not really. The lens is designed to work with a fan that sucks the air temporarily trapped between lens and hood out of the hood and vents it elsewhere. The lens without the fan only slows the inevitable.

A less expensive option that may work depending on the specifics of your set up are a regular fan that blows the air around your plants into another room or at least to the other end of the room if it is fairly large. It is the air under the light that heats up first so as long as you move that out the temp around the plant should stay cooler.

The "lens" is primarily a safety feature which MUST be fitted to metal halide lamps using bulb that are not rated for open use. These bulbs can shatter and release glass fragments and release dangerous amounts of UV when they fail. Open-rated bulbs include their own safety envelope and cutout mechanism and are safe to use without a shield or "lens".

As always, the true requirement for lenses has been obscured behind a myriad of marketing talk, including the idea that they are a cooling feature or a "lens" for focussing. A lens can be used in conjunction with a fan extracting air from inside the lamp enclosure to provide better cooling than you might achieve with an open lamp but it is not a magic solution to all your heating problems. Likewise, the "lens" may be a completely flat and clear piece of glass with no lens-like properties at all, or it may be a diffuser that actually scatters the light more evenly over a wider area, but rarely is it an actual lens that focuses the light onto a smaller area. The job of focusing the bulb output onto a restricted area is done by the reflector housing.

well, put a small fan blowing directly towards the bulb and i do NOT feel heat near the plants that will burn the leaves, the majority are orchids under the light

this may help someone who has burned leaves before

A closed room WILL heat up. Someone on another forum I visit has a 15 X 15 grow room in her basement with 4 1000 watt lights. She has a greenhouse-type ventilation system because otherwise the room will get over 90 degrees even in winter with the heat from the bulbs and ballasts.

With a thermostat-controlled ventlation system she keeps it in the mid 70s. At night it drops to the lower 60s.

Her setup inspired the one I'm working on.