Amblyopia Of The Visual Field, Scotomas, And Hemianopia

Amblyopia Of The Visual Field, Scotomas, And Hemianopia
By H. V. Wurdemann, M. D.,
Of Milwaukee, Wis.
The Normal Field.

The field of vision is that space perceived when the visual axis is directed to a stationary point. When both eyes are used the fields overlap, forming the binocular field or field of fixation (Figs. 277, 278).

The object fixed is within the range of direct vision, the rays of light falling directly upon the macula; those coming from surrounding objects fall upon other parts of the retina which have indirect vision. The visual acuity diminishes as images are removed from the macula to the periphery of the field. The normal field of vision is more or less constricted at the upper and nasal sides by the eyebrows and nose, forming the upper, inner, and lower limits of the field, the outer proceeding in normal eyes to a little beyond 90' from the fixation point. Form and white are most eccentric, followed in order by blue, yellow, red, and green (Fig. 279). Overhanging eyebrows or a large nose materially limit the field. If the chart be improperly taken, as when the patient does not bold his head erect, does not fix the sight hole of the perimeter, or nips the eyebrows or eyelids, variation may be found.

At the temporal side of the fixation point from 10 20' is the physiologic blind spot or scotoma of Mariotte (Fig. 279). By careful examination with very small test objects other blind spots, may be found which correspond to the places of division of the large retinal vessels. The physiologic scotoma may be larger or smaller according to the size of the nerve bead. In case of continuance of the medullary fibers of the disk the spot may be very large, including even the fixation point (Figs. 280 and 296). As this is covered by the visual field of the other eye in binocular vision, the existence of this spot is not noticed.

Although the fovea centralis is the point of best vision, yet astronomic observation has shown that feebly reflecting stars are better seen when the vision is directed a little to one side, for the fovea is less sensitive to both light and color in diminished light than the retina immediately surrounding it.'

ANOMALIES OF THE VISUAL FIELD.

Anomalies of the visual field occur as symptoms of disordered conditions which themselves are manifestations of well recognized affections, such as diseases of the eye, of the visual centers, or of their connections, which may be due to trauma, cerebral or spinal affections, and which may in their turn be part of some general infection or condition.

Besides amblyopia (loss of vision) and amaurosis (blindness), which occur in connection with actual anomalies of the visual field, there exist two distinct groups of anomalies (for amblyopia and amaurosis, see page 457).

1. Contraction of the visual field, which may be regular (concentric) irregular (eccentric), and sectoral. These defects may be due to local as well as central lesions. There is also a characteristic form occurring in both eyes, with symmetrical obliteration of halves of the visual field true hemianopia due to lesion within the cranial cavity.

11. Scotomata, a group characterized by formation of scotomata or blind spots in one or both eyes, in some instances having a hemianopic aspect. The positive scotoma is seen by the patient as a dark or black spot upon objects. In the former case it is relative, in the latter absolute.

The negative scotoma is not at first recognized by the patient, but is developed through the examination. A typical example of this is the normal blind spot. The scotoma may occupy various positions, be single or multiple, central, para or pericentral, or may have a circular form, the so called ring scotoma (see also page 169).

The special affections Of the organ of vision in which anomalies of the visual field occur are;

I. Optic hindrance in the refractive media; II. Diseases of the retina

111. Diseases of the choroid;
IV. Glaucoma; V. Diseases of the optic nerve;
VI. Diseases of the chiasm;
VII. Diseases of the optic tract from the chiasm to the visual centers;
V111. Functional diseases and nervelesions of difrerent kinds.
Changes in the Visual Field due to Optic Hindrance. Foreign bodies or opacities in the cornea, lens, vitreous (Fig. 281), or outer layers of the retina may be attended by obscuration of vision through optic hindrance, and cause amblyopia, contraction of the visual field, and scotoma.

Trauma of the eyeball may be followed by either destruction of tissue and bleeding, or both, causing changes in the visual field. Pre retinal hemorrhage causes diminution of the visual field and absolute or relative scotoma (Fig. 282).

Changes in the Visual Field in Diseases of the Retina.-Changes in the nutrition of the retina and choroid, such as occur in night blindness, produce amblyopia, which is especially noticeable in diminished light, together with contraction of the visual field, particularly noticeable for blue' (Figs. 283 and 284 (see also page 468)).

Embolism of the central artery of the retina and thrombosis of the central vessels give rise generally to amaurosis, proceeding to complete blindness, but where the blood stream is not completely cut off the vision is diminished and the field contracted, together with formation of scotoma, which is generally central (Fig. 285).

