Fig 1

Extraction and clarification of ESM. (A) Processing of ESM: ⅰ, demineralization in EDTA/imidazole solution for 24 h, the calcareous shell completely dissolved; ⅱ, ESM carefully peeled off and thoroughly rinsed; ⅲ, a clean, semi-transparent ESM0 membrane; iv, ESM0 immersed in 1 mol L−1 NaOH for varying durations (0.5–4 h) to yield a series of clarified samples. (B) Macroscopic images of ESM after alkaline treatment. (C) Visible-light transmittance spectra of ESM."

Fig 2

Impact of alkaline treatment on the microstructure, chemical composition, and transparency mechanism of ESM. (A) Representative SEM images: ⅰ, outer membrane; ⅱ, inner membrane. (B) EVG staining images. (C–E) High-resolution XPS C 1s and O 1s spectra of ESM0, ESM1, and ESM4, respectively. (F) FTIR spectra of ESM. (G) PS content of ESM. (H) Schematic illustration of the transparency mechanism."

Fig 3

Regulation of the physicochemical properties of ESM by alkaline treatment. (A) Thickness, measured by confocal microscopy. (B) Saturated water content. (C) Collagenase degradation test. (D, E) Static water contact angle: representative images and quantitative analysis. (F) Mean flow pore diameter. (G, H) Tensile stress-strain curves and ultimate tensile strength. (*p < 0.05, **p < 0.01, ***p < 0.001)."

Fig 4

In vivo repair efficacy of ESM in a rabbit anterior-lamellar corneal defect model. (A) Schematic diagram of the experimental design: a partial-thickness corneal defect with a diameter of 5 mm and a depth of 200 μm was created in the left eye of New Zealand white rabbits. A 7 mm ESM1 patch was implanted and sutured in place, while the non-implanted group served as a negative control. (B) Slit-lamp microscopic appearance of ESM-mediated corneal repair. (C) Representative anterior segment optical coherence tomography (AS-OCT) images of rabbit corneas at 1, 2, 4, and 8 weeks post-surgery. (D) Corneal topography of rabbit corneas at 8 weeks post-surgery. (E) Quantitative analysis of corneal epithelial healing over time."

Fig 5

Histological evaluation of ESM in rabbit corneal defect repair. (A) Representative images of hematoxylin and eosin (H&E) staining at 8 weeks post-surgery. (B, C) Quantitative analyses of central corneal stromal and epithelial thicknesses, respectively. (D) Immunofluorescence staining images of DAPI (blue) and α-SMA (green). (E) Immunofluorescence staining images of DAPI (blue) and tight-junction protein Occludin (green). (F, G) Quantitative analyses of α-SMA and Occludin expression areas from fluorescence staining images, respectively. (*p < 0.05, **p < 0.01)."