An explanation for the central to peripheral thickness variation in the mouse cornea.

BACKGROUND

The mouse corneal stroma varies in thickness across its diameter. The purpose of the present study was to explain this variation and to advance our understanding of stromal lamellar architecture in the mammalian cornea.

METHODS

Eight C57BL/6 mice were killed, eyes enucleated, immersed in 2% glutaraldehyde fixative, processed and sectioned transversely for light and transmission electron microscopy. Transmission electron micrographs were assembled into montages and printed at 5000× magnification and used for lamellar counts and thickness assessments.

RESULTS

The mouse cornea had an average of 49.8±2.4 lamellae centrally averaging 2.1µm in thickness versus 35.5±3.0 lamellae, averaging 1.9µm in thickness peripherally. The central to peripheral decrease in number lamellae and lamellar thickness measured utilizing the transmission electron microscope was statistically significant (P<0.005).

CONCLUSIONS

This study demonstrated that the thickness difference between the thicker central and thinner peripheral mouse cornea is explained primarily by the number of lamellae present and that the peripheral lamellar dropout occurred in the anterior 2/3 of stroma. The decreased lamellar count towards the periphery suggested that not all lamellae cross the cornea limbus to limbus. These findings may be relevant to the thickness variation of the human cornea.