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Ashlin Joye, Gerami Seitzman, Jeremy D Keenan, Thomas Lietman, John Alexander Gonzales; Automated analysis of the corneal sub-basal nerve plexus in neuropathic ocular pain. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1697.
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© ARVO (1962-2015); The Authors (2016-present)
Dry Eye Syndrome (DES) labels a heterogeneous group suffering from various pathologies. We are interested in a DES subgroup with neuropathic phenotypes; these patients report dry eye symptoms but do not demonstrate signs of true dry eye, particularly keratoconjunctivitis sicca (KCS). We hypothesize that neuropathic phenotypes will show quantifiable differences in symptoms, clinical signs, and corneal sub-basal nerves when compared with non-neuropathic phenotypes.
We recruited two DES subgroups: 1) non-neuropathic phenotypes including KCS, Sjögren’s Syndrome, ocular graft-versus-host disease, ocular rosacea 2) neuropathic phenotypes previously diagnosed by specific symptom quality and clinical features. Symptoms were assessed with the Ocular Surface Disease Index (OSDI), Dry Eye Questionnaire 5 (DEQ), and Neuropathic Pain Symptom Inventory (NPSI). Clinical assessment included Schirmer 1 (SCH), Tear Breakup Time (TBUT), and Ocular Staining Score (OSS). Corneal nerves were scanned using in vivo confocal microscopy (IVCM) and our own eye-fixation grid protocol. An automated corneal nerve fiber analytics software (ACCMetrics, University of Manchester) was used for image tracing and generation of the following corneal nerve metrics: nerve fiber density (CNFD), nerve branch density (CNBD), nerve fiber length (CNFL), total branch density (CTBD), nerve fiber area (CNFA), nerve fiber width (CNFW), and fractal dimensions (CFracDim). Wilcoxon rank-sum was used to generate p-values.
Compared with non-neuropathic subjects (n=7, age=59.9 ± 15.6), neuropathic subjects (n=6, age=58.3 ± 17.9) had significantly decreased CNFL (p=0.0027), CNFD (p=0.0223), CNBD (p=0.0321), CTBD (p=0.0152), CNFA (p=0.0027), and CFracDim (p=0.0027). Neuropathic subjects also scored significantly higher on the DEQ (p=0.0103) and NPSI (p=0.0150). There were no significant differences in clinical signs.
These results are consistent with our hypothesis that DES patients with neuropathic phenotypes have characteristic and quantifiable features of neuropathy on IVCM. Further studies are needed to distinguish symptoms, signs, and nerve features that can accurately characterize DES subgroups.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Comparison of groups with Wilcoxon rank-sum p-values.
Representative automated nerve fiber tracings from non-neuropathic (A) and neuropathic (B) subjects. Red = nerve fiber; Blue = nerve branch; Green = branching point.
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