Diseases Of The Crystalline Lens | Operating Microscopes

Diseases Of The Crystalline Lens By WILLIAM E. HOPKINS, M.D.,
OF SAN FRANCISCO, CAL.

Cataract. The general term '' cataract " is accepted in modern medicine as meaning any opacity of the crystalline lens. A capsular opacity is denominated a capsular cataract, and an opacity involving both capsule and lens substance a capsulo lenticular cataract.

History. While cataract was well known to the ancient Greek and Roman physicians, our knowledge of its true nature dates from the beginning of the last century. Even before this one or two savants, as Mariotte and Boerhaave, recognized the real situation of the opacity, but their doctrines failed to obtain general acceptance. In the year 1705, Brisseau, a French surgeon, had the opportunity of making an autopsy upon the body of a soldier who had a mature cataract. Brisseau performed depression of the cataract upon the cadaver and then opened the eye, when be found that the opacity which lie had depressed into the vitreous was the lens. He laid his observations, together with the conclusions drawn from them, before the French Academy, but they obtained no credence. The Academy confuted him by holding up the doctrines of Galen in regard to cataract. It was not till three years later, when new proof's had been brought forward, that the Academy recognized the new doctrine, which soon found general acceptance.

Varieties of Cataract. Cataract may be primary, or secondary to some ocular disorder, or it may be symptomatic of systemic disease or local injury.

It may be progressive or stationary, partial or complete, and in color black, white, or amber.

Various classifications of cataract have been adopted by different authorities, the simplest divisions being into the soft, bard, secondary, and irregular and special forms, with their subdivisions:

1. Congenital or juvenile Cataract. While the congenital or juvenile cataract is the commonest form of the soft variety, developing idiopathically, its complete variety is not frequently encountered, De Wecker having noted but 36 in 40,000 cases of ocular disease.

(a) Lamellar or Zonular Cataract. This is the most frequent variety of congenital opacity of the lens. The opacity exists only in certain layers of the lens, between which are perfectly clear spaces. it is distinctly seen with oblique illumination, the opacities appearing of a light gray color with translucent interspaces. When partial, little beyond a gray blur can be detected by close examination. Through the dilated pupil the ophthalmoscope will reveal, however, a sharply cut, well defined opacity, surrounded by a reddish circle due to reflection from the fundus.

Constitutional conditions are important factors in the development of this variety of cataract, rachitis, hereditary syphilis, or scrofula often being associated with it. There may be imperfect cerebral development, and Arlt found in 29 such cases that 25 were affected with convulsions. Dental defects are common, the incisors and canines being marked with transverse lines, furrows, or terraces. Usually lamellar cataract is doub1c, but it may be monolateral, and is either congenital or forms in early infancy. The former variety may be ascribed to developmental defects; the latter, to disturbances of nutrition dependent upon the causes just enumerated.

Congenital cataract m ay be found with other abnormal ocular states, coloboma, microphthalmos, irido choroiditis, and choroido retinitis being the most common. Disturbances of nutrition during intra uterine life, arrest of development, and the influence of heredity are factors in the production of congenital cataract. In forms of cataract developing during early life the influence of heredity is strong, and notable examples of the affection appearing in many members of the same family are on record.

(b) Complete Cataract of Young Persons. This is a soft cataract of milky or bluish white color. It has no yellow reflex ; it belongs to youthful life and rarely occurs after thirty five years, before which period the lens is CC soft " i. e. the nucleus is small. It may degenerate and become fluid, or cholesterin crystals or chalky deposits may be found in it. It may arise without known cause, and often is monolateral.

11. Traumatic Cataract. This may develop from direct laceration of the capsule and lens fibers, and the rapidity of its progress is dependent upon the amount of surface exposed by the torn capsule. A normal lens, freshly removed and placed in water, very soon will absorb abundant fluid, and in the process of doing so will swell and become opaque and disorganized. This is exactly what takes place when the capsule is wounded. If the anterior capsule is opened, the aqueous is absorbed; if the posterior capsule, the vitreous.