Hemorrhages into the retinal structure produce scotoma or irregular contraction of the visual field, the amount depending upon the extent of the lesion.

Foreign bodies in the retina cause scotoma (Fig. 286).

Detachment of the retina from traumatism or in myopia is attended by characteristic defects according to its extent (Figs. 287, 288).

Retinitis albuminurica," diabetica, and circinata are attended by scotoma (Fig. 289), usually central, and are followed in their retrogressive stages by atrophy of the retina and nerve, with amblyopia or amaurosis and contraction of the visual field.

Changes in the Visual Field in Diseases of the Choroid.Circulatory disturbances and changes in the nutrition of the choroid produce characteristic changes (Figs. 290, 291). Coloboma of the choroid is attended by sectoral defects and usually scotoma (Fig. 290). Rupture, hemorrhage, and tumor of the choroid give rise to defects depending upon the extent of the lesion (Fig. 291).

Choroiditis, especially the exudative form, usually causes multiple scotomata (Fig. 292) which are absolute or relative. By their coalescence larger scotomata are formed which may even take a peculiar ring form (Fig. 293). The visual fields may likewise be greatly reduced. If the choroiditis be at the macula, central scotoma will be developed.

Chorio retinitis pigmentosa is usually attended by great contraction of the visual field and amblyopia (Figs. 294, 295). In myopia staphyloma posticum may develop, and the blind spot be rendered abnormally large thereby, so that it may even extend to the fixation point. In senile atrophy of the choroid central scotoma and reduction of the visual fields, with amblyopia, result (Fig. 295), the shape of the scotoma bearing a relation to the shape of the atrophic area.

Changes in Glaucoma. In glaucoma there is often a characteristic reduction of the fields toward the nasal side; but many other types of visual field disturbance are common (for visual fields, see pages 380 and 381).

Changes in Affections of the Optic Nerve. Changes in the visual fields generally occur in affections of the optic nerve. The principal congenital defect is coloboma of the nerve and its sheath, and is attended by enlargement of the blind spot (Fig. 296).

In traumatism with rupture or bleeding into the nerve (Fig. 297) and in tumors of the nerve there is usually found a sectoral defect, with amblyopia and contraction of the visual field resulting in atrophy. Diseases affect¬ing the intraocular end of the optic nerve, such as papillitis, cause decided changes in the visual field, depending upon the amount of optic interference caused b y the swelling and bleeding into or destruction of the nerve tissue. The blind spot is usually much enlarged “(Fig. 298). The relation be¬tween the ophthalmoscopic appearances and the visual acuity is frequently not commensurate. These cases usually terminate in atrophy with contraction or sectoral defect and scotomata.

Retro bulbar neuro retinitis, or toxic amblyopia is usually attended by central scotoma due to implication of the axial fibers. (It is fully discussed on page 461.)

Atrophy of the Optic Nerve. Many cases coming under the foregoing result in sclerotic changes in the optic nerve. However, it is known that a large proportion of cases with diminished vision, due to atrophy of the nervefibers, are associated with sclerotic changes in the spinal cord. Among these is atrophy due to tabes, which in ma instances is a premonitory sign of this disease."' Various forms attended by non characteristic changes in the visual field occur in multiple sclerosis, progressive paralysis, syringomyelia, amyotrophic lateral sclerosis, exophthalmic goiter, cerebral syphilis, degenerative changes, and different mental diseases!

The visual field in optic nerve atrophy is usually constricted, and the contraction for color greater than that for form and white (Fig. 299). The color sense may be entirely absent, and yet the field be of moderate extent (Fig. 300). Scotomata may appear. The atrophy and consequent loss of sight may proceed for a while (stationary optic nerve atrophy), and then definitely stop, or may progress to absolute blindness (progressive optic nerve atrophy~. A peculiar progressive form associated with scotoma (hereditary atrophy) comes on usually between twenty and thirty years of age (Fig. 301).

THE VISUAL PATHWAY.

The visual tract or pathway (see Fig. 302) proceeds from the retina to its final termination in the brain, the separate subdivisions of nerve fibers lying in different relations at different portions of its course.

