The visual percept is not immediately dependent upon the retinal processes, for between the two are interpolated complex, inaccessible nervous processes.
If the sensitive retinal elements have a diameter of 0.
Retinal hemorrhages occurred in many of the patients.
In addition, lesions consisting of retinalhemorrhage and exudation were observed and 75% of the patients showing them had other signs of radiation injury.
It seems to me to exclude, at least, the hypothesis of the persistence of the retinal image; for the false image does not last so long as the effluvium, under the conditions mentioned by me.
These minute differences, registered as they are on the retinal image, come to stand for so much of distance.
The part played by the retinal image in judging distance is easily understood in looking at two trees, one thirty feet and the other three hundred feet distant.
The sensation of sight coming from this retinal image unaided by other sensations gives us but two qualities, light and color.
The eye's perception of distance depends in part on the sensations arising from the muscles controlling the eye, probably in part from the adjustment of the lens, and in part from the retinal image.
It has been found that when the temperature is raised above a certain point, retinal response shows rapid diminution.
Again, if one eye be cooled and the other warmed, the retinal oscillation in one eye is quicker than in the other.
When there is little friction we get an after-oscillation, to which we have the corresponding phenomenon in the retinal after-oscillation (compare fig.
We shall then briefly inquire whether even the abnormalities sometimes met with in retinal responses have not their parallel in the responses given by the inorganic.
There is much to be said in favour of this view, for it is an undoubted fact, that light gives rise to retinal currents, and that, conversely, an electrical current suitably applied causes the sensation of light.
Unlike muscle in this, successive retinal responses exhibit little change, for, generally speaking, fatigue is very slight, the retina recovering quickly even under strong light if the exposure be not too long.
Waller, in his excellent and detailed work on the retinal currents of the frog, has shown how the sign of response is reversed in the moribund condition of the eye.
From out this disc we see springing the retinal artery and retinal veins, sometimes centric, at others excentric, in their passage.
A stimulus too feeble to produce an effect upon a single retinal rod becomes recognizable when many in a row are similarly excited.
They certainly appear so, and were it not that retinal images of small areas tend to assume this shape might implicitly be credited with being what they seem.
The reason for optical circularity probably resides in the shape of the retinal cones and in their patterning into a mosaic floor.
The mere fact that a row of retinal cones is struck, although each be but feebly affected, is sufficient to raise the sum total into the sphere of consciousness.
The right disc is not atrophied, but the whole of the lower half of the fundus is coated with masses of black retinal pigment.
There was extensive damage to both eyes, hæmorrhage, and probably retinal detachment as well as choroidal changes.
Thus, by these methods, using the truth of color in the sense of following the nature of retinal functioning, Monet and his followers raised the color scale many degrees in brightness.
This is exemplified in the well-known facts of the fluctuation of the threshold of sensation, of the so-called retinal rivalry, and of the subjective rhythmizing of auditory stimuli, already mentioned.
All the other parts of the retinal image are seen imperfectly, and the more so the nearer to the limit of the retina they fall.
The walls of the edge of the optic cup become very much thinner than those of the true retinal part.
Their cavities gradually become obliterated by a thickening of the walls, the obliteration proceeding from the retinal end inwards towards the brain.
The retinal elements are inverted, and the optic nerve passes in at the side, but occupies, in reference to its ramifications, the same relative situation as the optic nerve in the Vertebrate eye.
The permanent part is formed by the retinalvessels of Mammalia, by the vessels of the pecten in Birds and Lizards, and by those of the processus falciformis in Fishes.
The line of the slit can easily be traced along the lower side of the retina; and close to the lens the retinal wall continues, as in the embryo, to be raised into a projecting fold.
The outer ends of the retinal cells terminate in rods, and their inner ends are continuous with nerve-fibres.
Owing to the growth of the optic cup the two layers of which it is composed cannot any longer be seen from the surface, but the retinal surface of the layer alone is visible.
It consists of a refractive portion, turned towards the cavity of the vesicle of the brain, and a retinal portion forming part of the wall of the brain.
Langerhans), and the outer layer of the optic cup or layer of retinal pigment (rp) contains numerous pigment granules, especially on its dorsal side.
Consideration of the anatomical changes that take place in glaucoma secondary to retinal and chorioidal hemorrhage.
Atrophy of the nerve fibers follows death of retinal neurons, but atrophy of some of the nerve fibers may be, and probably is, due to the pressure and traction exerted upon them at the margin of the disc.
There may be renal retinitis or retinal hemorrhages.
Atrophy and cystic degeneration of the nerve trunk follows destruction of retinal neurons and cupping of the disc.
Careful studies of theretinal vessels in glaucoma (Verhoeff Arch.
