USING HAMMER , SHISEL TO REPAIR MINER CONVEYOR CHAIN (EYE PROTECTION BEING USED). AS HE SWUNG HAMMER, SAFETY GLASSES SLIPPED DOWN AND HEAD OF PIN STRUCK HIS LEFT EYE. COMPLIANCE WITH REGS NOT A FACTOR, PROFIENCY NOT A FACTOR. DIFFERENT TYPE OF EYE PROTECTION COULD BE USED. POSSIBLE FACTOR.