Biomedical Engineering Reference
In-Depth Information
Table 2
(continued)
2
¼
Moderate loss of transparency. In addition to involving the anterior stroma, the cloudiness
extends all the way to the endothelium. The stroma has lost its marble-like appearance and is
homogeneously white. With diffuse illumination, underlying structures are clearly visible.
3
¼
Involvement of the entire thickness of the stroma. With the optical section, the endothelial surface
is still visible. However, with diffuse illumination, the underlying structures are just barely
visible (to the extent that the observer is still able to grade flare and iritis, observe for pupillary
response, and note lenticular changes).
4
¼
Involvement of the entire thickness of the stroma. With the optical section, cannot clearly
visualize the endothelium. With diffuse illumination, the underlying structures cannot be seen.
Cloudiness removes the capability for judging and grading flare, iritis, lenticular changes, and
pupillary response.
Corneal area
—The surface area of the cornea relative to the area of cloudiness is divided into five grades
from 0 to 4.
0
¼
Normal cornea with no area of cloudiness.
1
¼
1-25 % area of stromal cloudiness.
2
¼
26-50 % area of stromal cloudiness.
3
¼
51-75 % area of stromal cloudiness.
4
¼
76-100 % area of stromal cloudiness.
Pannus
—Pannus is vascularization or the penetration of new blood vessels into the corneal stroma. The
vessels are derived from the limbal vascular loops. Pannus is divided into three grades.
0
¼
No pannus.
1
¼
Vascularization is present but vessels have not invaded the entire corneal circumference. Where
localized vessel invasion has occurred, they have not penetrated beyond 2 mm.
2
¼
Vessels have invaded 2 mm or more around the entire corneal circumference.
Fluorescein
—For fluorescein staining, the area can be judged on a 0 to +4 scale using the same
terminology as for corneal cloudiness. The intensity of fluorescein staining can be divided into 0-4
scale.
0
¼
Absence of fluorescein staining.
1
¼
Slight fluorescein staining confined to a small focus. With diffuse illumination the underlying
structures are easily visible. (The outline of the pupillary margin is as if there were no fluorescein
staining.)
2
¼
Moderate fluorescein staining confined to a small focus. With diffuse illumination the underlying
structures are clearly visible, although there is some loss of detail.
3
¼
Marked fluorescein staining. Staining may involve a larger portion of the cornea. With diffuse
illumination the underlying structures are barely visible but are not completely obliterated.
4
¼
Extreme fluorescein staining. With diffuse illumination the underlying structures cannot be
observed.
(continued)
