Repeatability of Measuring Corneal Nerve Migration Rate in Individuals With and Without Diabetes.

PURPOSE: To assess the repeatability of measuring the corneal nerve migration rate in individuals with and without neuropathy.

METHODS

Wide-field montages of the subbasal corneal nerve plexus were generated at baseline and after 3 weeks for 14 participants. Montages were manually examined side by side to identify a referent landmark in the inferior whorl region (origin) and throughout each montage. A software program was developed to measure nerve migration of all identified points relative to the origin. Repeatability was determined by measurement of nerve migration for within observer (one researcher on 2 occasions, 5 days apart) and between observers (2 observers) within 4 different zones based on the distance from the origin and in the vertical section of the wide-field montage. The impact of images being montaged with fully automated software on repeatability was also investigated.

RESULTS

The mean difference between observations 1 and 2 for observer 1 was 0.02 ± 1.3 μm/wk (P = 0.94), with an intraclass correlation coefficient (ICC) of 0.99 [95% confidence interval (CI) = 0.99-1.00], and the mean difference between observer 1 and 2 was 0.3 ± 1.2 μm/wk (P = 0.41), with an ICC of 0.99 (95% CI = 0.99-1.00). The mean difference between observations 1 (images montaged by semiautomated software) and 2 (images montaged by fully automated software) was 1.2 ± 4.9 μm/wk (P = 0.41), with an ICC of 0.96 (95% CI = 0.87-1.00).

CONCLUSIONS

Measuring corneal nerve migration rate is highly repeatable for within and between observers and when using different methods of image montaging.