There are two kinds of facial line and they need opposite tools.
Dynamic lines appear when a muscle contracts and pleats the skin above it. Crow's feet on smiling, frown lines, forehead lines on raising the brows. The target is the muscle. The tool is botulinum toxin, which blocks the nerve signal telling that muscle to contract.
Static lines and volume loss are visible at rest — etched creases, hollows, deflation. The target is the missing volume. The tool is filler.
Botulinum toxin adds no volume at all. It occupies no space and fills nothing. Filler adds physical bulk and does nothing to muscle movement. A crow's foot is the textbook dynamic line, which is why the entire randomised evidence base for this area is a toxin evidence base.
The trials are large and controlled. One phase 3 trial randomised 417 people, 316 to onabotulinumtoxinA 24 Units and 101 to placebo: 63.9% versus 5.0% achieved none-or-mild crow's feet severity at maximum smile on day 30. Another randomised 787 people across combinations of upper-face areas. Both came out of Allergan's development programme — the manufacturer of Botox Cosmetic — which is normal for registration trials and worth stating. A competitor toxin not marketed in the US separately demonstrated non-inferiority to onabotulinumtoxinA for crow's feet in 290 people, with 72% responders in both arms, which shows the effect replicates outside one company's programme.
Where a crow's foot has become deeply etched and remains visible at complete rest, relaxing the muscle stops it deepening but may not erase what is already there. That is the point at which resurfacing, skin-quality treatments and, occasionally, a thin intradermal injectable get discussed — as an addition to toxin, not a substitute for it.
Two brands hold a US cosmetic indication for lateral canthal lines:
Botox Cosmetic (onabotulinumtoxinA): Approved 11 September 2013. Label dose 24 Botox Cosmetic Units, 12 per side. Its other cosmetic areas are glabellar lines (2002), forehead lines (2017) and platysma bands (2024).
Xeomin (incobotulinumtoxinA): Approved 5 July 2024 as part of an indication covering all three upper-face areas treated at once. Label dose for the lateral canthal area is 24 Xeomin Units, 12 per side.
Dysport, Jeuveau, Daxxify and Letybo hold cosmetic approvals for glabellar lines only: Dysport's cosmetic indication additionally applies to adults under 65, which is unusual and rarely mentioned.
Now the trap. Units are brand-specific and never interchangeable. Dysport's label states that its units "cannot be compared to or converted into units of any other botulinum toxin products," and the other labels say the same in their own words. "24 units" means nothing without a brand attached to it, and a number quoted for one brand cannot be carried across to another.
This is where a lot of published copy goes wrong in both directions, so it is worth being exact.
No FDA-approved dermal filler carries an indication for lateral canthal lines: Using filler on crow's feet is off-label everywhere in the US.
But the surrounding areas are not a blank. Several products hold approvals close by:
Temple hollowing: Juvederm Voluma XC (2023) and Restylane Contour (2026).
Infraorbital hollow, the under-eye: Juvederm Volbella XC (2021), Restylane Eyelight (2023), Belotero Balance (+) Lidocaine (2023), and RHA Redensity Eye (2026). The claim that no filler is approved under the eyes has been wrong since 2021.
Cheeks and midface: Juvederm Voluma XC, Restylane Lyft, Restylane Contour, RHA 4 and Belotero Volume (+) Lidocaine.
Skin smoothness: SKINVIVE by Juvederm, approved for the smoothness of the cheeks (2023) and for neck lines (2026). Not the outer eye.
Hold one more fact alongside those approvals. FDA's general consumer guidance for fillers still advises against injecting the glabella, nose, periorbital area, forehead or neck, and that page has not been reworded since the product-specific eye-area approvals were granted. The precise position is: specific products now hold specific approvals near the eye, and any filler used in the periorbital region without such an indication is being used off-label in a region FDA's general guidance flags as high-risk.
It is thin, and it does not test what most people are asking about. A PubMed search for lateral canthal lines and filler returns 10 records in total.
An open-label study in 59 women, mean age 52.6, injected a non-cross-linked hyaluronic acid — a thin skin-quality product, not a volumiser — into the lateral canthal and perioral lines at baseline, 3 weeks and 6 weeks. Skin firmness and visco-elasticity increased significantly at both sites at 8 weeks. Skin hydration did not reach statistical significance at any timepoint. Satisfaction was 93.1% at week 8, 91.1% at week 12 and 73.7% at week 16 — note the drop. There was no control group, no blinding and no randomisation, and the outcomes were device readings and satisfaction rather than a validated wrinkle scale. The authors also added oral herpes reactivation to the safety profile of intradermal hyaluronic acid in this region.
