Abstract
Purpose: :
To compare Laser Scanning and White Light Slit Scanning in vivo confocal microscopy (IVCM) of anterior corneal structures in normal and diseased eyes.
Methods: :
IVCM scans of 9 healthy corneas, 8 corneas with herpes zoster ophthalmicus (HZO) and 3 corneas with herpes simplex Keratitis (HSK) were assessed in this retrospective study. IVCM of the central cornea had been performed using the Heidelberg Retina Tomograph 3 with the Rostock Cornea Module (HRT3/RCM) (Heidelberg Engineering GmbH), and the ConfoScan 4 (Nidek, Inc). Two masked observers reviewed the images in regards to density of anterior stromal keratocytes, basal epithelium cells, and subbasal corneal nerves, including the total number of nerves, number of main nerve trunks, total length of nerves per image, branching pattern, and tortuosity.
Results: :
In healthy corneas, cell densities of basal epithelial cells and anterior stromal keratocytes were significantly (p<0.001) higher by HRT3/RCM than by Confoscan 4 (7331 vs 5665 and 1120 vs 876 cells/mm² respectively). Significant increase (p<0.001) in total number of nerves (24.7 vs. 9.1), main nerve trunks (5.9 vs. 4.9), and total nerve length (3811.8 µm vs. 2240.7 µm), were observed using HRT 3 compared to Confoscan 4. While branching was significantly (p<0.001) higher with the HRT3/RCM, tortuosity did not differ within the devices. Similarly, in patients with herpetic keratitis, total nerves (16.3 vs 10.1), main nerve trunks (5.2 vs 3.4) and total length (2596.3 µm vs 1036.1 µm) showed significant differences between HRT 3 and Confoscan 4 (p<0.001). However, anterior keratocytes density, branching and tortuosity did not show significant differences between both devices.
Conclusions: :
Confocal Scanning Laser Ophthalmoscopy provides more richness and detail of corneal nerve morphology than conventional white light slit scanning confocal microscopy. Corneal measurements from both devices are not interchangeable, likely due to their different optical properties.
Keywords: imaging/image analysis: clinical • cornea: epithelium • cornea: stroma and keratocytes