Hi, I too have had these yellow spots (one under each eye) for about 8 years. I posted 2 natural tricks under the heading "Xanthelasma".
One is the castor oil that I have been trying for the last 3 weeks. Although slow acting, this has made a difference. First the awful matte white yellowish colour (resembling uncooked chicken fat) started changing and looking more like the colour of my skin. This made the spots less obvious and easier to camouflage with make up (previously this was impossible, in fact, I felt make up made them more obvious). The spots also seem to have regressed slowly in size. Because there is slow but progressive change, I am persisting and will be posting news as time goes by.
Another suggestion I had read about was using lemon rind, and this seems similar but less drastic than the garlic treatment. Soak small pieces of lemon skin in vinegar 3 days and nights. Then put small piece (white side of the lemon on skin) to cover the spot with tape for 3-4 consecutive nights. The outer area of the spot should change to deeper yellow which indicates that it has matured and ready to be pressed out with finger tips.
I have no idea if this works, but thought that if the castor oil did not work and have them completely disappear after a few months, I would try the lemon rind technique.
If anybody tries this, please post your results.