**4. Associated symptoms**

Symptoms of corneal neovascularization often include the following:


cause a variety of symptoms, including eye pain and excessive tearing, light sensitivity,

Corneal neovascularization remains a significant risk factor for corneal graft rejection and subsequent graft failure after penetrating keratoplasty. The collaborative corneal transplantation study1 identified, in addition to several other factors, the extent of stromal vessels (quadrants) as a serious risk factor for corneal graft failure. During corneal neovascularization, an upregulation of angiogenic factors is seen in association with down regulation of antiangiogenic molecules. Studies in human and rat models have found vascular endothelial growth factor (VEGF) to be up regulated in inflamed and vascularized cornea .2 In a mouse model, it was observed that corneal avascularity during development is redundantly regulated. Lack of the antiangiogenic factors thrombospondin (TSP)-1 and/or - 2 resulted in no spontaneous corneal angiogenesis. By contrast, TSP-1, more than TSP-2, helped to suppress inflammation-induced corneal angiogenesis postnatally, implying that angiogenic privilege in the cornea is actively maintained .3 Bachmann et al4 in a mouse model found that neutralization of VEGF-A after high-risk corneal transplantation effectively inhibited postoperative hemangiogenesis, lymphangiogenesis, and recruitment

Vascular endothelial growth factor promotes several steps of angiogenesis, including proteolytic activities, endothelial cell proliferation, migration, and capillary tube formation . 5 Topical or systemic application of bevacizumab inhibited both inflammation-induced angiogenesis and lymphangiogenesis in the cornea. This finding suggestes an important role of VEGF-A in corneal lymphangiogenesis and bevacizumab may be useful in preventing

**Superficial**: In superificial corneal vascularization, vessels arrange in arborizing pattern in subepithelial layer and can be traced with conjunctival vessels. This type of vascularization

**Deep**: In deep corneal vascularization, vessels are derived from anterior ciliary artery and lie in corneal stroma. Vessels are usually straight and not anastomosing. This type of vascularization may be observed in graft rejection, interstitial keratitis, deep corneal ulcer,

**Pannus**: In pannus, extensive superficial vascularization occurs with cellular infiltration. It

redness, intolerance to contact lenses, and decreased vision. **Role of Corneal Neovascularization in Corneal Graft Rejection** 

of antigen-presenting cells, thereby improving corneal graft survival.

may be observed in trachoma, and phlyctenular conjunctivitis.

 Progressive: Infiltration is ahead of vascularization Regressive: Infiltration is behind the vascular leash.

Symptoms of corneal neovascularization often include the following:

immune rejections after penetrating keratoplasty.

**3. Types of corneal vascularization** 

and chemical burn.

**4. Associated symptoms** 

Tearing and photophobia

is of two types:

 Eye pain Redness

### **4.1 Advantages of neovascularization**

