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.