Corneal diseases like keratoconus can severely impair vision, affecting people’s daily lives. Traditional corneal crosslinking treatments using riboflavin and ultraviolet (UV) light have significant limitations and side effects. However, a groundbreaking new approach using ruthenium and blue light could revolutionize corneal treatments. This innovative technique has demonstrated remarkable biocompatibility and efficacy in an in-vivo study, paving the way for safer and more effective corneal therapies.
Corneal Crosslinking: A Critical Technique for Vision Restoration
The cornea is the clear, protective front part of the eye responsible for most of the eye’s refractive power. Keratoconus and other corneal thinning diseases can distort vision, significantly impacting a person’s quality of life. Corneal crosslinking (CXL) is a widely used technique to halt the progression of these ectatic diseases by increasing the thickness and mechanical strength of the cornea.
The standard CXL procedure involves applying riboflavin (a photosensitizer) to the cornea and then exposing it to ultraviolet A (UV-A) light. This process generates reactive oxygen species that induce the formation of covalent bonds between collagen molecules and fibrils, thereby stiffening the cornea. However, this method has several limitations and complications, including:
– Inability to treat corneas thinner than 400 microns due to the risk of endothelial toxicity
– Permanent corneal haze, keratocyte toxicity, and persistent corneal edema
– Limited effectiveness in advanced-stage ectasia where corneas are often thinner than 400 microns
Introducing Ruthenium and Blue Light: A Biocompatible Alternative
To address these limitations, researchers have developed a novel CXL technique using ruthenium and blue light. Ruthenium is a water-based photoinitiator that, when combined with sodium persulfate and exposed to blue light (400-450 nm), can covalently crosslink the free tyrosine groups on collagen chains.
In this study, the researchers performed CXL on rat corneas using either the ruthenium/blue light or the standard riboflavin/UV-A approach. Their findings revealed several key advantages of the ruthenium/blue light method:
1. Rapid Epithelial Healing: The ruthenium group showed 100% regeneration of the corneal epithelium by day 6, significantly faster than the riboflavin group.
2. Reduced Neovascularization: The ruthenium group exhibited significantly lower corneal and limbal neovascularization compared to the riboflavin group, indicating reduced inflammation and tissue damage.
3. Preserved Tissue Integrity: Histological analysis and TUNEL assays showed no signs of cellular damage or apoptosis in the ruthenium group, confirming the biocompatibility and non-toxicity of this method.
Maintaining Corneal Collagen Structure and Function
The researchers also examined the structural changes in the corneal collagen fibers after the crosslinking procedures. Their findings revealed that both the ruthenium/blue light and riboflavin/UV-A methods led to a denser arrangement of collagen fibrils and reduced interstitial spaces, indicating enhanced mechanical strength and stress-bearing properties of the cornea.
Importantly, the ruthenium group showed consistent expression of type I collagen, the primary component of the corneal stroma, suggesting the preservation of this vital structural element.
Towards Safer and More Effective Corneal Treatments
This study demonstrates the remarkable biocompatibility and efficacy of the ruthenium/blue light CXL approach, which could potentially overcome the limitations of the standard riboflavin/UV-A method. By avoiding the use of UV-A light and its associated toxicity, the ruthenium-based technique offers a promising alternative for treating corneal ectatic diseases, including keratoconus.
The researchers highlight the need for further studies in higher-order animal models and human clinical trials to validate the safety and long-term outcomes of this innovative corneal crosslinking approach. If successful, this breakthrough could significantly improve the quality of life for individuals suffering from corneal thinning disorders, providing a safer and more effective treatment option.
Author credit: This article is based on research by Ayesha Gulzar, Humeyra N Kaleli, Gülsüm D Köseoğlu, Murat Hasanreisoğlu, Ayşe Yıldız, Afsun Şahin, Seda Kizilel.
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