Nystagmus, specifically miner's nystagmus, is an occupational disease affecting miners, characterized by involuntary eye movements. It is associated with prolonged exposure to poor lighting conditions, such as those historically experienced in underground mines with inadequate illumination. This condition leads to symptoms like eye strain, dizziness, and difficulty focusing, affecting the eyes. It is not related to the liver, lungs, or stomach, which are associated with other occupational diseases like silicosis (lungs).
Thus, the correct answer is Eye.