Hey' has suggested that a defect in the inferior branches of the hyaloid artery, which gives nutrition to the lens while the peripheral fibres are developing, would produce just such a defect.
It is often associated with coloboma of the iris and choroid, and with disloca tion and small size of the lens. There is sometimes more- or less opacity of the lens.
TWO cases of coloboma of the lens. In one it was the sole anomaly present; in the other it w as associated with partial eoloboma of the iris and choroid. Rog man (Archives d'Oplital., May, '96).
Tremulousness of the iris has been ob served, but more especially in cases in which ectopia also has been present.
The defect usually occurs in the in ferior quadrant, but has been seen up ward, outward, and down and out.
Case of coloboma of lens in a young man, whose father and one brother pre sented the same condition. O. D.V= V20, O. S. V=1/..,,,, increased in O. D. by the almost complete closure of the eyes when the patient looked at near objects. The lenses were displaced upward and inward, and were transparent, presenting neither coloboma ( ?) nor atrophy. The ophthal moscope showed the lens a refraction of 20 D. and through the aphakic media of — 8 D. The papilla presented a physi ological excavation and posterior staphy loma. Hassler (Lyon Med., Feb. 9, '96).
It resembles in form the chord of an arc, nearly a straight line, but sometimes consists of a complete notch.
It may occur in one eye or in both, and is most commonly associated with my opia. Vision is almost always defective, ranging from absolute blindness up to V --=-N„ as a rule. But Bresgin re corded a case in 1874 with V 2, 0 CY, and fair accommodation.
Accommodation seems to be usually present in those cases in which vision is good enough to permit of reliable ob servation of this point. Nystagmus is sometimes present.
A case has been observed in which a projection from the lens-margin was as sociated with a eoloboma of the iris.
3. Congenital Smallness of the Lens. —In these cases the anterior chamber is deeper than normal, and the iris trem ulous. The condition can be recognized only after dilatation of the pupil with a mydriatic. An unusually wide space is then seen between the pupillary edge of the iris and the margin of the lens, which stands out as a dark ring against the fundus. -Unusual smallness of the lens often accompanies ectopia and colo boma lentis.
4. Aphakia.—Cases of this condition in microphthalmic eyes have been re ported, but Lang expresses the opinion that in many the absence of the lens is ai nt only, it being really only dis p.ackd ont of sight.
5. Lenticonus.—This may occur at kithk r the anterior or posterior pole of the Ikns, the latter being by far the «,initioner situation. Only two instances of the former are on record, and there is doubt whether they were congenital r acquired. The condition resembles keratoconus. Anterior lenticonus can
easily be recognized by oblique illumina tion.
Posterior lenticonus requires the oph thalmoscopic mirror for its diagnosis. _It gives the appearance of a large drop in the pupil, with a dark, well defined border. Opacities of the rior pole of the lens, are often associated with it. The refraction is found to be different through the central and periph eral portions of the lens. In one case a remnant of the hyaloid artery was ad herent to it.
Reference may perhaps be made here appropriately to the somewhat common cases in which the refraction is found, by estimation with the ophthalmoscope or skiascope, to vary in different parts withont any other indication of lenti conus. Sometimes decided differences are found in the upper and lower halves of the pupil. Sometimes the division sc,,eins sectional in character.
Case of lenticonus posterior in a girl 7 years of age. Examination of the eye with a concave mirror revealed a bright, circular patch, apparently about 4 milli metres in diameter. located between the iris and the iundus in the antero-posterior axis of the globe. Upon careful study of the reflexes, this was found to project be yond the normal curvature of the lens about 0.05 millimetre. The refraction of the eye through the centre of the lens was myopic about 12 dioptres, and through the periphery there was an hy permetropia of 3 '/, dioptres. The base of the cone was probably 2.5 millimetres in diameter. At the apex there was a opacity, possibly the remnants of ftetal blood-vessels. The eye bad been convergent since infancy. The fellow-eye showed remnants of the fcetal pupillary membrane. Weeks (Archives of Oph thal., Apr., '91).
Case of lenticomis in a man 65 years of age. \Vhen the cone cannot be made visible by focal illuinination the points Will enable a diagnosis to be made are: 1. The oil-globule-like disk. 2. The great difference in refraction between the margin of the lens and the central por tion, the latter being always highly myopic. 3. The kaleidoscopic move ments of the retinal vessels. 4. The ex clusion of conical cornea. Knagg,s (Lan cet, Sept. 19, '91).
Cases of false lenticonns; diagnosis from true lenticonus by Purkinje's images. Demicheri (Annales d'Ocul., Feb., '95).
Lenticonus posterior in a 9-year-old girl. The refraction of the peripheral portions of the lens was + 4 D., while the central portion was —11D. Cramer (Klin. Monatsb. f. prakt. Augenh., Aug., '97).
Two rabbits' eyes with lenticonus pos terior. Explanation is as follows: Lenti conus arises from ehanges in the posterior capsule, the hyaloid artery in process of absorption stretching, and finally rupt uring, the capsule. Vitreous liquid then causes the lens-fibres to swell and pro trude through the break in the capsule. Baeek (Archiv f. Augenh., xxxvi, 2, p. 160, '9S).
6. Congenital Cataract. (See CATA