241 



ON THE INCIDENCE OF KEKATOMALACIA AMONG RATb 

 SUFFEKINO FKOAi. AVITAMINOSIS. 



Airniuu DiGHTON Stammers, B.A. (Cantab), ^ P ^ ^.^"^i 



Sciiiur Lecturer in Physiology, University of the Witwatcrsrand ,, , „ 



Johannesburg. il"''^' \ ~ 





i^cad July lU, 1922. • '"^'A'd^^ 



Keratomalacia or xerophthalmia is an affection of the eyesr---,._Jl_ 

 which is associated with deficiency of Vitamin A. It has been 

 particularly noticed among rats used for vitamin experiments. 



It has been well known for some time that a primary symptom 

 of malnutrition among children is a conjunctivitis due to lowered 

 resistance, which offers a focus tor bacterial invasion at one of the 

 weakest points in the body. Hiistologically it has been shown 

 tha.t the condition, among rats fed on a diet deficient in Vitamin 

 A, results from a breakdown of corneal tissue caused by bacterial 

 invasion, which only occurs after a prolonged couree of diet 

 deficient in Vitamin A (Stephenson and Clark, 1920).'^' The 

 American workers, Osborne and Mendel (1921),^ have shown that 

 in experiments on 1,000 unselected rats, xerophthalmia was only 

 seen in animals with deficient fat-soluble vitamin : in this group — 

 the number of animals involved is not stated — the incidence was 

 50 per cent., most of the cases developing before any marked 

 decline in body weight had occurred. Administration of Vitamin 

 A — for example, 0'"1 gm. of butter-fat per day — caused the dis- 

 appearance of the eye disorder, even though in some cases the 

 animal subsequently died. 



Another worker (Emmett, 1920)^ had previoush' described 

 ■experiments on 122 rats, 120 of which developed xerophthalmia. 



In view of the discrepancy in the results of these workers, 

 the following details, collected by the author during the course 

 of thirteen exiDeriments upon the vitamin content of various oils 

 and fats, ma,y be of interest. One hundred animals were involved 

 in these experiments : 44 were fed with a fat known to have been 

 deprived of Vitamin A by steam distillation (Stammers, 1921),* 

 and the remaining 56 upon fats of varying degrees of deficiency. 



Of the 44 on the totally deficient diet, 40 were young animals 

 (33-49 days old) at the commencement of the experiments, and 

 of these 35 developed keratomalacia between the 31st and the 

 80th day of the experiment. The remaining 4 were adults, 145 

 days old, when they were used for experiment, and they all 

 developed the condition between the 104th and 129th days of the 

 investigation. Those animals, 56 in number, upon the partially- 

 deficient diets were not so susceptible, 24 only being affected 

 between the 35th and 98th days. 



From an examination of the ta.ble appended, which gives 

 details of these experiments as far as they relate to the incidence 

 of keratomalacia, the following deductions may be made: — ■ 



* The small numbers refer to the papers listed in the References. 



