title: A Novel Approach to Analyze the Progression of Measured Corneal Sub-Basal Nerve Fiber Length in Continuously Expanding Mosaic Images.
abstract: Purpose/Aim of the study: A recently proposed technique enables the generation of continuously increasing mosaic images of the corneal sub-basal nerve plexus (SNP) using in vivo corneal confocal microscopy (CCM). The aim of the present study was to investigate the progression of the corneal nerve fiber length (CNFL) measured in the growing mosaic images with regard to their increasing area.
  
  
  
  Five large datasets from three healthy volunteers were examined using the proposed CCM technique. Intermediate mosaic images were created and assessed for CNFL.
  
  
  
  The measured CNFL progression shows both over- and underestimation of the CNFL for small observed areas. Increasing the mosaic image area stabilizes the CNFL values and reduces the moving variance in all five datasets. The relative deviation of means from values of first and second examination of two of the subjects shows high differences for an observed area of <1.5 mm2.
  
  
  
  The present examination provides two measures to quantify different area-dependent aspects of the CNFL measured in an expanding mosaic image. The moving variance measures how stable the CNFL can be considered at a certain mosaic size. The relative deviation of means from two repeated CCM examinations on the other hand gives some indication on the level of reliability that can be expected from the measured CNFL. The progression of CNFL in the examined datasets manifests a potentially very high variability for mosaic sizes of less than about 1.5 mm2. Above that size, CNFL progression and the intra-patient relative deviations both stabilize significantly in all five datasets. The results of the present examination suggest a recommendation for a minimum sampled area of the central SNP of 1.5 mm2for reliable and meaningful measurement of CNFL.
authors: a Institute for Applied Computer Science , Karlsruhe Institute of Technology (KIT) , Karlsruhe , Germany.
authors: Stephan
authors: S
authors: Allgeier
authors: b Institute of Anatomy , University of Leipzig , Leipzig , Germany.
authors: Karsten
authors: K
authors: Winter
authors: a Institute for Applied Computer Science , Karlsruhe Institute of Technology (KIT) , Karlsruhe , Germany.
authors: Georg
authors: G
authors: Bretthauer
authors: c Department of Ophthalmology , University of Rostock , Rostock , Germany.
authors: Rudolf F
authors: RF
authors: Guthoff
authors: c Department of Ophthalmology , University of Rostock , Rostock , Germany.
authors: Sabine
authors: S
authors: Peschel
authors: a Institute for Applied Computer Science , Karlsruhe Institute of Technology (KIT) , Karlsruhe , Germany.
authors: Klaus-Martin
authors: KM
authors: Reichert
authors: c Department of Ophthalmology , University of Rostock , Rostock , Germany.
authors: Oliver
authors: O
authors: Stachs
authors: a Institute for Applied Computer Science , Karlsruhe Institute of Technology (KIT) , Karlsruhe , Germany.
authors: Bernd
authors: B
authors: Köhler
mesh_terms: D000328:Adult; D003315:Cornea / Q000294:innervation*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology*; D015203:Reproducibility of Results; D014276:Trigeminal Nerve / Q000033:anatomy & histology*
keywords: Corneal nerve fiber length; corneal sub-basal nerve plexus; guided eye movements; mosaic image; parameter variability