Why have I developed this dent between my eyebrows? (Photos)

This can be caused as a result of aging. Botox can give improvement. Botox results resolve in 3-4 months. See an expert. Best, Dr. Emer

Thank you for your question and posting your photos. The line or dent you are concerned with is caused by contraction of the muscles that allow us to frown or squint. While I can understand your reluctance to use a neuromodulator like Botox or Dysport, this is the treatment of choice. Neuromodulators will decrease the movement of the muscles that are creating this indention. If you decide this is not the course of action you want to take, this indention will likely become deeper and more permanent. I hope this was helpful - Dr. Moore.