1, 4 and 8 months follow-up of biomechanical efficacy and keratocyte repopulation after corneal stiffening by WST-D and near infra-red (NIR) illumination in rabbits

Session Details

Session Title: Moderated Poster Session: Miscellaneous
Session Date/Time: Saturday 11/02/2017 | 13:00-14:15
Paper Time: 13:16
Venue: Poster Area


First Author: J. Brekelmans THE NETHERLANDS
Co Author(s): A. Goz  A. Brandis  M. Dickman  R. Nuijts  A. Scherz  A. Marcovich  

Abstract Details

"Purpose:

The current study sets out to determine the long-term efficacy and safety of WST-D/NIR treatment for stiffening the cornea. Elastic moduli and histological sections of treated and untreated corneas of New Zealand White (NZW) rabbits were compared pairwise, 1, 4, and 8 months after treatment.

Setting:

Academic research institute. In-vivo laboratory study.

Methods:

One eye of 19 NZW rabbits was mechanically de-epithelialized and WST11 (Steba-Biotech, France) 2.5mg/ml combined with dextran-500 (WST-D) was applied topically for 20 minutes. Subsequently, samples were irradiated by a NIR (755nm) laser at 10mW/cm2 for 30 minutes. Untreated fellow eyes served as controls. One (n=6), 4 (n=9), or 8 (n=4) months after treatment corneal strips were cut in superior-inferior direction for extensometry testing. Remaining corneal tissue was fixed in 4% formaldehyde for histological examination where keratocyte distribution was evaluated at a 200x magnification in 4µm thick hematoxylin and eosin stained sections.

Results:

Four eyes were excluded due to problems during handling or technical errors. Elastic modulus after treatment, 16.0±2.3MPa, 18.1±4.5MPa and 18.6±3.6MPa, was significantly higher compared to paired controls, 9.6±3.6MPa [p=0.008], 12.6±2.3MPa [p=0.003], 14.2±3.6MPa [p=0.10], at 1, 4, and 8 months respectively. Contralateral eyes displayed a nonsignificant [p=0.11] increase in elastic modulus over time. A decrease in keratocyte count at the anterior part of the cornea was seen directly after treatment, however after eight months repopulation had occurred with similar keratocyte distribution for treated and untreated corneas. Corneal thickness was comparable between treated and untreated corneas.

Conclusions:

WST-D/NIR treatment, with parameters similar to the Dresden protocol, results in a significant and persistent increase in corneal stiffness. The gradually increasing stiffness seen in the untreated control eyes corresponds to ageing induced stiffening and confirms the suitability of this model for determining long-term results in corneal cross-linking. Initial keratocyte apoptosis is seen in the anterior stroma, however repopulation of keratocytes has occurred 8 months after treatment. The safe nature of NIR light allows treatment of corneas of any thickness without endangering corneal endothelium or deeper ocular structures, benefiting patients deemed unsuitable for currently clinically applied Riboflavin/UVA cross-linking.

Financial Disclosure:

gains financially from product or procedure presented, research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented"