Biomedical Engineering Reference
In-Depth Information
disease are commonly studied. Induced animal models of ocular
disease are most valid when they are similar clinically and patholog-
ically to the target ocular disease. Examples of induced ocular
disease used to study the effectiveness of therapeutics, and in
some cases to study the pathogenesis of disease, include corneal
scrape and infectious keratitis models [
21
-
23
], endotoxin induced
uveitis [
24
-
26
], glaucoma models [
27
-
31
], and laser induced cho-
roidal neovascularization models [
32
-
34
], to name just a few.
Genetically modified models of ocular disease are potentially pow-
erful tools to study the pathogenesis of ocular disease and also can
be used to determine clinical efficacy of medications. There are
numerous examples of these genetically modified models of ocular
disease [
35
-
38
].
Study of naturally occurring ocular diseases may provide a high
level of information regarding a specific ocular disease and results of
therapy, frequently with more valid results than in induced models
of disease because of the similarity of the ocular disease to that
observed in humans. Examples include, but are not limited to, the
open-angle glaucoma model in beagles [
39
-
42
], retinal disease
models in dogs [
2
,
43
-
49
], recurrent uveitis in horses [
50
-
57
],
and cataractogenesis in diabetic dogs [
58
-
61
].
Additional models of ocular disease, both induced and natu-
rally occurring will be discussed in subsequent chapters of this
topic.
5 Conclusions
Understanding the differences in ocular anatomy and physiology
along with understanding the relationship of the chosen animal
model to the target species is essential when planning studies to
determine ocular pharmacology, toxicity, and efficacy. For example,
determining that a drug applied topically to a mouse eye provides a
therapeutic concentration of a drug and/or is effective in treating a
disease, has virtually no relation to treatment of the human eye with
eye drops. On the other hand, success of treatment of a larger
animal, such as a pig or dog, with a similar size and ocular anatomy
to the human eye, would provide much more valid results, in most
cases. Another example is selecting appropriate animal for treat-
ment of retinal disease should involve use of animals with similar
retinal anatomy and retinal vascular supply. Use of appropriate
models is essential to decrease variability, minimize the number of
animals used in studies, and to increase study validity. It is the
responsibility of all researchers that perform biomedical research
to actively follow the three Rs (i.e., Replacement, Reduction, and
Refinement) [
1
] when designing studies.
