I have found that keeping bubble eyes safe and sound and protected from the intake tubes of filters to be a challenge. Using sponges or nylon stocking material to cover the intake didn't seem to work all that well, since it would clog and prevented larger bits from being taken into the filter.
I decided to see if I could attach a Tronic heater cover to act as a cage around the intake. I bought a 100 watt heater cover and only used the bottom half of it. The bottom section has a little "V" shaped notch to connect it to the top half. In this "V" shaped notch I pushed a thermometer suction cup. I used the kind with the loop that attaches around a floating thermometer. I cut off the loop but left a nub still at the base where the loop attached to the suction cup. Then I wedged that little nub that I left into the "V" of the Tronic heater cover.
I then slipped this up and over the filter intake tube and pressed the suction cup to the back wall of the tank to hold it. It provides approx. 1/2" of space all around the intake between the intake tube and the heater cover. It has worked for me to prevent any bubble damage, and it doesn't impede the flow of debris into the filter.
I have attached a picture of the heater cover in place.