Practicing with eyes open or closed is more of a personal preference.
There are Qigong forms that use the “gazing of the eyes” to circulate energy in a particular way, however, most exercises are not dependent on the eyes open or closed.
Most people, especially beginners, report that eyes closed reduces mental chatter by removing the visual stimuli that generate thoughts. In Qigong, we don’t need thoughts – we strive for relaxed, open mind.
Be careful not to get sleepy with the eyes closed. Not only could it be dangerous, but it could lead to a lazy practice as well.
Practicing with eyes closed is a preference, yet you should pay attention to how you feel. If it works for you, continue. If not, keep the eyes open.