To map, summarise and analyse the methodologies of corneal nerve fibre imaging in studies using in vivo confocal microscopy (IVCM) in diabetes and assess the potential for standardising methods and reporting.

A scoping review was conducted using five databases, MEDLINE, Embase, Cochrane, Web of Science and Scopus, with search terms related to IVCM, diabetes and corneal nerves. Two researchers independently screened the studies for eligibility. Relevant data were extracted and systematically analysed.

Out of 1533 screened articles, 195 met the inclusion criteria. Spanning from 2000 to 2024, the studies showed high variability in image acquisition, image processing, image analysis and reporting detail. Most studies used laser scanning confocal microscopy, examining the central cornea in both eyes in patients with type 2 diabetes, manually selecting 3–6 images from each eye, and using ACCMetrics and CCMetrics for quantifying corneal nerve fibre length in mm/mm². Many studies lacked sufficient methodological details for reproducibility.

IVCM studies of corneal nerve fibres in diabetes show substantial methodological heterogeneity and inconsistent reporting, limiting reproducibility. We propose a guideline to support standardisation and improve the reliability of future research.

Measurement of tear film stability is central in dry eye disease (DED) diagnosis. In this study, we aimed to compare the performance of two methods of tear film stability measurement: non-invasive tear break-up time (NIBUT) and fluorescein tear film break-up time (FTBUT).

Cross-sectional study.

The study involved 132 subjects of 65-year-old inhabitants of the Oslo region who were not seeking ophthalmic care.

The participants underwent a battery of DED tests, including NIBUT measured on Oculus Keratograph 5M and a traditional method using fluorescein drops (FTBUT). Oculus Keratograph 5M measures two types of NIBUT:; appearance time of the first dry spot (NIBUT_First) and average NIBUT_Avg.

74 participants (56%) were female and 58 were male (44%). Subjects presented with varying degrees of DED signs and symptoms. Mean values of NIBUT_First and FTBUT from all the participants were significantly different (6.2±4.9 s vs 8.6±6.2 s, pFirst and NIBUT_Avg values (6.2±4.9 s vs 8.3±5.5 s, pAvg values (8.6±6.2 s vs 8.3±5.5 s, p=0.655). The receiver operating characteristic curve analysis was performed to compare NIBUT and FTBUT in regards to other clinical tests (Ocular Surface Disease Index, ocular surface staining, blink interval, eye redness, corneal sensitivity, lid debris, Schirmer I test, tear osmolarity, meibum quality, meibum expressibility, lid hyperemia, tear meniscus height. irregular lid margin, conjunctival hyperaemia, margin telangiectasia, lipid layer and meibomian gland drop-out). While FTBUT demonstrated results with area under the curve>0.6, neither NIBUT_First nor NIBUT_Avg showed significant results.

NIBUT_First was shorter than FTBUT. Low correlation between NIBUT and FTBUT indicates that these diagnostic tests are not interchangeable. Other DED tests had correlation, though low, while NIBUT did not demonstrate correlation.