So far, in vivo image systems are not able to visualize or identify the limbal stem cells directly. One alternative practical is to visualize the histological morphology of POV, and to speculate the possible status of the stem cells accordingly. However, the microstructure of POV is not well defined or understood in spite of awareness of it's importance. Slit-lamp biomicroscope can be used routinely for clinical examination of the limbal morphology. However, this technology does not allow for high resolution imaging of structural details and only up to 20% of patients can be identified. In vivo confocal microscopy has been used to visualize the POV and can provide cellular level resolution images, but the technique is limited by high magnification that restricts the area of the scan. In addition, in vivo confocal microscopy requires direct contact with the eye. Although the quality of these images is impressive, the disadvantages existed included the direct contact during examination, the small field of view (~200μm x 200μm), and the limited axial resolution. Besides, both slit lamp biomicroscopy and in vivo confocal microscopy have the limitation of not being able to give an overall view of the dimension and structure of the whole palisades region.