Those that cause obstruction of the filtration angle by advancement of the iris and lens, as occurs when the volume of the contents of the vitreous chamber is increased, as from retinal or chorioidal hemorrhage or neoplasm.
In the fundus are seen increased tortuosity of the retinal vessels and their terminal twigs with more or less bending of the vessels at their crossings.
It is, therefore, a symptom of seriousretinal disease.
They are amblyopic, and this is due partially to a high degree of ametropia (caused by crushing of the eyeball in the endeavor to shut out light) and from retinal exhaustion and nystagmus.
In the Annual of the Universal Medical Sciences, 1888, there is a report of seven cases of retinalinjury with central scotoma, amblyopia, etc.
The retinal picture has not yet been photographed, but it seems probable, from the above recounted experiments, that it can be.
As to the detection of murderers by photographing the last retinal picture from their victims' eyes, while these discoveries do not leave this an impossibility, they do not much improve the probability of its ever being done.
This restoration is believed to be a function of the living choroid, and probably of the retinal epithelium, though it is independent of the black pigment which this epithelium contains.
Obviously the retinal processes are constant for the two interpretations of magnitude and the ambiguity is due to the concomitant factor of convergence.
It is in the phenomenon of ambiguity in the interpretation of the retinaleye processes that this case finds its value.
Here we have the retinal image constant for the apparent and the real size of the object (head).
Wheatstone, a long time ago, arranged his stereoscope so that a negative correlation obtained between the degree of convergence and size of the retinal image.
Whilst then a sort of community of vision exists for the upper and lower parts of the retinae, the sensations of the retinal area lying in the horizontal plane of the macula lutea of the squinting eye must be suppressed.
Defn: A brown, nitrogenous pigment contained in the retinal epithelium; a variety of melanin.
Image Purkinje (Physics), the image of the retinalblood vessels projected in, not merely on, that membrane.
Defn: A device for determining the refractive state of the eye by observing the movements of the retinal lights and shadows.
Defn: A yellow coloring matter, soluble in ether, contained in the small round fat drops in the retinalepithelium cells.
But each retinal cell is affected by any light that happens to come from its particular direction.
This disparity between the two retinal images is responded to by perception of the distance and relief of the object.
The disparity between the two retinal images, due to the different angles at which they view the object, is greatest when the object is close at hand, and diminishes to practically zero when it is a few hundred feet away.
How do we know that the impressions made on our retina by A at the instant [alpha] and B at the instant [beta] are transmitted by the same retinal fiber, although these impressions are qualitatively different?
These dorsal eyes are very perfect in elaboration, possessing lens, retinal nerve-end cells, retinal pigment and optic nerve.
Hickson and others, that in the bivalves Pecten and Spondylus, which also have eyes upon the mantle quite distinct from typical cephalic eyes, there is the same relationship as in Oncidiidae of the optic nerve to the retinal cells.
This is a retinal defect, the affected being able to see only in strong illumination.
The hyaloid artery remains, as a prolongation of the retinal artery to the lens, until just before birth, but after that its sheath forms the canal of Stilling.
This retinal sclerosis is consequently generally known as retinitis pigmentosa, a disease to which there is a hereditary predisposition.
In the cartilaginous fishes (Elasmobranchs) there is a silvery layer, called the tapetum lucidum, on the retinal surface of the choroid.
Loss of transparency in any of these media leads to blurring of the retinal images of external objects.
It marks the point of entry of the optic nerve, and at its centre the retinalartery appears and divides into branches.
Retinal inflammation may primarily affect either the nerve elements or the connective tissue framework.
Of these the outer cells become the retinal pigment, while the inner form the other layers of the retina.
In addition to these there is a retinal vein which accompanies its artery.
The gradual blindness which this causes is due to compression of the retinal nerve elements by the connective tissue hyperplasia, which is always associated with characteristic changes in the disposition of the retinal pigment.
The blind areas in the two fields of vision, corresponding to the outward projection of the paralysed retinal areas, are always symmetrical both in shape and degree.
The non-optical distinctness with which the words printed inside his hat were seen indicates that it was some inner non-retinal vision which received the impression from the phantasmogenetic centre.
Into the cerebral storage of impressions one element habitually enters which is totally absent from the mere retinal storage, namely, a psychical element--a rearrangement or generalisation of the impressions retinally received.
A retinal picture of an object seen after removing the gaze from the object.
In the typical invertebrate eye, on the contrary, the retinal cells are differentiated from the external ectoderm.
The lens of the lateral eye of the vertebrates is derived by an invagination of the ectoderm, which meets and fits in the retinal cup at the end of the optic vesicle.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "retinal" in a variety of sentences. We hope that you will now be able to make sentences using this word.
