What the diagonal line actually is
Most people know the tear trough — the groove that runs from the inner corner of the eye along the bone. In some faces, that line does not stop there: it continues diagonally downward and outward across the cheek, dividing the front of the cheek from the middle of it. In Korea it is called the "Indian band," after the face-paint line in old Westerns; in Japan it is known as the Golgo line. Whatever the name, it is a real anatomical boundary — a sunken line that separates soft-tissue compartments of the midface — and because it cuts across the light of the cheek, it adds a tired, drawn cast that makeup covers poorly.
A ligament anchored to bone, not a skin crease
The line exists because a retaining ligament runs from the facial bone to the skin along that exact path, holding the tissue down the way upholstery buttons hold fabric. This is why some people have the line faintly from childhood — it is a built-in feature of their anatomy, not damage — and why it deepens with age: the bone anchor does not move, but the skin, muscle, and fat around it gradually descend, so the tethered line rolls inward and reads deeper each year. People without the line simply do not have the ligamentous extension. Understanding this changes the whole treatment question: you are not treating a wrinkle in the skin; you are dealing with a structure that actively holds the surface down.
Why filling it tends to disappoint
The intuitive fix — inject filler or fat into the dent — collides with the anatomy. The tethered line itself cannot accept volume, because the ligament pins it down; injected material settles above and below the line instead. The ridges on either side rise while the line stays anchored, so the valley can look deeper, not softer, and the surface becomes irregular. Compensating by adding more volume to push the whole area outward creates its own problem: the cheek inflates into an unnatural mound while the band persists across it. This is a pattern ST regularly sees in patients arriving after injections elsewhere — not because injectors were careless, but because the structure sets a trap for any approach based purely on adding volume.
Cutting the ligament blind has a targeting problem
If a ligament causes the line, why not simply cut the ligament? Non-surgical release — dividing the band with threads or cannulas through the skin — sounds logical, but it is performed without seeing the target. The ligament cannot be precisely located from outside, the release is therefore incomplete or misplaced, and nearby structures can be injured in the attempt. Patients often look improved for the first month or two while swelling masks the line, then watch it return as the swelling clears. An honest rule of thumb: a structure that cannot be seen cannot be reliably released.
What surgery can reach — and what it cannot
During under-eye fat repositioning, the tear-trough ligament is exposed and released under direct vision — that is a core step of the operation. But the mid-cheek band lies farther down and deeper than the surgical field of the under-eye safely extends; dissecting down to divide it would put surrounding tissue at risk. ST’s answer is deliberately modest: after the under-eye structure is corrected, finely processed micro-fat — the same concealer-style fat used for thin-skin dark circles — is layered in small amounts just under the skin along the line. Because the goal is to soften the fold rather than inflate the compartment, only a little fat is needed, and the cheek contour does not change. The realistic outcome is a line about 60–70% softer — visible improvement, honestly short of erasure — and because grafted fat partially absorbs, a faint trace may remain or return.
Sequence matters: correct the under-eye first
The band rarely exists alone — it usually accompanies a tear trough, and often a fat bulge above it. Treating the extension while the primary groove is still tethered gets the order backwards: the repositioning corrects the bulge and releases the trough first, which alone changes how the whole lid-cheek region catches light, and the residual diagonal line is then assessed and softened as a refinement. Patients considering their options should also know the band is one of the three classic patterns of under-eye hollowing, alongside hollowing under the aegyo-sal and the tear trough itself — and each of the three has a different correction logic.