Objective evaluation of treatment effects on port-wine stains using L*a*b* color coordinates

Wide variations in port-wine stains and their responses to various therapies pose a need for the development of an objective method to evaluate the effects of treatment. Several techniques such as laser Doppler, reflectance spectrometry, and tristimulus colorimetry have been used to evaluate the color of port-wine stains, but these techniques are limited by cost, small test size area, and other factors. Therefore, we developed a simple and cost-effective method of evaluating treatment results on port-wine stains using the L*a*b* color coordinate system in combination with a personal computer. For 22 patients with port-wine stains, the slide photographs were digitized using a slide scanner. L*a*b* color differences of the normal control and port-wine stain sites were obtained before and after treatment, and treatment effect (percent) was calculated. By calculating each color difference between the lesion and normal skin both before and after treatment, problems arising from different illuminating conditions during photography were minimized. The results were compared with the visual evaluation conducted by three experienced plastic surgeons. The treatment effects analyzed by L*a*b* color coordinate ranged from 4 to 95 percent, with a mean of 48.1 percent, whereas treatment effects evaluated by the plastic surgeons ranged from 15 to 92 percent, with a mean of 51.1 percent. The subjective clinical grades correlated well with the treatment effects obtained by the proposed color analysis system (correlation coefficient, 0.89). The maximum difference in the effect of treatment for a patient evaluated by the three clinicians was up to 60 percent, which means that visual judgment is very subjective and variable. The color analysis system proposed as a result of this study is very easy, objective, quantitative, cost-effective, and can be useful for the evaluation of treatment effects on colored skin lesions such as port-wine stains.     

Argon laser therapy of port-wine stains: effects and limitations

One hundred and one patients (112 parts) with port-wine stains were treated by argon laser therapy. We strictly evaluated all patients according to color shift, scar formation, and pigmentation. We observed good to excellent results in 44 percent of patients, and less satisfactory results in 56 percent. The relationship between the effects of treatment and several factors, such as patients' age, anatomic site, and histologic type of the lesions, were investigated. More satisfactory results tended to be obtained in patients with neck lesions and with histologic type III lesions (dilated type). To date we have not discerned any definite criteria for precisely predicting the response of port-wine stains to argon laser therapy. Consequently, the performance of a test seems to us to be the best way of discovering the response and course of healing of an individual port-wine stain after laser therapy. Thirty-six consecutive patients were studied to determine whether compression and cooling would improve the outcome of argon laser therapy. The use of this method did not produce any noticeable effects.     

Preliminary study of the vascular dynamics of port-wine hemangioma with therapeutic implications for argon laser treatment

The vascular dynamics of port-wine hemangioma have been studied in several ways in order to better understand blood flow factors. Utilizing a laser Doppler velocimeter, differential perfusion/blood flow was studied and contrasted to normal skin, compared to heat and cold challenges, and finally measured in relationship to argon laser treatment. Results indicate that port-wine hemangiomas do not necessarily have different perfusion than normal skin but respond less vigorously to heat challenges. Cooling showed no uniform response by port-wine hemangioma vessels, while injection with Xylocaine plus epinephrine resulted in a markedly decreased perfusion and vasoconstriction contrary to previously held theories. Argon laser treatment did not uniformly alter laser Doppler perfusion to a predictable degree. Laser Doppler velocimeter flow studies were not able to predict future good versus bad results of laser treatment.     

Argon laser treatment of port-wine stains: the patients' evaluations of the result.

The argon laser is now a well-established method of treating port-wine stains (PWS) in the face and neck areas. Satisfactory results are reported in 44 to 75 percent of cases, but criteria for that classification and the patients' perceptions of the result are seldom given. In the present paper, a sample of 58 patients was used to assess the patients' own perceptions of the degree of lightening and scarring. Three felt the results were excellent, 23 good, 18 fair, and 14 poor. The treatment was considered as unpleasant by 76 percent, and 55 percent of the patients asked for a new consultation. Scarring was noticed by 50 percent. The patients' perceptions of the results and physicians' rating were the same in 69 percent. The best results were obtained in older patients with small port-wine stains. Such lesions also can be treated surgically with good results.     

