1902 Encyclopedia > Ophthalmology


OPHTHALMOLOGY. The scientific development of the diagnosis and treatment of diseases of the eye belongs to the last hundred years. Helmholtz's invention of the ophthalmoscope is little more than thirty years old. Our knowledge of the refraction and accommodation of the eye has been worked out by Airy, Young, Sanson, Purkinje, Donders, Sneller, Helmholtz. Many of the major opera-tions have been perfected by Von Graefe and his followers in quite recent times. Finally, the important relations of ophthalmology to general medicine have been worked out principally by Hutchinson, Hughlings Jackson, Clifford Allbut, and Gowers within the last few years. Diseases Acute Catarrhal Conjunctivitis begins with a feeling of of the stiffness of the lids, and pain as if from a particle of grit ?on" in the eye. The secretion increases, is at first watery, and junc iva. .g afterwarc[s yeuow and muco-purulent, collecting at the inner canthus and gumming the eyelids together. The conjunctiva, especially that on the lids, is reddened, and in severe cases may be so swollen as to overlap the cornea. The eye is generally well-HtrTa fortnight. The disease is caused by cold winds, and by irritating particles, and in one form is undoubtedly contagious. The eye must be left uncovered, bathed occasionally with an astringent lotion, and at night some ointment should be applied to the edges of the lids to prevent their adhesion and consequent reten-tion of the secretion.
Chronic conjunctivitis may result from the above, or be due to the irritation of dust. It occurs frequently from overstrain of hypermetropic eyes. The symptoms are similar, but less severe, and require similar treatment with correction of the hypermetropia where present.

Purulent Ophthalmia (ophthalmia of the newly born) is caused by contact of pus from a gonorrheal or leucorrheal discharge or from another eye similarly affected. It is one of the forms of Egyptian ophthalmia. In children both eyes are generally affected; in adults usually one. The symptoms begin, from one to three days after infection, with a watery discharge, which increases rapidly in amount, and becomes yellow and purulent. The conjunctiva becomes greatly congested and swollen, bleeding readily. The lids are so stiffened with infiltration that they can hardly be separated. When they are slightly opened quantities of pus escape. There is great pain in the eye, fever, and sleeplessness. The cornea is much endangered ; it may be perforated, may slough wholly or in part, and the eyeball may be destroyed. If one eye only is affected the other must be protected. Locally the greatest cleanliness is necessary, and the discharge must be constantly removed. Once daily the conjunctiva should be touched with a strong solution of nitrate of silver, and in the interval frequently bathed with astringent solutions. Recently, powdered iodoform has been much recommended as a local applica-, tion. In adults leeching the temple and the continuous application of ice to the eye may be needed. The attend-ants must be warned of the danger of conveying infection to their own eyes.

Diphtheritic Conjunctivitis is characterized by the forma-tion of a yellowish false membrane on the conjunctiva, which becomes thickened and almost solid from infiltration, and by great liability to sloughing of the cornea. It occurs most frequently in North Germany, attacking weakly children during epidemics of ordinary diphtheria, and, like it, often proves fatal by exhaustion. It should be treated by the internal administration of tonics and stimu-lants, and by the local use of ice, antiseptic lotions, and the strictest attention to cleanliness.

Chronic Granular Conjunctivitis is a contagious disease arising from prolonged overcrowding under bad sanitary conditions. It is thus specially common among the Jewish and Irish poor, and among workhouse children. The mucous membrane of the lids becomes reddened, thickened, and studded over with small firm "granulations," like boiled sago grains. The friction of these bodies produces a vas-cular opacity of the cornea (pannus), at first limited to the upper half of the cornea, but in bad cases involving its whole surface. There is considerable pain and discharge, and the eyelids are kept half-shut. There is a peculiar liability to acute exacerbations. The conjunctiva finally shrinks to a dense white scar, which curves the tarsal cartilage inwards, and brings the edge of the lids and the eyelashes to rub on the cornea, and increase its opacity.

It must be persistently treated by strong astringent or caustic applications to the conjunctiva. The pannus, as a rule, disappears with the granulations that caused it. If not, a zone of conjunctiva round the cornea may be divided; or, as a last resort, the eye may be inoculated with pus from a purulent case. All acute exacerbations must be treated by soothing applications. Incurving of the tarsal cartilage and displacement of the lashes need special surgical operations, which are more or less successful.

If a case occurs in a school or in barracks it must be at once isolated.

Pterygium is a triangular thickening of the exposed part of the conjunctiva, which may or may not be vascular. Its apex is towards the cornea, over which it tends to grow, and thus to interfere with vision; otherwise it causes no irritation. Pterygium is a disease of middle life and of warm climates. If it cause no deformity or interference with sight it should be left alone. If large it may be dissected up from the apex and cut off, or transplanted into another part of the conjunctiva, where it will shrivel up.

The diseases of the cornea are of extreme importance, Diseases from their great frequency and from the fact that a smallof tne lesion may seriously affect the perfect transparency andcornea" regularity of curvature so necessary for clear vision.

Chronic Interstitial Keratitis attacks young persons, nearly all of whom, as was first pointed out by Hutchin-son, can be shown to be the subjects of hereditary syphilis, and who present some or all of the following physiognomical characters :—a depressed bridge of the nose, scars at the angle of the mouth, and notched and peg-shaped central upper incisor teeth. The disease affects both eyes, one generally some time before the other. It begins by the appearance of cloudy spots in the cornea, which spread until the whole cornea has a ground-glass appearance, not uniform throughout but with denser opacities here and there. The corneal surface is "steamy." The ciliary zone of vessels, immediately round the cornea, is congested, and iritis is a frequent complication. As a rule pain and photophobia are not great. The cornea seldom clears in less than a year, and even then only im-perfectly. Internally, minute doses of mercurials, or where there is decided struma the syrup of the iodide of iron should be given. Locally, atropine should be used to prevent iritis. As the cornea clears, some stimulant, as the dusting of fine calomel powder, may hasten the absorp-tion of the exudation.

Phlyctenular Ophthalmia occurs in strumous or weakly children, especially after hooping-cough or measles. There is great intolerance of light, the slightest attempt to separate the lids causing a gush of tears. The patient is generally kept in bed in a dark room and buries his head in the pillow to exclude the light. The conjunctiva is reddened generally, but spots of localized congestion are seen near little greyish or yellowish elevations on the conjunctiva, or on the cornea near its margin. These papules or pustules may succeed each other in crops for a long time. On the cornea they give rise to vascular ulcers, which may be single or so numerous as to constitute a condition of pannus. As they heal the vessels shrink, and a small white speck is left to mark the seat of the ulcer. As regards treatment, the patient must have a shade or dark glasses, and be sent out of doors daily when the weather permits. Tonics and nourishing food are required. Locally, so long as the secretion is watery atropine must be used; later, mild astringent lotions ; and finally, to aid the healing of the ulcer and clearing of the residual opacities, some mercurial ointment or calomel powder should be applied.

