The Circle of Suboptimal Parameters, Etiology and Interrelatedness
Of all the parameters that influence the outcome of surgery, perhaps the single most important factor will be the height of the crease, as drawn from the mid-ciliary margin. The crease should be designed based on the central height of the tarsal plate, and no higher. In Asians this is often between 6.5 and 7.5 mm. When designed in this range, the crease often proves natural in appearance and well formed. When designed above the measured height of the tarsus, the result is often a crease that is unnatural in appearance, restrictive in upgaze and associated with increased lymphedema in the pretarsal region, manifesting as a ‘fat’ eyelid border. A crease that is designed lower than the lowest range of normal will often lead to a scar in the pretarsal skin region which is hard to camouflage, or the lymphatic stasis and eventual resolution lead to multiple creases and folds (see Figure 15-1 ).
Next in importance is the shape of the crease design, i.e. nasally tapered or parallel. The nasally tapered crease is popular and compatible with almost any Asian ethnicity. Its distinctive feature is a gradual convergence towards the medial canthus, and it converges on and joins the medial canthal angle. As it courses medially, the indented crease would join and merge towards any mild medial canthal fold the patient may already have. The nasally tapered crease seems more prevalent in southern Chinese, as well as in south-eastern ethnic groups such as Malaysians, Thais, Vietnamese and Cambodians. The parallel crease is more often seen in northern Chinese as well as northern Asians. The crease is uniform in width as it arches from one corner of the lid to the other. It appears to be aesthetically more compatible for someone with larger facial features, a more rectangular or squarish face, or someone who is tall and hence has a proportionately larger face. The parallel crease may be observed among southern Asians and the nasally tapered crease may likewise be seen in northerners.
If a crease is designed with the correct shape but with a height above the normal range, it becomes conspicuous and artificial in appearance. When a crease is designed without following the normal geometric contour for that particular crease shape, again one has the impression of artificiality, for example a crease that flares up medially, or one that converges laterally (both opposite to what may normally occur in those locations). This applies when one is comparing the symmetry of design between two eyelids: again, it would be less than ideal to have a crease shape on one side that differs from what is on the opposite side (although in the overall picture this is far less suboptimal than other outcomes). There are times when a surgeon finds that a semicircular crease is created unintentionally on one side. This can be revised back to the desired shape at the appropriate time, provided there are some skin reserves to work with.
During the design as well as the construction phase of the crease, and especially for a nasally tapered crease, if the surgeon does not steer the medial end towards and to merge with the medial canthal fold, then a bifid crease can be the result – a crease that splits either above or below the medial canthal fold.
An artificially high crease incision will naturally lead the surgeon to encounter a greater amount of fat in the preaponeurotic space because of its high entry. There is a chance that the surgeon will then be unknowingly steered towards a greater than normal degree of fat excision. This leads to:
A more hollowed preseptal region (enhanced supratarsal sulcus).
A greater chance of the formation of multiple creases or folds above the incision wound, in the preseptal region. There is then a confusing picture of competing creases, rather than a predominant and primary crease being formed.
A greater chance of a comparatively rigid preseptal segment of skin–muscle anterior lamella bounded to the posterior lamella.
Continuity relates to factors in the construction of a crease: the efforts must be uniform and deliberate, with varying techniques tailored to the particular terrain across the width of the eyelid fissure. If the effort should succeed in most of the length of the crease but fail in a small location, the result is a discontinuous or partial crease (or a partially obliterated crease). The crease may become indistinct, either medially, centrally (less often) or laterally.
Permanence refers to the ideal goal of achieving a crease that remains for more than 3–5 years. When the entire crease fades out over a 6-month period it is usually due to insufficient clearance of the soft tissue corridor along the preaponeurotic platform, with regression of the soft tissue barrier, including fat, along the zone where the crease would ideally form. It can also occur as a result of an excessively low incision path along the pretarsal plane.
Continuity, therefore, relates more to the overall effort of crease fixation, assuming the path is already on the correct level and plane. Permanence includes the effort made to ensure continuity but relates to long-term success and the efficacy of a particular method, as applied to an individual patient.
