EYE. In anatomy and physiology, the organ of vision. In order that vision may be distinct, it is necessary that the pencil of rays diverging from each point of the object and entering the pupil should converge to a focus on the retina. Near-sightedness (‘MYOPIA,’ L.) is due to the too great convexity of either the ‘lens’ or ‘cornea,’ causing the rays to converge to a focus before reaching the retina. The spectacles worn by myopic persons have concave glasses, which, by increasing the divergence of the rays falling upon the eye, have the effect of carrying back each focal point towards the retina. In the long sight of old people (‘PRESBYOPIA,’ L.) the foci of the refracted pencils are situated behind the retina, the ‘lens’ or the ‘cornea’ being not sufficiently convex. This defect is corrected by convex glasses, which increase the convergence of the incident rays.
Foreign Bodies in the Eye.—Particles of dust, small insects, hairs, and such like minute bodies frequently get under the eyelid, and thus become a source of considerable discomfort, and very frequently of great pain. Hence the necessity of their prompt removal. In order to effect this the inside of the lids should be so exposed as to reveal the intruding substance. The lower lid may be easily turned down so as to show the inner surface, but the upper lid cannot be so easily manipulated. The end, however, may be attained by taking firm hold of the lid with the finger
and thumb, drawing it downward and forward, placing a quill or a small pencil-case on the outer upper part, and turning the lid backwards over it. When the annoying particle is seen it should be removed by gently drawing over it, with a wiping motion, a piece of rag or linen handkerchief, wrapped round the finger, or by means of a camel-hair brush, if this latter be at hand.
If these means fail to remove it, and it should be imbedded too firmly in the membrane, it may be picked off with a tooth-pick, the end of a pair of tweezers, a fine ivory paper-knife, or with a stiff hair from a clothes-brush bent at right angles. If lime-dust has blown into the eye it is only the larger particles that can be removed in this manner; the finer particles may be dissolved out by washing the eye with a lotion made of one part of common vinegar and two parts of water. A drop or two of pure sugar syrup will also frequently dissolve the lime. When a powerfully destructive substance, such, for instance, as sulphuric acid or oil of vitriol, is, as sometimes happens, thrown by some person into the eye, the best course is to wash it out with a solution containing four grains of washing soda in an ounce of water. This should be done as quickly as possible, and pending the time the soda lotion is being got ready, the eye, being kept open, should be diligently washed with cold water. Grains of gunpowder should be carefully removed. Hot fluid, such as melted fat or pitch, may be got rid of by putting into the eye a few drops of almond or olive oil.
Upon removal of the foreign body the pain generally subsides; but it sometimes happens that the membranes may be lacerated, in which case more or less inflammation may ensue. Under these circumstances a medical practitioner should be consulted. For animals the same treatment may be followed. See Blindness, Colour Blindness, Vision, &c.
Eye Balsam, Vegetable (Martin Reichel, Würzburg). Opium, 5 parts; oxide of mercury, 5 parts; camphor, 2 parts; wax cerate, 52 parts. (Hager.)
Eye Drops. See Water (Eye).
Eye Essence (Dr Romershausen). A tincture prepared from fennel seeds and fresh young fennel. (Hager.)
Eye Powder (Laeyson, Paris), also known as Odorous Powder. For the strengthening, restoration, and preservation of the sight. A powder composed of—Burnt chalk, 100 parts; ammonia, 50 parts; charcoal, 6 parts; oxide of iron, 2 parts; cinnamon bark, 2 parts. (P. L. Geiger.)
Eye Pow′ders. See Collyria.