Corneal crystals Corneal cystine crystals 2024-07-07T09:42:28Z Accumulation of cystine crystals in the cornea. The crystals, which have a fine, uniform needle-shaped structure, are diffusely distributed within the corneal tissues. Patients present with crystal accumulation affecting the cornea and conjunctiva, but crystals can also be deposited in the iris, ciliary body, choroid and retinal pigment epithelium (RPE), and lens capsule. Corneal crystal deposition starts in infancy in the anterior periphery of the cornea, and progresses centrally and posteriorly.