What sort of range do you need?
If even basic tranquilizer darts are too potentially damaging, then that excludes ANY projectile weapon. Dissolving drug flechettes, stun balls, tazer darts, drug-delivering paintball pellets even. All of these could take out an eye.
Gas would work, but you have explicitly excluded that option.
How about a SuperSoaker type squirtgun, spraying liquids?
Tranquilizing drugs, superglue, etc..
Unfortunately the effective range of a portable squirtgun is rather limited. Even with the very best technology and a gel-like liquid, the stream will fall apart over more than about 20 yards, and very likely less than that.
Sonic stunner? Not sure how one would focus this to work as a directed weapon rather than an AoE device.
Microwave beamer? There is a crowd control device that is somewhat aimable and drops people by induced nerve pain. (some slight scortching smells from the skin are just propaganda, this device is really harmless!)
If the worry of a dart to the eye bothers you, then ANY tranquilizer should concern you. What happens if I get hit by your trank, and try to run away down stairs? Bonka-bonka-bonk-crunch-splat-dribble-dribble-gasp-die