OPACITY OF THE CORNEA. NEBULA. MACULA. LEUCOMA.
Nebula, macula, leucoma, pigment spots, infiltration, cicatrix, vascular or not, result of lead, silver or cocaine. Treatment: silver nitrate solution in young and vigorous; calomel: iodoform: avoid mercury and iodine at the same time. Tatooing.
As a sequel of inflammation of the cornea, persistent opacities are very common occurrences. These may last only a short time after the subsidence of the inflammation, or they may be persistent and chronic. They are of all degrees of severity from a mere bluish haze to a dense white cloud, or a dark pigment spot.
The term nebula is given to the slightest form which appears as a grayish blue but still transparent blue and may be so slight as to pass without recognition except under focal or oblique illumination. It shades off gradually into the adjacent healthy cornea, and is often seen as a marginal zone when the centre of the cornea is clear.
Macula is more marked, requiring no special illumination to detect it, especially when the dark pupil forms a background for the affected area. It is not, however, of a clear white, but of a grayish blue tint.
Leucoma is a dense white spot or patch which reflects all the light falling upon it, and has usually a sharply circumscribed margin.
Pigment spots are usually on the membrane of Descemet and are the result of a previous adhesion of the iris and detachment of a portion of its pigment.
The white opacity may be merely a remnant of inflammatory infiltration or it may be a fibrous cicatrix with or without a remaining minute ulcer. It may be the result of an insoluble deposit of lead or silver in the tissues. Sometimes it will form as the result of the application of cocaine.
Treatment. A case of slight inflammatory infiltration can usually be cleared up by touching it daily with a solution of 2 grs. silver nitrate in an ounce of distilled water. This is especially satisfactory in the young and healthy, in which the power of repair is greatest. Finely powdered calomel or iodoform applied to the cornea will often prove effective. In case potassium iodide has been given by the mouth, calomel or corrosive sublimate is liable to form mercurous or mercuric iodide and cause ophthalmia. The same is true of iodoform if mercury has been given internally. As a last resort tatooing the spot has been resorted to, to hide the opacity.