It is a fair question, and the honest answer is that three separate things happen when you apply an eye mask, and they get credited to the product as a single effect.
Some of what you see would happen with a chilled spoon. Some of it is genuinely the format doing something a cream cannot. And some of it depends entirely on what is in the formula and whether you use it for long enough to matter.
Separating those three is worth doing before deciding whether any eye mask is worth its price.
What the cold is doing
Most of the visible improvement in the first fifteen minutes is temperature.
Cold causes vasoconstriction. Blood vessels narrow, less fluid leaks into the surrounding tissue, and the fluid already there drains marginally faster. The area looks less swollen and, because the blood vessels beneath thin skin are temporarily narrower, slightly less shadowed.
This effect is real, reliable, and available for free. A chilled spoon does it. Cold water does it. So does a refrigerated mask, and none of them are doing anything the others are not.
It is also temporary. Vasoconstriction reverses as the area returns to body temperature, typically within an hour or two. Nothing has changed structurally, the appearance has changed while the temperature was different.
If a product produces a visible result within minutes, that result is almost certainly temperature. Being clear about that is not a criticism, immediate de-puffing is genuinely useful, but it should not be mistaken for what the formula is doing.
What the format is doing
This is the part that is not just cold, and it is a genuine advantage over a cream.
The eye area holds moisture poorly. Almost no sebaceous glands means no meaningful oil barrier, so water applied to the surface evaporates faster than it does elsewhere on the face. The area also moves constantly, so a cream migrates and thins across the surface within minutes.
An occlusive patch changes both conditions. It seals the formula against the skin for a defined period, so nothing evaporates and nothing migrates. Fifteen minutes of sealed contact delivers substantially more than the same formula rubbed in and left exposed.
Material matters here more than most people assume. A patch that adheres closely to the contour, following the curve under the eye and up toward the inner corner, seals properly. One that sits loosely leaves gaps at exactly the points where the skin curves most, which is where the formula is needed. Bio-cellulose was originally developed for wound dressings because it conforms to irregular surfaces without gaps, and that property is what makes it work here.
The delivery advantage is not a marketing claim. It is the reason the format exists.

What the formula is doing, and how long it takes
The slowest component, and the one that produces actual change rather than temporary appearance.
Hydrating actives make a genuine difference to how the area looks, though not immediately in the way cold does. Well-hydrated skin is slightly plumper, which means it creases less sharply and reflects light more evenly. Both reduce the visibility of fine lines and soften shadowing. Eye Catcher carries Sodium Hyaluronate, Panthenol and Allantoin for this, hydration and tolerance rather than intensity, which is the correct priority for skin this thin.
Brightening actives work on pigment specifically and take weeks. If your circles are pigmented, Niacinamide applied consistently will help over four to eight weeks. If they are vascular or structural, it will do nothing regardless of how long you use it, which is the most common reason people conclude eye products do not work.
Concentrated treatment formats sit between the two. The Gold Mask Eye uses gold foil over cellulose with 83% Rose of Jericho, and the foil traps warmth rather than cold, increasing absorption through a different mechanism. Better suited to treatment than to morning de-puffing.
How to tell which effect you are getting
A practical test, and it takes two mornings.
Chill a mask and use it as directed. Note the improvement. The following morning, hold something cold against the area for the same duration, a chilled spoon works, without any product.
If the results look comparable, temperature was doing the work. If the mask produced noticeably more, the format and formula were contributing. Either answer is useful, and neither means the product is bad, it means you know what you are paying for.
The second test is duration. Cold effects fade within a couple of hours. Hydration effects last through the day and improve with consistent use over weeks. If your improvement is gone by lunch, it was temperature. If the area looks better generally after a fortnight of regular use, the formula is working.
When an eye mask is genuinely worth it
For puffiness, if you value the convenience. The cold does the work, but a mask holds temperature evenly across the contour for the full duration rather than warming up in a minute, and it hydrates simultaneously. Most of what reduces morning puffiness is mechanical rather than topical, so this is a convenience decision rather than an efficacy one.
For hydration, yes, clearly. This is where the format advantage is real and difficult to replicate. The eye area loses moisture faster than anywhere else, and sealed delivery addresses that directly. Given that thin, dry skin shows fine lines and shadowing more readily, consistent hydration is one of the few interventions that improves several concerns at once.
For pigmentation, only with consistency. The mask is a delivery mechanism, the active does the work, and it takes weeks. Occasional use will not produce results.
For hollowing or structural volume loss, no. Hydration softens how sharply the shadow reads, but nothing topical restores volume, and any product implying otherwise is overstating what is possible.

Getting the most from one
Refrigerate before use if puffiness is the concern, since you may as well have both effects at once.
Fifteen minutes, not longer. Once a patch begins drying it starts drawing moisture back from the skin, reversing what it delivered.
Do not rinse afterwards. The remaining serum is the product, and the eye area absorbs slowly enough that it is still working after removal. Press it in gently rather than rubbing, since friction on skin this thin causes more harm than the product repairs.
Consistency over intensity. Two or three times a week produces more than an occasional intensive session, because the effects that compound are the slow ones.