I am running an experiment in which corneas are kept for about 21 days in culture medium after a wound model. I am using a Nikon inverted microscope that requires a flat mount. Even after producing radial cuts in the cornea I need a drop of PBS to both anterior and posterior surface to avoid shadowing from stroll folds (anteriorly) and small bubbles (posteriorly). However, soon after I do this, the cells start só slough off.