Abstract
Abstract: :
Purpose: To aquuire and evaluate oblique section images – comparable to slit lamp images – of the tear film and cornea using confocal in vivo laser scanning microscopy with the Heidelberg Retina Tomograph HRT II–Rostock Cornea Module RCM Methods:The Heidelberg Retina Tomograph HRT II was modified by adding a detachable contact lens system, the so–called Rostock Cornea Module RCM (FDA cleared in 2004). This module is combined with an external stepper–motor fine–thread z–drive to shift the focal plane in the cornea to the starting location of an optional image sequence or internal z–scan. Long working distance, water–immersion objectives with large aperture (63x, 0.95 W , WD 1.45 – ZEISS / 100x, 0.7 W, WD 8.0 – MITUTOYO) were selected to obtain a high magnification. During the examination, the distance between the cornea and the microscope was kept stable by using a PMMA–cap. An additional special contact cap with a 30 – 60 degrees inclined front surface alloweds also oblique confocal optical sections through the cornea. Results:The HRT II/ RCM system allows high contrast imaging of the layered structure of the cornea. By using the special slant PMMA–cap the imaging of a corneal segment of 60 µm thickness with all layers of epithelium from the superficial cells to basal cells, nerve plexus and Bowman's membrane in a single picture, comparable to slitlamp technology, is possible. Due to the good depth resolution of less than 2 µm , this combination enables unproblematic in vivo examination of the anterior section of the eye. The thickness of all layers of the cornea can be precisely measured. The external stepper–motor z–scan allows a 3D–reconstruction of the corneal microstructure. Conclusions: Imaging with the HRT II/RCM can be performed under stable and reproducible conditions. Higher quality images were obtained than when using confocal scanning slit microscopy. Microscopy of the cornea at up to 800fold magnification is possible and effective. In vivo ,,cytology" without staining is made possible. Keywords: Confocal imaging,, cornea , ocular conjunctiva, lens, cataract
Keywords: imaging/image analysis: clinical • cornea: epithelium • cornea: clinical science