Corneal nerve imaging in systemic neuropathy: A minireview of experimental and precision medicine applications

Table 1 Standardized terminology and reporting conventions for corneal confocal microscopy nerve metrics

Metric	Abbreviation	Standardized definition	Unit	Reporting convention
Corneal nerve fiber density	CNFD	Number of main nerve fibers within the analyzed corneal area	fibers/mm2	Main nerve trunks should be distinguished from secondary branches
Corneal nerve branch density	CNBD	Number of primary branches arising from the main nerve fibers within the analyzed area	branches/mm²	Only branches originating directly from main nerve fibers are counted
Corneal total branch density	CTBD	Total number of branch points within the analyzed area, including primary and higher-order branching	branch points/mm²	The branch-order convention and analysis software should be reported
Corneal nerve fiber length	CNFL	Cumulative length of all visible main nerve fibers and branches divided by the analyzed area	mm/mm2	The analyzed area, anatomical location, and analysis method should be specified
Corneal nerve fiber tortuosity	CNFT	Degree to which the course of a nerve fiber deviates from a straight path	Unitless coefficient, software-specific index, or ordinal grade	The calculation algorithm, grading method, and software should be specified
Inferior whorl length	IWL	Cumulative length of visible nerve fibers and branches within the defined inferior-whorl region divided by the analyzed area	mm/mm2	The location and dimensions of the inferior-whorl region of interest should be reported

CNBD: Corneal nerve branch density; CNFD: Corneal nerve fiber density; CNFL: Corneal nerve fiber length; CNFT: Corneal nerve fiber tortuosity; CTBD: Corneal total branch density; IWL: Inferior whorl length.