Text-book of ophthalmology . city may actually drop off altogether. Zonular opacity of the cornea generally develops in eyes which have nearly orquite lost their sight in consequence of some intra-ocular affection (irido-cyclitis, glau-coma), and in this case it is practically of little significance. It is only very rarely (andthen only in elderly people) that we encounter it in eyes which are otherwise perfectlysound, so that here the corneal opacity itself is the sole cause of the disturbance ofvision (senile zonular opacity). The anatomical changes which underlie zonular opacity of the corn
Text-book of ophthalmology . city may actually drop off altogether. Zonular opacity of the cornea generally develops in eyes which have nearly orquite lost their sight in consequence of some intra-ocular affection (irido-cyclitis, glau-coma), and in this case it is practically of little significance. It is only very rarely (andthen only in elderly people) that we encounter it in eyes which are otherwise perfectlysound, so that here the corneal opacity itself is the sole cause of the disturbance ofvision (senile zonular opacity). The anatomical changes which underlie zonular opacity of the cornea consist inthe deposition of lime in the form of very minute granules in Bowmans membrane(Fig. 105, b, Fig. 114), which thus becomes opaque, white, rigid, and brittle. In thespots where the calcification is far advanced we ordinarily find new-formed connectivetissue (Fig. 114) on Bowmans membrane, between the latter and the to the presence of this tissue the surface of the epithelium, e, becomes irregular,. Fig. 114.—Zonular Opacity op the Cornea in an Atrophic Eyeball. Magnified 68 X 1. Bowmans membrane, 6, stands out because of its dark coloration which it owes to minute gran-ules of lime deposited in it. At the left end of the drawing the deposit is slight, but increases to theright to such an extent that the individual granules can no longer be distinguished. At the same timethe membrane becomes thinner and on its posterior surface uneven. Where the calcification of themembrane is the greatest, a layer of compact connective tissue, g, is found lying upon the latter. At thepoint where this connective tissue is most pronounced it pushes Bowmans membrane backward againstthe parenchyma of the cornea, H, and has caused a rupture of the brittle membrane. Through thepoint of rupture, connective tissue goes down into the deeper parts. The epithelium, e, is normal onlyat the spot where the calcification of Bowmans membrane is as yet slight; further along it is r
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