Geometrical Features of Subbasal Corneal Whorl-like Nerve Patterns in Dry Eye Disease: An In Vivo Confocal Microscopy Study.

PURPOSE

To investigate the geometrical feature of the whorl-like corneal nerve in dry eye disease (DED) across different severity levels and subtypes and preliminarily explore its diagnostic ability.

DESIGN

Cross-sectional study.

PARTICIPANTS

The study included 29 healthy subjects (51 eyes) and 62 DED patients (95 eyes).

METHODS

All subjects underwent comprehensive ophthalmic examinations, dry eye tests, and in vivo confocal microscopy to visualize the whorl-like corneal nerve at the inferior whorl (IW) region and the straight nerve at the central cornea. The structure of the corneal nerve was extracted and characterized using the fractal dimension (CND), multifractal dimension (CND), tortuosity (CNTor), fiber length (CNFL), and numbers of branching points.

MAIN OUTCOME MEASURES

The characteristics of quantified whorl-like corneal nerve metrics in different groups of severity and subtype defined by symptoms and signs of DED.

RESULTS

Compared with the healthy controls, the CND, CND, and CNFL of the IW decreased significantly as early as grade 1 DED ( < 0.05), whereas CNTor increased ( < 0.05). These parameters did not change significantly in the straight nerve. As the DED severity increased, CND and CNFL in the whorl-like nerve further decreased in grade 3 DED compared with grade 1. Significant nerve fiber loss was observed in aqueous-deficient DED compared with evaporative DED ( < 0.05). Whorl-like nerve metrics correlated with ocular discomfort, tear film break-up time, tear secretion, and corneal fluorescein staining, respectively ( < 0.05). Furthermore, merging parameters of whorl-like and linear nerve showed an area under the curve value of 0.910 in diagnosing DED.

CONCLUSIONS

Geometrical parameters of IW could potentially allow optimization of the staging of DED. Reliable and objective measurements for the whorl-like cornea nerve might facilitate patient stratification and diagnosis of DED.

FINANCIAL DISCLOSURES

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.