cysts. Secondary cysts cause most of the times problems, and thus also need treatment. Secondary cysts usually have a rough surface, irregular borders, solitary and unilateral. Possible problems could be displacement of the iris, iritis and raised intraocular pressure. A clinician should also be able to tell the difference between a cyst and a tumor. The main differences are that cysts usually cause displacement or the iris whereas a tumor arises and grows into the iris stroma. In the presence of an intrinsic or sentinel vessel than you probably have to deal with a tumor. The last main difference can be shown with transillumination, since transillumination always creates a shadow with a tumor but almost never with a cyst. Ultrasound B-scan (USB) Ultrasound B-scan (USB) uses wavelengths of 10-20 MHz to form an image of the eye. USB can be used to identify the extension of the iris cyst in either the anterior or posterior chamber. It can also be used to identify midzonal cysts behind the iris and to determine whether there is ciliary body involvement. The preferred method to determine ciliary body involvement, however, is not USB but ultrasound biomicroscopy. Ultrasound biomicroscopy (UBM) Ultrasound biomicroscopy, (UBM) has a higher resolution than USB and it also uses soundwaves with a higher frequency from 50 to 100 MHz. UBM is used for the identification of thin ultrastructure's and for internal echogenicity of cysts. Due to the high resolution small cysts can easily be distinguished, multilocated cysts are easy to find and it is easier to determine whether the cyst is bilateral. The only disadvantage of UBM is its limited penetration. Despite this disadvantage, UBM is still the golden standard for the diagnosis of iris cysts. Anterior segment optical coherence tomography (AS-OCT) AS-OCT has the highest resolution of all diagnosis methods but it has a major disadvantage. AS-OCT creates a heavy shadowing caused by the iris pigment epithelium regarding iris lesions. AS-OCT is used to show the anterior border of an iris lesion. The internal structure of the cyst and what is behind the cyst, however, is not that clear due to heavy shadowing. That is why UBM is preferred over AS-OCT, the borders will be less visible but with UBM the whole structure of the cyst and the surrounding tissues is shown. Fine-needle aspiration (FNA) Fine-needle aspiration, FNA, is only used if every other method has failed to establish what