1. Shorter Duration, Higher Ultraviolet A Irradiation (UVA) Fluence Collagen Cross-linking (CCL) for Keratoconus (KCN)
Frank A. Killian, MD and A. John Kanellopoulos, MD
New York University School of Medicine/Manhattan Eye, Ear Nose and Throat Hospital, New York, NY, USA and Laservision.gr, Athens, Greece
*The authors of the study have no financial interests to disclose

2. Shorter Duration, Higher UVA Fluence CCL for KCN
Purpose
To evaluate the safety and efficacy of shorter duration, higher UVA fluence for collagen cross- linking in KCN
We designed a prospective, randomized comparative case series to evaluate CCL at a higher UVA light intensity (from 3mW/cm2 to 7 mW/cm2) while using the same adjunct 0.1% topical riboflavin sodium phosphate solution

3. Shorter Duration, Higher UVA Fluence CCL for KCN
Methods
15 patients with bilateral keratoconus were studied
All cases were evaluated for changes in UCVA, BCVA, refraction, keratometry (K), topography, endothelium cell count and cornea clarity
All eyes received CCL with topical 0.1% riboflavin solution and were randomized with regard to UVA duration
15 eyes received CCL with 7mW/cm2 for 15 minutes while the15 contra-lateral eyes received CCL with 3mW/cm2 for 30 minutes
Mean follow up was 1.5 years

4. Shorter Duration, Higher UVA Fluence CCL for KCN
Results
The mean improvement of UCVA was 0.2 to 0.4
BCVA improved from 0.4 to 0.7
The mean change in spherical equivalent was 1.5 D reduction in myopia, the mean change in cylinder was 2.1 D reduction
The mean highest keratometry was 51.2 D pre-op and D post-op
There was no statistical difference in the means for the two groups

5. Shorter Duration, Higher UVA Fluence CCL for KCN
Table 1: Comparison of shorter duration, higher UVA Fluence CCL vs standard CCL

6. Shorter Duration, Higher UVA Fluence CCL for KCN
Figures 1 and 2:
Patient with slit lamp photograph of CCL changes in the cornea 3 months post-op (above) and pre-op and post-op Pentacam changes (right)

7. Shorter Duration, Higher UVA Fluence CCL for KCN
Conclusions
Shorter duration, higher UVA fluence CCL appears to be a safe and effective method for ectatic stabilization in KCN
Shorter duration may cause less cell toxicity due to less corneal dehydration and shorter exposure of keratocytes and endothelial cells to UVA light and riboflavin
Further studies are needed to validate this data