Abstract
Purpose: :
To analyze the normal peripapillary choroidal thickness utilizing a commercial spectral domain optical coherence tomography (OCT) device (Cirrus HD-OCT) and determine the inter-grader reproducibility of this method.
Methods: :
36 eyes of 36 normal patients seen at the New England Eye Center were included in the study. All patients underwent high-definition scanning with the Cirrus HD-OCT. Two raster scans were obtained per eye, a horizontal and a vertical scan, both centered at the optic nerve. Two independent graders individually measured the choroidal thickness. The choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid-scleral junction at 500 µm intervals away from the optic nerve in the superior, inferior, nasal and temporal quadrants. Analysis of variance testing was conducted to compare mean choroidal thicknesses. Inter-grader reproducibility was assessed by intraclass correlation coefficient (ICC) and Pearson's correlation coefficient. Average choroidal thickness in each quadrant was compared to retinal nerve fiber layer (RNFL) thickness in their respective quadrants.
Results: :
The peripapillary choroid in the inferior quadrant was significantly thinner compared to all other quadrants (p< 0.001). None of the other quadrants were significantly different from each other in terms of thickness. The inferior peripapillary choroid was significantly thinner compared to all other quadrants at all distances away from the optic nerve (p< 0.001). Generally, the peripapillary choroid increases in thickness the farther it was away from the optic nerve, eventually approaching a plateau. ICC ranged from 0.62 to 0.93 and Pearson's correlation coefficient ranged from 0.74 to 0.95 (p< 0.001). Neither RNFL thickness nor average age was significantly correlated with average choroidal thickness.
Conclusions: :
Since manual measurement of peripapillary choroidal thickness is reproducible between graders, it suggests that this method is accurate. The inferior peripapillary choroid was significantly thinner than all other quadrants (p< 0.001). This suggests that the increased susceptibility of the inferior quadrant of the optic nerve to glaucomatous damage may be attributable to the normal vascular distribution in this area.
Keywords: imaging/image analysis: clinical • choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)