VISUAL ACUITY OF ESSENTIAL FATTY ACID-DEFICIENT RATS.

1. Rats were maintained on a diet deficient in fat and on a normal diet of rat cubes. 2. Rats were trained to discriminate between vertical and horizontal striations. The minimal stripe width that could be used for discrimination was determined. 3. In bright illumination (0.7 or 4.5 ft.lamberts) both deficient and normal rats had the same ability to discriminate between black and white stripes. 4. With an illuminance of 0.002 ft.lambert, supplemented rats could discriminate as efficiently as at 0.7 ft.lambert, but deficient animals were unable to discriminate at 0.002 ft.lambert. 5. Control rats had 14% of docosahexaenoic acid in their retinal fats but the deficient rats had only 1%. 6. Deficient animals had no vitamin A stores in the liver whereas the control animals had about 190 i.u./g. 7. The visual acuity of the rats used was about 45' of arc.