The ever-expanding list of body lines has a popular new entry: the eyeline or, less commonly, eye-line.
The term has nothing to do with the most frequently discussed line on Asian eyelids --namely, the crease of a double eyelid. Instead, it refers to the the overall shape of the eye and surrounding skin, particularly during the most expressive of facial gestures, smiling.
While controversial, Korean body lines are unique in their ability to efficiently describe complex contours and relationships rather than individual features by using only a single letter from the Western alphabet.
For instance, the common Western term "waistline" is really just another way of saying "waist" and adds little or no extra meaning. In contrast, the best-known Korean body line is the "S-line" that describes the curving flow from bust to waist to buttocks without needing to describe each anatomic part and junction separately.
Upon smiling, the muscles of the eyelid contract and the eye opening becomes narrowed, a change that is further accentuated by the skin and muscle of the cheek moving upward. The skin beyond the outer junction of the lids (area of the crowsfeet) tightens and sometimes folds into fan-like radiations.
It has become popular of late to use pen-type eyeliners on the lower lid to apply dark color past the end of the eyelid by a half inch or so, thus lengthening the eye's overall appearance and accentuating the strength, depth, and warmth of a smile.
The same can be done from the upper lid alone or with the lines from both eyelids merging into one another.
Interestingly, this method of wider eyeliner application can convey almost the opposite impression -- a look of power and aggression -- when the muscles around the eyes are at rest and not smiling.
Of course, there's much more to smiling than just what happens around the eyes. During a smile, the entire middle and lower face undergo a coordinated change and so talking only about the eyeline is far from complete (nor is it intended to be). However, the term "smile line" is not particularly useful since the simpler "smile" already captures it all.
It seems to us that the still-available designation "I-line" would be a more appropriate name than eyeline, if only to conform to the already well-established convention of using letters rather than literal anatomic terms but also because more than just the eyelid is involved (eyelid, brow, nose, upper cheek, and temple all make their own contributions to the eye smile).