That looks like a variant of the French Adrian helmet, which was issued (without the mail screen) to some American units. Here's another example along the same lines. Chainmail facemasks like this were issued to British tank crews to give some protection against 'splatter' or spalling (fragments of steel breaking off the interior of the armour plate and flying around the crew compartment when the tank was hit), but they were normally worn with leather helmets, and the masks weren't issued to the infantry. There's also this example of a British Brodie modified with a mail curtain, but it's the only one I've seen.

As the quote u/macwelsh007 has posted suggests, the intention is to protect the eyes from shell splinters or other debris. Most likely, it was a prototype or experimental design that wasn't issued in any significant amount; you can imagine how much this must restrict the vision. A huge array of personal armour apeared during WW1, much of it either impractical or largely useless and never issued officially, and a vast industry sprang up supplying non-standard kit for purchase along with endless media advertising which made sometimes fantastical claims for their products. This stuff ranged from foodstuffs and patent medicines, gadgets like luminous watches and trench periscopes, knives and tools, and all manner of clothing, including personal protective wear. Here are a few examples of advertising in the British press for body armour: 1 2 3.