Ulcers of the Cornea.—Ulcers occur under many forms, to which very various names have been given. All the forms have certain symptoms in common with each other and with the above diseases. There is great pain in and about the eye, great intolerance of light (especially in super-ficial ulcers), and congestion of the ciliary zone. They generally leave an opacity, which greatly interferes with sight if in the centre of the pupil. In severe inflammatory or suppurative ulceration the above symptoms are well marked ; the base of the ulcer is greyish in colour, its edges irregular, and the surrounding cornea infiltrated. It ex-tends superficially and deeply, and may cause hypopyon (pus in the base of the anterior chamber), and even perforation of the cornea, or iritis. The weak ulcer has little pain or congestion, and seems simply a loss of substance at one part of the cornea. It causes distorted or multiple images. Its existence is a sign of lowered health, and calls for local stimulation and tonic treatment:—The small central ulcer of children is a small greyish funnel-shaped spot in the centre of the pupil, with little pain or congestion. It sometimes goes on to abscess, but usually heals quickly. The senile or serpiginous ulcer is a very serious form. There is great pain and photophobia, and unless treated the ulcer gradually eats its way across the cornea, or extends at its margins so as to isolate the central part of the cornea.

The treatment of corneal ulcers varies very much with the type of disease and with its several stages. In the acute cases the eyes should be shaded, sometimes bandaged; atropine applied locally allays pain ; eserine is said to act similarly by reducing tension, and is preferable where con-junctival discharge is aggravated by atropine. The weak ulcer should be touched with a nitrate of silver solution, the senile bathed with a quinine lotion. If the inflammatory ulcer be not checked by atropine, and if hypopyon increase, tension may be diminished by incising the cornea at its margin, or through the base of the ulcer (Saemisch), or by performing iridectomy.

Abscess of Cornea may result from injury or ill-health.

It begins as a yellow spot in the substance of the cornea, with some surrounding haze. It may become absorbed, or burst forwards and be converted into an inflammatory ulcer, or backwards, giving rise to hypopyon. If hot fomentations and atropine do not check it, it must be treated surgically like the inflammatory ulcer.

Staphyloma of the Cornea is a bulging forward in whole or in part of the new tissue which replaces the cornea after ulceration or sloughing. It has a bluish or greyish colour, and may be slight in amount, or so great as to keep the eyelids widely separated and cause great irrita-tion. When there is no irritation it may be left alone; when it is increasing an iridectomy may check its progress. When it is large and causes irritation the eye may be removed entirely, or in part so as to leave a stump on which to fit an artificial eye.

Conical Cornea occurs principally in young women whose health has been much reduced from some chronic cause. The cornea becomes thinned in the centre, and is slowly bulged forward. The condition, which is easily recognized from the glistening appearance and the conical form of the cornea, causes great myopia, which can be only imperfectly remedied by biconcave lenses obscured except at a small central aperture or slit. In severe cases opera-tion may be of some service.

Keratitis Punctata is usually secondary to some deeper-seated disease, e.g., iritis, choroiditis, or sympathetic ophthalmitis. Minute greasy-looking dots are deposited at the back of the lower part of the cornea, generally arranged as a triangle with its apex upwards. The ocular tension and amount of aqueous humour increase. The treatment is that of the causal disease, usually iodide of potassium or a mercurial, with atropine locally.

Arcus Senilis is a whitish crescent or ring just inside the corneal margin. It is a senile change, a fatty degen-eration of the corneal tissue, not necessarily accompanied by fatty degeneration elsewhere. It does not influence the healing of corneal wounds in any way.

In Acute Iritis the iris changes in colour and its fibres Diseases lose their definition and look muddy. The pupil becomes of tne small, irregular in outline, and sluggish or immobile when ms-stimulated by light. There is a pink zone of congestion round the cornea (the ciliary zone). The aqueous humour is turbid; it may contain blood, and even pus. There is more or less pain in the eye and temple, which is usually worst at night; there is intolerance of light, great increase in the secretion of tears, and impairment of sight. In most cases lymph escapes from the posterior surface of the iris and fixes its margin to the lens at one or more points, or all round, and may even occlude the pupil. In some cases the exudation is entirely serous and no adhesions are formed (serous iritis). Iritis is one of the symptoms of secondary syphilis; it is caused by rheu-matism, by ulcers and diffuse inflammations of cornea, by injuries to the cornea, iris, and lens, and forms part of nearly all cases of sympathetic ophthalmitis. The syphilitic form usually involves both eyes; it produces much exudation and often little yellow nodules, and rarely relapses. Rheumatic iritis is generally serous, unilateral, and recurs frequently. Atropine must be freely applied locally to prevent the formation of adhesions, or to break down such as may have already formed. The temple may be leeched, and opiates given if pain is severe. In the syphilitic forms calomel must be given; in the rheumatic alkalis and colchicum. The eyes must be protected by a shade. Traumatic iritis should be treated by continuous cold and leeching. If it is due to a swollen lens, the latter must be removed. After the disease is past the pupil is frequently irregular from adhesions (synechias) of the iris to the lens-capsule. If adhesions have been broken down small brown specks will be seen in tlie pupil. The whole free edge (exclusion), or the whole posterior surface (total posterior synechias), may adhere to the lens-capsule, and the pupil may be completely covered with a film of lymph (occlusion). These three last conditions are apt to cause secondary glaucoma.


Coloboma of the Iris is a congenital defect in the iris. The defect is always in the lower part, and gives the pupil a balloon shape. It may or may not be accompanied by a similar defect in the choroid and retina. Diseases From the intimate association of their vascular supply, of the the ciliary body, iris, cornea, sclerotic, and choroid are ciliary freqUentiy affected together. Diseases in this region all agree in their tendency to relapse frequently during a very chronic course, and to involve separate patches.

