Fox eye and canthal tilt surgery

What it treats

• Fox eye, cat eye, and almond eye are patient and social-media terms, not clinical diagnoses; a 2021 commentary titled "Fox eye surgery: Who we cut when we pick up the knife" discusses the trend and the ethical questions around operating to chase it (PMID 34148836).
• Canthal tilt can be measured as the angle of the medial-lateral canthal line; in 76 Korean patients it averaged 8.45 degrees on the right and 8.42 degrees on the left, and was graded class I (mean about 3.2 degrees) or class II (mean about 9.6 degrees), with no class III cases in that cohort (PMID 33377462).
• The lateral canthus sits higher than the medial canthus in a youthful eye, and orbital bone, eyelid tension, and canthal tendon support all shape the palpebral aperture and its angle (PMID 2015744).
• The opposite finding, a downward-slanting outer corner, is called antimongoloid deformity; it gives a sad appearance with inferior scleral show and lower lid laxity, and has been treated surgically since at least 2002 (PMID 12029580).
• Facial feminization patients who received both brow lift and eyelid surgery had a higher preoperative rate of negative canthal tilt than those who had brow lift alone (p = 0.050), in a review of 34 patients and 38 surgical cases (PMID 38677276).
• Surgeons distinguish the aesthetic goal of tilting or reshaping the canthus from the reconstructive goal of supporting a lax or retracted lower lid; the anatomy, suspension techniques, and ectropion-prevention detail for the latter are covered in canthoplasty and canthopexy.

How it is done

Surgical lateral canthoplasty and canthopexy

• Aesthetic canthal suspension techniques span open and closed canthal suspension, commissure-sparing open canthoplasty, and canthopexy; choice depends on how much lift and how much lateral canthal tendon laxity is present (PMID 33906760).
• A 2026 update on lateral canthal management in esthetic blepharoplasty covers anatomy, surgical planning, and techniques to address laxity or malposition while avoiding ectropion and scleral show (PMID 41203326).
• One technique aimed at East Asian eyelids enlarges the palpebral fissure both laterally and vertically in a single integrated lateral canthoplasty; the inclination between the medial and lateral canthus significantly decreased after surgery, meaning this version of "lateral canthoplasty" opens and rounds the eye rather than raising the outer corner (PMID 40298151).
• A facelift-adjacent technique (Glidelift) adds canthal shaping and plication of the melo fat pad to the lateral orbital rim alongside brow and midface work, in 53 patients with a mean age of 42.3 years and mean follow-up of 17.3 months (PMID 41062668).
• Correcting a downward-slanting (antimongoloid) canthus has been done with a coronal subperiosteal mask-lift and deep musculo-aponeurotic suspension rather than a simple canthoplasty, for a more stable result (PMID 12029580).

Thread lifts

• "Brow gliding" uses polydioxanone (PDO) cog threads and buried knots anchored to the scalp fascia to lift the lateral brow and outer eye, marketed as a non-surgical route to a long-lasting, almond-shaped, upturned eye, in 34 patients followed at least 6 months (PMID 35880467).
• A multidirectional barbed PDO thread ("Sihler thread") technique anchors in the subgaleal aponeurosis after passing sub-superficial-temporal-fascia, targeting age-related lateral canthal ptosis and temporal hooding together, in 22 Asian women (PMID 42578186).
• General PDO eyebrow thread lifting changed the angle of the inner eyebrow by 4.00 to 4.44 degrees with only modest height change, in 29 patients followed 3 months (PMID 39860496).
• Multidirectional PDO threads have also been combined with transcutaneous lower blepharoplasty through a shared subciliary incision to lift the midface and lower lid together, in 84 patients (PMID 42318491).

Results and evidence

• Sihler thread lateral canthal lift: measured lateral canthal tilt rose from 2.1 ± 1.4 degrees to 4.3 ± 1.6 degrees at 6 months, easing to 3.6 ± 1.5 degrees at 12 months; vertical canthal displacement improved by 1.8 mm at 6 months and 1.2 mm at 12 months; global aesthetic improvement was rated "improved" or better in 90.9% of patients at 6 months and 77.8% at 12 months (PMID 42578186).
• Brow gliding: of 34 patients, 4 (11.8%) rated results "very good" and 19 (55.9%) rated results "beyond expectations" on follow-up (PMID 35880467).
• PDO eyebrow threads: 26 of 29 patients were "satisfied" or "very satisfied" at 3 months, with no serious complications observed (PMID 39860496).
• Integrated lateral canthoplasty for fissure enlargement: the distance from the midpupillary line to the lateral canthus, and both measures of lower lid position relative to the pupil, significantly increased after surgery (p < .05); no severe complications were reported (PMID 40298151).
• Glidelift: photographic and clinical review showed a more defined canthal tilt, shortened lid-cheek junction, and increased malar projection, with high patient satisfaction for periorbital shape (p < 0.01) (PMID 41062668).
• Combined PDO thread and lower blepharoplasty: mean perceived age fell from 57.0 ± 7.5 years preoperatively to 50.0 ± 6.6 years at 4 months (p < 0.001); the authors call the results preliminary given the short follow-up and subjective endpoint (PMID 42318491).