The challenge is that with any of the factors mentioned above and shown in the circle of suboptimal parameters, each may have a slight imperfection that can lead to less than perfect results. Aggregation of several suboptimal factors can pose a greater degree of challenge when it comes to revision attempts. It is not uncommon to see revision attempts aimed at the excision of multiple folds or a high crease lead to severe skin shortage, lagophthalmos and corneal exposure. Likewise, injection of free fat grafts may lead to mechanical ptosis, hypertrophy of injected fat, or lumpy fat grafts. Acquired ptosis is a common sequela following revision attempts and can be cicatricial (owing to high crease fixation) or mechanical (stiffened preseptal platform) in origin. Scarring in the middle zone and involving the levator muscle can lead to both lagophthalmos and ptosis, as well as poor closure of the palpebral fissure and corneal exposure.
It is hoped that with knowledge, skill and careful preoperative discussion, the surgeon can avoid the factors that lead to suboptimal results (as discussed in Chapter 14 ). There will, however, always be patients who seek revisions and this chapter will discuss some of the problems the author has encountered in the treatment of such patients, and their solutions.
The revision techniques for the various suboptimal configurations are discussed below.
By far the most frequently encountered problem is crease asymmetry. This includes creases that are unequal in height ( Figure 15-2 ), uneven in shape and continuity, have undergone shifting (downward migration or partial or complete obliteration of the crease) or have faded in the medial one-third of the lid ( Figure 15-3 ).
Inequality in Crease Height
When the crease of one eyelid appears higher than that of the other, often the higher crease is the abnormal one. It is essential to detect any acquired ptosis in that eyelid, because the levator aponeurosis often appears to have dehisced some of its lower terminal interdigitations and has only a portion of its superior lid crease attachments remaining ( Figure 15-4 ). Correction of the ptosis eliminates the apparently higher crease without any need to reposition the crease.
A higher than normal crease can arise from inappropriate marking of the incision lines, from inaccurate placement of the interrupted crease-forming sutures over the levator aponeurosis, or from persistent edema in the pretarsal plane. If a crease still appears high 6–9 months after the operation, the repair can be accomplished in the following manner.
Repair of a High Crease
The eyelid is everted and the central height of the tarsus measured (see Chapter 7 ). This serves as a reference point for crease placement. When the tarsal height is transposed on the skin side and is found to be closer to the eyelash line than the current crease, the difference in millimeters of skin can be excised with the previous incision scar, as long as a shortage of skin does not result and complete eyelid closure is not compromised ( Figure 15-5 ). It is helpful to lyse any subcutaneous aponeurotic attachment along the superior edge of the incision. Any scar tissue that may overlie the aponeurotic attachment along the superior tarsal border should be removed to allow for the construction of the new crease.
If the transcribed tarsal height on the skin side is higher than the supposedly high crease, one should examine the contralateral upper lid crease to see if it has an excessively low crease.
It is more difficult to repair an excessively low crease (one that is close to the lash margin) than to repair an excessively high one. The correction is tailored to whether there is any redundancy of skin.
Repair of a Low Crease
For patients who have some redundant skin, the best method is simple excision of the scar associated with the low crease, allowing it to heal, and then performing a subsequent crease procedure a minimum of 6 months later. In my experience, simultaneous revision and construction of a new crease often gives suboptimal control of crease height.
When the skin is taut and has no redundancy, simple excision cannot be performed because it may result in cicatricial ectropion or a prominent scar ( Figure 15-6 ). An acceptable option for a low crease with a scarcity of skin is complete excision of the crease and the adjacent pretarsal skin, replacing them with a full-thickness skin graft and reshaping the crease at the same time. This procedure is used if the graft covers only the pretarsal region. The patient should be forewarned that the crease will appear high for at least 6 months.
If the skin graft required spans both the pretarsal and the supratarsal regions, it is best to defer crease reconstruction for at least 6 months ( Figure 15-7 ).