Sclerotitis (episcleritis) forms a low painful swelling, of a peculiar rusty colour, under the conjunctiva in the ciliary region. It lasts for months, with frequent relapses. The subjects of this disease are mostly rheumatic or anaemic women. Internally, iodide of potassium is some-times useful. If that fail small doses of mercury should be given. Locally, atropine, blistering the temple, or massage of the swelling through the upper lid may be tried.
Iridocyclitis, inflammation of the iris and ciliary body, is characterized by congested patches of a violet colour in the ciliary region, cloudy areas in the cornea, and attacks _of iritis with much plastic exudation. There is great pain and intolerance of light. It relapses frequently, each attack leaving more cloudiness of cornea and more iritic adhesions, till ultimately the sclerotic presents a bluish bulging in the ciliary region (ciliary staphyloma), the cor-nea is opaque, its curvature irregular, and the sight gone.

Irido-choroiditis resembles a mild attack of iritis; there is little pain or photophobia. Small deposits form on the back of the cornea (keratitis punctata). Recent choroid-itis and sometimes opacities in the vitreous may be seen with the ophthalmoscope if the pupil be clear. This also relapses frequently, with the formation of much iritic adhe-sion, and sometimes of secondary glaucoma. This occurs mostly in delicate young persons, and generally involves both eyes. The treatment consists of atropine locally, -disuse of the eyes, and tonics with iodide of potassium internally ; only in mild cases is a good result obtained. The iritic exudation is generally too plastic to be absorbed.

Wounds or Diseases in the Ciliary Region are extremely liable to involve the other eye sympathetically. There .are two affections of very different moment. In sympa-thetic irritation the eye is tender and irritable, cannot bear .a bright light, and is easily fatigued by continued strain oof the accommodation, as in reading or other close work. This condition usually yields speedily when the other eye is removed, which should be advised without hesitation. Sympathetic inflammation is of much more serious mo-ment. It may begin quite insidiously, or with acute pain -and intolerance of light. Once begun, it becomes an independent disease, little influenced by treatment directed to the exciting eye, and usually ending at last in irrepar-able blindness. The symptoms are deposits on the back of the cornea (keratitis punctata), violet-coloured ciliary ocongestion, often great tenderness of the ciliary region, the iris muddy and in severe cases buff-coloured, and with many large blood-vessels on its surface. Extensive iritic adhesions form which cannot be absorbed. The process is an irido-cyclitis or irido-choroiditis. It may be set up two months or many years after the injury; the -eye is never safe. Treatment must evidently be mainly preventive. All blind eyes liable to cause sympathetic inflammation should be at once removed. If some vision .fee left in the wounded eye, and the patient can be kept under observation, it may be left,—the patient being warned of the danger to the other eye. The inflam-mation once arisen, the exciting eye, if blind, must be removed; but not if there be any sight in it, as it may be eventually the better eye of the two. The patient must be kept in a dark room and not allowed to use his eyes. Atropine solution must be applied locally. After the in-flammation is quite quiescent removal of the lens with a portion of the iris may be of use in giving an artificial pupil.

Cataract.—Cataract is an opacity of the crystalline Diseases lens. It is due to some alteration in the structure andot tne relationship of its fibres, as the result either of some senile j^*^ change or defect of development, of local interference with its nutrition (as in glaucoma), of some general diseases such as diabetes, or of local injury to the lens or its capsule. For practical purposes all cataracts are classified under three categories. (A) They may be hard or soft; below the age of thirty-five, and in diabetes of any age, cataracts are soft. (B) They may be general or partial, according to the amount of lens involved in the opacity. General cataract may be nuclear (beginning from the centre) or cortical (spreading inward from the periphery); or both conditions may coexist. Partial cataract may be (1) lamellar, where one or several of the concentric layers in an otherwise transparent lens becomes opaque. This form is often congenital. It is said to be frequently caused by infantile convulsions. (2) Pyramidal cataract is a small white spot on the lens-capsule in the centre of the pupil. This is the result of corneal perforation in purulent oph-thalmia. The cornea falls against the lens-capsule when the aqueous humour is evacuated, and becomes adherent to it. The aqueous, refilling after the healing of the per-foration, tears away the cornea and leaves the spot of lymph on the capsule. (3) In posterior polar cataract the opacity begins at the posterior pole of the lens. It indicates deep-seated disease. (C) Cataract may be primary or secondary, according as it arises in an eye otherwise healthy or depends on some other disease in it. Cataracts arising from injury to the lens are called traumatic.

Symptoms and Treatment of Cataract.—Vision becomes gradually impaired. If the cataract be small and central, vision improves in a dull light or when the eyes are shaded. On ophthalmoscopic examination (see below) the opaque parts appear either as dark striae converging towards the centre or as a dark central mass. The fundus, if visible, appears red. An attempt should be made to ascertain if it is healthy. On oblique illumination by a convex lens the opaque parts now appear white and the rest of the pupil black. When the cataract is ripe the pupil is filled by a homogeneous pearly-white or amber-coloured opacity. The rest of the eye is healthy if the pupil reacts to light, and the patient can tell the direction of a candle-flame at four feet distance. As a palliative atropine may be used . if it be found to improve vision. To remove the cataract operation is required. Operation is undesirable in pyra-midal, secondary, and immature cataract, and usually if, while the cataract in one eye is ripe, the other eye remains good, unless the patient specially desires the operation.

The Operation.—In the soft cataract of infancy, youth, and diabetes the needle operation should be chosen. The pupil having been dilated by atropine, a fine needle is passed through the cornea near its margin, and lacerates the lens-capsule freely. The lens, acted on by the aqueous humour, swells up and gradually dissolves,—the process of solution taking from two to three months, and generally needing one or two repetitions of the needling. In hard cataracts the lens must be extracted entire. The follow-ing is the most usual operation. With a narrow knife an incision is made through the upper part of the cornea at its junction with the sclerotic, in length somewhat less than half the corneal circumference. A portion of iris is drawn through the corneal incision and cut off (iridectomy). Then the lens-capsule is lacerated by a needle. The lens is forced out of the eye by gentle pressure on the sclerotic below. All fragments of lens-substance are carefully removed, the edges of the incision are brought together, the eyes bandaged, and the patient kept in bed for a few days. Ninety-five per cent, of the cases do well, the others .going wrong from haemorrhage into the eye, iritis, or sup-puration of the eye. In lamellar cataract two courses are open. If dilatation of the pupil by atropine enables the patient to see clearly, the removal of a portion of iris (artificial pupil) will be sufficient; if not, the solution of the lens must be effected by the needle operation. In traumatic cataract the pupil is kept dilated by atropine to prevent iritis. If severe iritic or glaucomatous symptoms arise an incision must be made in the cornea, and the softened lens removed along a grooved scoop or by suction.

