Induction of buphthalmos in chicks fed an excess of glycine

¹ Laboratory of Vision Research and Clinical Branch, National Eye Institute, National Institutes of Health, United States Department of Health, Education, and Welfare Bethesda, Md. 20014, Department of Poultry Science, University of Maryland College Park, Md. 20742
² Laboratory of Vision Research and Clinical Branch, National Eye Institute, National Institutes of Health, United States Department of Health, Education, and Welfare Bethesda, Md. 20014 Department of Poultry Science, University of Maryland College Park, Md. 20742.

A diet enriched in glycine leads to buphthalmia and growth suppression in chicks. This was shown in newly hatched chicks when fed a nutritionally adequate purified diet supplemented with 8 per cent glycine, 5 per cent gelatin, and 10 mg. per cent nicotinic acid for a period of seven weeks; however, when the concentration of gelatin in the diet was increased to 8 per cent while the level of glycine was lowered to 6 per cent, the btiphthalmic effect was retained while the suppression in body weight toas eliminated. Glycine-fed chicks, at seven weeks of age, appear to be essentially free of glaucomatous symptoms, i.e., increased intraocular pressure and decreased facility of aqueous humor outflow and the enlarged eye could almost wholly be accounted for by an increase in the size of the vitreous. The change in vitreotis volume noted in such chicks was due primarily to an overgrowth of connective tissue rather than an imbalance in osmolarity of ocular fluids. The comparison of the glycine-induced state with other known buphthalmic conditions in experimental animals are discussed.

Note:
Scientific Article No. A1856. Contribution No. 4766 of the Maryland Agricultural Experiment Station, Department of Poultry Science

Key Words: nutritionally-induced buphthalmos • glycine toxicity • globe enlargement • intraocular pressure • coefficient of outflow • vitreous • chickens

Submitted on January 19, 1973
Accepted on March 2, 1973