Giant Cell Arthritis
A new study is pblished where we present a detailed evaluation of the safety regarding visual function and patient tolerability in healthy subjects, and define the spectral signature in the healthy temporal artery. Photoacoustic imaging did not affect the best corrected visual acuity, colour vision (tested with Sahlgren's Saturation Test or the Ishihara colour vision test) or the visual field. The level of discomfort was low, and only little heat and light sensation were reported. The spectral signature of the artery wall could be clearly differentiated from those of the subcutaneous tissue and skin. Spectral unmixing provided visualization of the chromophore distribution and overall architecture of the artery. In coclusion, photoacoustic imaging of the temporal artery was shown to be well tolerated and can be performed without any risk to visual function, including the function of the retina and the optic nerve. The spectral signature of the temporal artery is specific, which is promising for future method development.
Perfusion monotoring
Large upper eyelid defects can be repaired by rotational full-thickness lower eyelid flaps. The aim was to measure the blood perfusion in such flaps, and how it is affected by the length of the flaps, and the degree of rotation and stretching. Blood perfusion in lower eyelid rotational flaps seems to be more sensitive to stretching than to rotation. Provided the flap is no longer than 1.5 cm, the perfusion will be greater than 20%, even when rotated, which should be sufficient for adequate survival and healing.
It is generally believed that large eyelid defects must be repaired using a vascularized flap for 1 lamella, while the other can be a free graft. Recent studies indicate that the pedicle of a tarsoconjunctival flap does not contribute to blood perfusion. The purpose of this study was to explore whether large eyelid defects can be repaired using a free bilamellar eyelid autograft alone. A free bilamellar eyelid graft appears to be an excellent alternative to the tarsoconjunctival flap procedure in the reconstruction of both upper and lower eyelid defects, especially in patients who cannot tolerate visual axis occlusion or the 2-stage procedure of the conventional staged flap procedure.
Canthotomy is frequently used to mobilize extra tissue when repairing larger lower eyelid defects. The aim of this study was to explore the effect of canthotomy on blood perfusion and oxygen tension. It could be concluded that canthotomy in combination with a wedge resection of the lower eyelid affects blood perfusion. A smaller length of remaining eyelid tissue will have less perfusion. This may not have any implications in cases of direct closure, but may play a role when the eyelid is to provide oxygen and nutrients to avascular grafts.
H-plasty reconstructive surgery is commonly used to close defects after tumor excision in the periorbital region. Revascularization of the bipedicle skin flaps is essential for healing. However, it has not previously been possible to study this revascularization in humans due to the lack of noninvasive perfusion monitoring techniques. The study monitor perfusion in H-plasty flaps during surgery and during postoperative follow-up, using laser speckle contrast imaging. Revascularization of the H-plasty procedure flaps was found to occurs quickly, within a week postoperatively, presumably due to the existing vascular network of the flap pedicle, and was not dependent on significant angiogenesis. This perfusion study confirms the general opinion that H-plasty is a good reconstructive technique, especially in the periorbital region with its rich vascular supply.
Skin cancer
The eyelids are susceptible to a number of skin cancers, which are challenging to excise radically without sacrificing excessive healthy tissue. To reduce reoperations due to nonradical excision, there is a need to develop a technique for identification of tumor margins preoperatively. Photoacoustic (PA) imaging is a novel imaging technology that combines the strengths of laser optics and ultrasound. We found that PA imaging can be used to differentiate between the main structures of the human eyelids, the orbicularis oculi muscle and the eyelid skin and tarsal plate, and that they could be visualized in three dimensions. PA imaging was also able to differentiate between BCC and healthy tissue and the spectral signature of cSCC was used to visualize tumor architecture and borders. This knowledge can potentially be used to delineate tumors prior to surgical excision.