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.

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.

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.

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.

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.].

The Success of Unilateral Surgery for Constant and Intermittent Exotropia and Factors Affecting It in a Large Scandinavian Case Series.

PURPOSE: To compare the results of surgery for constant and intermittent exotropia, to determine factors affecting surgical success, and to evaluate the effect of horizontal rectus muscle surgery on distance-near incomitance. METHODS: In this retrospective study of 291 Scandinavian patients, inclusion criteria were surgery for constant (n = 101) or intermittent (n = 190) exotropia with no vertical deviation, no previous strabismus surgery, and available postoperative follow-up data. Medical records of patients (age: 3 to 85 years) undergoing surgery were reviewed. Surgical success was defined as postoperative esodeviation of less than 5 prism diopters (PD) to exodeviation of 10 PD or less. RESULTS: Surgical success was 70% in constant exotropia and 80% in intermittent exotropia (P > .05). At follow-up 1.5 years after surgery, a significant drift was found in intermittent exotropia (P < .05). Different surgeons, spherical equivalents, anisometropia, amblyopia, gender, and age had no effect on surgical success (P > .05). The surgical success rate increased with decreasing preoperative angle (P < .05). Resection of the medial rectus muscle had a greater effect on the near deviation, whereas recession of the lateral rectus muscle had a greater effect on the distance deviation (P < .05). CONCLUSIONS: Surgical success was equally good in constant and intermittent exotropia, but better long-term stability was observed following surgery for constant exotropia. The only factor affecting surgical success was the preoperative deviation, with smaller deviations having a better outcome. A distance-near incomitance may be an important consideration in choosing the magnitude of medial versus lateral rectus muscle surgery. [J Pediatr Ophthalmol Strabismus. 2021;58(1):34-41.].

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.

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.

The Effect of Canthotomy on Blood Perfusion During the Repair of Lower Eyelid Defects.

PURPOSE: 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. METHODS: Eight pigs underwent a wedge resection of the lower eyelid and canthotomy (with cantholysis involving the lateral palpebral artery). The wedge resection was performed 8, 6, and 4 mm from the canthotomy. Perfusion and oxygen tension were monitored in the eyelid between the wedge resection and canthotomy using laser Doppler velocimetry and a Clark electrode. Verapamil was administered, and measurements were also performed 12 hours after surgery, to investigate the possible effects of vasospasm RESULTS:: The wedge resection alone did not affect perfusion. Canthotomy led to a reduction in perfusion; being 60% when the length of remaining eyelid was 8 mm, 32% when it was 6 mm, and 24% when it was 4 mm. Similar results were observed for oxygen tension. Vasospasm did not affect the results. CONCLUSIONS: 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.

Blood Perfusion in Rotational Full-Thickness Lower Eyelid Flaps Measured by Laser Speckle Contrast Imaging.

PURPOSE: 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. METHODS: Nine patients underwent the Quickert procedure for entropion repair in which a full-thickness eyelid flap of approximate width 0.5 cm and length 2 cm was dissected in the lower eyelid. This generates a full-thickness eyelid flap similar to that used to repair large upper eyelid defects. Perfusion was measured using laser speckle contrast imaging, before and after the flap was rotated 90° and 120°, and stretched using forces of 0.5, 1, and 2 N. RESULTS: Blood perfusion decreased gradually from the base to the tip of the flap; being 75% of the reference value 0.5 cm from the base, 63% at 1.0 cm, 55% at 1.5, 23% at 1.75 cm, and 4% at 2.0 cm. Rotating the flaps by 90° or 120° had little effect on the perfusion. Stretching reduced the perfusion from 63% to 32% at 2 N, when measured at 1 cm. The combination of stretching and rotation did not lead to any further decrease. CONCLUSIONS: 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.

Revascularization of Free Skin Grafts Overlying Modified Hughes Tarsoconjunctival Flaps Monitored Using Laser-Based Techniques.

PURPOSE: It has recently been shown that the flap pedicle does not supply blood to a tarsoconjunctival graft in the modified Hughes procedure in patients. This raises questions concerning the rate of revascularization of the free skin graft commonly used to reconstruct the anterior lamella. The aim of this study was, thus, to monitor the course of revascularization in free skin grafts overlying modified Hughes tarsoconjunctival flaps, using laser-based techniques. METHODS: Free skin grafts from the upper eyelid or upper arm in 9 patients were used to cover a tarsoconjunctival flap according to the modified Hughes procedure. Blood perfusion was monitored using laser speckle contrast imaging, and vascular reactivity was studied with laser Doppler velocimetry after heating the tissue to 44°C. Measurements were made at the time of surgery (baseline) and at 1, 3, 8, and 16 weeks postoperatively. RESULTS: The gradual increase in perfusion of the free skin grafts during the healing process indicates revascularization. A slight increase in perfusion was seen already after 1 week. Perfusion reached 50% of the baseline after 3 weeks, and complete restoration of perfusion was seen after 8 weeks. The vascular function monitored with heat-induced hyperemia increased in a similar fashion. CONCLUSIONS: Full-thickness skin grafts revascularize within 3 to 8 weeks, despite overlying a tarsoconjunctival flap, which has recently been reported to be avascular. This provides further evidence that it should be possible to repair large eyelid defects using free full-thickness eyelid grafts.

