Ophthalmic surgery / by Robert Brudenell Carter and William Adams Frost.

  • Robert Brudenell Carter
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Ophthalmic surgery / by Robert Brudenell Carter and William Adams Frost. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    CHAPTER I. ANATOMY AND PHYSIOLOGY. The human eyeball, or globe of the eye, is a nearly spherical organ, composed of coats or tunics inclosing transparent substances or fluids which are collectively called the internal refracting media, and which have the function of forming inverted images of visible out- ward objects. The external coat is formed of two different structures ; the posterior, larger, and opaque portion being known as the sclera, while the anterior, smaller, and transparent portion is the cornea. Within this external coat is a vascular membrane, the choroid, with which an anterior perforated muscular diaphragm, the iris, is continuous through the intervention of the ciliary body ; and within the choroid is a nervous membrane, the retina, for the reception and transmission of visual impressions. The cavities formed by these membranes contain the internal refracting media, that is to say, the aqueous humour, the crystalline lens, and the vitreous body, which not only fulfil the optical purpose already as- signed to them, but also preserve the shape and tension of the organ. In order to facilitate description, it is customary to apply to the globe other terms which are also borrowed from geography. Thus, the geome- trical summit or centre of the cornea is called the b—24
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