After the cataract is removed strong convex glasses must be worn for near vision and a somewhat weaker pair for distant vision. Their use must not be allowed till at least two months after the operation.

Dislocation of the Lens may arise from a blow or spon-taneously. The lens may pass into the anterior or posterior chamber. If in the posterior chamber it may be invisible, but the iris will be tremulous and the refraction very hypermetropic. If the dislocation be partial the edge of the lens may be seen with the ophthalmoscope as a dark curved line. The lens generally becomes opaque. It may, and often does, cause glaucoma. Glau- Glaucoma is a most serious disease, characterized in all coma. its forms by increased tension of the eyeball, impairment of sight, and ultimate irremediable blindness. Its course is usually chronic, lasting sometimes many years; sometimes absolute blindness comes on in a few hours or days.

In the chronic form the earliest symptoms are rapid onset of presbyopia, making it necessary to change the spectacles frequently, and attacks of mistiness of sight, during which artificial lights appear surrounded by coloured rings. Gradually sight is impaired and the field of vision contracted. The pupil is dilated and sluggish; the cornea _maybe "steamy" and insensitive, the anterior chamber shallow. Large veins pierce the sclerotic a little way from the corneal margin. The lens may have a greenish hue (hence the name), or may become opaque. The optic disk, if visible ophthalmoscopically, is " cupped ". or hollowed, and in advanced cases also atrophied. The retinal vessels bend abruptly in rising over its edge, or in deep cupping seem to have their course interrupted for a short distance. The arteries pulsate either spontaneously or on slight press-ure on the eyeball. The tension (ascertained by pressing the eyeball against the floor of the orbit) is variously increased. This form may be painless throughout, and the gradual impairment of vision may lead to the fatal error of a diagnosis of cataract. More usually there are occa-sional acute attacks. Acute glaucoma comes on suddenly ; there is much pain in the eye and temple and congestion of the globe; increase of tension and loss of sight are extremely rapid.

All the symptoms depend on the increased tension of the intraocular fluids. The loss of sight and contraction of the visual field result from compression of the retina and its vessels. Pressure on the ciliary nerve paralyses the iris and the accommodation (hence the presbyopia), and renders the cornea insensitive. The anterior chamber is shallowed by the lens being driven forwards, and the disk is cupped by being driven backwards through the lamina cribrosa, the least resistent part of the sclerotic. The veins of the sclerotic are enlarged in order to relieve the ob-structed vasa vorticosa. The explanation of the increase of tension is not yet complete. In most cases it is probably due to deficient removal of fluid. Normally this takes place through the suspensory ligament of the lens, round the free edge of the iris, leaving the anterior chamber at the angle of junction of the iris and cornea. Block-ing of any part of this channel (most often at the above angle) would cause increase in the tension. Increased blood-supply is also in many cases a cause. Glaucoma is most common after forty. It may be either primary or secondary to some disease or injury of the eye.

Eserine applied locally has proved useful in some early cases of glaucoma. Iridectomy—that is, the removal of a portion of iris through an incision in the cornea—is the most successful mode of checking the disease. In secondary glaucoma the treatment must be directed to the cause, if it is removable.

Muscae Volitantes.—The floating bodies, specks, &c, so Diseases often complained of are usually of no importance. They 0|'the occur most frequently in myopic eyes. Pathological muscx, *ltleous' however, depend on the presence of opacities in the vitre-ous, detectable by the ophthalmoscope. They are of very various sizes and shapes, from large masses, as in recent haemorrhage, to strings, specks, knotted bodies, or finely sparkling particles (cholesterin), or as a diffuse cloud or haze obscuring the retina. From the rate at which the bodies move an opinion may be formed of the fluidity of the vitreous. Disease of the vitreous is usually secondary to disease of some of the surrounding parts, as in high de-grees of myopia, in hemorrhagic and syphilitic choroiditis and retinitis, and diseases of the ciliary region. Haemor-rhage is frequent after blows on or wounds of the eye.

Disseminated Choroiditis is usually a symmetrical dis- Diseases ease, arising from acquired or inherited syphilis. There °| tne.d are no characteristic symptoms, but the ophthalmoscope shows in the early stage (rarely observed) yellowish patches (of exudation), over which, unless obscured by haze, the retinal vessels are seen to pass. Later, when the exuda-tion gives place to atrophy, white patches are seen of various sizes with masses of black pigment on or around them, distributed irregularly over the choroid. The re-tinal vessels may be seen to pass unaltered over some of the white areas. Sometimes the patches of atrophy in-volve merely the superficial layers and expose the deeper larger choroidal vessels. Vision is impaired, especially if the yellow spot is involved. The treatment is that for syphilis, with rest and protection of the eyes from light. This at least helps to prevent fresh accessions of the disease if it cannot restore the atrophied choroid. Similar spots are seen in non-syphilitic subjects, probably as the result of choroidal haemorrhage.

In myopia the choroid is frequently atrophied near the disk, especially at its outer edge, forming what is variously known as "posterior staphyloma," "myopic crescent," or " sclerotico-choroiditis posterior." This pos-terior staphyloma varies much in shape, sometimes sur-rounding the disk, sometimes limited to the yellow spot, causing then greatly impaired central vision.

Tubercles are sometimes deposited in the choroid, appear-ing as small yellow spots. Their presence may be of assistance in forming a diagnosis of tubercular disease.
Rupture of the Choroid from injury is generally seen as a long curved line of atrophy with the concavity towards the disk.

Coloboma of the choroid is a congenital defect, indicated by a large white patch of atrophy at the lower part, often embracing the disk,—the surface of the sclerotic often looking uneven. It may exist independently of similar defect in the iris.
Sarcoma of the Choroid is a malignant tumour, usually pigmented, which tends to destroy the eye, to spread along I the optic nerve, and to cause metastalic deposits elsewhere in the body. It causes defect of sight, and if the media are clear may be seen by the ophthalmoscope. It often causes glaucoma and cataract. The tumour must be excised with as much of the optic nerve and orbital tissue as can be reached. Diseases Detachment of the Retina is a separation of the retina of the from the choroid by an effusion of serum or of blood, or retina, by the growth of a tumour between them. It occurs most frequently in myopia and from blows on the eye (also from dislocation of the lens and in albuminuria). The detachment varies greatly in extent; it is most usually situated at the lower part of the retina. It causes blind-ness on the corresponding opposite part of the visual field. With the ophthalmoscope, instead of the red appearance, a greyish reflexion is seen, generally uneven on the surface, with the retinal vessels, reduced in size and dark in colour, coursing over it. The grey surface may be seen to undulate with movements of the eye. Treatment is generally unsatisfactory. Myopic cases should avoid stooping and strain of the eyes to prevent its extension.

