Basically a tear trough is a groove or very slight indent caused by thinning skin (so appears bluer and darker than just a dark circle) and slight bagging of the eye, which creates a slight shadow. Just using a plain old concealer isn't going to properly disguise them and loading more on will make it look even worse. You can google 'tear troughs' images to see what I mean.
You can get them in your thirties and genetic factors (thinner, paler skin) exacerbate it.
I am beginning to get the start of these not badly in all honesty but it really annoyed me as I think I look ok for my
age (39) except for this, which makes me look really knackered.
I bought all the concealers -- even Cle de Peau ($$$$$$), many eye creams (they don't work but do provide a nice surface
to apply stuff) and got more sleep. It did nothing.
The only way to get rid of them is to get restylane fillers or have blepharoplasty. I was starting to consider this as it just bugged the hell out of me and was the thing I'd zero in on if I caught my reflection. I just looked so tired.
Anyway. My makeup artist friend (big, has own makeup brand) helped me out. It really has made a huge difference, so much I
want to share it as you can be like me and spend a fortune and search for hours for a perfect concealer and it won't work and
just make you look too made up (especially in this harsh British daylight) or 160 years old.
You basically need to use two shades to recess and bring out the different areas of the undereye to disguise this trough.
I use a salmon corrector (not concealer). Eve Pearl is great but hard to get (US) but Bobbi Brown corrector is also very good. I apply this on the dark area but if you have any fine lines try not to apply too much to those and really just concentrate on the dark. Tap in.
Then use a very small brush (lip liner is good, I use a very small headed Bobbi Brown concealer brush as I happen to have one) and apply a tiny amount of concealer two shades lighter (I use BB warm ivory) JUST in the shadow the slight bag creates. It helps to look down in a mirror in natural light. Only apply in this line tapping lightly in. You are effectively trying to 'bring out' this area, not the skin around it. Any concealer will do but Bobbi Brown do a good range to pick a good two shades lighter, as do MAC or you could buy a Ben Nye or Kryolan wheel -- they go cheap on eBay.
I use a large EcoTools concealer brush to tap this line in.
I then use Laura Mercier Secret Brightening Powder with this brush just on this line. Apply too much and it makes the under
eye look chalky, and draws attention to any fine lines. Basically I sacrifice setting power with not having too much product
or powder. Any powder will do, I just happen to have this and want to use it up.
Other tips for knackered eyes is to use a lilac wash (really brightens -- Mac Digit is lovely) eyeshadow. I avoid too much sparkle although a slight sheen is fine. And I always wear something on the waterline. Either an Illamasqua nude pencil or a darker LM one. Again, anything will do, the trick is to disguise the red rim.
This takes a light hand, good light and practice but this one trick has single handedly made me look better, less knackered
than any expensive cream or eyewateringly expensive concealer.