Corneal Epithelium Treatment Procedures

Corneal Cross-Linking (CXL) Procedure

• The central corneal epithelium, measuring 9 mm, can be mechanically removed through various methods, including debridement with specialized tools.
• Riboflavin solution (0.1% riboflavin in 20% dextran) is applied to the de-epithelialized cornea for 30 minutes before exposure to UVA light (370 nm).
• UVA exposure is conducted at a power of 3 mW/cm2 for a duration of 30 minutes, with riboflavin solution applied every 2-5 minutes during the process.
• Potential complications from de-epithelialization include corneal haze and pain; a bandage contact lens is often used postoperatively for pain management.

Importance of Riboflavin and Corneal Thickness

• Riboflavin serves as a crucial agent for enhancing corneal stiffness and is subject to penetration limitations due to the epithelium acting as a barrier.
• Ultrasound pachymetry can assess corneal thickness and determine suitability for CXL; a minimum corneal thickness of 400 µm is preferred.
• For corneas thinner than 400 µm, hypotonic riboflavin ophthalmic solution can be used to ensure adequate riboflavin absorption.

Transepithelial CXL (Epi-On)

• Transepithelial CXL is a less invasive alternative that promotes faster healing, improved comfort, and a reduced risk of corneal haze.
• Clinical studies have shown significant improvements in visual acuity and decreased keratometric values after CXL treatment.

Keratoconus (KC) Details

• Keratoconus is a common form of spontaneous corneal ectasia occurring predominantly in younger individuals, with an estimated incidence of 1 in 2000.
• Initial treatment often involves rigid gas permeable or scleral lenses; penetrating keratoplasty is considered the gold standard in cases of severe irregular astigmatism.

Pediatric Population Considerations

• The efficacy of CXL in children (ages 9-18) for keratoconus remains debated; some studies show improvement while others report worsening of corneal thickness.
• The Siena Pediatrics CXL study, a significant study with 152 KC patients aged 10-18, gives insights into long-term outcomes post-treatment.

Risks and Complications

• Risks associated with CXL treatment include corneal haze, changes in corneal shape, and potential for disease progression or flattening.
• Steeper Kmax preoperatively may indicate a higher risk of progression after CXL.

Dry Eye and Nerve Damage

• CXL affects corneal subepithelial nerve fibers, with early regeneration observed within the first month, though symptoms of dry eye may persist.
• Long-term neuropathic symptoms can develop, impacting patient comfort.

Innovative Treatment Strategies

• Prophylactic and simultaneous treatments are being explored to improve corneal stiffness without the drawbacks associated with traditional CXL, especially in thin corneas.
• Recent advancements include the use of photosynthetic pigments and novel formulations to enhance treatment outcomes.

Summary of Findings

• Visual acuity improved by 1–1.5 Snellen lines after 1–2 years post-CXL, with a decrease in mean Kmax measurements.
• The approach must balance effectiveness with patient comfort and potential complications, requiring careful patient selection and monitoring.

This quiz covers the methods of mechanically removing the central corneal epithelium and the subsequent application of riboflavin solution. It highlights various techniques such as using a blunt hockey knife and transpethelial phototherapeutic approaches. Test your knowledge on the procedures involved in corneal treatment.