Risks and complications

• Failed aesthetic lateral canthoplasty: in 15 patients (25 eyelids, mean age 32.6) referred for revision, deformities included canthal webbing, canthal rounding, eyelid margin defect, mucosal exposure, lower eyelid retraction, sclera show, ectropion, symblepharon, and lagophthalmos; a modified lateral tarsal strip procedure restored canthal contour and eyelid function in this group (PMID 37622520).
• Canthal rounding, the opposite of the intended upward tilt, has its own repair technique; 12 patients with post-surgical canthal rounding across 3 centers had no peri- or postoperative complications after repair, with 1 case of recurrent rounding (PMID 33746208).
• Thread lift safety across facial indications: a meta-analysis of 42 studies found treatment-related adverse events in 20.0% of patients after nonsurgical thread facelifts (95% CI 8%-41%), most often pain (31.5%) and bruising (23.4%) (PMID 41047572).
• A reported bacterial complication after barbed PDO thread placement caused perforating abscesses along the thread tracks; the threads were fragile and required surgical removal, and delayed treatment left a persistent deformity (PMID 35265439).
• Canthal surgery can also move the corner too far in the other direction: correcting an over-rounded or downward-slanting canthus has required a second, more extensive procedure in published series (PMID 12029580), (PMID 33746208).

Recovery

• Brow gliding is described as an office-based procedure; patients were followed for at least 6 months to assess the lift (PMID 35880467).
• PDO thread lifting is presented as faster-recovery and scar-free compared with surgical facial rhytidectomy, though this comparison comes from the authors' framing rather than a head-to-head trial (PMID 39860496).
• Thread-based canthal tilt is not permanent: the measured tilt gain from Sihler threads fell from 4.3 degrees at 6 months to 3.6 degrees at 12 months, and brow tail height gain fell from 2.4 mm to 1.8 mm over the same interval (PMID 42578186).
• Combining PDO threads with lower blepharoplasty added about 5 to 7 minutes to operating time and required no extra incisions in one case series (PMID 42318491).
• A thread-related bacterial complication was still symptomatic 1 month after the original procedure when the patient sought care, and required 5 days of antibiotics before surgical thread removal (PMID 35265439).

Combined procedures

• Glidelift combines canthal shaping with melo fat pad elevation and a brow/midface suspension net in one facelift-adjacent operation (PMID 41062668).
• Sihler thread technique treats lateral canthal ptosis and temporal hairline hooding in the same pass, since both are stabilized by the same temporal fascia (PMID 42578186).
• Multidirectional PDO threads have been combined with transcutaneous lower blepharoplasty through a shared incision (PMID 42318491).
• In facial feminization surgery, brow lift (79% of a 34-patient series) and upper eyelid surgery (35%) are the most common periocular procedures paired with canthal tilt changes (PMID 38677276).
• Temporal and lateral brow position strongly affects the apparent lateral canthal tilt; surgical brow elevation technique is covered in temporal and lateral brow lift and browpexy and direct brow lift.
• Reconstructive lateral canthal tightening to fix eyelid laxity, ectropion, or retraction, rather than to change eye shape, is covered in canthoplasty and canthopexy.

Current questions

• "Lateral canthoplasty" is not one operation: one described technique decreases the inclination between the canthi to enlarge and round the eye (PMID 40298151), while thread and suspension techniques aim to raise the lateral canthal tilt for an upswept shape (PMID 42578186), (PMID 35880467); patients and surgeons need to agree on direction before naming the procedure.
• Durability of thread-based tilt is limited to one 12-month outcomes series, in which the measured gain had already started to regress by 12 months; no randomized or sham-controlled trial of thread lifting for canthal tilt was found (PMID 42578186).
• Patient-facing information online is inconsistent with the evidence base: an analysis of 173 YouTube videos on aesthetic canthoplasty found generally poor quality and reliability scores, with most videos from healthcare professionals weighted toward advertising rather than education (PMID 38918201).
• Gender-affirming relevance is new: upward lateral canthal tilt was endorsed as more feminine by almost all respondents in a 2026 survey, but the authors note cisgender-derived beauty standards may not match what transgender and nonbinary patients want from periocular surgery (PMID 42600132).
• A validated cosmetic-planning classification for canthal tilt does not yet exist; the only degree-based classification found was built for craniofacial orbital dystopia in 76 patients, not for aesthetic canthal tilt surgery planning (PMID 33377462).

Terms

• Canthal tilt: the angle of the line connecting the medial and lateral canthus relative to horizontal (PMID 33377462).
• Fox eye / cat eye / almond eye (patient terms, not diagnoses): social-media names for an upswept lateral canthal tilt (PMID 34148836).
• Lateral canthus / medial canthus: the outer and inner corners of the eyelids, anchored by canthal tendons to the orbital rim (PMID 2015744).
• Canthoplasty: surgery that cuts and reattaches the canthal tendon to change canthal position or shape (PMID 33906760).
• Canthopexy: suspension of the canthal tendon without cutting it (PMID 33906760).
• Antimongoloid deformity: a downward-slanting lateral canthus, the opposite of the fox eye goal (PMID 12029580).
• Canthal rounding: loss of the normal pointed lateral canthal angle after trauma or surgery (PMID 33746208).
• PDO thread: a polydioxanone suture with cogs or barbs, placed under the skin to suspend tissue without an incision (PMID 35880467).
• Scleral show: visible white of the eye below the iris when the lower lid sits too low, a risk of over-tightening (PMID 37622520).
• Facial feminization surgery (FFS): a group of procedures, including brow and eyelid surgery, intended to shift perceived gender of the face (PMID 38677276).

Papers