Management of parotid hemangioma in 100 children

Most problematic infantile hemangiomas are successfully treated with pharmacological therapy. However, there are reports that hemangioma of the parotid gland responds poorly to corticosteroid and interferon. To better clarify the management of parotid hemangioma, the authors retrospectively studied the records of 100 consecutive patients, seen between 1975 and 2002. The characteristics of the tumor, including sex ratio, presence at birth, size, side, complications, and involvement of adjacent structures, were recorded. The indications for and response to treatment and the need for surgical procedures were documented and statistically analyzed. The female-to-male ratio was 4.5:1. Forty percent of parotid hemangiomas were on the right side, 36 percent were on the left, and 24 percent were bilateral. Forty-five percent of patients had a premonitory cutaneous lesion at birth. Fifty-nine percent of parotid hemangiomas ulcerated during the early proliferative phase. Eighty-eight percent involved nearby structures (ear, 70 percent; lip, 34 percent; subglottic region, 21 percent; eye, 18 percent; and nose, 3 percent). Seven percent of patients required tracheostomy, and 3 percent had signs of congestive heart failure. Seventy infants received pharmacological treatment. Sixty-seven patients were initially managed with corticosteroids; regression or stabilization was noted in 83 percent of tumors (56 of 67 tumors). Twenty-one patients received interferon: 11 in whom corticosteroid therapy had failed, seven in whom the tumor stabilized with corticosteroid therapy but further regression was needed, and three who had interferon as primary therapy. Ninety-five percent of the lesions that were resistant to corticosteroid subsequently responded to interferon alfa-2a or -2b. The overall response rate to pharmacological therapy was 98 percent. A reconstructive procedure was necessary during the involuting or involuted phase in 66 percent of patients: 92 percent had preauricular excision of redundant skin and/or fibrofatty tissue and 37 percent of patients had auricular revision. In summary, drug therapy was effective in the majority of infants with parotid hemangioma, whether given because the tumor was large, deforming, ulcerated, or involved nearby structures with functional consequences. Infantile hemangioma in the parotid gland responded to pharmacological treatment in a similar manner as hemangioma in other locations.     

Conservative and operative treatment of mallet finger

One-hundred and thirty-five patients with mallet finger were treated and followed up at least 1 year after injury. Ninety-two patients with tendon rupture or chip fracture were treated by splinting, and 42 percent of them had a decreased range of motion, mostly of a minor degree, but only 18 percent stated complaints at the follow-up examination. The results of treatment in 43 patients with fracture were evaluated separately. In this group, 26 patients were operated on and the postoperative results were excellent in 58 percent, improved in 36 percent, and 8 percent ended with failure due to complications. Radiographic study showed bony union in 41 of 43 patients and resorption of the small fragment in 2 patients. The indications for conservative and operative treatment in the five different types of mallet finger are discussed.     

Evaluation of argon laser surgery in children under 13 years of age

Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively.     

Circular excision of hemangioma and purse-string closure: the smallest possible scar

Localized cutaneous infantile hemangioma acts like a tissue expander. This rapidly growing tumor can destroy elastic fibers or cause ulceration resulting in telangiectases, cutaneous laxity, scarring, and fibrofatty residuum. Although surgeons may dispute indications and timing, most would agree that the scar of resection should be minimized. For this reason, circular excision and purse-string closure is particularly applicable for hemangioma at any stage of its evolution. The purposes of this study were to: (1) analyze the results of circular excision/purse-string closure in all three phases of the life cycle of hemangioma; (2) quantify dimensional changes after resection; and (3) compare the scars after theoretical single-stage lenticular excision with those after staged circular excision/purse-string closure. The authors retrospectively analyzed their experience in 25 children with localized hemangioma who underwent circular excision/purse-string closure from 1997 to 2000. Each hemangioma was measured preoperatively and the scars were measured at most recent follow-up (minimum, 6 months). Preoperative and postoperative dimensions were analyzed using SPSS statistical software. The study included 22 girls and three boys, with an average time to follow-up evaluation of 13.1 months. Twenty-one lesions were in the face and scalp, and five were in the extremity. Five tumors were resected in the proliferative phase (either because of ulceration, bleeding, or visual complications) and 21 were excised in the involuting or involuted phase. Six patients had a second-stage procedure: three had another circular excision and three had later lenticular excision. After single circular excision/purse-string closure, the mean long-axial diameter (length) decreased by 45 percent, the mean short-axial width (width) decreased by 73 percent, and the mean scar area was only 15 percent of the original area. All these differences were statistically significant (p = 0.001). The average width/length ratio decreased by 50 percent, indicating a tendency for scars to linearize. There was no difference in linearization for the three phases of hemangioma (p > 0.05); extremity scars became more linear that those on the face (p = 0.01). The authors devised a formula for scar length after lenticular excision/linear closure, assuming a conventional excisional ratio of 3:1 for a circular lesion. Using this equation, the authors predicted that mean scar length after circular excision, followed by lenticular excision, would be 72 percent shorter than the calculated scar that would result from conventional lenticular excision. In three patients who underwent this two-stage approach, the resultant scar was 69 percent shorter. Circular excision of hemangioma and purse-string closure reduces both the longitudinal and transverse dimensions and converts a large circular lesion into a small ellipsoid scar. If subsequent revision to a linear scar is desirable, its length will be the same or slightly less than the diameter of the original lesion. No other excision and closure technique results in a smaller scar. Another advantage of this method is minimal distortion of surrounding structures.     

