Customized epithelial debridement for thin ectatic corneas undergoing corneal cross-linking: epithelial island cross-linking technique

Abstract

Thin corneas with a minimum corneal thickness less than 400 μm after epithelial removal represent a contraindication to standard epithelium-off cross-linking (CXL) treatment due to a significant endothelial cell density decrease and potentiality of permanent haze development. Preoperative swelling of the cornea with hypoosmolar riboflavin solutions broadens the spectrum of CXL indications to thin corneas. However the iatrogenic swelling effect might not be durable throughout the CXL procedure increasing the risk of postoperative complications. The transepithelial CXL technique proposed for thin corneas demonstrated poor clinical results and mid- to long-term keratoconus instability. The epithelial island CXL technique with customized pachymetry-guided epithelial debridement was evaluated by means of in vivo laser scanning confocal microscopy, corneal topography, and clinical examination in a 1-year follow-up, in order to assess if it may be considered an alternative surgical option for keratoconic patients with thin corneas undergoing corneal collagen CXL. According to our clinical and in-vivo micro-morphological results the technique results safe, and efficacious in stabilizing progressive keratoconus and may be considered a valid option in the treatment of thin ectatic corneas alone or in combination with hypoosmolar or dextran-free riboflavin solutions.

A Review of Collagen Cross-Linking in Cornea and Sclera

“…Though thin cornea could be swelling to safe thickness (over 400 μ m) with hypoosmolar riboflavin solution, the iatrogenic swelling effect was short acting, and the thinnest CT decreased significantly at the end of hypoosmolar riboflavin application [ 53 ], thus increasing the risk of corneal scarring and endothelial cells' damage. To solve this problem, a new technique that is epithelial island cross-linking (EI-CXL) with customized pachymetry-guided epithelial debridement was introduced [ 54 ]. In Mazzotta Cosimo and Ramovecchi study [ 54 ], EI-CXL technique was performed on 10 keratoconus patients with thin cornea (range 368–391 μ m).…”

“…To solve this problem, a new technique that is epithelial island cross-linking (EI-CXL) with customized pachymetry-guided epithelial debridement was introduced [ 54 ]. In Mazzotta Cosimo and Ramovecchi study [ 54 ], EI-CXL technique was performed on 10 keratoconus patients with thin cornea (range 368–391 μ m). The epithelium in the paracentral and midperipheral cornea where the cornea is thicker was removed carefully and the thin apical cornea epithelium was preserved.…”

Late Stage of Corneal Decompensation Caused by Progressive Keratoconus: Can We Treat It and Save the Cornea?

“…Mazzotta and Ramovecchi 2014 presented a new surgical option for treating thin corneas known as epithelial island cross-linking technique. Partial epithelial islands on corneal thinnest point area left together with intrastromal riboflavin shield make a safe barrier for corneal endothelium protection [ 27 ]. Hafezi 2011 reported a failure of collagen cross-linking with hypoosmolar riboflavin solution in an extremely thin cornea and concluded that the increase in biomechanical resistance was not sufficient to stop the progression of the disease; therefore, minimal preoperative stromal thickness of 330 μ m needs to be a limit for a successful CXL procedure [ 28 ].…”

Corneal collagen cross-linking (CXL) in thin corneas

“…Four weeks after the treatment, stromal haze and demarcation line were detected in the corneal areas with epithelial debridement, but not in the areas with intact epithelium; deepithelialized stroma outside the cone region displayed total keratocyte apoptosis and honeycomb-like edema, whereas it was minimal beneath the intact epithelium [ 69 ]. In contrast, Mazzotta et al [ 70 ] demonstrated keratocyte apoptosis at an average depth of 160 μm under the epithelial island compared to 250 μm under the de-epithelialized area in 10 eyes with 1-year follow-up.…”