الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 92 |  |  |
| | | from | 92 | | |
Abstract
cornea and cartilage are considered the only tissues in the human
body that lack of the blood vessels. The cornea has important
mechanisms to maintain its avascularity (corneal angiogenic privilege).
Disturbance of the angiogenic privilege of the cornea occursas a
result of several diseases: infections as trachoma and herpetic keratitis,
hypoxia (as in contact lens), and limbal barrier defects (as in chemical
burns). Usually, corneal hem-angiogenesis is accompanied by lymph-
angiogenesis. These lead to impairing of vision by inducing lipid
keratopathy, stromal edema and hemorrhage. They also contribute in
immune graft rejection after keratoplasty.
Corneal avascularityis achieved by balancing between angiogenic
stimulating factors and angiogenic inhibiting factors, both secreted in
normal cornea. However, when the balance is shifted towards angiogenic
growth factors such as VEGF, PDGF, FGF, etc., corneal angiogenesis will
take place.
Pathologic corneal lymphatic vessels are invisible by ordinary
examination by the slit-lamp magnification, but can be visualized by
specific immunohistochemical markers and confocal microscopy. The
new anti-angiogenic and antilymph-angiogenic therapies can inhibit
corneal (NV) and improve graft survival after both low and high-risk
keratoplasty by inhibition of immune graft rejections.
Antiangiogenic therapy includes three categories: angiostatic e.g.
steroids, ionidizing radiation, anti-VEGFs, and anti-IRS-1 eye drops;
angioregressive e.g. anti-VEGF, endostatin; and angio-occlusive e.g.PDT,
fine needle diathermy combined with topical anti-VEGFs.