Low Beams

As Tideland pointed out, your Model Three does not have factory LED headlights. If they are now LEDs, it is an aftermarket modification.

The front of the car does have LEDs, but they are DRLs (daytime running lights), not headlights. They only help others see you. Their light distribution pattern is completely worthless as a headlight for your night vision.

If these LEDs are the lights you are using at night, then your headlight switch is not turned to the right position. If this image illustrates your headlight switch (there are actually 3 types shown in the Owner's Manual), then turn the switch all the way up to Position 3:

Position 2 while correctly turn on all the side and rear lights, but will have the wrong front lights turned on.

If you have either of the other 2 switch types, then AUTO is an acceptable position, but will turn headlights off in daytime. You can force them all full-time by selecting this position on any switch type:
:

 

I'm taking that as a possibility to at least be checked. With a very cheap solution. A previous poster here gave several clues to mistakenly using the DRLs as headlights, but then vanished without giving us the next answers or a solution.

If this isn't it, the probable next thing is to replace a failing right headlight, and see if that brings enough light. Headlight aim should also be checked.

As for those "high beam at reduced intensity" DRLs, plenty of them exist down here too, on other car models (including my Subaru), and they cast a usable enough pattern that numerous folks get caught at night not realizing that they have the wrong lights, and that their rear and side lights are turned off. This is one reason I believe unpatterned LEDs are superior for DRLs, as they are much less likely to create this confusion.

 

Let me correct that: Prius gen 3 doesn’t have LED headlights in the US.
European can have - mine has also. I don’t know if that fits for US.

 

Further correction:

In the U.S. market, different trims of Gen3 Prius Liftback have different headlights -- LED on the top trim only, halogen on all the lower trims.

OP has a Three, which mean halogen headlights. For his year, the top trim with the LED headlights was called a Five.

 

Then it’s the about the same in Europe, only the top models have LED.

 

The namings are a tangled mess between countries, and between years within a given country. Almost as if they want to keep things confused. But as shown by the sequence of trim names within the U.S. (E.g. III, then 3, then Three) and re-use of the V (uppercase for trim level in 2010, then lowercase for model name from 2012-on), I'm believing it is more from lack of sufficient advance planning.

 

That confuse me too all the time.
And it’s even better, that in Europe the trim may be different by country.
Like I have a Belgian Prius with LED, but with the small bavigation with JBL. There was no such setup in Hungary. But also at the end of the model period, they add something to each trim - like big screen, JBL.

 

SOOOOOO many F'ers here do not understand DRL's and drive with the lights off.

 

I too just bought a 2015 that seems to have LED low beams for night driving, they are not good. The high beam is incredible. Is there anything that can be done? Different bulbs? My Prius A was imported 2nd hand from the Japanse market.