Clots of the central retina artery usually occur in older people who have arteriosclerosis (ar-teer-ee-oh-skluh-ROE-sis), a thickening and hardening of the arterial (ar-TEER-ee-ul) walls in other locations of the body.

The retina (RET-uh-nuh) is sometimes described as the layered network of wallpaper that lines the back of the eye. A retinal (RETT-uh-nul) detachment is the peeling away of the retina from the back of the eye, the way you might imagine wallpaper peeling away from a curved surface.

Retinal tumors and cysts are rare, and they're usually benign, or non-cancerous. However, when a cancerous one occurs, it can be one of several types: retinoblastoma (ret-ih-no-blas-TOE-muh); retinal pigment epithelial (ep-ih-THEE-lee-ul), or RPE (R-P-E); RPE hypertrophy (high-PER-truh-fee); and von Hippel angioma (an-jee-OH-muh).

The veins of the retina return blood from the retina to the general circulation. While the arteries bring oxygen-rich blood to the eye, the veins take oxygen-poor blood out of it.