Embolism of the Central Artery of the Retina is a plugging of this vessel by a small body, usually detached from one of the valves of a diseased heart. The eye becomes sud-denly blind, and on ophthalmoscopic examination the red reflex is found to be replaced by a diffuse white mist, except at the yellow spot where a "cherry-red" spot appears; and the retinal vessels are often reduced to mere threads. After a time the haze passes off the retina, but an atrophied disk and narrowed blood-vessels are left. Treatment is useless. If the embolism is impacted in one of the branches of the retinal artery these appearances will be localized, and a blind spot will correspond to the affected area.

Albuminuric Retinitis occurs in an advanced stage of chronic Bright's disease of the kidneys, usually when the general health has become much impaired. It is especially associated with the granular kidney, and is not seldom the first indication of this serious disease. It causes defective sight, and some of the following characteristic ophthalmo-scopic appearances. In the early stage (rarely observed) a greyish haze presents itself at the centre of the retina (from the presence of an albuminous fluid); later, pearly-white sharply-defined spots of various sizes appear, often grouped round the yellow spot (due to fatty degeneration of the coagulated albumen and nerve-fibres). With these there may be found many small haemorrhages, or a condi-tion of optic neuritis. Vision is seldom completely lost, and may, except in the severest cases, be expected to im-prove somewhat, especially in the albuminuria associated with pregnancy. Its treatment is that of its cause.

Syphilitic Retinitis is usually a symptom of the second-ary stage, affecting both eyes, and producing dimness of vision and night-blindness. Ophthalmoscopically the disk appears hazy, the vessels full and tortuous, the retina also hazy or showing white misty patches, especially near the yellow spot. It is much benefited by a mercurial course.

Hsemorrhagic Retinitis is indicated by the appearance all over the retina of small flame-shaped haemorrhages with dilated veins. It is perhaps due to gout (Hutchinson).

Haemorrhages may result from vascular degeneration. They seriously damage sight if they occur at the yellow spot.

Pigmentary Retinitis is a peculiar chronic disease affecting both eyes symmetrically. It is either congenital or begins early in life and advances gradually till it produces com-plete blindness. Its cause is not well known. It is strongly hereditary, occurring often in several members of one family; it has been found also in the descendants of parents nearly related to each other, and it is common among deaf-mutes. In many cases no cause can be assigned. Its earliest symptom is an inability to get about in the dusk (night-blindness). Then follows a gradual contrac-tion of the field of vision, the patient feeling as if he looked through a tube, seeing objects clearly within his field in good daylight, but nothing beyond. Eventually this central vision also fails. The ophthalmoscopical ap-pearances are symmetrical in both eyes, and are equally characteristic. At the periphery of the retina masses of black pigment are distributed in an irregularly reticulated or lace-like manner over the retina and along the retinal vessels. The disk is pale and " waxlike," and the retinal vessels are much contracted,—it may be, reduced to mere threads. As the visual field contracts the retinal pigment approaches the disk. Treatment is of little use. Galvanism has lately been recommended.

Glioma of the Retina is a tumour of excessive malignancy, arising in the retina and rapidly filling the eye, and spread-ing from the eye along the optic nerve to the brain, or through the sclerotic to the orbit. It occurs in young children. Thorough and early removal of the eye with the optic nerve may prevent its recurrence.

The optic nerve may be inflamed in any part of its Diseases course, within the skull, in the orbit, and within the eye. of the To the physician the most important of these inflamma- °Ptlc
. o o . H6I"V6

tions is that of the intraocular end of the nerve or papilla, Te^u^ known as Optic Neuritis or Papillitis (choked disk), on &c. account of its frequent association with tumour of the brain, of which it is one of the most diagnostic symptoms. The signs may be well marked to the ophthalmoscope before there is the slightest impairment of sight. At first the disk is seen swollen, reddened, its edge indistinct, and the veins distended and tortuous. Later, the swelling of the disk increases, obscuring the disk itself, and extending beyond its edge. The surface has a greyish appearance, streaked with reddish lines, which are enlarged blood-vessels. The retinal arteries and veins at their commence-ment are obscured by the exudation; at the edge of the swollen disk they bend downwards to reach the retina, over which they pursue a tortuous course, the veins being much distended. Small haemorrhages are often seen on the disk and retina. All traces of the exudation may pass away. More usually the disk becomes atrophied, of a pale-white colour, with an indistinct margin and shrunken retinal vessels.

Papillitis of both eyes sometimes also arises from lead-poisoning or anaemia. Papillitis of one eye, with subse-quent atrophy, is generally due to local injury to the nerve.

Atrophy of the Optic Nerve is sometimes primary, i.e., arises without previous neuritis. In this case the disk becomes gradually of a pale-white or pale-greyish colour, its edge more than usually distinct, and the vessels may not be contracted. Primary atrophy of the optic nerve is one of the most marked symptoms of locomotor ataxia. Many of the cases where no cause is ascertainable are undoubtedly precursory to the usual symptoms of ataxy. Vision always suffers in this form more or less.

Atrophy of the disk may be secondary to glaucoma, neuritis, pigmentary retinitis, and some forms of choroid-itis. When unilateral it may be due to embolism, or, if it follow an injury to the head, to fracture of the optic-canal, or to a retrobulbar neuritis.

Amblyopia, Amaurosis, dec.—Amblyopia means defect-ive sight; amaurosis, blindness without sufficient obvious cause. Such defective sight is not uncommon in a squint-ing eye, or one of a different refractive power from its fellow. Tobacco amblyopia occurs in adults from excessive tobacco-smoking, especially when combined with alcoholic-excess. There is loss of visual acuteness, as tested by reading, of one-fifth to one-tenth, and green and red blindness in the centre of the field. The disk may be normal or have a muddy colour. It usually recovers under abstinence from smoking and alcohol and the use of small doses of strychnia.

Hemianopsia means loss of one-half of the visual field. It is generally bilateral and affects corresponding halves of the two retinae, e.g., the two right halves or the two left; rarely the two inner halves or the two outer are involved. The dividing line is usually vertical, or nearly so, bending so as to avoid the fixation point. It is due to some disease of the brain, or of one optic tract. (It will be remembered that each optic tract divides at the optic commissure, and supplies one-half of each retina, the right tract going to the right halves, the left to the left.)
Night-blindness without organic change may be due to exposure to bright sunlight, sleeping in moonlight, or to scurvy. Snow-blindness is a similar condition, with con-gestion of the eyelids and intolerance of light.

