I no longer know for what the purpose of the cutoff (FCO) optics of streetlights.
I've noted that lanterns with cutoff optics (Flat lenses)(Grechi Lumada/Lumadina, GE MxxxXx FCO and other FCO cobraheads, etc...), tends to be superglaring, while not contribute to the reduction of light pollution.
However, I've seen that semicutoff lanterns (Like AEG Koffers and others) tends to be non glaring (With the exception of GE M400, M400A, M400R, M400A2/R2, M250 M250R and M250A2/R2), and they don't causes more light pollution than cutoff lanterns with the same lamp wattage and type.
So for what is the purpose of the cutoff optics in streetlighting.

All the residential streets in my area now have FCO lighting with the exception of one street which has fluorescent lighting (PL?) - these are relatively low wattage and with the height and spacing cover the street reasonably evenly, with no glare from lanterns further away and practically no sky glow. The light levels are fairly good and I no longer have a glare-bomb 70W HPS lighting my front bedroom (and loft!) with its light overspill.


BG

Glare is when a lot of light is emitted in your direction. If it is, and assuming that you stand on the road at some distance from the light, then the light is supposed to be emitted in that direction. If instead of road it hits you thats another problem - somebody used a fixture with the wrong optics for the location (specifically : too wide beam angle)

SoFCO optics and clear shallow covers reduce direct light pollution from the light fixture to the sky. FCO eliminate it completely, shallow covers still mak some pollution (very little), but are better at light distribution at wide angles

The Koffer 150 with a single 250W HPS lamp, isn't glaring at all, because its bowl isn't clear but prismatic and the lantern it is semi-cutoff. However a Grechi Lumada, or GE M4002A/3A/R FCO with the same lamp, are superglaring, because they have a clear flat glass.
I think the best is a flat glass with a finish like this .

The light fixture has an angle up to which there is a main beam of light. Above that there won't be much light. If you are standing in the way of the main beam you'll see the light of the main beam - it is supposed to be like that

I remember seeing my first installation of FCO streetlights in the 1980's. The first thought was - why are so many street lights out? Then it occurred me that you can't see the lantern working on approaching it. This is the whole idea really - sideward bound light is cut off. It's a clever concept but I feel it has it's place. For example, it FCO lanterns don't solve the problem of stray light falling on nearby homes. Most FCO lanterns installed for this purpose (at least in Brisbane) still require additional blockers attached in order to block off stray light from entering homes.

I remember requesting this once many years ago. The crew came out at night and 'manufactured' the blocker on the spot. It took about an hour and was very effective.