A practical treatise on the diseases of the eye / [John Vetch].

  • John Vetch
Date:
1820
Catalogue details

Licence: Public Domain Mark

Credit: A practical treatise on the diseases of the eye / [John Vetch]. Source: Wellcome Collection.

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    the subserviency of its circulation to that of the sclerotic. The sclerotic coat is supplied with blood from the ophthalmic artery,* given off from the internal carotid, and its inflammation inva- riably exhibits all the marks of strict arterial action. Inflammation does not take place in the cornea, and consequently neither suppuration nor » ulceration, until inflammatory action has been set up in the vessels of the sclerotic coat, even when the exciting cause is applied directly to the sub- stance of the cornea. No symptom of re-action * The circulation of the eye displays an interesting view of the ceconomy with which the singular mechanism of the organ is accomplished, the distribution of the blood being rendered subservient to the production of a camera obscura, associated with parts of the most perfect transparency, for the admission and refraction of light. The colouring particles of the blood be- come either concentrated in the circulation of the choroid coat, in which case it produces the tapetum lucidum, or they are depo- sited on the surface of this part, and on the posterior portion of the iris, while the serous albumenous parts are conveyed on to supply the parts concerned in the transmission of light. Patho- logy presents a converse illustration of the same view, for when the vessels of these parts which, in their natural and healthy state, permit the entrance of the transparent parts of the blood only, can no longer resist the admission of the red globules propelled by the impetus of inflammation, besides the high degree of irritation consequent on the distension, a smaller deposition of pigment would seem to take place, for the iris assumes a shade somewhat lighter, and the increased sensibility to light may certainly, in part, be owing to a correspondent diminution of pigment.
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