Abstract
Purpose :
To investigate whether analysis of limited area of the corneal sub-basal plexus in a standardized anatomic location can be used as a surrogate for whole plexus nerve analysis in type 2 diabetes.
Methods :
A total of 82 subjects, consisting of both healthy subjects and patients with T2DM were recruited. The central cornea in both eyes of study subjects (163 eyes) was imaged by in vivo confocal microscopy using Heidelberg HRT 3 with Rostock cornea module. IVCM images from the sub-basal layer of central cornea were analysed with respect to the sub-basal nerve length density both in the whole of mosaic image and also in a limited area of the mosaic represented by a ROI characterised by a specific length and width (1000 um x 650 um) located superiorly to the centre of the whorl in the mosaics, by cropping and nerve density analysis using image J.
Results :
Average size of mosaics was 6.0 mm2. Nerve length density was measured for whole mosaic images (mCNFL) and for cropped images (roiCNFL). The whole cohort consisted of several subgroups including normal subjects and patients with type 2 diabetes (duration > 10 yrs).
The analysis of the cropped region was performed with respect to the total nerve density, main nerve density and inter-nerve-distance. The analysis of the cropped regions indicated different results for the total nerve density in the cropped regions vs. full mosaics. Nevertheless, we found the same trend in the results of the main nerve density in the subgroups of the cohort across healthy, short- and long-term diabetes groups, as in the results achieved by full mosaic analysis. Other nerve analysis parameters in the cropped regions (ROIs) such as main nerve density and inter-nerve distance may provide a faster method of analysis, potentially useful for application in the clinical setting.
Conclusions :
The results of roiCNFL reflect the same tendency as mCNFL with respect to nerve degeneration in T2DM.
This study indicates the utility of the ROI method in measuring the nerve density in a fixed anatomical area as a potential alternative to full plexus analysis. Such an alternative could save time and speed the process of analysis in a clinical setting. This may help transition this procedure from bench to bedside in diagnosis and follow-up of small fiber peripheral neuropathy in diabetic patients and similar conditions.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.