Abstract
Purpose :
In vivo confocal microscopy (IVCM) imaging has been applied to evaluate structural alternation of cornea including corneal nerve fibers (CNF). Analysis methods for IVCM images are reported, but limited and not standardized so far. Our purpose is to detect the area of CNF (ACNF) with open and clear criteria, using new commercially available software: Quick Grain® (Inotech, Hiroshima, Japan) that can analyze IVCM images automatically.
Methods :
Eleven healthy volunteers were included in this study. CNF were visualized by Heidelberg Retina Tomograph 3 equipped with a Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany
). The highest-quality image was selected per 1 person to be analyzed. The selected image had a definition of 384 x 384 pixels over an area of 0.16 mm2. At first, in order to distinguish CNF from background, some spots whose size was smaller than 5 pixels were eliminated as luminance unevenness. Following this procedure, we adjusted the threshold of brightness to detect CNF adequately. This threshold was adjusted to match manually detected shapes of CNF. In accordance with these settings, ACNF was detected automatically, and then compared with manually detected ACNF.
Results :
The mean automatically detected ACNF and manually detected ACNF were 4.8%/image and 4.6%/image. Automatically detected ACNF was significantly correlated with manually detected ACNF (p<0.01).
Conclusions :
Our results suggested that this new method can be an objective index to detect ACNF. Furthermore, threshold to detect objects can be adjusted, therefore this method would allow us to measure area of other corneal structures such as normal keratocytes and dendritic cells.
This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.