Comparative quantitative assessment of the human corneal sub-basal nerve plexus by in vivo confocal microscopy and histological staining.
PurposeThis study was designed to compare and contrast quantitative data of the human corneal sub-basal nerve plexus (SBP) evaluated by two different methods: in vivo confocal microscopy (IVCM), and immunohistochemical staining of ex vivo donor corneas.MethodsSeven parameters of the SBP in large-scale IVCM mosaicking images from healthy subjects were compared with the identical parameters in ex vivo donor corneas stained by β-III-tubulin immunohistochemistry. Corneal nerve fiber length (CNFL), corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), average weighted corneal nerve fiber tortuosity (CNFTo), corneal nerve connection points (CNCP), average corneal nerve single-fiber length (CNSFL), and average weighted corneal nerve fiber thickness (CNFTh) were calculated using a dedicated, published algorithm and compared.ResultsOur experiments showed significantly higher values for CNFL (50.2 vs 21.4 mm/mm2), CNFD (1358.8 vs 277.3 nerve fibers/mm2), CNBD (847.6 vs 163.5 branches/mm2), CNFTo (0.095 vs 0.081 μm-1), and CNCP (49.4 vs 21.6 connections/mm2) in histologically staining specimens compared with IVCM images. In contrast, CNSFL values were higher in IVCM images than in histological specimens (32.1 vs 74.1 μm). No significant difference was observed in CNFTh (2.22 vs 2.20 μm) between the two groups.ConclusionsThe results of this study have shown that IVCM has an inherently lower resolution compared with ex vivo immunohistochemical staining of the corneal SBP and that this limitation leads to a systematic underestimation of several SBP parameters. Despite this shortcoming, IVCM is a vital clinical tool for in vivo characterization, quantitative clinical imaging, and evaluation of the human corneal SBP.
Department of Ophthalmology, University of Rostock, Rostock, Germany.|Institute for Biomedical Engineering, University of Rostock, Rostock, Germany.
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Kowtharapu
Institute of Anatomy, Faculty of Medicine, University of Leipzig, Leipzig, Germany.|Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany.
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Winter
Indiana University School of Medicine-Northwest, Gary, IN, USA.
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Marfurt
Institute for Applied Computer Science, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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Allgeier
Institute for Applied Computer Science, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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Köhler
Department of Ophthalmology, University of Rostock, Rostock, Germany.
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Hovakimyan
Department of Ophthalmology, University of Rostock, Rostock, Germany.
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Stahnke
Institute of Anatomy, Rostock University Medical Center, Rostock, Germany.
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Wree
Department of Ophthalmology, University of Rostock, Rostock, Germany.
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Stachs
Department of Ophthalmology, University of Rostock, Rostock, Germany.|Institute for Biomedical Engineering, University of Rostock, Rostock, Germany.
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Guthoff
D000328:Adult; D003315:Cornea / Q000294:innervation*; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods*; D008875:Middle Aged; D009412:Nerve Fibers; D013194:Staining and Labeling