Serious eye tumours are very rare. the ratio of a serious lesion versus a normal freckle / nevus is about 1:9000
A common naevus is a flat mole with a single uniform colour. In darker skin, naevi are darker in colour. Using Optos benign naevi are commonly found in 2-7% of adults. Most of the time a nevus are flat with feathered irregular edges, and may show some white surface deposits. These surface deposits are called drusen and occur with age. An older naevus is more likely to have drusen as in the nevus image below:
The image below is from a pigmented area with yellow deposits, lipofuscin
Furthermore the image is greener than the one above, greener color on Optos indicates increased thickness:
If you are concerned about pigmentation in your eye Optos is an excellent instrument to image and initially assess the area.