Micro.

"Topical retinoids are the most important drug class to reverse the signs of aging, also known as all-trans retinoic acid, tretinoin, sold under a variety of brands including Retin-A Micro, a prescription-only topical form of vitamin A that can visibly improve mild to moderate photo damage, including fine and coarse wrinkles, freckles, other pigmentation, and improve overall skin texture after months of daily use. This is accompanied by restoration of collagen formation. [...] One of the advantages we have discovered of using a topical retinoid is that it can improve the appearance of wrinkles because it gets down to the deeper layers of the skin to not only improve collagen production to smooth out wrinkles but also to help actively protect the collagen that you have. A skin biopsy taken before and after ten to twelve months of tretinoin versus placebo found that while skin collagen formation dropped fourteen percent in the control group, it rose eighty percent in the retinoic acid group."

"The micro sponges are basically little delivery systems with hollows that the tretinoin drug is stuck in, and those hollows allow the tretinoin to be protected from exposures like UVA. The micro sponges are a delivery system that helps overcome the photostability issue. In theory, if you are using tretinoin in a micro sponge delivery system, you could in theory use it during the daytime. In a laboratory test after 24 hours of continuous exposure to incandescent bulbs, Retin-A Micro retained 98 percent of the tretinoin, whereas only 31 percent of tretinoin gel remained. [...] The micro sponge delivery system used in Retin-A Micro does protect the drug tretinoin from degradation from fluorescent bulbs or incandescent bulbs. In another study [...] looking at solar simulated light, which is meant to mimic natural sunlight exposure, [...] after six hours of solar simulated light exposure only 16 percent of the tretinoin micro degraded, whereas 90 percent of the tretinoin degraded without the microsphere technology."

"Tretinoin applied to the skin is more than safe. It's been used for over 50 years in dermatology to treat a wide array of skin conditions, and it's been approved by the FDA since the 90s for the treatment of fine lines, mottled hyperpigmentation, and rough skin texture associated with photo damage. It does in fact work to improve collagen synthesis, smoothing out wrinkles and fine lines, and it does not thin the skin or thin the dermis. If you want to take a break from tretinoin for anti-aging purposes that's up to you, it can be drying and irritating and a pain to keep up with, and there are over-the-counter alternatives like retinol that are safe but not any safer, just sometimes less irritating. There is no evidence that tretinoin causes fat loss or is harmful to the pre-adipocyte population."

"I would not worry about tretinoin and all-cause mortality. Tretinoin has been used for about fifty years now and we really aren't seeing people dying from using it long term, so it's not something that I would worry about. This study does not prove tretinoin causes an increase in death, association does not equal causation, and there are multiple things from this study that suggest tretinoin is merely guilty by association. It's just important to understand the nuance of the study."

"Retin-A Micro is much less irritating for many people."

"I've been using Retin-A for 10 years now. When I first started, I didn't put it around my mouth or around the sides of my nose, but after acclimating to it really slowly over the course of a year, I did start putting it under my eyes, by the sides of my nose, around my mouth, and I haven't had a problem with it. It really takes nine months to a year before you start seeing any major anti-aging differences using Retin-A. The most important anti-aging skincare that we have is Retin-A, and it's the one that is proven to work with like 40 years of research that shows that it works so well for reducing wrinkles, for firming up your skin, for reducing discolorations, and for building new collagen in your skin."

"I really do think that Retin-A is responsible for at least 50 percent of the improvement in my skin that I've seen over the years. I started at 0.05 percent and eased into it slowly, only using it once a week for the entire first month, which is how I've been able to have success with it. It took me nine months to get up to using it every night. I then bumped up to 0.1 percent, and it probably took another six to nine months to get up to using that every single night. The fact that I waited 15 to 20 minutes for my skin to dry before applying it really cut down on the irritation as well. I feel like the biggest difference for me is in the crinkly texture of the skin underneath my eyes and my crow's feet were much much larger than they are today. I definitely see a reduction in the redness in my skin, and my skin tone overall looks a lot better and a lot clearer."