Automatic confocal microscopy provides accurate recognition of corneal nerves

Invest Ophthalmol Vis Sci. 2008;49(11):4801-4807.

Automatic in vivo confocal microscopy accurately traced differences in corneal nerve length compared with manual methods.

"The algorithm we propose for nerve recognition is fully automatic, requiring no user intervention," the study authors said.

Flat, elongated corneal nerve structures below the 10-µm sub-basal layer provide important clinical information on corneal changes related to aging, contact lens wear, corneal refractive surgery, transplantation or diseases such as dry eye, keratoconus or herpes keratitis.

The retrospective study included images of sub-basal epithelium from 76 subjects with normal corneas and 14 subjects with abnormal corneas. Images were obtained using the ConfoScan4 confocal microscope (Nidek Technologies).

The manual procedure accurately recognized 80.4% of corneal nerves in subjects with normal corneas and 83.8% of nerves in subjects with abnormal corneas. The correlation coefficient between manual and automatic lengths on the same image was 0.94 in all subjects, 0.95 in normal subjects and 0.86 in sub-normal subjects.

Evaluation of separate images from 80 normal subjects showed a correlation coefficient of 0.89 between manual and automatic measurements.