Safety and Long-term Scleral Biomechanical Stability of Rhesus Eyes after Scleral Cross-linking by Blue Light

ABSTRACT

Purpose: To assess the safety and long-term scleral biomechanical stability of rhesus eyes after blue light scleral CXL by investigating the biomechanical and microstructural changes.

Methods: Seven rhesus monkeys (14 eyes) were observed in this study. All right eyes received blue light scleral CXL at the superior temporal equatorial sclera, and the left eyes served as controls. Biological ocular parameters were followed up to 1 year after scleral CXL. Stress-strain measurements of three rhesus sclera were measured, three rhesus retinas were examined histologically by H&E and TUNEL staining. And the microstructure of both the sclera and retina were observed by transmission electron microscopy at 1 year.

Results: As for the retinal thickness, choroidal thickness, flow density of retinal superficial vascular networks and flash electroretinography (f-ERG) results, no significant differences were observed between the paired eyes at 1 year (P >.05). At the same time, the scleral collagen fibril distribution was much tighter, and the scleral biomechanical properties were significantly increased in the experimental eyes. However, apoptotic cells and retinal ultrastructural changes could still be found in the retina of the experimental eyes.

Conclusion: This study demonstrates that blue light scleral CXL could effectively increase the scleral stiffness of the rhesus eye for at least 1 year, but ultrastructural change was still observed in the retina of scleral CXL eye. Therefore, the long-term intraocular safety of the blue light scleral CXL technique for preventing myopia progression should be investigated further.

KEYWORDS:

• Blue light
• cross-linking
• sclera
• rhesus monkey
• safety

Acknowledgments

This work was supported by the National Natural Science Foundation of China under Grant [81570877 and 81873682; http://www.nsfc.gov.cn/]; the 215 High-Level Talent Fund of Beijing Health Government under Grant [number 2013-2-023; http://www.bjchfp.gov.cn/]; and the priming scientific research foundation for the junior researcher in Beijing Tongren Hospital, Capital Medical University (http://www.trkygls.com/business/login.jsp).

Declaration of interest statement

The authors declare that they have no conflicts of interest.

Ethical approval for animal experiments

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Author contributions

Conceptualization: Fengju Zhang, YuLi

Data curation: Yu Li, Lingbo Lai, Chong Liu, Xiaotong Lv, Mengmeng Wang

Formal analysis: Yu Li, Mingshen Sun

Funding acquisition: Fengju Zhang, Yu Li

Investigation: Yu Li, Chong Liu, Xiaotong Lv

Methodology: Yu Li

Project administration: Fengju Zhang