Abstract
Purpose :
To investigate the architecture and distribution of collagen and elastin in human limbal conjunctiva, Tenon's layer, and sclera.
Methods :
The limbal conjunctiva, Tenon's layer, and sclera of human donor corneal buttons were imaged with an inverted two-photon excited fluorescence microscope.(FluoView FV-1000, Olympus, Central Valley, PA). No fixation process was necessary. Laser (Ti :Sapphire) was tuned at 850nm for two photon excitation. Backscatter signals of SHG and autofluorescence (AF) were collected through a 425/30 nm emission filter and a 525/45 emission filter, respectively. Multiple, consecutive, and overlapping (z-stack) images were acquired. Collagen signals were collected with SHG, whereas elastin signals were collected with AF.
Results :
The size and density of collagen bundles varied widely depending on depth: increasing from conjunctiva to sclera. In superficial image planes, collagen bundles were < 10 um, in a loose, disorganized arrangement. In deeper image planes (episclera and superficial sclera), collagen bundles were thicker (> 100 um) and densely packed. Comparatively, elastin fibers were thinner and sparse, but also increased in density at deeper image planes. The direction of elastin fiber was independent of collagen fiber in superficial layers but it was partially dependent in deep sclera. In deep sclera, elastin fibers wove through collagen inter-bundle gaps. At the limbus, elastin fibers were compact and distributed perpendicular to the limbal annulus.
Conclusions :
Two-photon excited fluorescence microscopy has enabled us to understand in greater detail, the collagen and elastin architecture of the human limbal conjunctiva, Tenon's layer, and sclera.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.