Forehead flap perfusion monitored by laser speckle contrast imaging: Importance of flap length and thickness.

Purpose: Forehead flaps are commonly used in oculoplastic surgery to cover defects after tumor excision. Blood perfusion is vital for flap survival. The aim of this study was to monitor the perfusion in forehead flaps and investigate the impact of flap length and thickness. Methods: Nineteen forehead flaps in patients undergoing direct brow lift were studied. Perfusion was monitored using laser speckle contrast imaging, immediately after raising flaps consisting of epidermis, dermis, and subcutaneous tissue, and after removing the subcutaneous tissue resulting in a thin flap. Results: Perfusion decreased gradually along the length, the mean value being 44% at 5 mm and 26% at 15 mm from the base, in thick flaps. Perfusion was significantly lower in thin flaps, being 13% when measured 15 mm from the flap base (p < 0.0024). Perfusion was better preserved in thick than in thin flaps. Very low perfusion was observed 16.7 mm (16.0-17.3 mm) from the base in thick flaps, and from 10.2 mm (9.8-10.6 mm) from the base in thin flaps (p < 0.0001). Conclusions: Flap thickness is important in maintaining adequate blood perfusion and thus increasing the probability of flap survival. This may be particularly important in long flaps and in patients with impaired microcirculation.

The effect of traction force on eyelid blood perfusion during closure of defects.

PURPOSE: In oculoplastic surgery the eyelid tissue is frequently stretched in order to repair defects after tumor surgery. However, there is a paucity of research regarding how stretching affects eyelids. The purpose of this study was to gain insight into how traction force affects eyelid stretch as well as tissue perfusion, using a laser-based in vivo monitoring technique. METHOD: Lower-lid pentagonal resections were performed in eight patients and a total of nine eyelids. The medial section of the eyelid was then stretched using a dynamometer up to a force of 2.3 Newtons (N), and eyelid stretching and blood perfusion were continuously measured using laser speckle contrast imaging. RESULTS: Tissue perfusion decreased exponentially when eyelid tissue was stretched, with an initial sharp decline followed by a more gradual reduction. Perfusion approached zero at a force of approximately 2.0 N. The length of the eyelid increased with increasing force up to 1.5 N, after which there was only a very slight increase in length. CONCLUSIONS: Eyelid tissue seems to respond to traction in a non-linear fashion, where the initial force results in the greatest eyelid stretching and reduction in blood perfusion. The results provide information on the effects of a large force for direct closure of large eyelid defects. Considering how quickly perfusion approaches zero, the high success rate of eyelid reconstruction surgery is likely a testament to the extensive vascularization of the periocular region.

Oxygen saturation mapping during reconstructive surgery of human forehead flaps with hyperspectral imaging and spectral unmixing.

BACKGROUND: Optical spectroscopy is commonly used clinically to monitor oxygen saturation in tissue. The most commonly employed technique is pulse oximetry, which provides a point measurement of the arterial oxygen saturation and is commonly used for monitoring systemic hemodynamics, e.g. during anesthesia. Hyperspectral imaging (HSI) is an emerging technology that enables spatially resolved mapping of oxygen saturation in tissue (sO2), but needs to be further developed before implemented in clinical practice. The aim of this study is to demonstrate the applicability of HSI for mapping the sO2 in reconstructive surgery and demonstrate how spectral analysis can be used to obtain clinically relevant sO2 values. METHODS: Spatial scanning HSI was performed on cutaneous forehead flaps, raised as part of a direct brow lift, in eight patients. Pixel-by-pixel spectral analysis, accounting for the absorption from multiple chromophores, was performed and compared to previous analysis techniques to assess sO2. RESULTS: Spectral unmixing using a broad spectral range, and accounting for the absorption of melanin, fat, collagen, and water, provided a more clinically relevant estimate of sO2 than conventional techniques, where typically only spectral features associated with absorption of oxygenated (HbO2) and deoxygenated (HbR) hemoglobin are considered. We demonstrate its clinical applicability by generating sO2 maps of partially excised forehead flaps showed a gradual decrease in sO2 along the length of the flap from 95 % at the flap base to 85 % at the flap tip. After being fully excised, sO2 in the entire flap decreased to 50 % within a few minutes. CONCLUSIONS: The results demonstrate the capability of sO2 mapping in reconstructive surgery in patients using HSI. Spectral unmixing, accounting for multiple chromophores, provides sO2 values that are in accordance with physiological expectations in patients with normal functioning microvascularization. Our results suggest that HSI methods that yield reliable spectra are to be preferred, so that the analysis can produce results that are of clinical relevance.

