The effect of hyaluronidase injection on the vitreous humour of the rabbit.

THE effect of hyaluronidase injections on the slit-lamp appearance and the composition of the vitreous humour of the rabbit has been examinfed. The purpose of the experiments has been to see whether disaggregation of hyaluronic acid from a viscous to a non-viscous form in the vitreous humour is a permanent change and whether any visible change persists as a result of hyaluronidase action. Very little is known of the production or fate of hyaluronic acid, either in the eye or in. other fluids and tissues of the body, such as synovial fluid, skin, or Wharton's jelly, where it also occurs. Meyer (1947) has suggested that there is a circulation of hyaluronic acid in the eye, the viscous hyaluronic acid of the vitreous humour being disaggregated and removed through the normal exit channels. Presumably this is a very slow process in the normal eye and we do not know whether complete disaggregation of the vitreous hyaluronic acid, such as might take place under pathological conditions, can ever be reversed. Nor has any clinical change been correlated with such breakdown. Aggregated hyaluronic acid is the viscous material that contributes to the turgor of the vitreous humour and its loss-if irreversible-might possibly lead to considerable changes in the state of the vitreous body. von Sallmann (1948) has briefly described the effect of injections of hyaluronidase on the vitreous humour of the rabbit. He found that the enzyme caused a considerable inflammatory response and considered its use too dangerous for clinical purposes. In the experiments reported here the eyes have been watched for nearly a year after injection of hyaluronidase to see if permanent change occurred and the vitreous humours have been analysed to see whether,the chemical cihanges could be correlated with any clinical change. The eyes were examined with the slitlamp and ophthalmoscope, and the composition of the vitreous humour, sometimes also of the aqueous humour, was determined when the animal was killed. In a few animals the effec-t of hyaluronidase on intra-ocular pressure was noted. The state of aggregation of hyaluronic acid was judged by the type of mucin