Note the size and form. Both may be modified by morbid processes. Note
the surface with regard to curvature, evenness and smoothness. In
=keratoconus= the curvature is greatly increased. Noting the reflex
images in the cornea and comparing these with those of a normal cornea
will show any variation in curvature. Also any =unevenness of the
surface= may be noted by the irregularity or distortion of the images.
Uneven spots on the cornea may be =depressions or elevations= from loss
of substance; =wrinkles or collapse= from lowered tension.
If the smoothness or polish of the cornea is lost it looks like glass
that has been breathed upon or greased. It is lusterless and dull.
Note also the transparency of the cornea and determine the form, extent
and density of the opacity; whether it is diffuse or in spots; in the
deep or superficial layers. A magnifying glass should be used in the
study of opacities. According to the density of the opacity of the
cornea it is known as a =nebula= or a =nebulous opacity=, a =macula=
or a =leucoma.= The nebula is the least noticeable and the leucoma is
the densest opacity. A leucoma is a condition of complete opacity. The
cornea looks white.
Defects in the corneal epithelium may be made to show clearly by the
use of a 2% solution of fluorescein which stains them green.
Note the sensitiveness of the cornea by touching it with the end of
a thread, a little cotton or a shred of paper. The sensitiveness is
diminished or lost in glaucoma and some other diseases.