Within a few hours after the accident the lens in the vicinity of the injury becomes slightly puffed and cloudy. Soon this soft, pulpy mass forces itself through the capsular wound and protrudes into the anterior chamber. It may be absorbed, but in the mean time mass after mass of the swollen fibers follows and the entire lens becomes opaque and gradually disappears. Hence in favorable cases a clear, black pupil with good vision may be the result. In unfavorable cases some inflammatory complication arises iritis or cyclitis and if there is any infection through the corneal wound, a purulent process may develop which will probably destroy the eve. At best, adhesions result which may lead to detachment of the retina or increase of tension. A lens which swells very quickly may produce a pressure inflammation.

Cataract may develop from an indirect injury, without apparent rupture of the capsule, such as a blow on the head or side of the face, or as the result of an explosion, and it is then termed 11 concussion cataract." In these cases there is a slight rupture of either posterior or anterior capsule. Occasionally, after both direct or indirect trauma of the lens, the opacity is limited and remains stationary.

111. Complicated Cataract. This may develop as the result of pathological changes in almost any of the tissues of the eye. It is commonly associated with iritic adhesions, cyclitis, irido choroiditis, glaucoma, opacity of the vitreous, and detachment of the retina. The prognosis of complicated cataract is far less certain than in ordinary cases, and operation more difficult. Indeed, operative treatment is frequently contraindicated, or some special method of surgical procedure must be devised to meet the indications.

IV. Senile Cataract. Hard (because the nucleus is large), simple, gray, or senile cataract, as it is variously designated, develops after middle life, most commonly after forty five years.

The rate of development varies greatly. Sometimes the cataract will remain stationary for years; again, it will ripen completely in a few months. It may progress rapidly for a time, then remain stationary for years, and finally resume its rapid progress. It nearly always affects both eyes, but usually one considerably in advance of the other.

Almost from birth there is greater density in the deeper or more central layers of the lens than in the superficial. This is not appreciable until after the age of thirty five. Then close examination will discover that the lens consists of a dense, hard, more opaque, central part, the nucleus, and a softer and more transparent surrounding mass, the cortex.

This physiological condition may continue indefinitely, with perfect vision, or the central part may become denser, more deeply stained and opaque, and form a nuclear cataract (Fig. 250). But pure nuclear cataract is rarely found. The cortex almost invariably is involved in the cataractous process (cortical cataract) (Fig. 251), but the conditions of hard interior and softer surface continue in greater or less degree in all cases.

The commencement of a senile cataract is somewhat variable. It may first appear in dark, linear striations passing from the margin to the center of the lens, or it may proceed from the anterior to the posterior surface. There mav be stellate opacity or irregular and unequal dotted spaces. The cataract may commence at the equator or edge of the lens, or centrally at the nucleus. In some cases these linear striations remain stationary for many years. While evidently indicating beginning cataract, they have received the name of 11 gerontoxon lentis “or “arms senilis lentis."

V. Secondary Cataract. This includes three chief varieties:

(a) Anterior polar or pyramidal cataract results from a central perforating ulcer of the cornea (Fig. 252). It may appear as a conical mass protecting forward from the surface of the lens, attached to the margin of the ulcer, or having a thread like connection with it, or as a small white dot on the capsular surface. This condition is extremely unsatisfactory in regard to treatment, and its effect on vision is most serious.

(b) Posterior polar or pyramidal cataract is dependent on choroidal disease, especially disseminated choroiditis. It is found asa star shaped opacity associated with high myopia, and often with extensive opacities in the vitreous, and less frequently with pigmentary degeneration of the retina (Fig. 253). It is also caused by the vestigial remains of the hyaloid artery at its lenticular attachment. Small posterior capsular opacities from this source are common and do not disturb vision. Among 1884 patients examined by Mittendorf, 44 were thus affected. In the course of posterior polar cataract the lens itself will often become opaque, the opacity manifesting itself as a general cloudiness or as innumerable dots scattered throughout the tentacular tissue.

