Because the transconjunctival approach is more direct and less invasive, it provides a safer (but not foolproof) method to manage orbital fat.
1. Almost No Possibility of Scar-Related Lower Eyelid Retraction
The risk of internal scar-related lower eyelid retraction (an abnormal pulling down of the lid to expose the 'white' of the eyeball) is all but eliminated when transconjunctival lower blepharoplasty is used to trim bulging orbital fat. Since the operation does not violate the important but delicate middle layer of the eyelid, the negative consequences of contracture from deep scarring either immediately after or even years later do not develop.
If a transconjunctival approach is employed to do more than trim orbital fat (for instance, fat repositioning into a cheek hollow or placement of a tear trough or cheek implant), the dissection needed is much more extensive. Some (although still small) risk of internal scar-related retraction is then reintroduced.
Can pulling down of the lower lid occur for reasons other than internal scarring? Yes. Although rarely mentioned in discussions on blepharoplasty, if too much orbital fat is removed by any method, the eyelid may lose its support from below and collapse downward into the resulting hollow.
A recent study confirmed an interesting and important observation long noted by some oculoplastic surgeons but never formallly measured: pure transconjunctival lower blepharoplasty (no skin removal, canthopexy, etc.) does more than simply preserve the starting position of the lower eyelid margin.
In nearly 75% of the patients studied, the postoperative lower eyelid margin was actually elevated a very small but measurable amount.
The precise mechanism is unknown but was felt to be likely related to a weakening of the lower lid retractors that must be cut through during the operation in order to reach the fat pockets from the back surface of the eyelid.
The authors noted that in almost all study patients who had some scleral show prior to their surgery (that is, "white" showing between the bottom of the iris and the top of the lid margin), this (sometimes undesirable) finding was no longer present postoperatively.
Why is this important? Patients with prominent eyes and preexisting scleral show are often considered risky candidates for other forms of lower blepharoplasty because their lower lids tend to drift (retract) downward after surgery.
2. Increased Precision
Because the eyelid is not "taken apart" from the front, it is easier for the surgeon to gauge the effect of fat removal as the operation is in progress. What results is a more accurate assessment of the amount of fat to be trimmed and increased precision.
Is it still possible to over or under resect fat? Of course. Employing a safer approach is only one variable in the whole operation.
3. More Rapid Recovery
Because the transconjunctival approach is less invasive, there is generally less bruising and swelling (not none at all, but rather much less than with other operations).
4. More Natural Appearing Outcome
As noted previously, one of the most feared complications of lower blepharoplasty is eyelid retraction, a complication that is by no means rare with the full transcutaneous approach. Even if this does not present in full bloom, the eyelid is not uncommonly rounded and left less mobile.
With the transconjunctival approach, such internal scar-related problems do not occur.
5. No Visible Scar Extending Across Most of the Eyelid
If there is no skin incision extending from one side of the lid to the other, there's no corresponding external scar.
Still, the procedure is not a "no-scar operation," as it is sometimes misrepresented. There will always be a scar after any incision. With transconjunctival surgery, that scar is located on the inside surface of the lower eyelid where it is neither visible to others, able to be felt, nor a source of problems for the eyelid or eyeball.
If transconjunctival surgery is coupled with canthopexy, skin-only excision, and/or other external procedures, a scar will, of course, be created by these other operations. Is this bad? If the other procedures are indicated but not done, the final result will be less than optimal.
While certainly nice, patients tend to make too much out of the hidden scar advantage. Far more substantial benefits of this operation are noted above.
While hardly substantial negatives, here are two points you may wish to consider.
1. No Skin Can Be Excised
How can baggy skin on the front of the lower eyelid be removed when the operation is being performed entirely from the back surface of the lid. Obviously, it can't be. So, if a patient clearly has excess skin along with too much fat (a very common combo), does this mean the only option is to undergo a transcutaneous approach?
Hardly, even though this so-called "disadvantage" is frequently cited by proponents of the transcutaneous approach. If both fat and skin require excision, the surgeon can simply first employ the transconjunctival approach to most safely trim the fat and then make a second skin-only incision along the edge of the eyelid to safely remove any offending skin.
Okay, but then how could making two incisions be better than accessing both skin and fat from within a single incision? It is because it's safer in any number of ways, the most notable of which is that the orbicularis muscle and orbital septum (both crucial for proper eyelid support and function) remain fully preserved.
2. Requires Increased Technical Skill
For a beginning surgeon inexperienced with the transconjunctival approach (or even a seasoned cosmetic specialist who performs only a few blepharoplasties in between breast augmentations), the operation's learning curve can seem daunting if not treacherous.
Manipulating orbital fat from within a tiny opening located between the back of the eyelid and the front of the eyeball may not seem that appealing because it's easy for the uninitiated to get lost.
On the other hand, once the operation had been learned, it really isn't any more difficult to perform than any other. It's like learning the piano.
Once you progress past the hunt-and-peck stage and can finally play Chopin, you're now ready focus your energy less on finding the right keys and more on mastering nuances.
3. Yes, the Eyelid Can Be Hollowed
Since transconjunctival blepharoplasty is an operation designed to remove fat, it is, of course, possible to remove too much.
Unfortunately, the full negative effect of orbital fat removal may not be fully noted until years after healing.