Treatment of progressive keratoconus by riboflavin-UVA-induced cross-linking of corneal collagen: ultrastructural analysis by Heidelberg Retinal Tomograph II in vivo confocal microscopy in humans.
OBJECTIVE
To assess ultrastructural stromal modifications after riboflavin-UVA-induced cross-linking of corneal collagen in patients with progressive keratoconus.


METHODS
This was a second-phase prospective nonrandomized open study in 10 patients with progressive keratoconus treated by riboflavin-UVA-induced cross-linking of corneal collagen and assessed by means of Heidelberg Retinal Tomograph II Rostock Corneal Module (HRT II-RCM) in vivo confocal microscopy. The eye in the worst clinical condition was treated for each patient. Treatment under topical anesthesia included corneal deepithelization (9-mm diameter) and instillation of 0.1% riboflavin phosphate-20% dextran T 500 solution at 5 minutes before UVA irradiation and every 5 minutes for a total of 30 minutes. UVA irradiation was 7 mm in diameter. Patients were assessed by HRT II-RCM confocal microscopy in vivo at 1, 3, and 6 months after treatment.


RESULTS
Rarefaction of keratocytes in the anterior and intermediate stroma, associated with stromal edema, was observed immediately after treatment. The observation at 3 months after the operation detected keratocyte repopulation in the central treated area, whereas the edema had disappeared. Cell density increased progressively over the postoperative period. At approximately 6 months, keratocyte repopulation was complete, accompanied by increased density of stromal fibers. No endothelial damage was observed at any time.


CONCLUSIONS
Reduction in anterior and intermediate stromal keratocytes followed by gradual repopulation has been confirmed directly in vivo in humans by HRT II-RCM confocal microscopy after riboflavin-UVA-induced corneal collagen cross-linking.
Mazzotta
Cosimo
C
Department of Ophthalmology and Neurosurgery, University of Siena, Siena, Italy.
Balestrazzi
Angelo
A
Traversi
Claudio
C
Baiocchi
Stefano
S
Caporossi
Tomaso
T
Tommasi
Cristina
C
Caporossi
Aldo
A
D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000528:radiation effects*; D003319:Corneal Stroma / Q000166:cytology / Q000528:radiation effects*; D003432:Cross-Linking Reagents; D018450:Disease Progression; D005347:Fibroblasts / Q000528:radiation effects; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy*; D018613:Microscopy, Confocal; D008875:Middle Aged; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D014054:Tomography; D014466:Ultraviolet Rays; D014945:Wound Healing
D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin