1. Corneal CXL in Pediatric Patients with Progressive Keratoconus Stephanie Wise, Christian Diaz, Karolien Termote, Paul J. Dubord, Martin McCarthy, Sonia N. Yeung The authors have no financial interests to disclose.

2. Purpose -To evaluate the outcomes of corneal cross linking (CXL) in the treatment of keratoconus in pediatric patients -To investigate the effect of CXL on uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (BDVA), manifest refraction, keratometric measurements and higher order aberrations

3. Methods -Retrospective, observational case series of patients who underwent standard epithelium off CXL between January 2009 and August 2013 -Inclusion criteria: progressive keratoconus, 18 years old and younger -Exclusion criteria: nonprogressive keratoconus, combined procedure such as intra-corneal segment implantation

4. Methods -Preoperative and one year postoperative data including UCVA, BDVA, manifest refraction, keratometry readings and higher order corneal aberration measurements when available were extracted from clinical charts and topographical imaging -Visual acuity was converted to logMAR scale -Mean refractive spherical equivalent (MRSE) was calculated from manifest refraction -Differences in pre and postoperative parameters were analyzed by paired t tests and a p value less than 0.05 was considered significant

5. Results - The group consisted of 39 eyes from 28 patients -21 males (75%) and 7 females (25%) -mean age was 16.3 years old (range 11-18, SD=1.81) - There were no complications noted

6. Results - There were no significant differences seen in any of the examined parameters PreoperativePostoperative p value UCVA (logMAR) 1.2 (SD=0.57)0.90 (SD=0.67)0.19 BCVA (logMAR) 0.34 (SD=0.27)0.34 (SD=0.23)0.50 Mean Keratometry 48.49 (SD=5.44)48.25 (SD=4.74)0.34 Mean MRSE (D) -3.29 (SD=4.04)-3.53 (SD=4.07)0.31 Table 1. Mean, standard deviation (SD) and p values for pre and postoperative parameters

7. Results -There were corneal aberration measurements available for 10 eyes -Stability of aberrations was demonstrated – there were no significant differences found PreoperativePostoperative p value Total 9.27 (SD=5.73)9.00 (SD=9.16)0.93 High 3.23 (SD=5.73)3.34 (SD=3.61)0.92 Coma 2.30 (SD=1.38)2.36 (SD=2.59)0.94 Trefoil 1.50 (SD=0.89)1.71 (SD=2.10)0.74 Spherical 0.54 (SD=0.47)0.64 (SD=0.77)0.71 Table 2. Mean, standard deviation (SD) and p values for pre and postoperative root mean-square of higher order aberrations (μm)

8. Conclusions -CXL is an effective procedure that halts the progression of keratoconus in pediatric patients in one year follow up -One year postoperative data suggests CXL is safe in the pediatric population -Longer follow up is required to validate these findings