Mapping of Perfusion During Full-Thickness Blepharotomy Using Laser Speckle Contrast Imaging.

PURPOSE: The aim of this study was to monitor how the blood perfusion in human upper eyelids is affected during full-thickness blepharotomy. METHODS: Seven eyelids in 5 patients with upper eyelid retraction due to Graves' disease underwent full-thickness blepharotomy. Perfusion was measured using laser speckle contrast imaging in the eyelid margin and in the conjunctival pedicle. RESULTS: Immediately following the procedure, a nonsignificant reduction in perfusion was observed in the skin of the pretarsal eyelid margin, being 66% of the initial value ( p = n.s.). However, a statistically significant decrease in perfusion, to 53% of the initial value ( p < 0.01), was seen in the central pedicle of the conjunctiva. There were no surgical complications such as infection, signs of ischemia, or bleeding. CONCLUSIONS: In this study, eyelid perfusion was mapped during full-thickness blepharotomy for the first time using laser speckle contrast imaging. The results showed that perfusion is sufficiently preserved during surgery, probably due to the rich vascular supply in the periocular region, which may explain the low risk of postoperative complications such as ischemia and infection.

Hyperspectral and Laser Speckle Contrast Imaging for Monitoring the Effect of Epinephrine in Local Anesthetics in Oculoplastic Surgery.

PURPOSE: Epinephrine is used in local anesthetics to induce vasoconstriction and thus reduce bleeding and prolong the anesthetic effect. Finding the optimal delay between the administration of the anesthetic and skin incision to ensure vasoconstriction and minimize bleeding is important and has recently become the subject of debate. This is the first study to assess blood perfusion and oxygen saturation (sO 2 ) simultaneously in response to a local anesthetic containing epinephrine in human oculoplastic surgery. METHODS: A local anesthetic consisting of lidocaine and epinephrine (20 mg/ml + 12.5 µg/ml) was injected in the eyelids of 9 subjects undergoing blepharoplasty. The perfusion and sO 2 of the eyelids were monitored using laser speckle contrast imaging and hyperspectral imaging, respectively. RESULTS: Laser speckle contrast imaging monitoring showed a decrease in perfusion over time centrally at the site of injection. Half-maximum effect was reached after 34 seconds, and full effect after 115 seconds, determined by exponential fitting. The drop in perfusion decreased gradually further away from the injection site and hypoperfusion was less prominent 4 mm from the injection site, with a spatially dependent half-maximum effect of 231 seconds. Hyperspectral imaging showed only a slight decrease in sO 2 of 11 % at the injection site. CONCLUSIONS: The optimal time delay for skin incision in oculoplastic surgery is approximately 2 minutes after the injection of lidocaine with epinephrine. Longer delay does not lead to a further decrease in perfusion. As sO 2 was only slightly reduced after injection, the results indicate that the use of epinephrine is safe in the periocular region.

Photoacoustic imaging of periorbital skin cancer ex vivo: unique spectral signatures of malignant melanoma, basal, and squamous cell carcinoma.

Radical excision of periorbital skin tumors is difficult without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imagi--ng modality that has potential for intraoperative micrographic control of surgical margins. This is the first study to assess the feasibility of PA imaging for the detection of periocular skin cancer. Eleven patients underwent surgical excision of periocular skin cancer, one of which was a malignant melanoma (MM), eight were basal cell carcinomas (BCCs), and two squamous cell carcinomas (SCCs). Six tumors were located in the eyelid, and five in periocular skin. The excised samples, as well as healthy eyelid samples, were scanned with PA imaging postoperatively, using 59 wavelengths in the range 680-970 nm, to generate 3D multispectral images. Spectral unmixing was performed using endmember spectra for oxygenated and deoxygenated Hb, melanin, and collagen, to iden--tify the chromophore composition of tumors and healthy eyelid tissue. After PA scanning, the tumor samples were examined histopathologically using standard hematoxylin and eosin staining. The PA spectra of healthy eyelid tissue were dominated by melanin in the skin, oxygenated and deoxygenated hemoglobin in the orbicularis oculi muscle, and collagen in the tarsal plate. Multiwavelength 3D scanning provided spectral information on the three tumor types. The spectrum from the MM was primarily reconstructed by the endmember melanin, while the SCCs showed contributions primarily from melanin, but also HbR and collagen. BCCs showed contributions from all four endmembers with a predominance of HbO2 and HbR. PA imaging may be used to distinguish different kinds of periocular skin tumors, paving the way for future intraoperative micrographic control.

Laser Speckle Contrast Imaging of the Blood Perfusion in Glabellar Flaps Used to Repair Medial Canthal Defects.

