Retino A microsphere gel is a topical treatment for acne and fine lines. It carries Tretinoin as an active component, which functions by increasing the cell turnover in the skin, also beneficial for other skin issues. The product is available in the gel form in two concentrations, including 0.1% and 0.04%. The presence of microspheres in the formulation releases the medication more slowly to allow it to be effective on your skin for a longer period.