After transmittance measurements, the corneas were fixed with 4% buffered paraformaldehyde and embedded in paraffin. Sections 5-μm thick were stained with Picrosirius-red (0.1% Sirius red in saturated aqueous picric acid for 1 h) (Junqueira et al., 1979) . Sections were examined under an Axiophot microscope (Zeiss Axiophot HBO-50; Carl Zeiss, Oberkochen, Germany) with polarized light. Photomicrographs were captured using the AxioCam HRc Digital Camera and Axiovision release 4.8 software (Carl Zeiss) under the same plane of polarization. Polarization colors are associated with different collagen fiber thicknesses, packing density, and spatial arrangement (Dayan et al., 1989) . Orange to red colors were correlated with thick collagen fibers that were tightly packed and well aligned. Yellowish-green colors were correlated with thinner fibers that were less tightly packed.
Other 5-μm sections were stained with a modification of the Gomori's Silver Impregnation technique to demonstrate the presence of collagen type III fibers [54] . The sections were examined under an Axiophot microscope (Zeiss Axiophot HBO-50; Carl Zeiss, Oberkochen, Germany) and photomicrographs were obtained with an AxioCam HRc Digital Camera and Axiovision release 4.8 software (Carl Zeiss).
Other 5-μm sections were stained with a modification of the Gomori's Silver Impregnation technique to demonstrate the presence of collagen type III fibers [54] . The sections were examined under an Axiophot microscope (Zeiss Axiophot HBO-50; Carl Zeiss, Oberkochen, Germany) and photomicrographs were obtained with an AxioCam HRc Digital Camera and Axiovision release 4.8 software (Carl Zeiss).