Eyeworld

22 | EYEWORLD | JUNE 2022 ASCRS NEWS References 1. Subasinghe SK, et al. Current perspectives on corneal collagen crosslinking (CXL). Graefes Arch Clin Exp Ophthalmol. 2018;256:1363–1384. 2. Wollensak G, et al. Riboflavin/ ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003;135:620–627. 3. Podskochy A. Protective role of corneal epithelium against ultraviolet radiation damage. Acta Ophthalmol Scand. 2004;82:714–717. 4. Malhotra C, et al. In vivo imaging of riboflavin penetration during collagen cross-linking with hand-held spectral domain optical coherence tomography. J Refract Surg. 2012;28:776–780. 5. Wollensak G, Iomdina E. Biomechanical and histological changes after corneal crosslink- ing with and without epithelial debridement. J Cataract Refract Surg. 2009;35:540–546. 6. Spoerl E, et al. Safety of UVA-riboflavin cross-link- ing of the cornea. Cornea. 2007;26:385–389. 7. Dhawan S, et al. Complications of corneal collagen cross-linking. J Ophthalmol. 2011;2011:869015. 8. Leccisotti A, Islam T. Tran- sepithelial corneal collagen cross-linking in keratoconus. J Refract Surg. 2010;26:942–948. 9. Cifariello F, et al. Epi-off versus epi-on corneal collagen cross-linking in keratoconus patients: A comparative study through 2-year follow-up. J Oph- thalmol. 2018;2018:4947983. ectasia was determined by change in maximum keratometry (Kmax) at the 2-year follow-up as compared to baseline, with stability defined as change in Kmax within ±1 D of baseline and progression or regression falling greater than 1 D above or below this range, respectively. Ad- ditional outcome measures included corrected distance visual acuity (CDVA), manifest refrac- tive spherical equivalent (MRSE), corneal densi- tometry, and topographic measurements such as Kmax and simulated keratometry (SimK). Results Among the 58 eyes that met inclusion criteria, standard epi-off CXL was performed in 34 eyes, TECXL in 10 eyes, and CACXL in 14 eyes. Pa- tients were mostly male (71%) with a mean age of 19.26 years. Baseline parameters were largely comparable between groups, with no significant difference found among CDVA, MRSE, or Kmax in the groups. Patients who underwent TECXL were significantly older than those who under- went standard epi-off CXL and CACXL. Mean thinnest pachymetry was similar between the CACXL and TECXL groups and, as expected, sig- nificantly thinner when compared to those that underwent standard epi-off CXL. Of note, there was a trend for eyes in the CACXL group to have a higher Kmax at baseline as compared to the two other groups (p=0.09). All three techniques were similarly effec- tive at halting progression of ectasia at 2 years (p=0.61). In the standard epi-off CXL group, regression was seen in 62% of eyes (n=21), stabilization in 32% (n=11), and progression in 6% (n=2). In the CACXL and TECXL groups, regression was seen in 79% (n=11) and 80% (n=8) of eyes, respectively, while the remaining eyes demonstrated stabilization. No progression was seen in any eyes in the CACXL or TECXL groups. At the 2-year follow-up, the largest reduction in Kmax was seen in the CACXL group at –3.18±2.74 D, followed by –2.83±3.35 D in the standard epi-off CXL and –2.02±1.66 D in the TECXL group. Between group comparison of reduction in Kmax as well as reduction in the flat, steep, and mean simulated keratometry at 2 years was comparable among all three groups. Assessment of CDVA at 2 years demonstrat- ed improvement in all groups when compared to baseline, however, this reached statistical significance only in the standard epi-off CXL group (p=0.006). Between group comparison revealed that improvement in CDVA was similar among all groups (p=0.46). A statistically sig- nificant improvement in MRSE was seen within all three groups that also remained similar in all groups throughout the follow-up period. One patient in the TECXL group developed herpetic epithelial keratitis (geographic ulcer) at the 3-week follow-up and was managed successfully with topical ganciclovir. No other complications were reported. Discussion Variability in CXL protocols among studies, especially for newer techniques, can make comparison of outcomes difficult. This is the first study that compares standard epi-off CXL, TECXL, and CACXL simultaneously in one clinic setting. The results of this study suggest that both TECXL and CACXL are comparable to standard epi-off CXL in regard to structural out- comes, as demonstrated by halting progression of ectasia and reduction in Kmax, as well as functional outcomes, as evidenced by improve- ment in CDVA. Although the exact cut-off for a "thin" cornea remains a topic of debate, TECXL and CACXL performed on corneas as thin as 357 microns in this study showed effective results and no evidence of endothelial toxicity. While the reduction in Kmax was significant among all groups, the greatest reduction was seen in the CACXL group, which was possibly related to the relatively higher baseline Kmax in this group, or the thinner baseline pachymetry— continued from page 20 Each of these three techniques must be chosen judiciously and can play a useful role in the treatment of patients with progressive keratoconus …

• Cover