Recently started using SkinMedica retinol 0.5% and would like to know if Retin-A will produce better results.

Thanks for your question. Although Skin Medica’s Retinol cream is a great product the chemistry between retinol and tretinoin is different enough that generally speaking tretinoin should be more effective than retinol. In the retinoid pathway there is an irreversible reaction that takes place between retinol and tretinoin which makes it so your body cannot shift tretinoin to an inactive form which can happen to retinol. So retinol only gets utilized by the body if there is a need for it otherwise it is shift to an inactive form where tretinoin continues in its active form regardless of whether there is a deficiency. The draw back to this comes in that your prescription strength retinoids are going to be more irritating than your over the counter retinol. 
One product I really like for those with more sensitive skin is SkinBetter Science’s AlphaRet Intensive as this is retinoic acid (chemistry past that irreversible reaction) but is conjugated to lactic acid so it gives you the benefit similar to the lower strength prescription products but not as irritating due to the moisturizing effect of the lactic acid. In the end the product you are using is great but prescription strenghth retinoids are generally going to be more effective. Hope that helps.