Excimer laser-assisted selective corneal de-epithelialization for corneal collagen cross-linking

Session Details

Session Title: Corneal Cross-Linking

Session Date/Time: Monday 16/09/2019 | 16:00-18:00

Paper Time: 16:00

Venue: South 5

First Author: : J.Brekelmans THE NETHERLANDS

Co Author(s): :    M. Dickman   S. Verma   S. Arba Mosquera   A. Scherz   R. Nuijts   I. Pinkas   R. Goldschmidt   A. Goz   T. Berendschot   A. Brandis   A. Marcovich

Abstract Details

Purpose:

Corneal collagen cross-linking (CXL) has shown to provide an effective treatment modality in arresting corneal ectasia, and is currently being investigated for other indications. A major downside of current CXL procedure is the need of de-epithelialization, related to discomfort and potential complications such as infection and haze formation. The epithelium is removed, currently in full, to allow for sufficient Riboflavin (RF) penetration to ensure effective CXL treatment. In this study, we set out to evaluate the possibilities of selectively removing the epithelium using an excimer laser, creating epithelial channels while over 60% of the epithelium remains in situ.

Setting:

Academic research institute. Ex vivo study, porcine eyes.

Methods:

We included 244 paired ex-vivo porcine corneas. The epithelium was removed either fully by mechanical debridement (n=120) or selectively (to different extents) using excimer laser (n=124). De-epithelialized corneas were then impregnated with hypo- or hyperosmolar formulations of the chromophores RF (RF, n=24 and RF-D, n=56, respectively) or WST11 (WST11, n=44 and WST-D, n=56, respectively), or kept unimpregnated (n=84). Sixty corneas were subsequently exposed to ultraviolet A (UVA) or near-infrared (NIR) irradiation, inducing CXL, while their paired contralateral eyes served as untreated controls. Biomechanical testing, corneal light absorption and fluorescence were measured to determine corneal stiffening, chromophore saturation and diffusion patterns.

Results:

Corneal CXL, either RF or WST11 based, resulted in significant corneal stiffening (p<0.001) regardless of the chromophore formulation and either full or partial epithelial removal (p=0.24 RF/UVA; p=0.55 WST11/NIR). Corneal chromophore concentration was significantly lower in partially de-epithelialized corneas compared to full debridement (p<0.001). Nonetheless, full chromophore penetration was observed in all RF treated samples, both in de-epithelialized and epithelialized areas. Similarly, no difference in penetration depth was seen with WST11 impregnated samples, when removing only 40% of the epithelium (p=0.48).

Conclusions:

Selective epithelial removal (40%) using excimer laser may allow effective corneal crosslinking while reducing treatment burden. Nonetheless, chromophore penetration depth and stromal concentration may be reduced. This may have safety implications for RF/UVA CXL, since UVA irradiation may be less attenuated. However, this is not an issue with WST11 based CXL due to the safe nature of NIR irradiation. Further studies using an in vivo model are needed to evaluate the safety and effectiveness of CXL after partial epithelial removal.

Financial Disclosure:

gains financially from product or procedure presented, receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, is employed by a for profit company with an interest in the subject of the presentation