(c) After cataract (also called secondary cataract) is the condition usually left after the operation of extraction of cataract. The changes occur in the capsule; the opening may be closed by a delicate veil; the capsule cells may proliferate, resulting in increased thickening; or there may be a plastic deposit, leading to occlusion of the pupil.

VI. Capsular Cataract. This name is applied to any thickening or hyperplasia of the capsular epithelium, which resembles connective tissue. It may be congenital or result from ulcerative processes in the cornea, either with or without perforation of' the cornea. According to Mules, cretified remains of the pupillary membrane explain some cases.

VII. Capsulo lenticular Cataract. Not only is there lenticular change in this variety, but there is hyperplasia of the cells on the posterior surface of the anterior capsule, causing thickening of that membrane, com in its center.

VIII. Special Clinical Forms of Cataract. a. Diabetic Cataract. This is usually of the soft variety, is rapid in its formation, and almost invariably affects both eyes. If it develops in elderly persons, it may be more consistent and have a more or less firm nucleus. It is often accompanied by lesions of the deeper tissues of the eye, as retinitis or optic neuritis. If possible, prior to operation these facts should be carefully ascertained on account of their bearing on the prognosis.

b. Albuminuric Cataract. Although changes in the lens are sometimes found in association with Bright's disease, they are infrequent, and no direct connection between the two can be traced. It is well known that, as a rule, cases of cataract attributed to albuminuria make good recoveries after operation, and a fair degree of vision is secured. Other uncommon forms of cataract are

c. Central lental catar act, which consists of a white opacity in the center of the lens, due probably to faulty development at an early stage of intra uterine existence.

d. Punctate cataract, in which the opacities present themselves in the form of fine points and dots, either occupying the center of the lens or distributed throughout its substance. Punctate cataract may be congenital or develop in later life. Usually it remains stationary for a long time, but occasionally progresses to maturity.

e. Fusiform. cataract, which is characterized by an opaque stripe passing from the anterior to the posterior pole of the lens.

Pathology and Pathological Anatomy of Cataract. While the exact process which produces cataracts is still obscure, the development of opacity of the crystalline lens, most frequently associated with old age, is undoubtedly dependent upon some error of nutrition or upon some nutritive change secondary to disease in the deeper seated tissues of' the eye. This is evident from its frequent origin in some inflammatory disease in the iris, choroid, ciliary body, or vitreous humor. Any process which interrupts or diminishes the vascular supply to the anterior region of the globe, or interferes with the osmotic action of' the nutritive fluids, will directly affect the normal conditions of healthful stability.

This interruption of natural conditions leads to slow but progressive changes in the lens fibers. There is primarily a slight contraction, followed by increase in volume, owing, to the imbibition of fluids; cholesterin is increased in amount, and the albuminoids diminished. The new cell produc from the intracapsular cells can be plainly seen with the microscope. Later, the lens fibers atrophy, their volume diminishes, and irregular interspaces are formed, within which large amounts of fluid accumulate (Mor globules). Often the fibers show punctate cloudiness, transverse striations, molecular degeneration, fat globules, and cholesterin (Fig. 254).

Forster states that in the process of transformation of the inner layers Of the lens into a nucleus the layers diminish in volume. Normally, this process is so slow and gradual that the cortical layers adapt themselves to tile contracting nucleus. If, however, the shrinking progresses rapidly or irreg there is extreme pulling or traction, with consequent separation of the layers which lie between the nucleus and cortex. In this condition fine fissures are formed and fluid accumulates in them ; the adjacent lens fibers become opaque and form the initial impulse which leads to complete lenticular opacity.

Etiology. Cataract may be considered a disease of old age. While complete cataract is found at almost any period of life, it is comparatively rare before the fiftieth year.

Sex does not influence the development of cataract, except in the zonular variety, in which greater liability of females has been recorded. Occupation has but little influence on the development of the disease, although it has been observed to occur more frequently in those who are constantly subjected to intense beat, as laborers in Turkish bath houses, glass blowing factories, smelting foundries, etc. Heredity has an undoubted influence.

