Abstract
Purpose: :
To characterize the retinal ganglion cell (RGC) loss in a mouse model with elevated IOP using an in vivo imaging approach.
Methods: :
A mouse model with elevated IOP was induced in WT mice and Thy1-CFP mice aged 3 to 6 months by injecting the microbeads into the anterior chamber. Awake IOP was measured every other day using a Tonolab tonometer after microbead injection. The degree of RGC loss in WT mice with elevated IOP was assessed quantitatively using immunohistochemical staining (both Brn3b and DAPI) of RGCs in fixed retina 1, 2, 3, and 4 weeks after IOP elevation. In Thy1-CFP mice with elevated IOP, the number of CFP-positive RGCs in the same area of retina was assessed every week in vivo using a confocal scanning laser microscope for 6 weeks. The results from in vivo imaging of Thy1-CFP mice were compared with the results from WT mice with immunohistochemical staining.
Results: :
A progressive loss of RGC was found after IOP elevation with 5.2%, 11.2%, 19.6%, 26.6% of RGCs at 1, 2, 3 and 4 weeks after IOP elevation using immunohistochemical staining. In Thy1-CFP mice with elevated IOP, the earliest decrease of CFP-positive RGCs was detected at 2 days after IOP elevation. Three weeks after the IOP elevation, CFP-positive RGCs were reduced by 21%. CFP-positive RGCs continued to decrease in number over time and, 6 weeks after IOP elevation, CFP-positive RGCs were reduced by 30%. These results are comparable with the results from immunohistochemical staining of WT mice with elevated IOP.
Conclusions: :
Anterior chamber injection of microbead effectively induced IOP elevation and a progressive RGC death. In vivo confocal scanning laser microscope imaging provides an effective and noninvasive approach to monitor the progress of RGC damage.
Keywords: retina: proximal (bipolar, amacrine, and ganglion cells) • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • ganglion cells