Vision in health and disease; the value of glasses for its restoration, and the mischief caused by their abuse. Being the substance of lectures delivered at the Central London Ophthalmic Hospital / by Alfred Smee ... ; illustrated by one plate and numerous woodcuts.

  • Smee, Alfred, 1818-1877.
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: Vision in health and disease; the value of glasses for its restoration, and the mischief caused by their abuse. Being the substance of lectures delivered at the Central London Ophthalmic Hospital / by Alfred Smee ... ; illustrated by one plate and numerous woodcuts. Source: Wellcome Collection.

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    LECTUEES ON VISION. LECTURE I. NORMAL VISION. (2-8.) Physical requisites for healthy vision.—(9-12.) Range of vision.—(13 ) Optic nerves, —(14, 15.) Modification of vision by the use of two eyes.—(16-18.) In judging of dis¬ tance.—(19.) Estimation of magnitude;—(20, 21.) of height.—(22.) Estimation by one eye.—(23.) Sense of measurement.—(24.) Inversion of image.—(25.) Single vision of the two eyes. — (26, 27.) Estimation of position and relation of objects.— (28.) Power of vision.—(29.) Sustainment of impressions.—(30.) Action of convex lenses.—(31.) Ad¬ justment of vision for various distances.—(32, 33.) Mechanism of adjustment;—(34, 35.) for near objects;—(36.) for distant objects.—(37, 38.) Vitreous and aqueous humours and ciliary processes, their use in adjustment. — (39.) Oblique vision.— (40.) Rate of adjustment.—(42.) Iris.—(43.) Estimation of motion,— (44.) Colour.—(45.) Time re¬ quired for perception of vision.—(46.) Recapitulation.—(47.) Light.—Conclusion. Gentlemen, (1.) I HAVE in my former lectures described to you the various diseases which attack the numerous tissues composing the eye ; I have shewn you how they may injure its delicate fabric, and it only remains for me now to point out the various abnormal conditions of vision which arise either from the effects of traumatic injury, the alteration of structure produced by disease, from the decay of age, or from original congenital defect. (2.) Before, however, I enter upon this important part of my subject, allow me briefly to recall to your mind the physical conditions necessary to vision, the parts of the body which are required for that purpose, and the leading phenomena presented in its normal state. (3.) For healthy vision various physical conditions are essential. In the first place, we require a nervous expanse, the retina, to receive a perfect image of the external object; and, moreover, to this nervous expanse must be continually supplied bright arterial blood, for if the supply of bright arterial blood fail, vision fails, as blood and nerve are conjointly necessary for this purpose. (4.) Having a nervous expanse supplied with arterial blood, an appa¬ ratus is required to cause a perfect image of the object to fall upon the retina, which apparatus is made up successively of cornea, aqueous hu¬ mour, lens, and vitreous humour, the combination of which may be re-