There are examples where many members of the same family are afflicted. The author has met with cataract in the four children of one family, both father and mother having developed the disease at an early age. Hasket Derby has recorded 8 cases of rudimentary double cataract among 10 members of the same family, and John Green 21 cases of cataract among 71 persons belonging to 6 successive generations of one family.

Both acute and chronic diseases of the eye iritis, irido choroiditis, iridocyclitis, glaucoma diseases of the vitreous, and most commonly extensive and long standing detachment of the retina frequently cause cataract. It is especially apt to develop after purulent processes, such as hypopyon keratitis or purulent choroiditis.

Such diseases as idiopathic fever, typhoid fever, diabetes, albuminuria, atheroma of the carotid, gout, syphilis, influenza, rachitis, bronchocele, meningeal inflammation, and convulsive seizures have been associated with cataract formation. It has been attributed to pregnancy and prolonged lactation.

In epidemics of ergotism cataracts are frequently found (raphanic cataract), and artificial cataract may be induced in animals by feeding them with naphthalin (naphthalin cataract). For that form of cataract found in diseases of the uveal tract and in anemia and marasmus the name " starvation cataract" has been suggested.

The influence of accommodative strain on the production of cataract, as well as other serious ocular disturbances, is not thoroughly understood. A large proportion of cataractous eyes are ametropic. It is probable that the constant effort of the ciliary muscle unfavorably influences the nutritive processes of the lens.

The influence of traumatism in the production of cataract has been described. Some cases have followed a lightning stroke, but have also been associated with optic neuritis, rupture of the choroid, iritis, or irido cyclitis.

Symptoms. During the development of cataract, especially the senile form, the chief subjective symptom is a gradual but steady loss of vision. In those cases where the periphery of the lens is first affected very extensive opacity may form without great loss of vision; but if the opacity invades the center or nucleus, the interference with sight becomes marked at an early stage. This may be beautifully demonstrated by the instillation of a mydriatic improvement in vision will at once appear. It is in this latter class of cases that an iridectomy may prolong vision for years.

The presence of floating spots or musce diplopia, often monocular, or polyopia, changes in refraction with the development of astigmatism, or the alteration of the axis of a pre existing astigmatism, are exceedingly common,and are mainly due to the irregular swelling of the lens substance. This is so great at times as actually to produce a true myopia (the " second sight " of the aged), and necessitates a greatly diminished convex, or at times a concave, glass (see also page 222).

Among the objective symptoms will be found a narrowing of the anterior chamber in the early stages, consequent upon the advancement of the iris and due to the swelling and bulging of the lens; photophobia, due to the iritis irritation caused by the same pressure; strie or opaque spots, demonstrable by oblique illumination; and, finally, the changed pupil, which is altered from a brilliant black to a staring yellow, white, or brown. Sometimes the lens becomes so deeply stained as to appear dark brown or black (cataracts nigra); sometimes it is of a milky, bluish white color; and sometimes the cortex degenerates, becomes fluid, and the hardened nucleus sinks to the bottom of the shrivelled capsule (Morgagnian or overripe cataract).

For clinical study Fuchs divides the periods of the development of a progressive cataract into four stages, as follows :

1. Stage of Incipiency (Cataracta Incipiens). In this stage opacities are found throughout the lens, usually in the shape of sectors or spokes, with spots still transparent. The anterior chamber is of normal depth.

2. Stage of Swelling (Cataracta Intumescens). The lens has now absorbed more fluid, swelled tip, and has pushed the iris forward and reduced the depth of the anterior chamber. The opacity becomes total in this stage. The lens is bluish white and has a silky luster. The markings of the stellate figures are very distinct.

3. Stage of Maturity (Cataracta Matura). Contraction has now taken place, and most of the fluid absorbed has been lost. The anterior chamber has resumed its normal depth, and the lens, losing its brilliant, iridescent look, has a dull gray or brownish appearance.

4. Stage of Hypermaturity (Cataracta Hypermatura). If the change continues, the cortex undergoes disintegration and becomes either a soft, pultaceous mass without structural elements, or, if the fluid is absorbed, a dry, inspissated, flattened, cake like body. The anterior chamber is normal, and the surface of the lens is homogeneous, or reveals irregular dots instead of the usual radial markings.

