Sweaty helmet

I use a Gore Universal sweat band. It stopped the sweat-in-eyes problem for me stone dead.

don't live in the persistently warm bit of Aus' but hopefully soon the temperatures will start heading back to the hihg 20's and in summer mid 30's is norm - picked one of these up at local cycle shop having used various buffs - and def' is my go to on hot days, some sort of plastic ridge thing stops sweat running into eyes and it doesn't get soaking seems to evaporate off under my compulsary helmet - quick google gives UK availability - not as cheap a non brand buff but if I lost mine I'd happily pay for another

https://www.haloheadbanduk.com/product/halo-protex-bandana/

My Kask helmet has a small foam band at forehead level. When that's fully soaked i take off my glasses and press the helmet against my forehead, squashing out the sweat that then trickles down my face. A quick wipe, replace the glasses and we're off again!

I suffered with the same thing with various helmets i agree its no fun sweat streaming into your eyes.

A couple of months ago i bought a catlike tako £35 or so,Nothing fancy or too sporty as its mainly for my commute and i wear normal clothes.

I've had no problem at all with sweat running in to my eyes or the helmet getting too sweaty or smelly,Infact i hadn't even thought about the absence of sweaty eyes until i read your post and i wore it all through the heat the other month.

I have remarked though its the first helmet i pretty much forget i'm wearing.

Caps for me if it's not too warm. I'll sweat regardless so it soaks some up. If it's roasting I use a buff, bunched up like a sweatband. A bit more absorbent than a cap (but doesn't keep the sun out your eyes).

I rely on bushy eyebrows, but not all have the technical expertise to develop this form of sweat protection Several friends wear a bandana under their (cycling) helmet for this problem. Has the advantage of not covering the whole head so allowing plenty of heat loss in warm conditions.

On the turbo with fan running, a good quality headband such as https://www.amazon.co.uk/SWOOSH-TENNIS-SQUASH-BADMINTON-HEADBANDS/dp/B00B6CWQCG/ref=sr_1_3?ie=UTF8&qid=1502371896&sr=8-3&keywords=nike+headband works for me. Mine fills with sweat every 30 mins, so I turn it 180 degrees and eventually wring it out. Don't bother with cheap ones, which are thinner and work less well.

Another vote for a buff.  I wear it as a sahariane what ever that is, I had to look it up, but look up Buff sahariane and you will get the jist.  Keeps sweat out of the eyes and sun off the back of the neck and seems to help keep my head cool.

As peted76, I used to use vaseline when rowing to great effect. Not sure how it would work in a head down position.

Otherwise something to absorb sweat (sweat band, Buff, cap, etc.) before it gets to the eyes.

What make/model helmet are you wearing? Helmets that do not vent well will make your head warm and sweaty. Adding a cap or liner under your helmet only makes your head warmer. If you're thinking of replacing your helmet gives a price range so we can recommend some to you.

I wear a cotton cap all year around as I'm a sweaty git and can't get more than a couple of miles before the sweat is puring into my eyes. I have a few planetX caps and they're quite thin and cheap (<£5). Caps can also be thrown in the wash along with the rest of your kit after a ride so they're fresh every ride.

When its really hot I also wear a B'Twin cap that's lightweight like the Walz one, but cost half the price https://www.decathlon.co.uk/cycling-cap-500-black-id_8326918.html

Another reason to wear a cap is to keep the sweat off the soft parts of the helmet (pads, straps). As these can get a bit minging after being left lying aroud full of sweat.

This:

https://www.sweathawg.com/helmet-liners/

absolutely brilliant

Walz do a 'lite' technical cap, I find it's less intrusive than a cotton cap, more airy, wicks sweat away as opposed to allowing the sweat to pool in the cap band.

Can be had in either 3 or 4 panel design - I prefer 3 panel as it fits my head shape better (and IMO looks better - no pointy apex...)

Sweaty helmet?  Vaseline applied to unlikely body parts?  There's a joke in here somewhere but I'm far too refined .......

Vasaline above your eye brows. 

Could be made worse by the helmet are you wearing... the difference between an aero helmet and an airy helmet can be significant from a heat build up perspective. 

I'd also reccomend a headband over a buff, as there's less material to make your head even hotter involved. There are loads of these available thin, thick etc... 

If none of the above helps, then you can get special 'keep sweat out of your eyes things' to stop it from happening. Search silicone sweatbands, I've also seen what look like little stick on opaque silicone eyebrows for your head in a shop recently. Sweat in your face, who knew it was a big thing. 

A Buff works quite well.  If you bunch up the loose fabric below the back of the helmet it looks a bit 'pirate-like'!

A cycling cap will probably help, also much easier to wash regularly than the helmet pads. Walz cotton caps are good, I find. Wear both the cap and helmet sufficiently low on the brow for maximum mopping, safety and steez