A needle safety device is provided having a housing, a needle assembly movably mounted within the housing and a spring for biasing the needle assembly within the housing. The needle assembly is movable along a first axis and the spring is movable along the second axis different from the first. There is also provided a lens for enhancing visualization of the flow of fluid through the needle safety device. There is further provided a safety sheath for covering a needle of the needle assembly and restraining the needle assembly against movement due to the bias of the spring.