Purchase this article with an account.
D. J. Brown, N. Morishige, A. Neekhra, D. S. Minckler, J. V. Jester; Application of Second Harmonic Imaging Microscopy to Assess Dynamic Structural Changes in Optic Nerve Head Structure. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3294.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
This study investigated the feasibility of non-invasively examining the three-dimensional structural changes of the human lamina cribrosa induced by increased ocular pressure using second harmonic generated (SHG) signals from collagen fibers. The ability to dynamically visualize the lamina cribrosa may clarify variations in topographic vulnerability of the laminar structures during glaucomatous injury and damage to optic nerve axons.
Fresh, post mortem human eyes were dissected to remove the retrobulbar optic nerve at the level of the sclera. The eyes were cannulated with a 25 guage trocar system attached to a reservoir of buffered saline solution to adjust intraocular pressure. The laminar tissues were analyzed by SHG using a femtosecond laser tuned to 800 nm. SHG signals were collected using a 350-450 nm band pass filter. 300 micron stacks of images were collected using Zeiss 510 LSM software and analyzed using Meta Imaging Series software.
The method allows for visualization of the "channels" (openings or pores) between collagen beams of the lamina cribrosa through which nerve fiber bundles pass into the orbital optic nerve. With an increase in pressure, a majority of these channels increased in area (P<0.001). However, channels near the peripheral margin of the structure were generally compressed.
Imaging of SHG signals from collagen allows rapid, non-invasive, near real- time visualization of the lamina cribrosa and the immediate changes in its structure due to increased ocular pressure. The data demonstrates that a change in ocular pressure increases the size of channels in the mid-central and mid-peripheral regions of the ONH while pores at the periphery generally collapse. This finding correlates with the anatomic and clinical topography of optic nerve injury in glaucoma in which the peripherally located ganglion cells responsible for peripheral visual field, projecting to the peripheral optic nerve, are most vulnerable early in the injury process.
This PDF is available to Subscribers Only