Corneal diseases like keratoconus can severely impair vision, affecting people’s daily lives. Corneal crosslinking (CXL) is a widely used technique to halt the progression of these ectatic diseases by increasing the cornea’s thickness and mechanical strength. However, the standard CXL procedure using riboflavin and ultraviolet A (UV-A) light has significant limitations and complications, including potential toxicity to the corneal endothelium and keratocytes.
In this groundbreaking study, researchers from Koç University in Turkey have developed a novel CXL approach using the metal ruthenium and bovine corneas, the ruthenium-blue light CXL approach resulted in significantly greater corneal stiffness, resistance to enzymatic digestion, and improved optical properties compared to the traditional riboflavin CXL technique.
3. Enhanced Corneal Penetration: The use of blue light, which has a longer wavelength than UV-A, allows for better tissue penetration and potentially broader applicability, even in corneas thinner than 400 μm.
Evaluating the Biocompatibility and Efficacy of Ruthenium-Blue Light CXL in Vivo
To further validate the safety and effectiveness of their approach, the researchers conducted a comprehensive in vivo study using Click Here
 has emerged as a clinically proven method for treating these ectatic disorders, as it increases the cornea’s <b>biomechanical stiffness and rigidity</b>, preventing further thinning.</p>
<p>The standard CXL procedure involves the use of <b>riboflavin</b> as a photosensitizer and <b>ultraviolet A (UV-A) light</b> to generate reactive oxygen species (ROS). These ROS induce the formation of covalent bonds between collagen molecules and fibrils, thereby strengthening the corneal structure. While this approach has been widely adopted in clinical settings, it is not without its limitations and complications.</p>
<p>One of the significant challenges with the traditional CXL method is that it is not suitable for patients with corneas thinner than 400 micrometers (μm). When applied to thinner corneas, the UV-A beam can reach the corneal <b>endothelial cells</b>, causing <b>endothelial toxicity</b>, permanent <b>corneal haze</b>, <b>keratocyte toxicity</b>, and <b>persistent corneal edema</b>. These complications often require further surgical interventions, such as <b>penetrating keratoplasty</b>, to address the damage caused by the standard CXL procedure.</p>
<p><h3>Introducing a Novel Biocompatible Crosslinking Approach</h3>
</p>
<p>To address the limitations of the traditional CXL method, researchers from Koç University have developed a novel crosslinking technique that utilizes the metal <b>ruthenium</b> and <b>blue light</b> as an alternative to riboflavin and UV-A.</p>
<p>Ruthenium is a water-based <b>photoinitiator</b> that can be activated by blue light between 400-450 nanometers (nm) to covalently crosslink the <b>free tyrosine groups</b> on collagen chains. In the presence of <b>sodium persulfate (SPS)</b>, the ruthenium (Ru2+) is oxidized to Ru3+, donating electrons to SPS. The dissociation of SPS into <b>sulfate anions and radicals</b> then forms new covalent bonds between nearby tyrosine groups on collagen chains, effectively crosslinking the corneal tissue.</p>
<p><figure class="wp-block-image size-large"><img decoding="async" src="https://famefreq.s3.us-east-2.amazonaws.com/1729763167_41598_2024_71871_Fig1_HTML.jpg" alt="figure 1" class="wp-image-1" /><figcaption class="wp-element-caption">Fig. 1</figcaption></figure>
</p>
<p>This innovative approach offers several key advantages over the standard CXL procedure:</p>
<p>1. <b>Reduced Cytotoxicity:</b> Ruthenium and blue light have been shown to be safe for corneal <b>epithelial cells</b>, <b>limbal stem cells</b>, and <b>fibroblast cells</b> in vitro, unlike the potential toxicity associated with UV-A light.</p>
<p>2. <b>Improved Corneal Integrity:</b> In ex vivo <a href=){kind=link}
![Click Here](https://en.wikipedia.org/wiki/Wistar<em>rat’>Wistar albino rats</a>. The corneas of the rats were subjected to CXL procedures using either the ruthenium-blue light method or the standard riboflavin-UV-A technique, with the untreated left eye serving as a control.</p>
<p><figure class="wp-block-image size-large"><img decoding="async" src="https://famefreq.s3.us-east-2.amazonaws.com/1729763170_41598_2024_71871_Fig2_HTML.png" alt="figure 2" class="wp-image-2" /><figcaption class="wp-element-caption">Fig. 2</figcaption></figure>
</p>
<p>The researchers closely monitored the corneas of the rats for various parameters, including:</p>
<p>1. <b>Corneal Opacity:</b> The ruthenium-blue light group exhibited rapid epithelial healing, with 100% regeneration of the corneal epithelium and no corneal opacity by day 6, outperforming the riboflavin-UV-A group.</p>
<p>2. <b>Corneal and Limbal Neovascularization:</b> The ruthenium group showed significantly reduced corneal (p < 0.01) and limbal neovascularization (p < 0.001) compared to the riboflavin group, indicating a lower inflammatory response.</p>
<p>3. <b>Histological Analysis:</b> Examination of the corneal tissue revealed no signs of cellular damage or apoptosis in the ruthenium group, confirming the biocompatibility and non-toxicity of the ruthenium-blue light CXL approach.</p>
<p><figure class="wp-block-image size-large"><img decoding="async" src="https://famefreq.s3.us-east-2.amazonaws.com/1729763174_41598_2024_71871_Fig3_HTML.png" alt="figure 3" class="wp-image-3" /><figcaption class="wp-element-caption">Fig. 3</figcaption></figure>
</p>
<p>Complementary analyses, including <b>confocal microscopy</b> and <b>scanning electron microscopy (SEM)</b>, further validated the effectiveness of the ruthenium-blue light CXL method. The researchers observed a high density of collagen fibrils and a well-organized stromal architecture, indicating efficient crosslinking and enhanced structural integrity of the cornea.</p>
<p><h3>Implications and Future Directions</h3>
</p>
<p>The findings of this study suggest that the ruthenium-blue light CXL approach offers a promising alternative to the standard riboflavin-UV-A CXL procedure. By leveraging the unique properties of ruthenium and blue light, this novel technique has demonstrated remarkable biocompatibility, safety, and functionality in strengthening the cornea without the adverse effects associated with UV-A exposure.</p>
<p><figure class="wp-block-image size-large"><img decoding="async" src="https://famefreq.s3.us-east-2.amazonaws.com/1729763177_41598_2024_71871_Fig4_HTML.png" alt="figure 4" class="wp-image-4" /><figcaption class="wp-element-caption">Fig. 4</figcaption></figure>
</p>
<p>The ability of the ruthenium-blue light CXL method to preserve corneal integrity and promote rapid epithelial healing could have significant implications for the treatment of a wide range of corneal ectatic diseases, including keratoconus. Furthermore, the enhanced corneal penetration capabilities of this approach may expand the applicability of CXL to patients with thinner corneas, who were previously ineligible for the standard procedure.</p>
<p>As the researchers continue to explore the potential of this innovative crosslinking technique, further studies involving higher-order animal models and long-term clinical trials will be crucial in validating its efficacy and safety for widespread clinical adoption. The successful development and implementation of this biocompatible CXL approach could revolutionize the management of corneal disorders, ultimately improving the quality of life for countless individuals affected by these debilitating conditions.</p>
<p>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.</p>
<hr />
<p>For More Related Articles <a href=){kind=link}