Purpose:
To compare intra-visit and inter-visit reproducibility of retinal thickness and retinal nerve fiber layer (RNFL) measurements amongst adult and pediatric patients using the Spectralis Spectral Domain OCT.
Methods:
One eye of 54 adult and 32 pediatric consented glaucoma patients, glaucoma suspects, or normal controls, were imaged using the Spectralis OCT (Heidelberg Engineering). Two baseline images were obtained at the initial visit as the reference scans. A retinal thickness map centered on the macula was obtained as a 30 X 25 degree raster scan with 61 lines(see figure). Next, a single circular RNFL thickness scan, set at 20 degrees, centered on the optic nerve was obtained. Both scans were then repeated twice the same day for intra-visit reproducibility and once on a separate day for inter-visit reproducibility. The retinal thickness measurements were calculated using inbuilt software, along a rectangular grid, and coefficient of variance (COV) was calculated for each 3x3 degree square. The COV of the average RNFL measurement as well as along six equally divided quadrants of the circle was calculated.
Results:
The average COV for all squares in the macular grid was 0.65% (adults) and 0.65% (pediatric) for the intra-visit measurements; and 0.76% (adults) and 0.66% (pediatric) for inter-visit comparison. RNFL thickness scans had an average COV of 2.38% (adults) and 2.28% (pediatric) for the intra-visit measurements; and 2.57% (adults) and 2.45% (pediatric) for inter-visit comparison.
Conclusions:
Reproducibility of macular thickness measurements were better than that of the peripapillary RNFL measurements in both adult and pediatric patients (p<0.05). Given the high reproducibility due to the tracking function of the Spectralis OCT, with the appropriate algorithm, both, retinal thickness and RNFL measurements may represent a reliable objective test to monitor glaucoma progression.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical