32 MICROSCOPY OF THE LIVING EYE 



origin ; it is clinically of great importance to be able to determine 

 the exact level in the cornea of any pathological processes as well 

 as their nature. The aqueous fluid in the anterior chamber, AC, 

 is secreted by the ciliary body, C, and drained away through 

 filtration channels in the angle between the front of the iris, I, 

 and the back of the limbus, 1. In inflammation of the ciliary 

 body, C, cellular products are thrown out ; some, x, find their 

 way into the vitreous fluid, V, and form " dust " particles or larger 

 " floaters " in it ; others migrate forward and are deposited as 

 " keratic precipitates," K.P. (Parsons), on the back of the cornea, 

 where they give rise when gross to a very characteristic appearance 

 wrongly misnamed in the past " Keratitis profunda." Such 

 precipitates, in a very fine form detectable only by slit-lamp 

 microscopy, are often the earliest premonitory sign of oncoming 

 cyclitis. Apart from revealing formed products, the aqueous 

 fluid, in pathological states of the ciliary body, may undergo an 

 increase in its colloid contents revealed by increased visibility of 

 a minute beam of light traversing it. 



The iris, I, consists of a translucent anterior layer, the stroma, 

 backed by a pigment-layer, P, which is highly obstructive to the 

 passage of light. In inflammation of the iris its pigment layer 

 may form adhesions, minute or large, to the anterior lens capsule, a, 

 or small detached portions of pigment may become adherent to 

 the lens-capsule, accessible to inspection when the pupil is dilated 

 by a drug. The lens is held in its position behind the iris by 

 numerous fibres from the ciliary body {e.g., Z), which together 

 form the suspensory ligament. The anterior lens-capsule, a, 

 has a curvature of greater radius than the posterior lens-capsule, p. 

 Beneath the anterior capsule there is a layer of cells, and those 

 near the equator are always forming new lens fibres which, con- 

 tinually through life, lay new lens-matter, both front and back 

 beneath the capsule, on to the surface of the deeper material 

 nearer the centre which is always shrinking and becoming more 

 dense. Hence, at any period of life the lens matter nearest the 

 centre is the oldest — that right in the centre is the original 

 embryonic lens-matter — and that beneath the capsule is the latest 

 to have been formed. The lens-fibres, as they grow in from the 



