Do not look directly at any student for long. In some cultures, looking directly at a person for more than a few moments is considered rude. As a teacher, you may feel that you know them and that certain individuals appreciate eye contact. However, distinguishing between students this way could lead to suspicions of favoritism. Treating all students with the same eye contact protocol is best.
Allow students to answer questions or interact with you with diverted eyes. Do not make mention of it or take offense. Recognize this as simply another culture's way of interacting with you. It may be a sign of respect for a superior, rather than a sign of low respect. By treating this body language as offensive, you could confuse the student about roles in the classroom.
Keep a list of the students that you believe are from low-contact cultures, such as Korea or Japan. These cultures are particularly sensitive to eye contact issues. You are not the only one in the classroom who may be offended by this behavior and you may have to sort out squabbles between students and between parents. Knowing who is most sensitive to this issue will allow you to lower tension in difficult situations.
Teach a lesson about the concept after you have studied it for yourself. Include information about various cultures in the lesson and make sure eye contact is discussed in the material. Do not point out specific students, but you should allow them to address the topic as it relates to themselves.