When the lens floating in the vitreous causes iridocyclitis or secondary glau coma, its removal is indicated. To do this is a matter of great difficulty. If the case be one in which the lens some times passes into the anterior chamber, attempts should be made to bring about this change of position by such move ments as liave previously effected ii. Once in the anterior chamber it should be fixed there by the use of a miotic by the introduction of Agnew's bident behind it. If the lens cannot by volun tary movements be made to enter the anterior chamber, it may be brought to the anterior part of the eye by the bident and fixed there. lt may then be removed bv corneal incision, and its delivery usually requires the use of the vectis, OF sharp hook. 8onte vitreous is usually lost, and this is most apt to occur during the removal of the bident„ which seems te be the most dangerous part of the o peva t ion.
Luxated lens successfully removed from the posterior chamber of an eye by first performing a downward iridectomy, fol lowed two months later by extraction \Nall the aid of a curette, a small amount of vitreous being lost. In eighteen days vision equaled two-thirds of normal. Despagnet (Ruud! d'Ophtal., June, '89).
Two cases of dislocation of the lens into the vitreous humor, in which extraction was successfully accomplished by first making an upper corneal section and then expelling the lens by methodical external pressure in the ordinary manner, the speculum having been removed during the latter part of the procedure. Knapp (Archives of Ophthal., Jan., '90).
In the extraction of dislocated lenses it is possible "in many cases, perhaps in the majority, to extract the lens by external pressure, and to confine the use of instru ments to assist in the removal of the lens after it has presented in the wound, or, at least, in the field of the pupil." C. S. Bull (N. Y. .Med. Jour., Sept. 6, '90).
Lens dislocated into the vitreous r&. moved without irideetomy while the pa tient was lying prone on an operating table. Higgins (Lancet, Dee. 26, '96).
Knapp and Bull maintain that such lens.es can be removed, and have pub lished reports of cases showing such to be the case, without the use of the bident, and without the introduction of any in strument into the eye, by means of exter nal manipulation only.
When an eye is blind and the seat of absolute glaucoma or of iridocyclitis due. to dislocated lens, the pain so caused is best relieved, and the danger of sympa thetic affection of the other eye most effectually avoided by enucleation.
In a case of dislocation of both lenses into the vitreous, of congenital origin, reported by Bickerton in the Trans. Oph.
Soc. U. K., '98, the lens of one eye passed into the anterior chamber, causing re duction of vision to the perception of light and shade. After sixteen days the
lens was replaced in the vitreous by a spatula introduced through a corneal cis.ion, with the restoration of perfect vision, the aphakic refraction being cor rected.
Case of spontaneous dislocation of both crystalline lenses into the anterior cham bers occurring in myopic eyes. The right eye, which was entirely blind and painful, was enueleated, while from the left an terior chamber a partially-degenerate lens was successfully removed. With the ex ception of an aggravated spasmodic en tropion, necessitating operative inter ference, rapid healing took place, leaving a vision of "/., without the necessity of any correcting lens. De Schweinitz (Univ. Med. Mag., Nov., '89).
Congenital Anomalies.
1. Ectopia Lentis. See ANOMALIES OF POSITION.
2. Coloboma lentis is a rare condition due to arrest of development at a late period of embryonic growth. The fre quent association of coloboma of the iris and choroid with it suggests its relation to imperfect closure of the foetal cleft.
Its immediate cause lies in defective de velopment of the zonula of Zinn. This is developed from adhesions, which form between the sides of the lens and ciliary body during the stage of embryonic life when they are in contact. As the eye en larges, that portion of the capsule to which adhesions have failed to occur would not be held taut and made to expand like the remainder, and a cor responding depression in the lens would result. Absence of the ciliary body would, of course, be a probable cause of this failure to adhere.
TWO cases of coloboina of lens in a brother and sister 8 and 11 years old, respectively. The condition is best ex plained as the result of an alteration, in flammation, or absence of formation of a portion of the zonula, which would per mit but a part of the lens to come in im mediate contact with the sclera, and that the adhesion thus produced would be the starting-point and cause of the displace ment of the lens. Sous (Jour. de Med. de Bordeaux, Oct. 13, '95).
Instance of congenital coloboma of the lens in the left eye of a man 20 years of age. The lens could be seen to exist only for about the upper half of the pupillary space. Extending from the inferior bor der of the lens-substance to and behind the inferior border of the pupillary mar gin there was a delicate membrane show ing fine, vertical parallel strize. The in ferior border of the lens appeared terraced and transparent, but above this it be came opaque. The diameter of the cor nea was from one to two millimetres less than that of the right eye. The iris was dull dirt yellow, that of the fellow-eye being brown. In two places the pupillary membrane could be seen. Dunn (Ar chives of Ophthal., July, '96).