Errors of In Hypermetropia parallel rays falling on the eye meet in a point refrac- behind the retina. This is due in most cases to shortening of the tion. axis of the eye (axial hypermetropia), in rarer cases to absence of the lens, and is the physiological condition, after the age of fifty-five, of all previously normal eyes, owing to diminution of the refractive power of the lens. Clear vision is obtained only when the entrant rays are focused on the retina. In the hypermetropic eye this is effected by increase in the refractive power of the lens by the action of the ciliary muscle. In slight hypermetropia this is easily accomplished, and no complaint may be made. In higher odegrees the continuous severe strain on the accommodation in read-ing and other fine work gives rise to aching, watering, and misti-ness of the eyes (accommodative asthenopia). These symptoms may first appear after an exhausting illness or prolonged strain of the eyes,—in both cases from reduction of the tone in the ciliary muscle. Convergent squint is a common symptom. In the highest degrees, where no amount of accommodation gives distinct vision, the attempt is given up, and no complaint made. In most cases the continuous use of the accommodation produces a spasm of the ciliary muscle, which renders some of the hypermetropia "latent," what remains being the " manifest" hypermetropia. Both together oconstitute the "total" hypermetropia. To ascertain the hyper-metropia place the patient 20 feet from Snellen's test-types. If a weak convex lens makes sight no worse try stronger and stronger glasses till the best vision is obtained. This gives the " manifest" hypermetropia. If there be no improvement with convex glasses the hypermetropia may be all latent. Paralyse the accommodation by putting a drop of atropine solution and test the " total " hyper-metropia. For the ophthalmoscopic tests, see below. Children with asthenopia should wear constantly glasses which nearly correct the hypermetropia. For adults it is not usually necessary to wear glasses for distant vision. For reading the manifest hypermetropia should be corrected, the strength of the glasses being increased as often as asthenopic symptoms reappear.

|n Myopia or Short-sight the retina lies behind the focal point of parallel rays entering the eye; it will therefore be at the con-jugate focus of some point at a definite distance from the eye,—its "far point." Objects beyond this point are seen indistinctly. Within this point and up to the "near" point objects are distinctly seen. Myopia is generally due to elongation of the posterior part _of the eye, the sclerotic and choroid at the macula being thinned .and bulging backwards. In severe cases the bulging is general, _thinning all the coats and enlarging the eye. Myopia is highly hereditary. It rarely begins before seven, and rarely advances rafter twenty-five. It is always aggravated, and may be produced, by using the eyes on fine work, especially in a bad light and in a ostooping position. Myopia results also from increased curvature of the cornea, as in interstitial keratitis and conical cornea.

The symptoms of myopia are well known. Distant vision is indistinct, and fine work or printed type is held near the eyes. In high degrees after reading for a time the letters seem to be blurred ,and to ran into each other, while the eyes ache and water owing to oinability of the internal recti to keep up the necessary convergence (muscular asthenopia). Divergent squint may be present The eyes are often kept half shut (hence the name "myopia") to exclude the excess of light. Ophthalmoscopic examination often shows the " myopic crescent" at the outer side of the disk, or all round it, or at the macula. The other tests are described below. As regards treatment, all myopics should work in a good light, and not in a stooping position. If desired, concave lenses may be given for dis-tant vision. For near vision in high myopia concave lenses not fully corrective may be given, to enable the patient to hold his work at a greater distance and to avoid stooping. If there is muscular .asthenopia prisms with their bases inwards may be used to relieve the strain on the internal recti. Myopic eyes are liable to various affections,—muscas volitantes, opacity and fluidity of vitreous, choroidal haemorrhage, and detachment of retina.

Astigmatism is either regular or irregular. Regular astigmatism is due to the fact that the surfaces of the cornea and lens are not segments of spheres. The principal abnormality is in the cornea, and it is found that the meridians of greatest and least curvature (the principal meridians) are always at right angles to each other, and that the intermediate meridians pass by regular gradation from the one to the other. It is evident that rays of light from a point passing through the plane of greatest curvature will have met before those passing thriJugh the plane at right angles to it, which will form a line, that similarly the first set of rays will have crossed and will in their turn form a line by the time the second have reached their focus, and that between these two points the image will be circular or oval, but blurred. In no case will the image be a point, and hence vision will never be distinct. If one of the principal meridians be emmetropic the astigmatism is "simple" ; if both be either hypermetropic or myopic it is "compound"; if one be hypermetropic and the other myopic it is "mixed."

If spherical lenses do not raise the sight of otherwise healthy eyes to the normal standard astigmatism is probable. On ophthalmo-scopic examination the disk will be found oval, and altering its shape when the lens is removed from the eye ; with the direct method the vessels are not seen with equal distinctness, and may pass across the field in the two principal meridians in the same direction but at different rates if the astigmatism be compound, in opposite directions in "mixed" astigmatism. If the patient look at an arrangement of radiating lines of equal thickness he will not see them all with equal distinctness. Astigmatism is corrected by neutralizing the inequality of the refractive surfaces by means of cylindrical lenses. In many cases the vision cannot be brought up to the normal standard.

There are many ways of estimating astigmatism. One methoc' is to find by the test-types the spherical lens which gives the best distant vision ; then, by means of a narrow slit in a metal disk, to find the plane in which vision is further most improved. Spherical lenses are placed in front of this slit till the one which gives the best attainable vision is found ; this gives the cylindrical lei necessary for this plane. A similar inquiry is conducted with the plane at right angles to this. Spectacles are ordered compounded of the spherical lens and the two cylindrical lenses with their axes at right angles to each other.

Irregular astigmatism depends on irregularities in the surface of the cornea or in the refractive power of the lens. It can seldom be remedied.

Presbyopia.—From ten years onwards the "near" point of theDis-eye gradually recedes, owing to increasing firmness of the lens and orders of probably diminishing power in the ciliary muscle. Presbyopia has accom-been arbitrarily fixed as commencing when the near point recedes moda-to 9 inches, because then discomfort in reading is generally com- tion. plained of. In normal eyes it begins about forty, in hypermetropia earlier, and in myopia later. There is no increased difficulty in seeing distant objects, but ordinary type has to be held incon-veniently far away. The treatment consists in giving glasses to enable the patient to read at 9 inches. In practice it is usually sufficient to enable him to read at 12 inches' distance. As age advances the presbyopia increases, and it is necessary from time to time to increase the strength of the spectacles.

