Study of the effects of the deposit of rust in the cornea by placing particles of iron in the corners of cuts. Five minutes were sufficient to make the iron reaction appreciable, metallic iron being chemically irritant, while iron oxide was not. The ring of rust found about the foreign body consisted of hy drated oxide of iron, and was chemically innocuous. The corneal epithelium showed itself to resist extraordinarily the invasion of the oxide of iron. Gruber (Archiv f. Oplith. [Grilfe], B. 11, H. 2, '94).
Powder-grains imbedded in tbe cornea at first cause much irritation and in flammation. But if this has passed away the remaining stain, consisting of mi nute particles of carbon, may be retained indefinitely, without being a source of further trouble or danger.
Cornea, Opacities of.
The bulk of the cornea, being a highly specialized tissue closely related to or dinary connective tissue like that com posing the sclera, is liable by slight de generation to lose its transparency. All considerable injuries or losses of sub stance of the cornea are repaired by cic atricial connective tissue, which usually fails to become entirely transparent. Hence, corneal opacities are a probable sequel of all other diseases or injuries of the cornea. Slight haziness of the cornea is spoken of as nebula. A more dense localized haziness, amounting to almost complete opacity is called a macula. More dense and complete Congenital opacity of the cornea is rare. It may arise from intra-uterine inflammation, or from an arrest of the clearing of the cornea, which is origi nally opaque. This clearing beginning at the corneal margin, such opacities usu ally involve the centre. They may di minish in early childhood, although this is unusual; and occasionally somewhat similar opacities are said to occur after birth and to increase.
Two cases of symmetrically-placed opacities of the cornea, occurring in mother and son. The boy was 8 years opacity, from its usual color, white, is called leucoma. The density of the opacity indicates the severity of the lesion causing it and the age of the patient, recovery from the severe lesions being more complete in early life.
Varieties.—The opacity usually occur ring with age as a gray arc slightly within the upper and lower margins of the cornea is the arcus senilis. It extends in some persons to form a complete ring, annulus senilis, separated by a zone of comparatively-clear cornea from the sclera. Sometimes it occurs in early life;
and even in early childhood.
of age, and presented in each cornea (as shown in lower portion of figure) a cen tral macula surrounded by a ring of superficial pin-point opacities. These had been observed for a long time, but one year previously had enlarged, fol lowing an attack of malaria fever. Laveran's corpuscles could not be de tected and there was no evidence of con genital syphilis. Examination of the mother's eyes showed similar opacities in each cornea, which had been present as long as she could remember. These are shown in the upper portion of the figure. Oliver (Amer. Jour. of Ophth., Aug., '92).
Record of an instance where the first, second, and fourth children of a family were blind from congenital opacity of the cornea, most dense at the centre. There was a deep anterior chamber and rather large eyeballs. The third child had normal eyes. The mother was healthy, the father when 20 years old had suffered from inflammation of both eyes, lasting eight months; and leaving a central clouding of the cornea. Wer nicke (Ann. dUculistique, Oct., '96).
_Microscopical examination of the cor ilex of an infant suffering from con genital opacity, dying on the third day, and without other congenital anomalies. The chief lesions were found in the pos terior layers of the cornea and were allied to those of interstitial keratitis.
Telpljfischin (Archives of Oplithal., Jan., '97).
Attention called to a form of corneal cloudiness occasionally seen in patients complaining of asthenopic symptoms rather inore severe than those usually attending refractive errors. This corneal turbidity appears to be simply an exag geration of the normal cloudiness, and can be seen with a highly magnifying lens and lateral illumination. Henry Cradle (Phila. Med. Jour., July 16, '9S).
Opacities due to inflammation of the cornea are most dense immediately after the subsidence of the inflammation, from which thne they diminish with greater or less rapidity according to the age of the patient and the nature of the opacity. Sometimes quite a noticeable macula will be left by an inflammation occurring a few weeks previously that has been quite overlooked or forgotten. The general clouding of the cornea from interstitial keratitis clears first from the margin, and, usually in the course of several months, or one or two years, is reduced to a nebula, although perfect recovery is rare.