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Sheng-Lin Lee, YANG-FANG CHEN, Chen-Yuan Dong; Depth-dependent Corneal Suprastructure by Fourier-transformed Second Harmonic Generation Microscope. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3912.
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© ARVO (1962-2015); The Authors (2016-present)
High tensile strength with optical clarity is the unique characteristic of cornea and the key role in corneal tissue development and wound healing. However, details on the suprastructure of corneal stroma are still not fully understood. We hypothesize that the depth-dependent structure of corneal lamella could be quantified non-invasively using SHG microscopy and optimized Fourier-transform techniques
Specimens of adult avian cornea were used in this study. The fresh corneal samples were fixed with 10 % formaldehyde in phosphate-buffered saline (PBS) solution. Prior to the imaging experiment, corneas were dissected as wide strips along the temporal-nasal direction and marked with scissors on the temporal side to identify the specimen’s orientation. When doing experiments, the samples were enclosed in a confinement chamber attached to a cover slide and sealed with a cover glass and high-vacuum grease. Through the combination of the second harmonic generation (SHG) microcopy and post-processing of Fourier-transform images, mature avian corneas are investigated to observe and track the depth-dependent structure of the corneal stroma at different position.
Our results show that the anterior stroma behaves like a fan-like distribution of successively and counterclockwisely rotated fibrous lamellae for paired corneas from the same chicken. However, the posterior stroma maintains a non-rotating pattern while increasing in depth. The overall thickness of anterior stroma was 300 ± 14μm of the left and 279 ± 11μm of the right cornea. Results showed no significant difference between the total thickness of the left and right cornea at p < 0.05. But the thickness of anterior stroma was different between left and right cornea at p < 0.05 (T = 2.54, p = 3.5E-02).
Through quantitative analysis, we determine the natural transition between the anterior and posterior stroma. These findings enhance our understanding of biophysical behavior in the chicken cornea model. Moreover, the Fourier-transform-based modality, in combination with SHG microscopy, serves as a promising tool to determine collagen alignment in embryonic development, tissue engineering and corneal diseases.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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