceptable alternative color vision tests for pilots. The Farnsworth lantern and the OPTEC 900 are essentially the same thing. The Farnsworth Lantern is no longer being manufactured and the OPTEC 900 is water resistant. There are many acceptable alternatives to the tests which FAA medical examiners commonly use, such as the Ishihara and other pseudoisochromatic plate books.
While the Farnsworth Lantern and the OPTEC 900 are among many tests still used to qualify operators of ships, vehicles, and aircraft with known to have failed screening tests, these testing units are often difficult to find in comparison to other alternative FAA color vision tests.
Pilot Medical Solutions maintains a list of alternative color vision test providers. Clients may be referred to the practitioner nearest you.