Yes - they DO exist!
If you choose to light your coop for the sake of adding more "natural" day light to get your girls to lay, we found at Lowes Shatter-Resistant regular light bulbs the other day. They are a little bit costly (3 will run you about $9.00) but - it stops the worry of if they break you're trying to find the little shards of glass and if your girls ate any or cut their feet.
They are coated in a heavy type of plastic (think like tempered glass) and should they shatter, they stay together and implode vs. explode.
Great idea I think - even with a guard over your light fixture!
Just wanted to share....

If you choose to light your coop for the sake of adding more "natural" day light to get your girls to lay, we found at Lowes Shatter-Resistant regular light bulbs the other day. They are a little bit costly (3 will run you about $9.00) but - it stops the worry of if they break you're trying to find the little shards of glass and if your girls ate any or cut their feet.
They are coated in a heavy type of plastic (think like tempered glass) and should they shatter, they stay together and implode vs. explode.
Great idea I think - even with a guard over your light fixture!
Just wanted to share....