In the last two decades, structured light patterns with orbital angular momentum (OAM) have been extensively utilized in quantum cryptography or quantum key distribution (QKD), which is generally considered an unconditionally secure method of a secret key transmission between two distant communicating entities. High-dimensional encoding of quantum bits in quantum key distribution improves the security and information-carrying capability of a quantum signal. However, the free space optical channel significantly degrades the efficiency of such communication due to the aberration of OAM states under atmospheric turbulence. This paper focuses on analyzing the impact of atmospheric turbulence on QKD error-rates. These aid in analyzing the security of such communication over the quantum channel in the presence of an intruder (man-in-the-middle). Our results showed that the turbulence under normal conditions does not significantly affect the successful transmission of secret quantum bits between sender and receiver. Furthermore, our results show a unique pattern of variation in the quantum bit error rate, index transmission error rate and efficiency that helps to clearly detect the presence of an intruder as a result of medium-level turbulence. [ABSTRACT FROM AUTHOR]