The barrier between the blood system and the anterior segment of the eye is not as tight so some fluorescein can penetrate it even under normal conditions. However, since the Fluorotron can make a precise measurement of the amount of fluorescein that gets in, it can easily differentiate a normal amount from an abnormally high amount.
Inflammation can markedly increase the permeability of the blood-aqueous barrier. Inflammation can be caused by bacterial infection, surgery and other diseases such as diabetes.
The resolution of these scans can be enhanced by about 2X using the Anterior Chamber Adapter.
A number of drug companies have used Fluorotrons to run clinical trials on their anti-inflammatory drugs. These drugs decrease inflammation after surgery and thus also decrease permeability of the blood aqueous barrier.