Just like your skin, the external and internal surfaces of the eye can display variations in pigmentation. Some people are born with spots such as naevi (freckles) in their retina or the deeper choroidal layer of the eye. Spots can also develop over time in response to sun exposure.
Naevi are benign but some may require monitoring to ensure they do not change over time. More serious pigmentations such as melanoma can also occur inside the eye. Optometrists use specialised equipment to routinely examine the retina and choroid, screening for and monitoring lesions such as these.