The peripheral percipient elements in the retina are the rods and cones, which are connected by fibers with the outer and inner granular layers, which in the region of the macula lutea are very fine and anastomose freely, and cannot, as elsewhere, be separately traced. The anatomic relations of the optic nerve fibers, as given by Henschen and described by Wilbrand, 23 are as follows:

(a) The macular bundle lies ventro laterallyin the papilla and also immediately behind it. At the latter place it forms a keystone .shaped sector, with its base turned toward the pial sheath and its point toward the central vessels. Farther back this bundle is half moon shaped. Still farther back it takes the form of an upright oval and approaches nearer the axis of the optic nerve. In the optic foramen it assumes an axial position, and in front of the chiasm the form of a horizontal oval, the macular bundle contains crossed and uncrossed nerve fibers. In front in the papilla the crossed fibers lie ventrally and the uncrossed ones more eccentrically, being in proximity to the other uncrossed fibers. The fibers spread over the retina. Farther back the macular fibers become drawn together toward the center. The dorsal half of these fibers goes to the dorsal half of the retina, whilst the ventrally placed fibers go to the ventral half.

(b) The uncrossed (not the macular) bundle is divided in the anterior division of the optic nerve into two fascicles a dorso lateral uncrossed dorsal part and a ventrolateral uncrossed ventral portion. In the lamina cribrosa these fibers are separated by the macular bundle. Behind the entrance of the central vessels the fascicles approach one another and form a united half moon shaped bundle, which includes the lateral periphery and lies somewhat ventro laterally.

(c) The crossed bundle (not macular) forms a closed cord in the whole optic nerve. In the papilla it is situated dorso medially, and retains this position until it passes the chiasm.

The papillo macular bundle, which reaches the chiasm in the shape of an oval lying horizontally, retains its central position until it reaches the chiasm. Farther back toward the center of the chiasm it almost reaches the periphery, and here the fibers belonging to the fasciculus cruciatus cross one another. It sinks once more and lies ventro centrally in the tract. The crossed fibers of this bundle lie more centrally, and the uncrossed ones more laterally.

When a cross section of the optic tract is made immediately in front of the chiasm, it will be found that the crossed fibers occupy the dorso medial part of the periphery of the section, and the uncrossed fibers are situated in the ventro medial portion of the periphery of the section. The bundles then become divided into a number which are flattened horizontally, and these intermix with one another. The crossed fiber bundles come together again at the velltro lateral margin of the chiasm, forming the tract. Then there is a displacement. The crossing does not take place all at one point, but the dorsal nerve fiber bundles first cross, followed by the more centrally situated ones. At the posterior angle of the chiasm the commissural. nerve fibers, described by von Gudden, Meynert, and Forel, which have no influence on vision, are found.

The macular bundle courses centrally in the tract, Th e un crossed bundle I ies dorsolaterally, forming a close cord. The bundles retain this position until they enter the corpus geniculatum, where they separate into a mass of separate fibers. The crossed bundle lies ventro medially, and forms a bundle which lies slantingly and hangs loosely together.

The tractus winds around the crus cerebri, and terminates in two roots upon the corpora gesticulate externa and interna, and upon the posterior part of the optic thalamus, called the pulvinar. Fibers also go to the anterior part of the corpora quadrigomina, but these organs are not regarded as concerned in vision, but in the activity of the pupil. The parts just referred to are called the primary visual ganglia, or primary optic centers.

In them are found innumerable ganglion cells in which the fibers of the tractus lose themselves, and thereafter a new set of fibers proceeds backward through the posterior part of the internal capsule to the cortex, under the name of the visual radiations, or fibers of Gratiolet or of Wernicke. Passing through the internal capsule, they cross the sensitive fibers coining down from the hemisphere, are rather closely massed, and then, spreading out like a fan, rise upward, wind outside the tip of the lateral ventricle to reach their destination at the lower part of the median surface of the occipital lobe (Fig. 302).

DISEASE WITHIN THE CRANIUM.

Diseases of the brain affecting the optic nerve or tracts give rise to characteristic lesions. Optic neuritis is common, although not a constant symptom of brain tumor. It is attended by changes in the visual field, already described.

Hemianopia or Hemianopsia. Hemianopia, or half blindness of the visual field, resulting from a localized cause, is common to both eyes. If the obliterated half be toward the same side in both eyes, it is called homonymous (lateral hemianopia) ; if the opposite sides be affected, it is called heteronymotis (nasal or temporal). The term hemianopia should be limited to half blindness affecting both eyes Sectoral defects simulating hemianopia may arise in one or both eyes ~Figs. 281, 287, 290, 291, 297) from diseases of the optic nerve or retina, but are not to be considered in this connection.

