Conservative treatment of keratoconus by riboflavin-uva-induced cross-linking of corneal collagen: qualitative investigation.
OBJECTIVE
To assess corneal tissue modifications after riboflavin-UVA-induced cross-linking of corneal collagen in patients with progressive keratoconus as well as regeneration of epithelium and subepithelial nerve plexus by in vivo HRT II system confocal microscopy in humans.


METHODS
Ten patients with progressive keratoconus were treated by riboflavin-UVA-induced cross-linking of corneal collagen, involving assessment of ultrastructural modifications of the corneal epithelium and subepithelial nerve plexus by HRT II system confocal microscopy. Treatment included instillation of 0.1% riboflavin-20% dextrane solution 5 minutes before UVA irradiation and every 5 minutes for a total of 30 minutes. Radiant energy was 3 mW/cm 2 or 5.4 Joule/cm 2 and the source was dual UVA (370 nm) light-emitting LED. The protocol included the operation followed by antibiotic medication and eye dressing with a soft therapeutic contact lens. Changes in epithelium and subepithelial and stromal nerve plexus were assessed by HRT II system confocal microscopy in vivo.


RESULTS
After 5 days of soft contact lens wearing, corneal epithelium has a regular morphology and density. Disappearance of subepithelial stromal nerve fibers was observed in the central irradiated area where, 1 month after the operation, initial reinnervation was microscopically observed. No changes in nerve fibers were observed in the peripheral untreated with a clear lateral transition between the two areas. Six months after the operation, the anterior subepithelial stroma was recolonized by nerve fibers with restoration of corneal sensitivity.


CONCLUSIONS
HRT II system confocal microscopy confirms corneal epithelium restore and re-innervation after riboflavin-UVA-induced collagen cross-linking directly in vivo in humans.
Mazzotta
C
C
Department of Ophthalmological Sciences, Siena University, Viale Bracci 8, 53100 Siena, Italy.
Traversi
C
C
Baiocchi
S
S
Sergio
P
P
Caporossi
T
T
Caporossi
A
A
D003094:Collagen / Q000378:metabolism / Q000528:radiation effects*; D003315:Cornea / Q000294:innervation; D003319:Corneal Stroma / Q000294:innervation / Q000378:metabolism / Q000528:radiation effects*; D003432:Cross-Linking Reagents / Q000528:radiation effects; D019573:Epithelium, Corneal / Q000294:innervation; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy*; D018613:Microscopy, Confocal; D009412:Nerve Fibers / Q000502:physiology; D009416:Nerve Regeneration / Q000502:physiology*; D009882:Ophthalmic Nerve / Q000502:physiology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use*; D013997:Time Factors; D014054:Tomography; D014466:Ultraviolet Rays
D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin