Summary Vitamin A (retinol) has been used both topically and systemically in the treatment of skin disease for approximately 40 years (Berson, 1983). Retinol taken in high doses over a period of time can cause fatigue, headaches, cheilitis, anorexia, peeling of the skin and can cause papillary oedema and hepatotoxicity (Dahl et al., 1977). These symptoms form the hypervitaminosis A syndrome and can be caused by acute or chronic intoxication with vitamin A or vitamin A analogues (retinoids). Because of this toxicity and the only marginal therapeutic benefit, the use of systemic vitamin A declined. Since 1977 two synthetic retinoids, isotretinoin (13‐cis‐retinoic acid) (Korner & Vollum, 1975) and etretinate (Meyskens et al., 1983) have been found to be of clinical use in the treatment of acne, psoriasis and the disorders of keratinization. These drugs have been found to be of such therapeutic benefit to patients that some of their side‐effects (Moon et al., 1979) have become acceptable. The realization of the therapeutic potential of retinoids for skin disease has led to an expansion in retinoid pharmacology research. As a consequence new retinoids are reaching the stage of clinical testing in patients. We report our experience of unusual side‐effects which occur during a phase II clinical trial of (N‐[4‐Hydroxyphenyl] retinamide)(4HPR) in the treatment of severe chronic plaque psoriasis.

Color vision abnormalities indicated by the Farnsworth-Munsell 100-hue Color Vision Tests (FM-100) were analyzed by computer to better characterize and group congenital and acquired color vision disorders and to help establish statistically significant diagnostic criteria. Standard evaluation of the FM-100 is by axis and error score calculations. A method has been established for computer-averaging many tests from patients with the same color abnormalities determined by history, standard FM-100 and Nagel anomaloscope. The computer calculated an average error score and standard deviation for each of the 85 color caps. Every time a new patient was evaluated for color vision abnormality, his score was compared with averaged tests with common diagnoses, by calculating distance scores. The averaged test with the lowest distance score consistently tended to coincide with the diagnosis. An analysis of 130 FM-100 color tests found technician-calculated error scores to be incorrect, although usually minor, in 40% of the tests. The computer-calculated axes agreed well with the technician's estimates. The distance scores predicted the diagnosis accurately 89% of the time. Many errors were due to the small number of protanopes averaged and inability to distinguish trichromats from dichromats.