The hemianopia may include half of the fields (complete), or affect sectors (incomplete or partial), or involve one half of the field on one side and a sector in the other, or the blindness may occur in the whole of one eye and part of the field in the other eye. In the hemianopic field the vision may be totally obliterated (absolute) or partially retained (relative). Pressure upon the hemianopic sides of the eyeball does not cause phosphenes, and this fact may be of importance in cataractous patients with hemianopia.'

The condition and reaction of the pupils are of diagnostic importance in cerebral diseases, and especially in those accompanied by ocular lesions and changes in the visual field. Illumination of both eyes in uncomplicated diseases of the centripetal portion of the optic reflex are never produces unequal pupillary reaction. Both pupils may fail to react to light, though sight remains good (involvement of Meynert's fibers), or both pupils may react alike, though there be complete amaurosis (lesion in some part between the Gratiolet fibers and psycho optical cortical center).' In the case of hemianopia, when light is cast into the eye upon the seeing side of the retina, if the lesion be anterior to the primary optical ganglia, the pupil will contract, but if light is directed upon the blind side there will be no contraction. If the lesion be beyond the thalamus, such hemianopic pupillary inaction cannot occur. This reaction is often called Wervicke's symptom.

DISEASE OF THE CHIASM.
Heteronymous Hemianopia. 1. Nasal hemianopia has never been shown to be due to disease behind the chiasm.' Since these fibers do not decussate and are never in contact, it is almost impossible to conceive of a bilateral cerebral lesion of the same extent and size affecting the function equally on both sides (Fig. 303). In the few reported cases a bilateral affection of the trunks, of' both optic nerves in front of the chiasm, extending to these and chiefly intense symmetrically at each side, has been found or diagnosed.3 The visual fields are obliterated at the nasal sides of the fixation point. The dividing line is apt to be irregular and not precisely in the vertical meridian. The obliterated areas are not entirely deficient in light perception, and there is hemianopic pupillary inaction. Usually evidences of inflammatory changes will be seen on ophthalmoscopic examination in disturbances of circulation ' swelling, or hemorrhages on the disk, followed later by atrophic changes. Disturbance of vision as regards walking about is not very great.

2. Temporal hemianopia (Fig. 304) is caused by disease of the chiasm where the decussating fibers of both tracts interweave. The visual fields are obliterated at the temporal side' of the fixation point. The dividing line is usually irregular and the blind areas may retain some perception of light. Hemianopic pupillary inaction is present. Ophthalmoscopic examination is usually negative except in the later stages, when atrophy of the optic nerve may occur. Disturbance of the vision is great, as the patient may only see directly ahead and has difficulty in orientation."

Diseases of the Optic Tract from the Chiasm to the Visual Centers. Lateral or homonymous hemianopia is due to disease affecting the optic tract behind the chiasm. Corresponding sides of the visual fields are affected (Fig. 305). The dividing line between the seeing and the blind areas is usually well defined, running perpendicularly through the fixation point, the visual acuity and color sense being normal up to the edge of the obliterated area, the hemianopic field having no perception. In many it will be found that the central vision has either remained or is entirely obliterated, this being due to the fact that the macula in these cases receives fibers through both optic tracts (also proved by the occurrence of double hemianopia), and if the field be carefully taken it will be found that there is a bulge in the line of demarcation between the hemianopic and the seeing field. If the fixation point lies in the obliterated field, there will be cent al blindness; if in the remaining field, the central vision will remain. Right sided hemianopia causes more disturbance than left sided, as we read from left to rights Patients see and walk fairly well by turning the head to one side.

At first no lesion will be found on ophthalmoscopic examination, although signs of' atrophy ultimately appear. If the left tract be affected, producing right hemianopia, the right optic nerve will in time become wholly atrophic, and the left optic nerve look normal for the reason that in the left eye the tract fibers are diminished and the crossing fibers are good ; the former are covered by the whole of the disk. In the right eye the crossing fibers (derived from the left tractus) are injured and the direct tract fibers are sound. The crossing fibers are in front, and they give the disk a look of general atrophy, with lesion of the left tract (with right homonymous hemianopia). The left nerve looks normal; the right nerve will appear atrophic.'

A few cases of hemi achromatopia, in which the sense of color is lost for corresponding halves of either eve, have been reported. The cerebral chaeacter of the lesion may be established by paresis and unconsciousness. Tile site is supposed to be in the cortex.' A separate color center, however, is denied by Ole Bull, Dahms, and Ward Holden.

