Abstract
Methods: :
Dark Agouti (DA) rats (n = 20) with surgically-induced chronic ocular hypertension (OHT) in the left eye were imaged in vivo using methods we have previously established. RGC apoptosis was assessed using DARC and measurements of RNFL, inner plexform layer (IPL), and inner nuclear layer (INL) thickness were acquired simultaneously using the OCT Spectralis (Heidelberg Engineering). Imaging was performed in vivo at baseline, 3 and 8 weeks after IOP elevation.
Results: :
DARC RGC apoptosis reached peak levels at 3 weeks following OHT induction. At the same time point, all the retinal layers measured were significantly thinner (mean RNFL 32.12 µm, IPL 54.86 µm, and INL 27.44µm) compared to baseline (mean RNFL 51.05 µm, IPL 65.08 µm, and INL 32.48 µm) (p<0.01). Among them, the RNFL was notably affected, showing 36.4% reduction in thickness compared to the IPL (15.9%) and INL (15.5%).
Conclusions: :
Our results show that the maximal RGC apoptosis occurs simultaneously with documented significant changes in the RNFL in experimental glaucoma. Significant reduction in INL and IPL thickness suggests other retinal neurons, such as bipolar, horizontal and amacrine cells may be also affected in glaucoma. These results highlight the advantages of using real time parameters with imaging to record both cellular and tissue changes in the retina in glaucoma models.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • ganglion cells