The appropriate use of the duplex scan in carotid arterial disease.

The duplex scan has become the definitive test in the diagnosis of carotid arterial disease. Its significance, however, has been diminished its extensive use for inappropriate indications. We performed a retrospective study over a four year period at two major hospitals to evaluate the different indications for carotid duplex scans. Symptoms which prompted the test, associated diseases, the type of physician ordering the test, and demographic data were recorded on all patients. Statistical analysis was used to indicate which symptoms and associated diseases were significant in predicting carotid disease. A total of 4,764 scans were reviewed. There were 4,289 studies (90%) which were negative for disease requiring surgery. There were a total of 12 indications for the carotid duplex scan in this study; the most common indications were dizziness, (20%) transient ischemic attack symptoms (19%) and a bruit (16%). Vascular surgeons (28%), Internal Medicine physicians (27%) and Family practice physicians (15%) ordered the duplex scan most frequently, but 39% of the positive scans were ordered by vascular surgeons. A history of seizures, confusion, stroke and as a preoperative evaluation all had a very low yield and should not be used as an indication for a duplex scan. However, a long smoking history, a history of known carotid disease, and peripheral vascular disease all had a statistical correlation with an abnormal duplex scan. The use of the duplex scan to rule out carotid arterial disease for patients with vague, uncommon symptoms is inappropriate and wasteful.

Color vision testing for the U.S. Naval Academy.

Normal color vision is a prerequisite for admission to the United States Naval Academy. The Farnsworth Lantern (FALANT) is the Navy's definitive test for color vision. A FALANT is not available at many locations where candidates are examined, so satisfactory performance on pseudoisochromatic plates has been considered an acceptable alternative. Until recently, the Farnsworth Dichotomous Test Panel D-15 had also been used as an alternative test, but is now considered unacceptable. In the summer of 1991, a large number of candidates reported for induction who were unable to pass the FALANT. Since their screening physical examinations had been reported to show normal color vision, a shadow of doubt was cast upon the ability of the alternative tests to predict performance on the FALANT. Four hundred subjects were then tested on several color vision tests to determine if these tests could predict FALANT success. The results of this study and recommendations are presented.