ANNUAL REPORT, 1938 71 



this pathologic change to be studied under carefully controlled conditions. It is 

 hoped that the results of animal research may ultimately suggest some clinical 

 applications. That cataract could be produced in rats by feeding a diet adequate 

 in every respect, but supplemented with galactose, was discovered in 1935. 

 Apparently no vitamin or mineral deficiency is involved, but there is some met- 

 abolic disturbance as yet unsolved. This method of producing cataract in a 

 few weeks without other apparent injury to the rat is being used to study the 

 influence which other dietary factors may have upon lenticular changes. A 

 paper on the subject was given before the New England Ophthalmological Society, 

 December 21, 1937. A popular review was broadcast from Station WAAB over 

 the Colonial Network, January 28, 1938, under the auspices of the American 

 Chemical Society. 



1. Factors Influencing Progressive and Regressive Changes. During the sev- 

 eral years of work on cataract, data on the progressive morphologic changes in 

 the lens were recorded. A careful study of these data revealed certain consistent 

 findings which might be of particular interest to the ophthalmologist. In rats 

 fed on the galactose rations the lens begins to show, by the fifth day, early changes 

 observed through an ophthalmoscope. A dense shadow appears at the equator 

 of the lens and spreads rapidly over the anterior surface. This film, which appears 

 to have a vacuole or cell-like structure, then disintegrates and disappears before 

 the true opacities of the lens become visible to the naked e>e. The visible cataract 

 appears first as a posterior opacity, then becomes nuclear, and finally the entire 

 lens is dead white instead of the clear glassy red of the normal eye. These pro- 

 gressive changes continue even after the rat is returned to a normal ration. There 

 is apparently a lag in the effect of galactose or else a physiologic sequence of 

 events, which, once started, cannot be altered. After several weeks on the 

 normal ration certain regressive changes seem to occur, the complete opacities 

 again becoming nuclear in type. A suggested explanation of this latter phen- 

 omenon is that new lens fibers grow around the opaque ones forcing them to the 

 center. The age of the animal and the extent of the injury seem to influence the 

 degree of retrogression. These data plus a review of previous work were pub- 

 lished in the Archives of Ophthal. 19:22, 1938. 



2. The Effect of the Type and Amount of Protein on the Cataract- Producing 

 Action of Galactose. It was previously reported that a protein deficiency (5 per- 

 cent) hastens the development of cataract in rats fed on a diet containing 25 

 percent galactose. Further work indicates that a high level of protein (45 per- 

 cent) greatly inhibits the cataractous change in the lens compared with that 

 observed in rats fed the control ration containing 15 percent of protein. The 

 degree of galactemia is not significantly altered by the level of protein ingested. 

 The striking results obtained with rations containing casein led to the use of five 

 other sources of protein: egg albumin, lactalbumin, beef muscle, fish muscle, and 

 soybean meal, fed at comparable levels of 5, 15, and 45 percent protein. The 

 protective action of the crude proteins measured in terms of time and incidence of 

 mature cataract varies to a significant degree, showing egg albumin to be more 

 protective and the others less protective than casein. With a lower level of galac- 

 tose (15 percent), the influence of the amount of protein in the diet becomes more 

 pronounced. A high incidence of mature cataract develops when 5 percent of 

 protein is fed, early lens changes occur with 15 percent of protein, and complete 

 protection is common with 45 percent of protein. As previously reported, the 

 slight inhibitory effect of cystine upon the cataract-producing action of galactose 

 does not seem to explain the protective effect of proteins. Methionine also 

 exhibits some inhibitory action, but not commensurate with that of protein con- 

 taining an equivalent amount of this amino acid. The abstract of a paper given 