Diagnosis. The old catoptric test may still be used to detect the presence of cataract, as well as to determine the presence of the lens or of a black cataract. In a darkened room a lighted candle is moved before an eye with properly dilated pupil. If two erect images and one inverted image are reflected respectively from the anterior surface of the cornea and the anterior and posterior surfaces of the lens, the lens is intact. If, however, the posterior inverted image is absent, there is some opacity behind the anterior capsule, and if the deeper erect image is wanting, the opacity involves the anterior capsule.

With oblique illumination the opacities appearing as gray spots or striations may be easily recognized. The use of the ophthalmoscope has caused all other methods to be abandoned. It has rendered the detection of cataract a matter of immediate and certain demonstration. The patient, with pupil dilated with cocain or homatropin, is taken to a darkened room and placed in the position for ordinary ophthalmoscopic examination. Light is reflected from the mirror through the enlarged pupil, and the interruptions to the normal reflex from the choroid will indicate the lenticular opacities, which appear as black spots or as lines or streaks radiating from the margin to the center. The nucleus may be hazy, or the center may appear clear with opaque rings surrounding it. The sectors of the lens may be denser than normal, or lenticular flaws, resembling cracks in glass, may be seen. Finally, there may be entire absence of the reflex due to complete opacity of the lens body.

The Process of Ripening. The course and development of cataract vary greatly. In the simple or senile form the time from incipiency to ripeness may vary from a few months to many years; the usual time is from one to four years. Cortical cataract may remain immature for a prolonged period (fifteen to twenty years) ; hence the wisdom of a guarded prognosis. Finally, when the entire substance of the lens has become opaque, when the swelling has subsided, and the anterior chamber has resumed its normal depth, the cataract is ripe. This period may be determined by illuminating the pupil and carefully observing if the shadow of the margin of the iris is reflected from the lens. In case no shadow is seen the cataract is complete and ripe ; if the shadow is present, there is still a transparent reflecting layer of the lens beneath the capsule (Fig. 255).

A mature cataract has the property of separating readily from its connection with its capsule. As suggested by Arlt, it lies in its capsule like a ripe fruit in its rind. The cause of this will probably be found in the preliminary swelling and contracting of the lens substance, and the consequent loosening of the surface from the capsule.

Prognosis. This should be guarded in immature cataracts of all varieties, but especially in the linear cortical variety, with which good vision may be retained for a period varying from fifteen to twenty five years. The following considerations should influence the prognosis with reference to the result of operative procedure : The want of health in surrounding tissues; disease of the nasal or lachrymal passages various forms Of inflammation of the conjunctiva and margins of the lids the size and consistence of' the nucleus ; the degree of maturity of the cataract; the general condition of the patient and the presence of general disease, such as diabetes, chronic nephritis, or bronchitis, with constant Cough ; the presence of extreme myopia or hyperopia; immobility or tremulousness of the iris ; and contraction of the light field, or want Of light perception due to serious ocular disease, such as glaucoma or retinal detachment. The presence of diabetes or Bright's disease, while complicating, does not contraindicate operation. Extreme age does not necessarily complicate the result.

The light field, upon which the final prognosis is based, providing other complicating circumstances enumerated are absent, is thus tested: Place the patient before a lighted candle about four meters distant; the flames should be distinctly recognized. This gives evidence that the macular region is probably free from coarse disease. Now cause the eye under examination to fix the flame attentively, and move a second lighted candle radially through the field of vision. The flame should be recognized as soon as the rays strike the edge of the cornea, and the patient should be able to indicate the direction in which the light is coming. Thus the "light field," or the "projection of light," is tested, and, if the answers have been accurate, 44 projection of light is good in all parts of the field."

Even after complete absorption of congenital cataract under the influence of repeated discissions, useful vision is not always restored, because of associated optic nerve atrophy, choroidal disease, or changes at the macula. The functional condition of an eye with total congenital cataract is usually less favorable than one with the zonular variety of the disease.

