AQUEOUS HUMOR 



103 



(a) 



(&) 



(ft) 



Fig. III-2. 



(a) Normal cornea, (b) Conical cornea (keratoconus). 



Corneal reflections photographed with a keratoscope. (cO Normal. (c 2 ) and (c 3 ) 

 irregular astigmatism. 



(Photographs by courtesy of A. Marfaing, Institute of Ophthalmology, New York 



City.) 



By Courtesy of W. S. Duke-Elder [1927]. 



between 25 and 30 mm of mercury. Pressure equilibrium is maintained 

 by drainage through the canal of Schlemm (Fig. Ill— 3, S), and through 

 the crypts in the anterior surface of the iris, or between the suspen- 

 sory ligaments of the lens into the vitreous humor. Its index of refrac- 

 tion, which may be obtained by means of an Abbe refractometer, is 

 1.336. 



If the temperature of the unclothed head and hence the aqueous 

 humor is taken as 35° C, and since water at this temperature has an 

 index of 1.3316, one can appreciate the contribution made by the salts 



