Lantern
Instead of the Ishihara test, the US Navy and US Army also allow testing with the a lantern, such as the Farnsworth Lantern Test. Lanterns project small colored lights to a subject, who is required to identify the color of the lights. The colors are those of typical signal lights, i.e. red, green and yellow, which also happen to be colors of confusion of red-green CVD. Lanterns do not diagnose colorblind, but they are occupational screening tests to ensure an applicant has sufficient color discrimination to be able to perform a job. This test allows 30% of color deficient individuals, generally with mild CVD, to pass. Arrangement tests
Arrangement tests can be used as screening or diagnostic tools. The Farnsworth–Munsell 100 hue test is sensitive enough that it not only can detect color blindness, but also evaluate the color vision of color normals, ranking them as low, average or superior. The Farnsworth D-15 is simpler and is used for screening for CVD. In either case, the subject is asked to arrange a set of colored caps or chips to form a gradual transition of color between two anchor caps. Anomaloscope
An instrument called an anomaloscope can also be used for diagnosis. These instruments are very expensive and require expertise to administer, so are generally only used in academic settings. However, they are very precise, being able to diagnose the type and severity of color blindness with high confidence.
These cannot be determined by plain films, as the x-ray passes through the soft tissue. A study by Giles et al., stated that sixteen of the thirty patients (53%) had retrolisthesis of L5 on S1 ranging from 2–9 mm; these patients had either intervertebral disc bulging or protrusion on CT examination ranging from 3–7 mm into the spinal canal. Fourteen patients (47%) without retrolisthesis (control group) did not show any retrolisthesis and the CT did not show any bulge/protrusion. On categorizing x-ray and CT pathology as being present or not, the well positioned i.e. true lateral plain x-ray film revealed a sensitivity and specificity of 100% ([95% Confidence Interval. = [89%–100%]) for bulge/protrusion in this preliminary study.” (7)Spinal cord compressions are also possible with patients experiencing pain, rigidity and neurologic signs that may follow some distance along nerves to cause symptoms at some distance from the location of the retrolisthesis. Diagnosis
Complete Retrolisthesis - The body of one vertebra is posterior to both the vertebral body of the segment of the spine above as well as below.Stairstepped Retrolisthesis - The body of one vertebra is posterior to the body of the spinal segment above, but is anterior to the one below.Partial Retrolisthesis - The body of one vertebra is posterior to the body of the spinal segment either above or below. (3)

Grading
Since the vertebral body in a retrolisthesis moves in a posterior direction, the grading used for spondylolistheses is of little use.