Scheimpflug imaging of corneas after collagen cross-linking.
OBJECTIVE
To compare geometrical shape factors of keratoconus corneas after cross-linking (CXL) by means of Scheimpflug imaging with those of untreated fellow eyes.


METHODS
Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland.


METHODS
Scheimpflug imaging of the anterior segments was performed with the Pentacam (Oculus, Wetzlar, Germany) in 21 patients with progressive keratectasia before and after CXL. Only 1 eye per patient was treated with corneal cross-linking using the riboflavin/UV-A approach, the fellow eye serving as control. The following corneal parameters and their postoperative evolution during 1 year after treatment have been evaluated: minimal curvature radius and its location, thickness at the thinnest point, location of the thinnest point, anterior and posterior elevation, conoid asphericity constants of the anterior and posterior surface, and 7 keratoconus indices. Statistical comparison was performed by means of the Wilcoxon test.


RESULTS
None of the treated eyes showed topographic progression in contrast to the untreated group where 8 eyes experienced significant progression. Minimal curvature radius increased significantly after 1 year compared with preoperative (6.14-6.21 mm), whereas in the untreated fellow eye, it significantly decreased (6.94-6.86 mm). Minimal corneal thickness was significantly reduced after treatment (P < 0.002 at 12 months). The cornea showed an evolution toward a more regular shape as indicated by a significant reduction in 4 of 7 keratoconus indices. No complications of CXL occurred in this small study group.


CONCLUSIONS
After cross-linking, the corneal shape undergoes a process of regularization. This process is active during the first year after treatment and may continue. Longer follow-up is warranted to estimate the full amount of regression of the keratectasia after CXL.
Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland; and daggerIstitut Clinico Humanitas, Milano, Italy.
Tobias
T
Koller
Hans Peter
HP
Iseli
Farhad
F
Hafezi
Paolo
P
Vinciguerra
Theo
T
Seiler
D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000187:drug effects*; D003315:Cornea / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D016896:Treatment Outcome; D014467:Ultraviolet Therapy; D055815:Young Adult
D003432:Cross-Linking Reagents; D003094:Collagen; D012256:Riboflavin