"Can I chant with my eyes closed? I find it easier that way."

Do you still have a Gohonzon? Have you ever connected with it? It might be harder without one of our senses but yes, you can chant with your eyes closed. Blind people do so. Also, ill people when very sick might chant with their eyes closed. Even in most types of Vipassana (silent Buddhist meditations) such as Dhammakaya meditation, the instruction is to keep the eyes open slightly. The main reason to keep one's eyes open is out of respect and gratitude for the Gohonzon, as if we were having an audience with the Buddha.