Eye cyst. Cystic growth of the conjunctiva of a patient's eye. This may be a form of squamous cell carcinoma. Conjunctival cysts may also be caused by trauma to the eye or a chemical splash, which cause proliferation of conjunctival cells. The conjunctiva is the delicate membrane that covers the outer surface of the eyeball and lines the inside of the eyelid. A cyst is an abnormal sac, filled with liquid or semi-solid matter. If no pain or discomfort is felt then the cyst may be left; however, treatment may be necessary if the cyst is obscuring vision.