Abstract
Purpose: :
To investigate the feasibility of generating OCT fundus images (OFI) from datasets acquired with a Spectralis OCT instrument (Heidelberg Engineering) and using the en-face information encoded in the OFIs to evaluate the accuracy of the Spectralis eye tracking system.
Methods: :
Ten normal volunteer were enrolled in this study. OCT scans were acquired on each eye, using a Spectralis OCT instrument. A scan pattern consisting of 193 B-scans, each averaged 11 times, covering a retinal area of 20x20 degrees was used. The scan target included the optic disc, in order to maximize the number of easily recognizable features in the OFIs. The scans were exported as .avi files and loaded into a Matlab custom program to process the images and generate the corresponding OFIs. The SLO fundus images were also extracted and compared to the OFI after a suitable rescaling.
Results: :
The characteristics of the OCT signal along B-scans as well as across different B-scans are quite variable on datasets acquired with the Spectralis, making it difficult to obtain OFIs of uniformly "good quality". The retinal features visible on the OFIs match well with those on the SLO image, with differences typically below 100 µm over the 20x20 degrees area. Larger discontinuities in the blood vessels are occasionally visible in the OFIs. In our sample their size did not exceed 200 µm.
Conclusions: :
The OFIs obtained from Spectralis OCT datasets match well with the SLO images, showing that the tolerance of the eye tracking system is tipically well within 100 µm. However, occasionally clear discontinuities in features across B-scans can be observed.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical • retina