Nov
PhD defense - Kajsa Tenland
Title: Reconstruction of Large Eyelid Defects Using Tarsoconjunctival Flaps, Opportunities for Novel Surgical Techniques
Opponent: Associate professor Dyonne Hartong, Amsterdam
Abstract: Large lower eyelid defects resulting from tumor removal are frequently reconstructed using a tarsoconjunctival flap from the upper eyelid together with an overlying free skin graft. One disadvantage of this technique is that the tarsoconjunctival flap occludes the eye during the revascularization of the graft, which is particularly troublesome for patients with poor vision in the other eye. Alternative single-stage methods for reconstructing large lower eyelid defects have not been widely used in clinical practice, since it is generally believed that an avascular graft is dependent on a vascularized flap for survival. However, previous studies have raised the question of whether the flap contributes to perfusion in the graft, and if a single-stage surgical procedure using free full-thickness composite grafts could be a surgical option.
Microvascular perfusion and oxygenation were studied in patients and a porcine model undergoing reconstructive surgery of large lower eyelid defects, using laser speckle contrast imaging (LSCI), laser Doppler velocimetry (LDV), and a Clark electrode. Perfusion was monitored in tarsoconjunctival flaps in patients during surgery, and the results showed that perfusion decreased gradually along the length of the flap, and that
there was almost no blood flow at the distal end of the flap. Perfusion was then monitored in free skin grafts overlying tarsoconjunctival flaps in patients. The results showed that, despite the minimal perfusion of the flaps, the free grafts overlying the flaps reperfused within the first 3-8 weeks postoperatively. These findings support the hypothesis that the grafts do not appear to be dependent on a vascularized pedicle for survival.
The perfusion of free full-thickness composite grafts used to reconstruct eyelid skin was monitored in patients during and after surgery, showing that all grafts were reperfused within the first 8 weeks postoperatively. This paves the way for a single-step procedure in which occlusion of the eye during the revascularization period is not needed. The impact of cantholysis, often necessary during reconstruction to mobilize tissue and reduce stretching of the tissue, on blood perfusion was studied in a porcine model. Canthotomy and a wedge resection were performed in pigs, and blood perfusion and oxygenation were monitored perioperatively. Canthotomy resulted in a decrease in blood perfusion of the remaining eyelid, and this may affect healing, especially if the
remaining eyelid needs to provide perfusion to an avascular graft. In conclusion, the avascular grafts do not seem to be dependent on a vascularized flap. A single-stage graft using a free eyelid composite graft may be used as an alternative. A free composite graft would be of considerable advantage to patients, since the occlusion of vision post-surgery could be avoided, and the number of surgical procedures reduced.
About the event
Location:
Belfragesalen, BMC Lund
Contact:
kajsa [dot] tenland [at] med [dot] lu [dot] se