BACKGROUND: The glabellar flap is a common technique for surgical repair after tumor excision in the medial canthal area. However, the outcome may be affected by partial flap necrosis. Little is known about the impact of surgery on blood perfusion and the postoperative course of reperfusion due to the absence of reliable and noninvasive perfusion monitoring techniques. The aim of this study was to use a modern imaging technique to assess blood perfusion in glabellar flaps. METHODS: Glabellar flaps were used to repair medial canthal defects following tumor excision in 7 patients. Blood perfusion was monitored using laser speckle contrast imaging: during surgery, immediately postoperatively (0 weeks), and at follow-up, 1, 3, and 6 weeks after surgery. RESULTS: Perfusion decreased gradually along the length of the flap, and reached a minimum 15 mm from the flap base. Perfusion in the proximal 20 mm of the flap was completely restored after 1 week, while the distal part of the flap was gradually reperfused over 6 weeks. Both the functional and esthetic surgical outcomes were excellent. CONCLUSIONS: The rapid reperfusion of the glabellar flap may be explained by its connection to the vascular network via the flap pedicle. In flaps longer than 20 mm, the distal part can be considered a free skin transplant, and a combination of a glabellar flap and a free skin graft could then be considered.

Blood Perfusion of Human Upper Eyelid Skin Flaps Is Better in Myocutaneous than in Cutaneous Flaps.

BACKGROUND: The aim of this study was to monitor blood perfusion in human upper eyelid skin flaps and examine how the perfusion is affected by the thickness of the flap. METHODS: Twenty upper eyelids were dissected as part of a blepharoplasty procedure in patients. The medial end of the blepharoplasty flap remained attached to mimic a flap design often used in reconstruction in the periocular area, a myocutaneous flap in which the blood supply follows the fibers of the orbicularis muscle and is thus parallel to the long axis of the flap. The muscle was thereafter dissected from the flap to create a cutaneous flap. Blood perfusion in the 2 types of flaps was compared using laser speckle contrast imaging. RESULTS: Blood perfusion decreased gradually from the base to the tip of all the flaps. Perfusion was significantly higher in the myocutaneous flaps than in the cutaneous flaps (p < 0.0004): 69% in the myocutaneous flaps and 43% in the cutaneous flaps, measured 5 mm from the base. Blood perfusion was preserved to a greater extent distally in the myocutaneous flaps (minimum value seen at 25 mm) than in the cutaneous flaps (minimum seen at 11 mm). CONCLUSIONS: Blood perfusion was better preserved in myocutaneous flaps, including both skin and the orbicularis oculi muscle, than in cutaneous flaps. This may be of clinical interest in patients with poor microcirculation in which a long flap is required for reconstructive surgery.

Perfusion Monitoring During Oculoplastic Reconstructive Surgery: A Comprehensive Review.

PURPOSE: Knowledge of how blood perfusion is affected during and after reconstructive surgery is of great importance to predict the survival of grafts and flaps. When commonly used reconstructive procedures were developed a century ago, they were based on empirical observations of clinical outcome. METHODS: This is a comprehensive literature review that summarizes the current state of knowledge regarding microvascular perfusion monitoring during oculoplastic procedures. RESULTS: Over the years, a number of techniques for perfusion monitoring have been developed as an attempt to be more objective than clinical examination using traditional methods such as observations of skin temperature, turgor, color, smell, and capillary refill time. There are limited publications regarding microvascular perfusion monitoring during reconstructive procedures in the periocular area. Modern laser-based techniques have been attractive due to their noninvasive nature. CONCLUSIONS: Today, modern, noninvasive techniques are available to monitor perfusion during and after surgery. This has increased our knowledge on the perfusion in common oculoplastic surgery procedures. A detailed understanding of how blood perfusion is affected will hopefully allow the improvement of surgical techniques for better clinical outcome.

[Acute orbital trauma - risk of permanent impaired vision and double vision]. / Viktigt att agera snabbt vid traumatiska orbitala tillstånd.

The purpose of this article is to highlight the importance of appropriate management of acute orbital trauma, in order to prevent permanent impaired vision and double vision. Orbital blowout fractures with entrapment, so-called trapdoor fractures, occur more often in children than in adults, and require immediate surgical intervention. A blowout fracture with impingement, so-called open door fracture, does not require immediate intervention. However, if the motility does not improve within 1-2 weeks surgery may be required. The symptomatology in children with orbital fractures may differ significantly from that in adults, and vasovagal symptoms such as bradycardia and nausea are common.  Orbital compartment syndrome is characterized by an acute increase in orbital pressure, and may result in irreversible blindness if not promptly treated with lateral canthotomy and cantholysis.