Treatment. From the earliest period ophthalmologists have eagerly sought some method of absorbing or dissipating the cataractous lens. Various suggestions have been made, and various methods of procedure, such as massage and passing the electric current have been tried, but with negative results. So long as glasses, changed in accordance with the altering refraction of the eye, improve vision, they may be worn. Tonics are useful as adjuvants, and various alteratives e. g. iodid of potassium to relieve choroidal congestions may be exhibited. During incipiency moderate mydriasis may assist vision. At the proper time, however, surgical interference becomes necessary.

Various important questions arise in determining the best course to be followed to bring the treatment of cataract to a happy conclusion. When should extraction be made? Are we justified in hastening the process of ripening, and should we interfere when one eye is intact and has normal vision?

1. Extraction of Immature Cataract. Most ophthalmic surgeons delay extraction until the process of ripening is complete. While this is, perhaps, the wisest plan, everything considered, it is by Do means the only one. The danger of an early operation the swelling of the softened unripe cortex can be largely overcome by washing out the cavity with warm saline solutions, after the method of Panas and other operators, subsequent to extracting the nucleus.' About the sixtieth year of life, and even earlier, an unripe cataract may be successfully extracted.

2. Artificial ripening of cataract is rarely justifiable. It subjects the patient to a second major operation on the eye, with the attendant dangers. When this operation is determined upon it may be performed according to one of the methods described on page 584.

3. Extraction of Monocular Cataract. Unless the cataract is hypermature or a cosmetic effect is greatly desired, we are hardly justified in extracting an opaque lens when the other eye has normal vision. The advantages of a successful operation are that the field of vision of the affected side becomes more extensive, and the patient possesses an eye ready for use should vision in the other eye become involved from any cause. On the other band, while binocular vision is possible, objects are constantly blurred and sharpness of contour is wanting. The operated eye sometimes lags behind the other, giving an awkwardness of expression more grotesque and less pleasing than the presence of the cataract.

4. Operations for Cataract. For soft cataracts discission, the method Of suction, a combination of these methods, or linear incision may be practised. The use of the needle, repeated if necessary, will suffice in the usual soft varieties, while the suction method will quickly extract the contents when of semifluid consistency. It is not wise to delay the removal of a congenital cataract beyond the early weeks of life, as interference with the development of the retina and other deeper tissues of the eye may result.

Partial congenital cataracts are treated by optical iridectomy or discission. The former method is applicable to those cases whose vision is improved by dilating the pupil.

Discussion is practised for the after cataract, not to produce absorption, but to open a passage for the light rays (see page 585).

For the removal of the hard or senile cataract one of the various methods of extraction should be followed. The results of this operation are such that the older method of couching has been completely abandoned. While the exact technique of the various operations will be found elsewhere (see chapter on Operations, p. 580), several important points may be properly referred to here. The corneal incision should be ample in size, and should be completed with as few motions as possible, the subsequent rapid union of the cut surfaces being somewhat dependent upon this. The question of an iridectomy is much discussed, each individual operator having finally to determine the method from his own experience. Probably simple extraction (without iridectomy) is now performed in 60 per cent. of the eases, the maturity of the cataract, the condition of the iris, and the question of drainage determining the method. A wise rule is to perform simple extraction, examine the eye within twenty four hours, and, if the conditions are not favorable, separate the lips of the wound and resect the iris. The extrusion of the vitreous during the operation is usually due to insufficient rupture of the capsule and excessive pressure in delivering the lens. Unless it is so great as to cause total collapse of the globe the removal of the lens may be successfully attempted by other means. A degenerated or fluid vitreous may instantly force the operator to desist.

