The pattern of the inferocentral whorl region of the corneal subbasal nerve plexus is altered with age

Reza A Badian,Mattias Andréasson,Per Svenningsson,Tor Paaske Utheim,Neil Lagali

doi:10.1016/j.jtos.2021.08.015

Abstract

PurposeTo describe the pattern of the nerves in the inferocentral whorl region of the human corneal subbasal nerve plexus (SBNP) in health and diseases known to affect the subbasal nerves. MethodsLaser-scanning in vivo confocal microscopy (IVCM) was used to image the SBNP bilaterally in 91 healthy subjects, 39 subjects with type 2 diabetes mellitus (T2DM), and 43 subjects with Parkinson's disease (PD). Whorl regions were classified according to nerve orientation relative to age and health/disease status. ResultsOf 346 examined eyes, 300 (86.7%) had an identifiable whorl pattern. In healthy subjects, a clockwise nerve orientation of the whorl was most common (67.9%), followed by non-rotatory or ‘seam’ morphology (21.4%), and counterclockwise (10.7%). The clockwise orientation was more prevalent in healthy subjects than in T2DM or PD (P < 0.001). Healthy individuals below 50 years of age had a predominantly clockwise orientation (93.8%) which was reduced to 51.9% in those over 50 years (P < 0.001). Age but not disease status explained whorl orientation in T2DM and PD groups. Moreover, whorl orientation is bilaterally clockwise in the young, but adopts other orientations and becomes asymmetric across eyes with age. Finally, we report reflective ‘dot-like’ features confined to the whorl region of the subbasal plexus, sometimes appearing in close association with subbasal nerves and present in 84–93% of examined eyes regardless of disease status, eye or sex. ConclusionSubbasal nerves in the inferocentral whorl region are predominantly clockwise in young, healthy corneas. With aging and conditions of T2DM and PD, counterclockwise and non-rotatory configurations increase in prevalence, and bilateral symmetry is lost. Mechanisms regulating these changes warrant further investigation.

Highlights

In vivo confocal microscopy (IVCM) has in recent years become increasingly utilized as a non-invasive imaging technique for the ex amination of the cornea in health and disease [1]
The remainder of the group consisted of subjects with different pathologies; 39 subjects with type 2 diabetes mellitus (T2DM) and 43 subjects with Parkinson’s disease (PD)
The inferocentral whorl region in the human cornea is the most recognizable feature of the subbasal nerve plexus (SBNP), surprisingly few studies have investigated the orientational characteristics of this region

Summary

Introduction

In vivo confocal microscopy (IVCM) has in recent years become increasingly utilized as a non-invasive imaging technique for the ex amination of the cornea in health and disease [1]. The orientation of the whorl [3,18], and the central corneal innervation has been sug gested to be symmetric between right and left eyes in healthy in dividuals, based on a study of 6 healthy individuals, (3 males and 3 females, mean age ± SD: 30.5 ± 5.8 years), where a clockwise orien tation of the whorl was observed in all eyes [22]. These were all younger subjects and it is not known whether increasing age has any effect on the whorl pattern in health and disease. A third, ‘linear seam’ morphology was described in animal corneas [24]

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Results

Conclusion