SUSPENSORY APPARATUS OF THE LENS. 



1475 



Cornea 

 Canal of Schlemm 



Sclera 



can be exactly localized by the X-ray, and if of iron or steel, may often be removed 

 by a magnet. The accident is always serious and may be followed by a virulent 

 inflammation, demanding an excision of the globe to prevent a sympathetic involve- 

 ment of the other eye. Because of the risk of infection aatd loss of fluid, operative 

 interference in the vitreous chamber is usually to be avoided; 



Sympathetic ophthalmitis, or more accurately, infective irido-cyclitis, or uveitis, 

 is an inflammation of one eye, usually called the "sympathizer^ owing to injury or 

 disease of the fellow eye, usually called the "exciter." Traumatisms of the ciliary 

 region (danger zone) which have set up an irido-cyclitis or uveitis are responsible 

 for fully 80 per cent, of the cases of so-called sympathetic inflammation. This 

 disease was formerly supposed to be due to reflex action through the ciliary nerves, 

 and this theory in a modified form is still maintained by a few clinicians. The " mi- 

 gration theory ' ' propounded by Leber and Deutschmann that the inflammation is a 

 progressive process in the continuity of the tissue of one eye to the other by way 

 of the optic nerve apparatus and is of bacterial origin, has not been proved. It is 

 believed by some investigators that the bacteria which enter the primarily affected 

 eye produce a toxin which causes the disease, and by others that it represents an 

 endogenous infection produced by invisible bacteria, that is, that it is a metastasis 

 (de Schweinitz). 



THE SUSPENSORY APPARATUS OF THE LENS. 



The lens is held in position by a series of delicate bands, which pass from the 

 vicinity of the ora serrata over the ciliary processes to be attached to the periphery 

 of the lens. These 



fibres collectively con- FIG. 1233. 



stitute the suspen- 

 sory ligament, or 

 zonula of Zinn, a 

 structure of impor- 

 tance not only for the 

 support of the lens 

 but also in assisting 

 the ciliary muscle in 

 effecting the changes 

 in the curvature of 

 the lens incident to 

 accommodation. The 

 zonula is not, as for- 

 merly believed, a con- 

 tinuous membrane, 

 but is composed of a 

 complicated system 

 of fibres. The latter, 

 varying in thickness 

 from .005-. 022 mm., 

 arise chiefly from the 

 cuticular membrane 

 covering the pars ciliaris retinae in the vicinity of the ora serrata. The investigations 

 of Retzius, Salzmann and others indicate that some fibres arise also from the mem- 

 brana limitans interna of the pars optica retin<z, whilst others pass into and end 

 within the vitreous body. The greater number of the fibres pass forward chiefly in 

 the depressions between the ciliary processes, and along the sides of the latter, closely 

 applied to the surface ; they then proceed outward across the circumlental space to 

 be attached to the capsule of the lens. Some of the fibres are inserted anterior to 

 the equator, others posterior to the equator, and some directly into the lens margin. 

 Those inserted anteriorly arise behind and chiefly from the valleys between the ciliary 

 processes, whilst those inserted back of the equator come from the ciliary processes 

 in front. As they diverge to gain their insertion in the lens-capsule, the crossing 

 fibres enclose an annular space, triangular in section, whose base is directed toward 



Meridional section of ciliary region, showing ciliary processes and suspensory 

 ligament of lens. X 20. 



