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The Factors which Determine the Production of Intraocular 



Fluid. 



By E. E. Henderson and E. H. Starling, F.R.S. 



(From the Physiological Laboratory, University College.) 

 (Received November 23, 1905.— Read January 18, 1906.) 



In spite of the very numerous researches which have been made during the 

 last half century on the seat and mechanism of production of intraocular 

 fluid, ophthalmologists and physiologists are still far from an agreement on 

 the subject, and a review of the literature reveals many discrepancies in the 

 experimental evidence which it is impossible to clear away without a 

 re-exammation of the whole subject. The following paper contains the 

 results of experiments made with the view of determining the weight to be 

 ascribed to different experimental investigations. 



As to the seat of production of the intraocular fluid, nearly all authorities 

 are agreed that it is produced by the ciliary processes. From these processes 

 a minute proportion travels backwards into the vitreous cavity, to be absorbed 

 by the lymphatics of the optic disc, while by far the greater part makes its 

 way between the lens and the ciliary processes, through the fibres of the 

 suspensory ligament, into the posterior chamber, whence it passes round the 

 margin of the iris into the anterior chamber. In addition to this mode of 

 production, it has been suggested by Ehrlich that an appreciable amount of 

 intraocular fluid may be secreted directly into the anterior chamber by the 

 anterior surface of the iris. The experiments of Ehrlich (1) were made by 

 the injection of a diffusible substance, fluorescine, and we agree with Leber (2) 

 in regarding them as proving the possibility of diffusion between the vessels 

 in the iris and the anterior chamber, but not the secretion of a normal intra- 

 ocular fluid by this channel. At any rate, any fluid formed in this way is 

 negligible when compared with that which is produced in the neighbourhood 

 of the ciliary processes. 



On the other hand, the place of absorption of the intraocular fluid is 

 universally agreed to be the angle of the anterior chamber. Here the fluid is 

 passed under pressure into the spaces of Fontana, whence it makes its way 

 into the canal of Schlemm, between the endothelial cells lining this canal, and 

 so is carried away into the venous system. This absorption is continuous, 

 and its rapidity is largely determined by the height of the intraocular 

 pressure. Since we have a constant absorption and a constant pouring out 

 of fluid into the eyeball, it is evident that the intraocular pressure must be 



