Corneal nerve fibre changes and altered tear cytokine profile in migraine patients with photophobia

Abstract

Purpose : The current study investigates changes in corneal nerves morphology and tear cytokine profile in migraine patients with ocular symptoms such as photophobia.

Methods : Thirty-six eyes of 18 subjects with migraine and photophobia (Group 1), 24 eyes of 12 subjects with migraine without photophobia (Group 2) and 10 eyes of 10 controls (Group 3) were analyzed in this study. Tear samples were collected in Schirmer’s strips after informed patient consent and prior approval of the Institutional Ethics Committee. The sub-basal nerve plexus from central cornea was assessed by confocal imaging (Heidelberg Engineering GmbH) using a 400x400microns² frame. Quantitative analyses of nerve fibers were performed using Automatic CCMetrics software, Ver.1.0. Nerve parameters analyzed were corneal nerve fibre density (CNFD), corneal nerve fibre length (CNFL), corneal nerve branch density (CNBD), corneal total branch density (CTBD), corneal nerve fibre width (CNFW) and corneal nerve fibre area (CNFA). Tear proteins were extracted from the Schirmer’s strips and cytokine analysis by cytometric bead array was performed in a subset of the study subjects.

Results : Significant reduction in CNFL (14.76±0.67 mm²), CNBD (30.19±2.66 mm²), CTBD (43.37±3.65 mm²) and CNFA (0.005±0.0003 mm²) were found in group 1 as compared to group 2 (CNFL – 18.13±0.69 mm²; CNBD – 43.48±3.66 mm²; CTBD – 63.38±4.82 mm²; and CNFA – 0.007±0.0003 mm²). Similar observations were made with reference to corneal nerve features and tear cytokine between group 1 and group 3 (CNFL – 17.26±0.92 mm²; CNBD – 43.87±4.31 mm²; CTBD – 59.24±6.43 mm²; and CNFA – 0.006±0.0005 mm²) subjects. Higher levels of tear cytokines were observed in group 1 (IL-1α – 104±29; IL-17F – 207±23; IL-8 – 810±205; CXCL10 – 108586±18300; VEGF – 2739±383 pg/ml) subjects compared to group 2 (IL-1α – 76±58; IL-17F – 133±14; IL-8 – 566±156; CXCL10 – 18281±11822; VEGF – 1193±529 pg/ml) and group 3 (IL-1α – 33±10; IL-17F – 55±37; IL-8 – 359±152; CXCL10 – 18179±3891; VEGF – 1307±276 pg/ml).

Conclusions : Distinct corneal nerve fibre features and increased tear cytokine profile was observed in migraine patients with photophobia, indicating their potential association with ocular symptoms in migraine patients.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.