Recently several cases of double homonymous hemianopia, with preservation of small central field in each eye, show that there is a cortical visual center which supplies the macula lutea .4

Monocular hemianopia is supposed to be caused by lesion of part of one tract involving only a portion of its fibers, but no cases have been well established .4 The same may be said of vertical hemianopia (Figs. 291 and 297). Many diseases of the nerve and retina simulate a hemianopic field, but cannot be considered under the classical definition. The causes of the three varieties of hemianopia include traumatism, hemorrhages, embolisms, periostitis, tumors, softening and sclerosis of that portion of nerve lying within the skull.

The Significance of Hemianopia. Hernianopia is not in itself a localizing symptom. There are usually other symptoms which assist in the diagnosis. Seguin's rules are as follows:

" 1. Lateral hemianopia always indicates an intracranial lesion on the opposite side from the dark fields. 2. Lateral hemianopia with pupillary immobility, optic neuritis, or atrophy, especially if joined with symptoms of basal disease, is due to lesion of one optic tract or of the primary optic centers of one side i. e. the corpora quadrigemina and parts included within primary optic centers (including corpora quadrigemina, corpora geniculata, and pulvinar of the thalamus opticus) (Fig. 306). 3. Homonymous sector like defects of the same geometric order, with hemianesthesia and choreiform or ataxie movements of one half of the body, without marked hemiplegia, are probably due to lesion of the caudo lateral part of the thalamus; or of the posterior (caudal) portion of the internal capsule, fasciculus opticus, and radiating visual fibers of' Gratiolet in the internal capsule. 4. Lateral hemianopia with complete hemiplegia (spastic after a few weeks) and hemianesthesia is probablN, caused by an extensive lesion of the internal capsule in its knee and caudal part (pulvinar) i. e. farther back and more profound than in supposition 3. 5. Lateral hemianopia with typical hemiplegia (spastic after a few weeks) aphasia if the right side be paralyzed and with little or no anesthesia is quite certainly due to occlusion of the middle and adjacent cerebral arteries with extensive superficial lesion, softening of the motor zone and of the gyri lying at the extremity of the fissure of Sylvius viz. the inferior parietal lobule, the supramarginal gyrus, and the gyrus angularis. There may also be alexia, word blindness. 6. Lateral hemianopia with moderate loss of power in one half of the body, e6pecially if associated with impairment of the muscular sense, would probably be due to a lesion of the inferior parietal lobule and gyrus angularis with their subjacent white substances, penetrating deeply enough to sever or compress the optic fasciculus on its way posteriorly to the visual center. If mental blindness exists, the lesion would lie in the more anterior central parts of the occipital lobe. 7. Lateral hemianopia, without motor or common sensory or any accompanying symptom, is due to lesion of the cuneus mly, or of it and the gray matter immediately surrounding it, on the mesial surface of the occipital lobe in the hemisphere opposite the dark half fields. The lesion may be partial or total. Most surgical cases come at once or after convalescence within this rule or within rule No. 6. In all cases coming under rules 3 to 7, inclusive, the pupils react normally, and rarely does the ophthalmoscope show any lesion of the optic nerve, except, of course, in some tumor cases, 'where neuro retinitis may be expected." 12

Amaurosis Partialis Fugax (Transient Hemianopia). Flickering sctoma is a form of temporary blindness of a hemianopia character usually associated with unilateral migraine, which is, accompanied by malaise, vertigo, sometimes disturbances of memory or speech. It is supposed to be due in disturbance of the circulation from spasm in the vessels of the brain, and, when accompanied by headache, in those of the dura mater.' A typical attack usually begins with a dark spot in both eyes in the same part of the visual field. This spreads, but remains in the nasal half of one visual field and the temporal left of the other. Silvery flickering points or shadows move in a zigzag manner. Part of the dark spot extends toward the end of the visual field. The blindness usually lasts a quarter to a half hour and disappears. If the visual field be examined during the attack, a defect will be found. und. In one case 13 the scotoma appeared as in the illustration (Fig. 306), growing larger and larger, finally obliterating the object and then disappearing. In another case' central scotoma with loss of light , color , and form sense was found. In only one case in the writer's experience has this condition been associated with hysteria, the others happening in persons of nervous organization whose general state of health was somewhat lowered. In one case,' of a physician who was subject to the flickering scotoma, an attack was followed several weeks later by hemianesthesia, hemiplegia, and death with bulbar symptoms. At the autopsy the right vertebral artery was found thrombosed and obliterated. In this case the “flimmer scotom “was certainly due to disturbance of the circulation.