Successful repair of a full upper eyelid defect following traumatic amputation by simply suturing it back in place.

There is a general belief that a full-thickness eyelid defect is best repaired using a vascularized flap in combination with a free graft, and that a free full-thickness eyelid graft would not survive due to poor blood perfusion. However, we describe a case in which an upper eyelid was traumatically amputated. The eyelid was sutured in place and healed well in situ. The long-term outcome was good regarding motility and function. This raises the question of whether a blood-supplying pedicle is necessary for the survival of the graft when repairing large eyelid defects.

Hypoperfusion following the injection of epinephrine in human forearm skin can be measured by RGB analysis but not with laser speckle contrast imaging.

BACKGROUND: The time taken for epinephrine to achieve its optimal effect during local anesthesia has recently become the subject of debate. The time from injection to commencement of surgery is traditionally quoted to be 7 to 10 min, while recent reports claim that it may take 30 min to achieve maximum hypoperfusion, which would prolong the time required for surgical procedures. The discrepancy may be related to difficulties associated with the techniques used to measure blood perfusion. The aim of this study was to test two methods of determining the time to maximum hypoperfusion. METHODS: Laser speckle contrast imaging (LSCI) and red, green, blue (RGB) analysis of images obtained with a commercial digital camera, were used to monitor the effect of infiltration with commonly used local anesthetic preparations: lidocaine (20 mg/ml) + epinephrine (12.5 µg/ml), lidocaine (10 mg/ml) + epinephrine (5 µg/ml), and lidocaine (20 mg/ml) alone, in healthy subjects. RESULTS: LSCI showed a paradoxical increase in signal after the injection of local anesthetics containing epinephrine, probably due to a change in the laser penetration depth resulting from blanching of the skin. However, RGB analysis of digital photographs gave more reliable results, showing skin blanching that corresponded to the expected effect of epinephrine in local anesthetics. The time to maximum effect was found to be 7 (range 5-10) minutes for 12.5 µg/ml epinephrine, and 9 (range 7-13) minutes for 5 µg/ml epinephrine in lidocaine. CONCLUSIONS: RGB analysis of digital images proved to be a valid technique for monitoring the effect of local anesthetics with epinephrine in human skin. The technique requires only a commercial digital camera and constitutes a cheap, simple method. The optimal delay between epinephrine injection and incision, to minimize bleeding, was found to be 7 to 9 min, which is in good agreement with common surgical practice.

Perfusion Monitoring Shows Minimal Blood Flow From the Flap Pedicle to the Tarsoconjunctival Flap.

BACKGROUND: A previous study in pigs has shown that the pedicle of the tarsoconjunctival flap does not appear to have adequate blood perfusion. The aim of this study was to monitor perfusion in tarsoconjunctival flaps in patients with large lower eyelid defects resulting from tumor surgery. METHODS: The modified Hughes procedure was performed in 13 patients. Blood perfusion was monitored using laser Doppler velocimetry and laser speckle-contrast imaging. RESULTS: Blood flow decreased gradually from the pedicle base to the end of the flap and was 19% at the flap base, 11% in the middle of the flap, and 4% in the distal end of the flap. The flaps survived, and there was no tissue necrosis. CONCLUSIONS: Tarsoconjunctival tissue survival does not seem to be dependent on a conjunctival flap. Free tarsoconjunctival grafts or composite grafts might be considered as viable alternatives in reconstruction of major eyelid defects.

A waiting time of 7 min is sufficient to reduce bleeding in oculoplastic surgery following the administration of epinephrine together with local anaesthesia.

OBJECTIVE: The time taken to reach maximal haemostatic effect following local anaesthesia with epinephrine is generally believed to be <10 min. This is based on clinical experience and indirect measurements of perfusion using methods such as laser Doppler flowmetry and oxygen spectroscopy. However, the only study in which bleeding has been measured quantitatively in an intra-operative setting in humans showed that the full haemostatic effect was not achieved until 30 min after anaesthesia. The aim of this study was to determine the time taken to reach maximum haemostatic effect when using epinephrine for local anaesthesia in oculoplastic surgery. METHODS: Intra-operative bleeding following infiltration anaesthesia with either lidocaine 20 mg/ml (2%) or lidocaine + epinephrine 12.5 µg/ml (1:80 000) was measured after 7, 15 and 30 min in the eyelids of 16 patients undergoing upper eyelid blepharoplasty. RESULTS: Bleeding was decreased by 74.6% (with 95% CI, 6.16-87.6%) 7 min after the injection of lidocaine + epinephrine (p = 0.0048) compared with lidocaine without epinephrine. There was no further decrease in bleeding after 15 or 30 min (p = n.s.). CONCLUSION: The optimal time for skin incision in eyelid surgery is within 7 min of injection of lidocaine with epinephrine. Waiting longer does not lead to a further decrease in bleeding.