A text-book on diseases of the eye / by Henry D. Noyes.

  • Noyes, Henry D. (Henry Drury), 1832?-1900
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: A text-book on diseases of the eye / by Henry D. Noyes. Source: Wellcome Collection.

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    cornea does not reach back to the place from which the iris spring's; hence, a puncture into the anterior chamber can be made tliroug-h the anterior edge of the sclera. A clear perception of this fact is indispensable in operating at this region. The existence of that congeries of vessels called the canal of Schlemm, or the circular venous sinus, is also to be noted. It has important relations to the physiology of the anterior chamber. It is the outlet by which the aqueous humor finds its way into the circulation, and is sup- posed by Schwalbe to have in its wall, minute clefts for this purpose; but this is disputed by Leber. At the angle are to be found deli- cate fibres passing from the cornea across to the iris. They are in- FiG. 2. significant in man, and are called the pectiniform ligament. In lower animals, viz.: in the ox and in swine, etc., they are more developed, and constitute the canal of Fontana. Upon theories of intraocular pressure, the parts now alluded to, have important value. The aqueous humor is derived from the vessels of the iris and of the ciliary processes. The posterior chamber is entirely shut off from the anterior chamber by contact of the iris with the lens, and even when the pupil is well dilated the contact continues. The anterior chamber, whose depth is from 2.6 mm. to 3.5 mm., does not seem to be so deep, because the refraction by the cornea and aque- ous humor makes the iris seem nearer to us than it really is—just as, in wading a brook, the water looks more shallow than we may
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