Use of the Inferior Whorl for Detecting Age-Related Changes in Human Corneal Subbasal Nerve Plexus with Laser Scanning Confocal Microscopy

Purpose: The purpose of this study was to determine the effect of aging on the corneal subbasal nerve plexus (SNP) by employing a wide-field mapping technique of composite images, scanned at the location of a distinctive spiraled subbasal nerve pattern located 1–2 mm inferior to the corneal apex (the inferior whorl) for SNP structural quantification. Materials and Methods: Central corneal tactile sensitivity (CCTS) and inferior whorl length (IWL) were compared among individuals in 3 age-groups (20–39 years, 40–59 years, and 60–79 years). Statistical analyses constituted the Kruskal-Wallis test, one-way analysis of variance (with the post hoc least significant difference test), Spearman correlation coefficient, and linear regression analysis. Results: CCTS remained stable until the age of 50 years, when it began to decrease; the mean CCTS was 58.15 ± 2.46 mm in the group aged 20–39 years, 55.74 ± 3.85 mm in the group aged 40–59 years, and 50.23 ± 3.27 mm in the group aged 60–79 years. IWL decreased with increasing age, with a corresponding linear decline of 0.2088 mm/mm² per year, and the mean IWL was 25.43 ± 4.50 mm/mm² in the group aged 20–39 years, 22.71 ± 6.19 mm/mm² in the group aged 40–59 years, and 18.60 ± 4.21 mm/mm² in the group aged 60–79 years. Conclusion: Our work provided a more accurate and repeatable method for corneal nerve analysis using laser scanning confocal microscopy. By using this technique, we confirmed that aging is associated with progressive reduction in subbasal nerve length.