Corneal Neovascularization
Corneal Neovascularization (CNV) is the abnormal growth of blood vessels in the normally clear cornea. The healthy cornea is naturally transparent and avascular (lacks blood vessels). CNV is usually triggered by oxygen deprivation, which can result from improper contact lens wear, eye disease, or trauma.
Signs and Symptoms
During a professional eye exam, CNV may present with the following clinical signs:
Physical Changes
Redness around the corneal edge (Limbal hyperemia) is often the earliest sign. This can progress to active engorged vessels, leakage, and corneal edema.
Patient Experience
Common symptoms include light sensitivity, blurred vision, and a sudden intolerance to contact lenses. YELLOW-white opacities (lipid deposits) may also form around the vessels.
Critical: Left unchecked, CNV can threaten vision due to scarring, hemorrhage, or lipid invasion. Regular eye exams are essential for contact lens wearers.
Causes and Risk Factors
CNV is most common in contact lens wearers, especially those using older hydrogel materials with low oxygen permeability.
- - Contact Lens Use: Poor hygiene, overwear, or ill-fitting lenses.
- - Infections: Viral infections like Herpes Simplex or corneal ulcers.
- - Trauma: Chemical injuries (alkali burns) or physical trauma.
- - Systemic Conditions: Acne rosacea, Sjögren’s syndrome, or immune disorders.
Management and Treatment
Non-Surgical Measures
- - Lens Modification: Discontinue wear or switch to higher oxygen-permeable (Silicone Hydrogel) or Rigid Gas Permeable (RGP) lenses.
- - Medication: Topical corticosteroids to reduce active inflammation or anti-VEGF drops (bevacizumab) to shrink vessels.
- - Primary Condition: Treat underlying dry eye, blepharitis, or rosacea.
Surgical Interventions
For severe or central scarring, more invasive options may be required:
- - Superficial Keratectomy: Physical removal of surface vessels.
- - Corneal Transplantation: Required if transparency is permanently lost.
- - Amniotic Membrane Transplantation: Used for ocular surface regeneration.
Summary
CNV is preventable and highly manageable if caught early. By reducing contact lens overwear, following strict hygiene protocols, and attending regular eye exams, the risk of permanent vision loss is significantly minimized.
Clinical References
1. American Academy of Ophthalmology.
Corneal Neovascularization. Edited by Scott IU, Fekrat S.
2. Wikipedia. Corneal Neovascularization - Causes and Risks.
3. Medscape. Management of Ocular Surface Vascularization.