Erratum to: Successful repair of a full upper eyelid defect following traumatic amputation by simply suturing it back in place, JPRAS Open volume 19, March 2019, pages 73-76.

[This corrects the article DOI: 10.1016/j.jpra.2018.12.002.].

Laser Speckle Contrast Imaging of a Rotational Full-Thickness Lower Eyelid Flap Shows Satisfactory Blood Perfusion.

Full-thickness eyelid flaps from the lower eyelid are frequently used to repair larger upper eyelid defects. Perfusion monitoring has recently been implemented in several reconstructive surgical procedures, however, perfusion monitoring of a rotational eyelid flap has not yet been described. The authors' employed laser speckle contrast imaging to monitor blood perfusion in a rotational flap from the lower eyelid, used to cover a large tumor defect in the upper eyelid. Perfusion in the flap decreased by only 50% during surgery and was almost completely restored 5 weeks later at flap division (91%). The excellent surgical outcome in the present case is deemed to be the result of satisfactory blood perfusion of the flap.

Reperfusion of Free Full-Thickness Skin Grafts in Periocular Reconstructive Surgery Monitored Using Laser Speckle Contrast Imaging.

PURPOSE: Free skin grafts are frequently used in reconstructive surgery. However, little is known about the course of reperfusion due to the previous lack of reliable perfusion monitoring techniques. The aim of this study was to use state-of-the-art laser speckle contrast imaging to monitor free skin grafts in the periocular area. METHODS: Seven patients needing surgery due to tumor removal or cicatricial ectropion in the periocular region underwent reconstructive surgery using free skin grafts from either the contralateral upper eyelid or the upper inner arm. The free skin grafts measured 10-30 mm horizontally and 9-30 mm vertically. Blood perfusion was monitored using laser speckle contrast imaging immediately postoperatively (0 weeks) and at follow-up after 1, 3, and 7 weeks. RESULTS: All grafts were reperfused gradually during healing, the median value being 46% in the central part of the graft after 1 week and 79% after 3 weeks. The grafts were completely reperfused after 7 weeks. No difference was observed in the rate of reperfusion between the center and periphery of the grafts (p = not significant). The cosmetic and functional outcome was excellent in all but 1 patient, who developed ectropion that had to be surgically corrected. CONCLUSIONS: Skin grafts in the periorbital area are fully reperfused after 7 weeks. The periocular area is known to be well-vascularized and thus forgiving to reconstructive surgery. Future investigations of the reperfusion of free skin grafts in other parts of the body or in higher-risk populations should be carried out.

Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems.

PURPOSE: Current hypothesis regarding the mechanism of active tear drainage is based on studies performed ex vivo or under nonphysiological conditions. Novel ultra-high-frequency ultrasound has the advantage of generating images with superior resolution, enabling measurements of low flow in small vessels, and the tracking of tissue motion in real time. The purpose of this study was to investigate the lacrimal drainage system and active drainage using this modality. METHODS: The upper lacrimal drainage system was investigated with 40-70 MHz ultrasound in 22 eyes in 13 patients. Irrigation confirmed a lacrimal obstruction in 10 eyes. Motion tracking was used to map movement of the lateral lacrimal sac wall and to measure flow when possible. RESULTS: The anatomy of the upper lacrimal drainage system was mapped in vivo, including the proximal canaliculi, which have not previously been imaged. The lacrimal sac lumen is slit shaped in its resting state but is distended when irrigated or if a nasolacrimal duct obstruction is present. Thus, the healthy lacrimal sac is not a cavity, and the medial retinaculum does not act against a stretched structure. Motion tracking visualized the "lacrimal pump," showing that the direction of motion of the lateral lacrimal sac wall is mainly in the sagittal plane during blinking. CONCLUSIONS: Ultra-high-frequency ultrasound allows detailed physiological monitoring of the upper lacrimal drainage system in vivo. Our findings suggest that current theories of active tear drainage need to be reappraised.

Successful Free Bilamellar Eyelid Grafts for the Repair of Upper and Lower Eyelid Defects in Patients and Laser Speckle Contrast Imaging of Revascularization.

