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Updated: Sep 26, 2026
Corneal Confocal Microscopy: A Novel Non-invasive Technique to Quantify Small Fibre Pathology in Peripheral Neuropathies
Published on: January 3, 2011
Impact of image selection on corneal nerve and dendritic cell density quantification using in vivo confocal
Jenny Roth1, Karthikeyan Baskaran1, Ava Dashti2
1Department of Medicine and Optometry, Linnaeus University, Kalmar, Sweden.
Aim:
The aim of this study was to measure the impact of image selection on quantification of corneal nerve fibre length density (CNFL) and dendritic cell density (DCD) using in-vivo confocal microscopy images.
Methods:
We used images from 80 participants (mean age 51 years; 55 female), averaging 1030 images per participant. CNFL and DCD were quantified using independently selected sets and same-image sets. Inter-grader agreement was computed using 10 or 5 images per participant (patient-level data point). Grader agreement was quantified by intraclass correlation coefficients (ICC).
Results:
Using independently selected images, the ICC for CNFL was 0.82 with 10 images, which was significantly higher by 0.07 than with 5 images (p = 0.009). For DCD, the ICC was 0.92 with 10 images and was not significantly higher than with 5 images. Using same-image sets, the ICC for CNFL was 0.94 with both 5 and 10 images. For DCD, the ICC improved by 0.03 when 10 images were used compared with 5 images (p = 0.02).
Conclusion:
Independent-image selection gives poorer reproducibility of CNFL and DCD than multiple graders using the same-image sets. The same-image sets yielded excellent agreement, suggesting that studies relying on a single selection of five or fewer images should be interpreted with caution, as a single selection is more prone to rater bias. Because independent-image selection reflects real-world practice, we recommend that future studies use multiple graders, each independently selecting and grading images, with more than five images per participant where feasible.
