IV. In vivo confocal microscopy (right eye) A Heidelberg confocal microscope engineered in house with remote controlled scanning capabilities will be utilized in this study. One drop of topical tetracaine will be placed in the subject's eye; the subject's head is then placed in the headrest as for regular slit lamp examination. A drop of Genteal (Alcon Laboratories) is placed upon the top of the objective lens to serve as an immersion fluid. The cornea is then applanated using the standard objective lens tip. Both confocal microscopy through focusing scans and static images of the corneal epithelial surface will be acquired in the central cornea and all four quadrants of the limbus by controlling for the patient's direction of gaze. Similar image sequences will be performed to sequentially image the upper and lower lid wiper region at the midpoint of the eyelid (corresponding to the 5 and 7 o'clock position of the limbus). For upper lid imaging, the lid will be everted prior to image acquisition. Sequential imaging will allow for subsequent montage generation of the mid-point of the upper and lower lid.