Aphakia. In the normal eye the removal of the lens (aphakia) causes a high degree of hyperopia, about 11 D. In myopia the degree of hyperopia will be lessened, and, indeed, in myopes of high degree emmetropia may result from extraction of the lens, or, if the myopia has been very great, a portion will remain unneutralized by the artificial hyperopia. In addition to the hyperopic refraction which results from cataract extraction, regular astigmatism is often found. It is probably produced by the irreg¬ular contraction of the cicatrix, and is usually “contrary to “or “against the rule." It is always greatest in the early months after the operation, and slowly diminishes. 'These conditions can be much relieved by the application of suitable glasses. In the average case a simple sphere of from 8 D. to 12 D., with the addition of a cylindrical glass of from 2 D. to 3 D., axis contrary to the rule, will usually suffice for good distant vision. For reading an additional sphere of from 4 to 6 D. must be added.

Perfect vision i. e. 6/6 is often secured after extraction, but I/6 or even to 1/10 of normal vision is sufficient to place the case within the list of successes. Frequently the vision can be materially improved by splitting the capsule. Glasses should not be adjusted until all signs of irritation have subsided.

Changes of Position of the Crystalline Lens. The various changes which the position of the crystalline lens may assume, termed luxation and subluxation, may be congenital or acquired. The lens is supported firmly in its natural position by the zonula of Zinn or the suspensory ligament, and displacement of the lens is only possible by relaxation or elongation of the zonula fibers or by their destruction.

1. Congenital dislocation, or ectopia lentis, is almost invariably a subluxation, and is due to the unequal length of the zonula in various directions. The zonula being shortest above, the lens will be found displaced upward or upward and outward. Later in life the displacement may become complete. Both eyes are usually affected, but monocular cases are reported. Heredity appears to exert a marked influence on the production of congenital dislocation.

2. Acquired dislocations are the result of injury, usually a concussion which forces the aqueous backward and ruptures the delicate membrane of the zonula. The displacement may be complete or incomplete, the lens being forced forward into the anterior chamber or backward into the vitreous, or through a laceration of the external coverings of the eye beneath the conjunctiva, and even under Tenon's capsule. Occasionally it is completely expelled (see also page 366).

Symptoms. In subluxation the anterior chamber is found of unequal depth, the iris being pushed forward at one point by the margin of the lens. The iris, losing its support in part, is no longer stationary, but trembles with every motion of the eye. With the ophthalmoscope the edge of the lens is seen as a dark grayish line. There may be loss of accommodation and monocular diplopia. In complete luxation forward the lens will be easily recognized by its shape as it rests in the anterior chamber or bulges out beneath the conjunctiva. In posterior dislocation the conditions simulating extraction are present. With every form of luxation very considerable changes in vision are noticed. In subluxation myopia may be present, and a considerable degree of astigmatism. In complete dislocation backward the extreme hyperopia of the aphakic eye is produced. The lens almost invariably undergoes cataractous changes, and by pressure may produce very serious inflammatory changes in the other tissues of the eye iritis, cyclitis, and clioroiditis or by closing the angle of the anterior chamber, giving rise to glaucoma (see also page 366).

Treatment. In partial dislocations the vision should be improved as much as possible by appropriate glasses. In complete anterior dislocation the lens should be removed through a proper incision. Where the dislocation is backward, unless there is some irritation, no attempt at removal should be made. When there is danger to the eye an effort should be made to press the lens forward into the pupil space by passing a needle through the sclera behind the lens, and then extracting it through a corneal wound (see also page 582).

Congenital Anomalies. Congenital cataract and congenital ectopia lentis have been recorded. In addition, there remain to be described

1. Congenital Aphakia. Total absence of the lens at birth is a condition of which there is no recorded example. Total absence of the lens has been found, however, in rare instances, as the result of some intra uterine disease.

2. Coloboma of the Lens. Coloboma of the lens almost invariably accompanies a similar condition of the iris or choroid, especially the former. The evenly rounded margin of the lens is replaced by a straight border or, it may be, by a notch of greater or lesser depth. Heyl states that the coloboma is almost invariably found in the lower segment of the lens. It may considerably disturb the visual acuteness.

3. Lenticonus. This rare anomaly consists of a conical projection from the surface of the lens, usually from the posterior surface, or it may simply be an exaggerated curvature of the lens. On examination with the ophthalmoscope it resembles a drop of oil resting on the surface. It may or may not be associated with lenticular opacity. Anterior lenticonus also occurs.

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