QUANTIFICATION OF INTRASTROMAL MICRO-DOT DEPOSITS IN THE CORNEA OF LONG-TERM CONTACT-LENS WEARERS

Background Some months ago we described morphological changes in the s troma of the cornea of patients with a history of long term contact le ns wear. These degenerations consist of little highly reflective struc tures called ''micro-dots'' For a more precise quantification of the m icro-dots we established a clinically practicable method for measuring and counting. Material and methods The micro-dots can be visualized i n optical sections with the scanning slit confocal microscope. To get the real thickness of a single optical section we had to develop a in vitro model, which consists of a gel of agar with particles of latex o f different size. Results Some stereological methods made it possible to calculate the thickness of an optical section as seen with the conf ocal microscope. We found out that the thickness shows a variation dep ending on the reflectivity and size of the particles as well as on the aperture of the objective used. From the area of the frame and the th ickness of the optical section we could calculate the density of the h ighly reflective particles. Discussion Up to now we could determine th e morphological changes (micro-dots) in the cornea of patients with a history of long term contact lens wear in a semiquantitative manner on ly. With the presented method we are able to make a quite precise nume rical estimation of micro-dots. This is very useful to follow up the p rogress of these stromal changes over many years.