Original article
Corneal Healing After Riboflavin Ultraviolet-A Collagen Cross-Linking Determined by Confocal Laser Scanning Microscopy In Vivo: Early and Late Modifications

https://doi.org/10.1016/j.ajo.2008.05.042Get rights and content

Purpose

To assess early and late micromorphological modifications of cross-linked corneas in vivo by means of Heidelberg Retinal Tomography (HRT) II confocal microscopy.

Design

Prospective nonrandomized open trial.

Methods

Micromorphological examination of 44 cross-linked keratoconic corneas was performed in vivo by HRT II confocal laser scanning microscopy. Riboflavin ultraviolet (UV)-A–induced corneal collagen cross-linking (CXL) was performed according to the Siena protocol: pilocarpin 1% drops 30 minutes before, topical anesthesia with lidocaine 4% drops 15 minutes before irradiation, mechanical scraping of epithelium (9-mm-diameter area), preirradiation soaking for 10 minutes in riboflavin solution 0.1% (Ricrolin, Sooft, Italy) applied every 2.5 minutes for 30 minutes, 30 minutes exposure to solid-state UVA illuminator (Caporossi; Baiocchi; Mazzotta, X-linker, CSO, Italy), 8-mm-diameter irradiated area, energy delivered 3 mW/cm2. All patients were examined by confocal scans preoperatively and at the following times after treatment: one, three, and six months, and one, two, and three years.

Results

No damage to the limbal region was observed. Epithelial regrowth was complete after four days of soft contact lens bandage. The anatomy of the subepithelial plexus was restored one year after the operation with full corneal sensitivity. Increased density of extracellular matrix in late postoperative period indicated cross-linked collagen to a depth of 340 μm expressed by a late demarcation line.

Conclusion

In vivo confocal microscopy showed early and late modification of corneal microstructure after the treatment. The three-year stability of CXL recorded could be related to increased cross-links formation, synthesis of well-structured collagen and new lamellar interconnections.

Section snippets

Methods

Since September 15, 2004, micromorphological examination of 44 cross-linked corneas has been performed at Siena University Ophthalmological Department by Heidelberg Retinal Tomography (HRT) II confocal laser scanning microscopy in vivo (Rostock Cornea Module; Heidelberg Engineering, Heidelberg, Germany). We report confocal analysis of the first 10 Italian patients treated (Siena Eye Cross Project 2004 to 2007)8 three years after the operation. All patients had clinically (uncorrected visual

Limbus

All corneal layers, especially the epithelium, regenerated rapidly (four days) and no damage to the limbal region was observed. Slightly increased reflectivity of extracellular tissue surrounding palisades of Vogt was detected without any pathologic significance and without affecting the germinal epithelium (Figure 1).

Epithelium

In all cases, epithelial regrowth was complete after four days of soft contact lens bandage. No growth retardation or persistent epithelial deficit was detected after corneal

Discussion

Riboflavin UV-A corneal collagen CXL is the only “pathogenetic approach” to progressive keratoconus and post-LASIK corneal ectasia that can delay or block their progression, reducing demand for donor keratoplasty. In vivo confocal study in humans demonstrated early and late modification of corneal microstructure after corneal collagen CXL treatment. The limbal region, where the corneal epithelium joins the conjunctival epithelium, contains a radial arrangement of trabecular conjunctival

Cosimo Mazzotta MD, PhD, graduated from University of Siena, Italy, Medical School in 1997. He has a Specialist diploma in Ophthalmology in 2001 and received his PhD in Ocular Pathology in 2006 from the University of Siena, Italy. With Professor Aldo Caporossi, MD, he introduced the Corneal Cross-Linking in Italy in 2004. Currently, Dr Mazzotta works as a Researcher at the Department Ophthalmology of Siena University and his areas of interest includes keratoconus, corneal dystrophies, and

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    Cosimo Mazzotta MD, PhD, graduated from University of Siena, Italy, Medical School in 1997. He has a Specialist diploma in Ophthalmology in 2001 and received his PhD in Ocular Pathology in 2006 from the University of Siena, Italy. With Professor Aldo Caporossi, MD, he introduced the Corneal Cross-Linking in Italy in 2004. Currently, Dr Mazzotta works as a Researcher at the Department Ophthalmology of Siena University and his areas of interest includes keratoconus, corneal dystrophies, and refractive surgery.

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