Mosaicking the subbasal nerve plexus by guided eye movements

A growing number of studies provide evidence that the morphology of the corneal subbasal nerve plexus (SNP), examined by corneal confocal microscopy (CCM), is a sensitive marker for diabetic peripheral neuropathy. However, it has been established that the field of view of a single CCM image (≈0.16 mm(2)) is insufficient for reliable assessment of corneal nerve fiber morphology. The present work proposes a highly automated technique for imaging an extended area of the SNP and creating large-scale montages. A moving fixation target is presented on a small display in front of the nonexamined eye. By guiding the viewing direction of the subject in an expanding spiral pattern, the scanned corneal area is continuously expanded. Specialized software algorithms subsequently assemble a mosaic image from the acquired CCM image data. The proposed technique was applied in 12 healthy subjects. Montage images of the SNP were successfully created from all examinations performed. The mean imaged SNP area was 9.86 mm(2) (range, 1.62-18.31 mm(2)). The mean CCM duration was 65.33 seconds (range, 14.58-142.58 seconds). The key advances embodied in the proposed technique are its high degree of integration and automation (both for image acquisition and image processing) and the resulting short duration of CCM. By providing an easy-to-use tool for obtaining large-scale mosaic images of the SNP, this technique has the potential to facilitate larger clinical trials where SNP morphology is used as a surrogate marker for peripheral neuropathy.