PURPOSE: 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. METHODS: Ten large upper and lower eyelid defects resulting from tumor excision were reconstructed using bilamellar grafts harvested from the contralateral or opposing eyelid. Revascularization of the flap was monitored during healing using laser speckle contrast imaging, and the surgical outcome was assessed. RESULTS: The functional and cosmetic results were excellent. All grafts survived and there was no tissue necrosis. Only 1 patient underwent revision after 4 days as the sutures came loose. Two patients developed minimal ectropion but needed no reoperation. All patients were satisfied with the surgical results. Perfusion monitoring showed that the grafts were gradually revascularized, exhibiting 50% perfusion after 4 weeks and 90% perfusion after 8 weeks. CONCLUSIONS: 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.

Revascularization After H-plasty Reconstructive Surgery in the Periorbital Region Monitored With Laser Speckle Contrast Imaging.

BACKGROUND: 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 aim was to monitor perfusion in H-plasty flaps during surgery and during postoperative follow-up, using laser speckle contrast imaging. METHOD: H-plasty, i.e., bipedicle random advancement skin flaps, was used for reconstruction of the eyelids after tumor removal in 7 patients. The median length and width of the skin flaps were 13 mm (range, 8-20 mm) and 10 mm (range, 5-11 mm), respectively. Blood perfusion was measured using laser speckle contrast imaging during surgery and at follow up 1, 3, and 6 weeks postoperatively, to monitor revascularization. RESULTS: Immediately postoperatively, the perfusion in the distal end of the flaps had fallen to 54% (95% CI, 38%-67%). The perfusion then quickly increased during the healing process, being 104% (86%-124%) after 1 week, 115% (94%-129%) after 3 weeks, and 112% (96%-137%) after 6 weeks. There was no clinically observable ischemia or tissue necrosis. CONCLUSIONS: Revascularization of the H-plasty procedure flaps 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.

Perfusion in Upper Eyelid Flaps: Effects of Rotation and Stretching Measured With Laser Speckle Contrast Imaging in Patients.

PURPOSE: The aim of this study was to investigate how the blood perfusion in human upper eyelid skin flaps is affected by the length of the flap and the degree of stretching and rotation of the flap. METHODS: Twenty-nine upper eyelids were dissected as part of a blepharoplastic procedure in patients. The 1-cm wide proximal end of the flap remains attached, to mimic a random pattern skin flap (hereafter called a "skin flap"). Blood perfusion was measured with laser speckle contrast imaging before and after the flap was stretched with forces of 0.5, 1, and 2 N. The flap was then rotated 90°, and the same tensions were applied. RESULTS: Blood perfusion decreased gradually from the base to the tip of the flap. The flap was only well perfused in the proximal 1 cm (60% at 0.5 cm and 37% at 1.0 cm) and was minimally perfused beyond 2 cm (22% at 2.0 cm). Stretching the nonrotated flaps affected perfusion slightly (decreased to 43% at 0.5 cm). Simply rotating the flaps by 90° had no significant effect on the perfusion. The combination of rotation (90°) and stretching reduced the perfusion to 22% at 2 N, when measured 0.5 cm from the base. CONCLUSIONS: Blood perfusion in upper eyelid skin flaps decreases rapidly with distance from the base of the flap. Rotating and stretching the skin flap reduces blood perfusion even further, leading to minimal perfusion in this kind of flap at distances greater than 1.5 cm from the base.

Spectral Signatures in the Different Layers of the Human Eyelid by Photoacoustic Imaging.

BACKGROUND AND OBJECTIVES: The eyelids are susceptible to a number of skin cancers, which are challenging to excise radically without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used for intraoperative micrographic control of the surgical margins of eyelid tumors. In this study, non-cancerous human eyelid tissue was characterized using PA as a first step in the development of this technique. STUDY DESIGN/MATERIALS AND METHODS: Twelve full-thickness samples from nine patients were analyzed ex vivo using PA imaging. Two-dimensional PA images were acquired using 59 wavelengths in the range of 680-970 nm to obtain the spectral signatures of the skin, orbicularis oculi muscle, and the tarsal plate. Three-dimensional images were obtained by scanning the tissues using a linear stepping motor. Spectral unmixing was performed to visualize the chromophore distribution. RESULTS: The resulting PA spectra could be used to differentiate between the orbicularis oculi muscle and the other two structures (P < 0.05). The signals from the skin and the tarsal plate were more similar in appearance, probably due to similarities in their molecular composition. Spectral unmixing provided a clear visualization of the overall architecture of the eyelids. CONCLUSIONS: PA imaging can be used to differentiate between the orbicularis oculi muscle and the eyelid skin and tarsal plate. The main structures of human eyelids could be visualized in three dimensions using PA imaging. This technique could potentially be used to examine eyelid tumors intraoperatively in the future. However, further studies on tumors in vivo are needed before considering such clinical use. Lasers Surg Med. © 2019 Wiley Periodicals, Inc.