Paralysis of the Accommodalionis not uncommon after diphtheria; it forms one of the symptoms of paralysis of the third nerve.

Spasm of tJie Accommodation is common in hypermetropia, and is sometimes present in the opposite condition of myopia.

In strabismus the two eyes are not directed to the same point in Strabis-space. The deviation may be inwards or outwards, downwards or mus or upwards,—the first two forms being by far the most common. In- squint. ward or Convergent Strabismus is due either (1) to paralysis of the external rectus muscle or (2) to over-development of the interni. (1) Paralytic convergent squint is the result of some affection of the sixth nerve or its nerve-centre, owing generally either to syphilis or to nervous exhaustion. It varies in amount from slight weak-ness to complete paralysis of the muscle. When the paralysis is complete the eye is turned inwards and cannot be moved outwards beyond the middle of the fissure of the eyelids. In minor degrees, where the deformity is not so evident, it may be difficult to tell which is the squinting eye. If the patient be told to look r.t &il object held a short distance in front of him. and a piece of ground glass be placed before the squinting eye, neither eye will move ; if the sound eye now be co 7eied the squinting eye will turn outwards to fix the object, while the sound eye will move a greater distance inwards; the "secondary" is greater than the "primary" squint. The reason of this is that the nerve to the paralysed externus and that to the sound internns of the other eye, which wcrk togetner, both receive the same stimulus from the will, and that the sound muscle acts more strongly wian the other. Owing to the displace-ment of the yellow spot double vision is produced, the false image 1 being projected towards the side of the paralysed muscle (homonymous diplopia). The diplopia is always most distressing, and may-cause giddiness when the strabismus is slight. The treatment consists in the use of iodide of potassium in the syphilitic, and in nervine tonics in the neurasthenic cases. The muscle may be fara-dized to keep up its tone. In bad cases tenotomy of the internal rectus may be necessary. The squinting eye may be covered to pre-vent the diplopia. (2) Convergent strabismus from over-development of the internal recti ("concomitant" strabismus) is almost always due to hypermetropia. Its production depends on the intimate relation between accommodation and convergence, every degree of the one evoking a constant quantity of the other, so that nor-mally the two eyes are converged upon the object accommodated for. In hypermetropia clear vision needs an excess of accommoda-tion which in its turn produces an excess of convergence, so that the two eyes meet in a point nearer than that looked at; they squint, in short. The eyes may squint only during accommodation for a near object (periodic squint), but generally the internal recti be-come so developed as to produce a constant convergence. If either eye is used indifferently for vision the squint is "alternating." Generally one eye is habitually used, the sight in the other eye becoming defective. The amount of squint bears no ratio to the amount of hypermetropia, being frequently absent in the higher degrees where accommodation fails to give clear sight and is not exercised. Double vision does not occur, because the image of the squinting eye is unconsciously suppressed.

In periodic squint glasses to correct the hypermetropia ought to be given. For permanent squint division of the tendons of one or both internal recti muscles is necessary. The operation diminishes the power of these muscles by allowing them to become attached to the globe farther back. Care must be taken not to produce too great an effect, it being preferable rather to leave a little convergence.

In rare cases myopia is associated with convergent squint.

Divergent Strabismus arises from weakness of the internal rectus, as in myopia. In the condition known as muscular asthenopia it is present only after a prolonged effort of convergence. It arises also where the sight is defective, as with corneal opacities, or from unskilful operation for convergent squint. It can generally be improved by tenotomy of the external and "advancement" of the internal rectus muscle.

In paralysis of the superior oblique muscle the deviation is slight. Owing to interference with the movement downward and outward, double vision is present when the eyes are directed below the hori-zontal line.

Paralysis of the Third Nerve causes ptosis, loss of accommodation, and dilatation of the pupil, and the eye can be moved only slightly downwards and outwards. All the branches are seldom affected alike. Diseases Ophthalmia Tarsi (blepharitis) is a chronic inflammation of the of the follicles of the eyelashes and their glands, attacking strumous eyelids, children, especially after measles. The edges of the lids are covered with small scabs, which gum the lashes into pencils ; when the scabs are removed small freely-bleeding ulcers are exposed. The conjunctiva is also reddened. Eventually the lashes either fall out or become misdirected, the border of the lids looks thickened and bald, and the eyes continually water from eversión of the orifice of the tear-duct. The scabs must be removed daily by means of an alkaline lotion, and a weak mercurial ointment applied to the lids. In bad cases the lashes must be pulled out, and the ulcers touched with nitrate of silver.

A Stye is an abscess in a Meibomian gland, or in the cellular tissue of the lid. Styes are apt to occur in crops, and generally point to some derangement of health. They should be poulticed till the matter points, then opened with a lancet. Tonics are needed internally.

Chalazion is a cyst in a Meibomian gland. It forms a small pea-sized painless swelling under the skin of the lid. It should be opened from the conjunctival surface and its contents expressed.

Epitlielioma (rodent ulcer) occurs in old people, grows slowly, forming a hard irregular mass, with an ulcerated surface covered by scabs ; it may extend in all directions, destroying the tissues it reaches. The treatment consists in complete removal by the knife or chloride of zinc paste. Diseases The lacrymal gland sometimes suppurates, and must be treated of the like any other abscess. Most of the diseases of this systsm arise lacrymal in the punctum, canaliculi, lacrymal sac, or nasal diet, and all appara- cause overflow of tears on the cheek. The punctum may be everted, tus. from disease of the conjunctiva, paralysis of the -acial nerve, or the dragging of a scar in the cheek. The canaliculus may be constricted or obliterated. The nasal duct may be obstructed from chronic disease of its mucous membrane or bony wall. Tho result of this is the retention of tears in the lacrymal sac, then the formation by distension of this sac of a small tumour at the inner i-,ngle of the eye, from which first clear mucus, and possibly, at a later period, also pus may be pressed back into the eye. Finally, it the case is neglected an abscess may form which may burst externally and cause a troublesome fistula. The treatment in the first placo must be the dilatation of the stricture. The canaliculus is first slit on its conjunctival surface along its whole length, then successively larger probes are passed through the stricture. Abscesses when formed must be opened, and when inflammation has subsided the stricture dilated. The sac may be washed with astringent solutions. When the stricture is due to bone-disease its cure is not hopeful.

