The most common cancer of the eye is melanoma, also known as ocular melanoma. Melanoma is a type of cancer that develops in the cells responsible for producing the pigment that gives your skin, hair and eyes color. Just as you can develop a melanoma on your skin, you can also develop it in your eye. Although it is the most common type of eye cancer in adults, ocular melanoma is rare.
Ocular melanoma also known as uveal melanoma because it usually develops in the part of the eyeball called the uvea — a layer in the eye wall between the sclera and retina. Melanoma nearly always develops in the part of the uvea called the choroid, a pigmented layer lining the eyeball, because choroid cells have the same kind of pigment as cells in skin. While most ocular melanoma begins in the choroid, a smaller number develop in the iris (also a part of the uvea), which is the colored area around the pupil. Melanomas in the iris usually grow slowly and generally don’t spread to other areas of the body.
Ptosis is a drooping or falling of the upper eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired. This condition is sometimes called "lazy eye", but that term normally refers to amblyopia. If severe enough and left untreated, the drooping eyelid can cause other conditions, such as amblyopia or astigmatism.
This is why it is especially important for this disorder to be treated in children at a young age, before it can interfere with vision development.