The scotoma scintillans of Listing is a peculiar subjective visual sensation the same character. In some cases there is a kind of after image of the true scotoma appearing at night or in dim light, lasting but half an hour, in a rapid succession of luminous figures with dark intervals. In one case these appeared in the upper right quadrant of the binocular a glittering figure quite close to the fixation point, of an irregular, crescentic shape, increasing for a while and gradually receding from the center of the field, growing larger and dimmer and finally fading away. Reading was not materially interfered with.

Treatment of this condition consists in restriction from brain work, regulation of diet and daily life. The administration of antipyrin, phenacetin, or caffein may cut short the duration of the attack and relieve the symptoms. Bromid of potassium and quinin have been advised.

FUNCTIONAL DISEASES.

(Retinal Anesthesia; Neurasthenic Asthenopia; Hysteric Amblyopia.)
Anesthesia of the retina (see also page 410) is characterized by reduction of, the visual acuity and concentric contraction of the visual field or other changes, together with functional disturbances in other parts of the body.

It occurs for the most part in anemic women who are often the subjects of uterine and ovarian disease or chlorosis, or in children at puberty; occasionally cases are seen in young men. The loss of sight is usually partial, although it may be total, and in some cases the apparent loss is heightened by malingering. It is purely an hysteric manifestation, and as such may last from a few hours to days, weeks, or months. Indeed, patients have been known to shut themselves up in dark rooms for a long time, especially if attended by sympathizing friends or relatives. The subjects usually complain of considerable eye pain, dazzling and photophobia, headache, and blinding by artificial light, haziness, dimness of letters and lines on reading, lachrymation, and occasional diplopia.

The causes of the condition are over exertion at school or over work, traumatic neurosis from injuries which are often trifling, general ill health, and diseases of the genital organs (kopiopia hysterica), and other manifold causes of hysteric conditions. The location of an hysteric symptom is frequently more or less dependent upon an actual local lesion. Thus it is that the cause of hysteric blindness in a neurasthenic person may depend upon eyes that are already weak from an error of refraction or actual extrinsic muscle weakness, conjunctiva! trouble, etc. There are cases in which these causes may not be found, and a diagnosis of true nervous asthenopia may here be made. There is usually weakness of accommodation and the extrinsic muscles, especially deficient adduction (insufficiency) or imbalance of the muscles (heterophoria). The levator is sometimes likewise affected (pseudoptosis). There may be sensory motor paralysis and parasthesia or anesthesia in various parts of the body.

There is generally concentric contraction of the visual field, usually more on one side than oil the other (Fig. 307). The extents and shapes of the fields will vary, depending upon the size of' the test objects and the condition of the patient. The contraction may be more pronounced if' a second field (the counter field) be taken immediately after the first, the difference being caused by nervous exhaustion (Ermudungs Typus) ' or the second field may overlap the first (Verschiebungs Typus)' (Fig. 308), or the colors may overlap or be reversed (reversal of the color fields)" (Fig. 309). Mixed forms are common and the boundaries are frequently not sharply defined. 1 relative central scotoma is sometimes found. The field may even have a hemianopic character, or be greatly contracted, or show sectoral. defects (Figs. 310 and 311 ). A peculiar form is the oscillating field," in which the patient first recognizes an object at one meridian, then loses it for a moment, only to see it again.

The diagnosis may be made by the accompanying general symptoms and the absence of actual ophthalmoscopic signs of disease. The pupils are active to light and accommodation and the visual fields are usually typical. The amblyopia is usually of sudden occurrence and disappears quickly."

Treatment is directed toward restoration of general health, and should include massage, exercise, good food, and tonics, with rest of the eyes from work, and the use of tinted glasses, care being taken that the subject does not depend too much upon their use. Although subject to constant relapses, manv cases may be rapidly brought from complete or partial blindness to full visual acuity and restoration of the visual field by suggestion, electrical treatment or simple medicines.

Nerve lesions and general diseases are sometimes attended by disturbance of vision and changes in the visual field.

The Significance of Amblyopia and Changes in the Visual Field. The diagnostic importance of loss of vision depends upon its nature. If the disease be found in the eve, it will depend upon the extent of the lesion. If the blindness be associated with symptoms of spinal or brain disease, diagnostic points of value will be determined from study of the visual acuity, of the character and extent of scotomata, and of alterations in the field. If the latter be hemianopic in character and associated with other symptoms, a definite localization of the lesion may be assigned, although in themselves these are not diagnostic, as such may be simulated by hysteria. The character of scotomata is sometimes diagnostic, especially those of central nature which occur in toxic amblyopia. The peculiar vacillations in the visual field associated with functional disease are characteristic.

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