Musely / The Eye Serum

What it is

The Eye Serum is a compounded prescription serum for the periorbital area, sold at $41 a month on subscription, $78 on auto-refill, or $111 as a one-time purchase. It is marketed for crow's feet, puffiness, under-eye bags, fine lines and dark circles.

The page lists eight ingredients. There are two published formulas. Smooth 2.0 is tretinoin 0.001%, caffeine 1%, hyaluronic acid 2%, niacinamide 2% and bisabolol 2%. Smooth+Bright 2.0 adds hydroquinone 3% and exosomes. Vitamin C is advertised on the page and appears in neither.

First, the thing they got right

Hydroquinone here is 3%. We have spent seven reviews on this company, several of them arguing that 12% hydroquinone is being applied where it should not be. On the thinnest and most permeable facial skin there is, they chose a conventional, restrained, below-threshold concentration.

That is the correct judgement and it is evidence that someone in the formulation chain understands site-specific dosing perfectly well. Bisabolol at 2% for irritation and caffeine at 1% for transient puffiness are similarly well judged. Four of the seven ingredients in the Bright formula are doing sensible work at sensible concentrations.

The arithmetic that decides this review

The product page makes a specific comparative claim: prescription tretinoin is a retinoid up to twenty times more potent than over-the-counter retinol. That is a reasonable statement about the molecules. It becomes a problem when you put it next to the concentration.

Tretinoin here is 0.001%. Using the company's own multiplier — twenty times — that is equivalent to roughly 0.02% retinol. Retinol on a pharmacy shelf is commonly sold at 0.25%, 0.5% or 1%.

We want to be fair about the counter-argument, because there is one. Periorbital skin is thin, reactive and adjacent to the eye itself, and reducing a retinoid for that site is genuinely good practice. Musely's own help material says the low concentration is chosen to avoid irritation, which is an honest rationale.

But a considered reduction for the eye area is 0.01%, or 0.025% for a tolerant user. Going to 0.001% is not a dose adjustment; it is two orders of magnitude below where the evidence begins. And whatever the rationale, it cannot coexist on the same page as a boast about prescription potency.

The exosomes

The Bright formula contains what the page calls iPSC exosomes, quantified as '100 million'. That is a count, not a concentration — one hundred million per what volume is not stated anywhere we could find, which makes the figure unassessable by construction.

Three things are worth stating carefully here, because this is an area where it is easy to be either credulous or alarmist.

• ▸No exosome product has completed the FDA drug approval process. The agency's public safety notification and its warning letters concern exosome products marketed as regenerative medicine and administered as biologics — that is a different context from a topical on intact skin, and we are not suggesting otherwise. But there is no approved exosome product of any kind.
• ▸Published evidence for topical exosomes on intact skin is thin. Most of the interesting data involves delivery through a compromised barrier, such as after microneedling — which the FDA treats as administration of a biologic rather than topical use.
• ▸There is a straightforward physical question. Exosomes are lipid vesicles of roughly 30 to 150 nanometres. The stratum corneum is a formidable barrier to molecules far smaller than that. How intact vesicles of this size are expected to cross it is not addressed.

None of that makes the ingredient dangerous. It makes it, on published evidence, a reason to pay more rather than a reason to expect more.

What no eye serum can do

This is the most useful thing we can tell anyone reading a review of an under-eye product, and it applies to every brand rather than this one. Dark circles have three distinct causes, and they respond to completely different things.

Structural dark circles come from loss of volume and the shadow cast by the tear trough. No topical product restores orbital fat or changes the architecture of the midface. That is not a limitation of this serum; it is a limitation of the entire category, and it is the reason so many eye creams disappoint.

A page selling into a complaint where a large share of buyers have an untreatable cause ought to help them work out which group they are in. The thirty-second stretch test above costs nothing and would prevent a great many disappointed purchases.

Three prices, one product

The same page shows $41 a month, $78 on auto-refill and $111 for a one-time purchase. We could not reconcile these into a single clear statement of what the product costs, and with no published container size there is no way to compute cost per application either.

On any of those numbers this is the most expensive product Musely sells that we have reviewed. It contains the lowest retinoid concentration of anything in the range, and one ingredient whose quantity is expressed in a unit that cannot be evaluated.

Where we stand

This is the lowest score in the register, and it is worth being explicit that a low score is not the same as a warning. The Private Cream scored higher and we told people to avoid it, because its problem was safety. This product's problem is different: it is unlikely to hurt you, and reasonably likely to underdeliver relative to what you paid and what you were told.

There is a good product buried in here. Hydroquinone 3% with bisabolol and caffeine, honestly described and sensibly priced, would be a genuinely useful periorbital treatment for pigmented dark circles. It is surrounded by a retinoid at a hundredth of the company's own working dose, an ingredient measured in a unit with no denominator, and a potency claim its own formula refutes.

If you have brown, pigmentary under-eye darkening, ask for the Bright formula and understand that the hydroquinone is what you are buying. If your circles are shadow, keep your money — no serum on the market, at any price, is going to move them.