The sight of his left eye is still affected, being very weak--the retina was probably torn away.
In order to see, it is at once necessary that the retina be suitably exposed toward the object to be seen, and that the mind be favorably disposed to the assimilation of the impression.
A man may have his retina or his optic nerve injured, and so be blind in the ordinary sense of the word.
Accordingly, when the retina is disturbed by any exceptional cause, such as a blow on the head or an electric shock to the optic nerve, we have a sensation of light projected outward into space.
In a general way we see the same thing all the time, and the image on the retina does not change.
The retina may be exposed a thousand times and take but few pictures; or perhaps it is better to say that the pictures may be taken, but remain undeveloped and evanescent.
Again, the stimulation of the retina is ordinarily due to the impinging upon it of light-waves emanating from an external object.
In the vertebrate eye, the spot where the optic nerve pierces the external layer of the retina is not sensitive to light impressions; hence, it is called the "blind spot.
The electrically lighted instruments on the market now have so simplified the technic that any physician should be able to see the grosser changes which take place in the arteries and veins of the retina and in the disc.
Long before there are any subjective symptoms, changes can be seen in the blood vessels of the retina which, while not always diagnostic, at least call attention to a beginning chronic disease.
Exceptions to this are seen when inflammatory effusion has overfilled the globe of the eye, and by pressure on the retina has paralyzed it, or when the exudation into the substance of the retina itself has similarly led to its paralysis.
In the case of excessive effusion into the globe of the eye that is found to have become tense and hard so that it can not be indented with the tip of the finger, paralysis of the retina is liable to result.
The attacks vary greatly in severity in different cases, but the recurrence is characteristic, and all alike lead to cataract and intraocular effusion, with pressure on the retina and abolition of sight.
And, that Red is an impression on the Retina of an oblique and confus'd pulse of light, whose strongest part precedes, and whose weakest follows.
This Retina is an Elongation from the Brain; and by this Means it is, that we receive those various agreeable or disagreeable Sensations with which we find ourselves affected, by the Sight of external Objects.
It is probable that these reappearances of the image, after the light which produced the original impression has been withdrawn, are occasioned by spontaneous affections of the retina itself which are conveyed to the sensorium.
Whether the puncture should penetrate the overlyingretina is still a disputed point.
Detachment of the retina may follow loss of vitreous even months after operation.
Detached retina as the result of organization in the vitreous; this may occur months after the original injury.
In cases of glioma of the retina it is especially desirable that the optic nerve should be cut as far back as possible and the cross-section carefully examined for gliomatous tissue, since the disease spreads to the brain along this structure.
Unfortunately, recurrence is very liable to take place whichever method be used, even if reattachment of the retina be obtained.
Or, worse, imagine a disease of the retina which caused a like curious change in the landscape itself wherein a mountain appeared to be a mole-hill, and a mole-hill a mountain.
It is, therefore, evident that the several portions of one and the same line, seen through the intervals of the bars, form on the retina of the eye so many different radii.
But, with the pictures which are taken upon the retina of the eye, no such delay and labor is necessary before you can look at them.
I tried then to make plain how God pictures or photographs all our acts upon the rays of light, and how we see the objects about us when the rays of light fall upon the retina of the eye.
The moment the eye is turned in any direction, instantly the picture is photographed upon the retinaof the eye, and then stamped indelibly upon the memory and becomes a part of ourselves.
As the mirage refracts distant objects upon the retinaof the eye, so some spiritual mirage must have thrown upon my mind the image of things that were real.
O that I could again look with living eye on these bright pictures, that even thus palely outlined upon the retina of memory, impart pleasure to my soul!
Frogs in whose eyes the color of the retina has apparently been all changed by sunshine are still able to take a fly accurately and to recognize certain colors.
The retina of the eye is changed in color by exposure to continued rays of light.
Whether the changes produced by light upon the retina are all chemical or all physical or partly both remains open to discussion.
His mental retina formed a perfect mirror to hold up to nature.
Thus we became witnesses of what happens upon the horse's retina when a moving object passes in front of his eye.
The cells of the retina that are sensitive to light, the rods and cones, might therefore be correspondingly larger than those of the human eye, without thereby making the whole organ less efficient than the human eye.
And besides, there are two specially adapted areas within the retina of the horse.
This is not astonishing after all, when we recall that the periphery of the retina possesses a relatively high sensitivity for movement impressions, although its chromatic sensitivity is very low.
Even in man, the central part of the retina is alone capable of precise perception of form, but a moving object is observed by the peripheral tract.
Even more important is the action of the judgment and imagination, which complete the blanks in the sensorial picture, and translate the shorthand of the retina into a full-length description.
The retina catches the light-disturbance, and the optic nerve conveys it to the brain, and the brain-cells are agitated by it; but where does sight come in?
If we were to show a fine landscape to a Hottentot, it would be a mistake to say he saw it, though the image might be demonstrable on the retina of his eye.
Light opens the eye without our intention, and we are at no trouble to paint on the retina what must there appear.
For one reason or another the distance between lens and retina becomes too great for a person to distinguish distant objects clearly.
The image of anything seen is thrown on the retina upside down, and the brain reverses the position again, so that we get a correct impression of things.
Now, the retina cannot be pushed nearer to or pulled further away from its lens, like the focussing screen of a camera.
Bose showed his artificial retina previously exhibited at the Royal Institution which not only detected luminous radiation but also invisible lights in the intra red and ultra violet regions.
I still retain in my mental retina a picture of the king.
All objects, as is well known, are reflected in the retina thus, and it is our familiarity with the size and comparative relations of things which enables the brain to visualize an object or scene at its proper angle.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "retina" in a variety of sentences. We hope that you will now be able to make sentences using this word.