A real-world observational study followed 136 people receiving 451 injections of a Teoxane hyaluronic acid product across the periorbital region. More than 70% showed improvement on a global aesthetic scale, 84.3% were satisfied, and the effect was observed out to 12 months. Only 38 of those 451 injections — 15.1% — were for crow's feet; the rest went to the tear trough, palpebromalar groove, outer canthus and brow. It was unblinded, uncontrolled, and the product and author list point to company involvement. A subgroup of 38 injections cannot carry a claim.
Fair summary: What has been published on filler in the lateral canthal area is open-label, uncontrolled, and mostly about the texture and firmness of the skin rather than the lines produced by muscle movement.
None of this is a recommendation, and all of it is a consultation conversation. But there is a real answer to "could filler help how my outer eye area looks?" and it is not "fill the lines."
Volume loss in the temple: As the temple hollows, the skin over and beside the outer eye loses its underlying support and the whole lateral area reads as more crepey and more shadowed. Two products hold a temple hollowing indication, so this is a treatment with approved products and trial data behind it — for the temple, not for crow's feet.
Flattening of the upper cheek: The cheek supports the lower orbital rim. Restoring midface projection changes how light falls across the area and how much skin bunches at the outer corner on smiling.
Both change how the region looks without touching a dynamic line. Neither stops the muscle from folding the skin, so neither replaces toxin for the lines themselves.
Also worth knowing before choosing a product: hyaluronic acid fillers can be broken down with hyaluronidase; Radiesse, Sculptra and Bellafill cannot. Around the eye, where a lump or a misplacement is highly visible and the skin is unforgiving, that difference is not academic. A consensus review of calcium hydroxylapatite specifically advises against using it in the periocular area because of the higher rate of nodules there.
Vascular occlusion is the serious risk of every filler: Material enters or compresses an artery, and blood supply to what that artery feeds stops. Around the eye, the arteries connect directly to the circulation supplying the retina, so filler can travel backward and then forward into the vessels that feed the eye. The volume needed is tiny — measurements of the supratrochlear artery from the glabella to its branch point put it at an average of 0.085 mL, less than a tenth of a standard syringe.
The scale of the published record: a review of a century of cases found 511 published cases of blindness after filler, 365 of them reported between 2018 and 2023. The materials in those 365 were hyaluronic acid 79.6%, autologous fat 13.5% and calcium hydroxylapatite 1.6%. Of 318 cases with a documented outcome, 6.0% recovered completely, 25.8% improved partly and 68.2% did not recover at all. No treatment used was significantly associated with improvement; what predicted outcome was how much vision was preserved at the moment it happened. These are counts of published cases with no denominator, so they cannot be converted into a personal risk figure — but they establish that the outcome is usually permanent and that hyaluronidase is not a reliable rescue for it.
The other periorbital problems are less dangerous and more common:
Tyndall effect: A blue-grey cast where gel sits too superficially under skin this thin. Widely reported; no reliable incidence figure has been published.
Persistent swelling: This region drains poorly and hyaluronic acid draws in water, so puffiness can last months.
Lumps and contour irregularities, which show far more here than elsewhere.
Cold sore reactivation after intradermal injection in this area has been reported.
A survey of 52 experienced injector-trainers is worth one more line: 62% reported at least one intravascular injection in their career, and pain was mild or absent in 47% of those events. Pain is not a reliable warning sign.
Questions worth asking at a consultation:
Are my crow's feet only there when I smile, or are they visible at complete rest?
Which brand of toxin, and how many of that brand's units?
If filler is being suggested, which area is it going into and what is that product approved for?
Is the product you are using dissolvable?
What is your plan and referral pathway if vision changes during or after the appointment?
Go to an emergency department or call 911 for any of these, during or after the appointment. They can indicate filler in a blood vessel, and time matters in hours.
Any change in vision — blurring, a dark or missing patch, double vision or loss of sight in either eye: This is the single most important item on the page.
Sudden severe pain, or pain out of proportion to the procedure
Skin turning white or pale (blanching), then dusky, purple or mottled
Weakness, facial droop, slurred speech or any other stroke-like symptom
Swelling keeps increasing after the first few days rather than settling
A lump forms and does not settle, or one appears weeks or months later
Redness spreads outward from the injection site, or the area becomes warm and tender
The skin under the eye or beside it takes on a blue-grey tint
Tenderness or swelling appears weeks after treatment, which can indicate a delayed inflammatory reaction or an infection
A cold sore develops around the treated area