title: Hyperopic correction: clinical validation with epithelium-on and epithelium-off protocols, using variable fluence and topographically customized collagen corneal crosslinking.
abstract: OBJECTIVE
  To report novel application of topographically-customized collagen crosslinking aiming to achieve hyperopic refractive changes. Two approaches were evaluated, one based on epithelium-off and one based on epithelium-on (transepithelial).
  
  
  METHODS
  A peripheral annular-shaped topographically customizable design was employed for high-fluence ultraviolet (UV)-A irradiation aiming to achieve hyperopic refractive changes. A total of ten eyes were involved in this study. In group-A (five eyes), a customizable ring pattern was employed to debride the epithelium by excimer laser ablation, while in group-B (also five eyes), the epithelium remained intact. In both groups, specially formulated riboflavin solutions were applied. Visual acuity, cornea clarity, keratometry, topography, and pachymetry with a multitude of modalities, as well as endothelial cell counts were evaluated.
  
  
  RESULTS
  One year postoperatively, the following changes have been noted: in group-A, average uncorrected distance visual acuity changed from 20/63 to 20/40. A mean hyperopic refractive increase of +0.75 D was achieved. There was some mild reduction in the epithelial thickness. In group-B, average uncorrected distance visual acuity changed from 20/70 to 20/50. A mean hyperopic refractive increase of +0.85 D was achieved. Epithelial thickness returned to slightly reduced levels (compared to baseline) in group-A, whereas to slightly increased levels in group-B.
  
  
  CONCLUSIONS
  We introduce herein the novel application of a topographically-customizable collagen crosslinking to achieve a hyperopic refractive effect. This novel technique may be applied either with epithelial removal, offering a more stable result or with a non-ablative and non-incisional approach, offering a minimally invasive alternative.
authors.affiliation: LaserViison.gr Clinical and Research Eye Institute, Athens, Greece ; Department of Ophthalmology, New York University Medical School, New York, NY, USA.
authors.forename: Anastasios John
authors.initials: AJ
authors.lastname: Kanellopoulos
authors.affiliation: LaserViison.gr Clinical and Research Eye Institute, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Asimellis
keywords: CXL hyperopic correction; CXL presbyopic correction; KXL II; PiXL; epi-on and epi-off CXL; high-fluence cross linking; topography customizable crosslinking