Blows may rupture the coats of the eye,—the sclerotic and Injuries-underlying coats being generally injured. Haemorrhage takes place of the between the coats and into the chambers of the eye. The eye may eyebalL be removed at once ; if any perception of light remain, the excision should be delayed to see if there be any chance of the eye being saved. Usually the eye shrinks and becomes quite useless.

Blows may cause damage to the interior of the eye without injuring the outer coats. There may be haemorrhage into the anterior or the posterior chamber,—the latter a most serious con-dition, seldom completely recovered from. The choroid ma}' be ruptured, the lens dislocated, or the iris torn from part of its ciliary attachment; and the retina is not seldom detached from the choroid.

Wounds.—Small foreign bodies—bits of steel, &c.—are often impacted in the cornea. They should be removed as soon as possible, as they give rise to great pain, and may seriously injure the cornea. If there is much after-irritation atropine should be used freely to the eye.
Burns with caustic alkalis and acids or molten lead are common. When seen the whole conjunctiva should be carefully freed from all of the irritant. If lime has been the cause, a weak acid lotions should be used. Then oil should be dropped into the conjunctival sac, and any inflammatory symptoms treated as they arise. If the epithelial layer of the cornea only has been destroyed, it often clears to a wonderful extent; but deeper injuries may cause severe-ulcerative inflammation of the cornea, and the conjunctiva may slough in part, with ultimate formation of a scar binding the lid. to the eye (symblepharon).

Penetrating Wounds.—Such wounds of the cornea and sclerotic, if only the foreign body be not in the eye, generally do well. Usually some of the deeper structures are involved, and these cases are always very serious. The eye may be rapidly lost from general inflammation, or if not it may become completely blind. In almost any ease, especially where the wound is in the ciliary region, the other eye is apt to be sympathetically involved. If the injured eye therefore is blind, and if there is inflammation in the ciliary region, it must be at once excised. If the eye be not blind, the ciliary region quiet, and no foreign body in the lens or vitreous humour, the eye may be preserved,—the danger of involvement of the other eye being put before the patient. In such cases it is impossible to lay down any general rules. Each case must be judged on its own merits by the ophthalmic surgeon.


The ophthalmoscope consists of a small mirror with a small Use of aperture in the centre. Most instruments have now in addition a the opli-series of concave and convex lenses arranged on a disk so that they thalino-can be brought successively behind the central perforation. A large scope, lens of about 3-inch focus is also required.

Rays of light entering the eye in any given direction are reflected by the choroid along the same direction. Ordinarily, therefore, the fundus cannot be seen, because an eye so placed as to see the emerging rays intercepts the entrant ones. The ophthalmoscope, by placing the source of light in front of the observer's eye, enables it to see and examine the interior of the other eye.

There are two methods of examination,—the indirect and the direct. (1) The indirect method, which forms a real, inverted, and slightly magnified image in front of the observed eye, may be illustrated thus. Place a convex lens of 2-inch focus in front of this page, and let these represent crystalline lens and retina respect-ively. Place now a second similar lens in front of the first, and the print will be seen inverted and slightly magnified. (2) The direct method forms a virtual, erect, much magnified image. Place one of the above lenses within 2 inches of the page and your own eye close to it. The letters will appear erect and enlarged.

To use the ophthalmoscope,—place the patient in a dark room, with a lamp to one side of and a little behind the head. If the indirect method is to be employed, sit in front of the patient, with the mirror in your right hand before your right eye, the large lens in your left. Reflect the light from a distance of about 2 feet into one of the eyes, and when you see a red reflexion place the lens in front of it, and you will obtain the inverted image of the fundus. (A) Begin your examination with the optic disk by telling the-patient to direct the observed eye a little inwards. Note the follow-ing points :—(a) the colour of the disk, normally a yellowish pink, tut varying considerably owing to tint of surrounding choroid, &c.;; (5) a paler spot in its centre, which may be due to the funnel-shaped expansion of the nerve, the physiological crip ; (c) the distinctness, of tha edge (spots of black pigment here are of no importance),-. (d) when the lens is removed from the eye the image of the disk remains of the same size if the eye is emmetropic, becomes smaller if the eys is hypermetropic, and larger if it is myopic, and alters-I in shape if there is astigmatism. (B) The retinal vessels appear as red lines, the arteries paler and about two-thirds the size of the darker veins. They arise in the centre of the disk, run usually in pairs, branching as they pass over the retina. Note their light central streak, their amount of tortuosity, and the presence or absence of white lines by their side. (C) Note the usually uniform redness of the choroid. In light-haired and dark-haired persons the vessels appear as dark or light red bands on the general red ground. (D) The yellow spot is indicated either by a deeper redness of the choroid or by a bright yellow spot surrounded by a shifting white halo.

By the direct method the mirror is used without the large lens, — if necessary, one of the smaller lenses being placed behind the cen-tral perforation. (A) Examine the crystalline lens (see "cataract" above). (B) Opacities in the vitreous humour are detected as mov-ing bodies when the eye is moved about and then brought to a standstill. (C) Ascertain the refraction. The eye is ametropic if the vessels are seen distinctly at more than 18 inches' distance. It is hypermetropic if the observer on moving his head finds the vessels moving in the same direction ; myopic if they go the opposite way. To measure the amount of ametropia needs practice and power of the observer to relax bis accommodation completely. Rays leaving the hypermetropic eye are divergent; to be seen clearly by the observer they must be rendered parallel. The strongest convex lens, therefore, which, placed behind the central aperture, gives a clear image of the fundus is the measure of the hypermetropia. Similarly the lowest concave lens with clear image indicates the amount of myopia. (D) To examine the details of the fundus, the mirror is approached closely to the observed eye.

Retinoscopy.—The observer sitting at a distance of 4 feet from the patient reflects the light into his eye, after dilating the pupil with atropine, and rotates the mirror slightly. A shadow will be seen to cross the pupil,—in myopia of more than ID (TV) in the same direction as the rotation, in all other cases in the opposite direction. This method is useful in determining and correcting the refraction where the patients are too young or too stupid to assist with their answers. (A. BR.)


The term '' ophthalmia " is now limited to conjunctival inflammations.

The above article was written by: Dr Alex. Bruce.

About this EncyclopediaTop ContributorsAll ContributorsToday in History
Terms of UsePrivacyContact Us

© 2005-21 1902 Encyclopedia. All Rights Reserved.

This website is the free online Encyclopedia Britannica (9th Edition and 10th Edition) with added expert translations and commentaries