Biomedical Engineering Reference
In-Depth Information
Fig. 13 A Welch-Allyn direct ophthalmoscope
this can be lacking in color dilute or lemon beagles. Finally, NHPs
are foveated and this region must be examined carefully for
abnormalities.
Additional techniques to evaluate the retina may include fluo-
rescein angiography, OCT, confocal scanning laser ophthalmo-
scopy, fundus photography, and electrodiagnostic testing. When
these tests are used correctly and in combination they can provide
additional en face, cross-sectional, and functional information of
the retina that may be then correlated with histopathology.
Prior to study initiation, a pretest ophthalmic examination should
be performed on all study animals. This is done for two reasons.
The first is to eliminate from the study animals with current signifi-
cant or potentially progressive ophthalmic abnormalities. The sec-
ond is to establish a baseline of ocular findings to compare to as the
study progresses and subsequent ophthalmic examinations are per-
formed. Examples of pretest abnormalities that should automati-
cally result in an animal's elimination from the study would include
all ocular findings with a severity score of moderate or higher and all
abnormalities that currently prevent or may prevent if progressive
complete examination of intraocular structures. Examples of ocular
findings that may be progressive during the course of the study and
2.3 Pretest
Examination