Applications of the classic dermal fat graft in primary and secondary facial rejuvenation

Volumetric facial aging occurs primarily as a descent of facial soft tissues, followed by their secondary atrophy. Proper volumetric facial rejuvenation, therefore, demands effective superior redistribution of fallen soft tissues, for which the author prefers malar imbrication. Only then do augmentative adjustments become appropriate, including solid facial protheses, "soft-tissue" fillers, dermal fat grafts, free-fat micrografts, and Erol's "tissue-cocktail." Of these, the author prefers the time-honored dermal fat graft for all primary volumetric augmentations within the surgical field, reserving free-fat micrografts for adjustments outside the field and those performed secondarily. Dermal fat grafts are added to the face in three categories: "camouflage" grafts from the anterior face lift discard specimen to correct contour irregularities in the sculpted subcutaneous cheek in half of patients; "transition" grafts from the suprapubic abdomen to the zone between the midface and lower face in 5 percent of patients with an emaciated quality to their aging; and "secondary" grafts from the abdomen in occasional patients with volumetric deformities following inexpert face lift and other forms of trauma. All grafts were harvested, prepared, and placed according to 10 straightforward technical principles. The grafts were highly effective and predictable in their ability to augment contour; none of 283 total grafts were regarded as a treatment failure. The use of such grafts was extremely safe, with complications limited to cyst formation in 1.5 percent of grafts, all of which were treated nonoperatively. The use of the dermal fat graft is seen as safe, effective, and convenient when the subcutaneous plane of the face is exposed during facial rejuvenation. The majority of grafts were derived from the face lift discard specimen. Although those that came from outside the head and neck presented extra inconvenience and operative time, their use was limited to occasional and challenging circumstances that justified extra investment.     

The outcome of long-term follow-up after palatoplasty

The speech outcome was studied retrospectively in 140 cleft-palate patients who underwent push-back palatoplasty. Velopharyngeal function and articulation disorders were evaluated serially at 4, 7, 10, and more than 10 years of age. On comparison of velopharyngeal function between 4 years of age and the most recent review (>10 years), it was unchanged in 90 patients (64.3 percent), whereas it showed deterioration in 14 patients and showed improvement in 8 patients. The other 28 patients underwent pharyngeal flap surgery; this group also included patients with functional deterioration. Changes of velopharyngeal function often occurred between 4 and 7 years of age but sometimes occurred after 10 years of age. Articulation disorders were observed in 49 subjects (35.0 percent) at 4 years of age. Many of the patients with glottal stop showed improvement from 4 to 7 years of age. Palatalized articulation showed less improvement than glottal stop (p < 0.01). The number of patients with articulation disorders decreased significantly between 4 years of age and the most recent review (p < 0.001). These findings suggest that speech does not become stable before 10 years of age and that patients with cleft palate should be carefully followed until they are beyond this age.     

Late recurrence of localized cutaneous melanoma: its influence on follow-up policy

This paper reports 11 cases of recurrence 10 years or more after primary treatment of clinically local cutaneous melanoma at the Peter MacCallum Cancer Institute. Using the product-limit method for estimating recurrence-free survival, two late recurrence rates have been calculated. The estimated late recurrence rate among all treated patients is 5 percent (95 percent confidence interval: 2 to 8 percent), and the estimated late recurrence rate for the group who survived the first 10 years without recurrence is 7 percent (95 confidence interval: 3 to 11 percent). No prognostic factors were found that could identify a patient subgroup significantly at risk of late recurrence. Recurrence-free survival curves show that most recurrences have presented by the end of 6 years, but later recurrences are seen, the latest in this series being 18.2 years following treatment. While patients probably do not require long-term follow-up in specialist clinics provided they are adequately educated in the nature of their disease, this paper shows the value of long-term statistical surveillance.     

Management of the recalcitrant total-hip arthroplasty wound

The infection rate for total-hip arthroplasty is around 1 percent. This small group is usually managed by complete removal of the prosthesis and the cement and closure over suction catheters to "collapse" the wound and eventually achieve a girdlestone arthroplasty. Occasionally, there are patients who have a persistent draining wound after this treatment and repeated efforts at wound closure. We present 27 patients who had recalcitrant, noncollapsible wounds of the hip that were present for many months to years. Twenty-eight cases of infected total-hip arthroplasties that did not respond to removal of the prosthesis and cement and closure were seen by the authors between January of 1977 and December of 1988. One patient had bilateral involvement. Average age was 64 years (range 33 to 79 years). There was an average of 4.2 previous surgical attempts at closure (range 1 to 21). Staphylococcus aureus was the most common organism, but the infections were virtually all multiple. Thirty-three muscles were utilized in 27 patients. The rectus femoris was used in 23 cases, the vastus lateralis in 8, tensor fasciae latae in 1, and combined latissimus dorsi-serratus anterior free-tissue transfers were carried out in 2. Multiple combinations of transpositions and free flaps were utilized. Follow-up ranged from 1 to 10 years, with an average of 6.4 years. Eighteen patients were ambulatory with minor degrees of pain, five ambulated with a cane, seven ambulated with a walker, six ambulated with crutches, and four ambulated unassisted, all of whom had reimplantation of their hip arthroplasty at least 12 months following the muscle flap procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term outcome of autogenous rib graft nasal reconstruction.

Whereas reconstruction of the hypoplastic nose with rib grafting is common, the long-term outcomes of nasal growth and aesthetics are unknown. This study assessed nasal morphometrics, patient satisfaction, and the perception of nasal appearance by others up to 15 years after nasal reconstruction using cantilevered autogenous chondro-osseous rib grafting with rigid internal fixation in children. Records of all patients who received nasal rib grafts between 1983 and 1998 by one senior surgeon were reviewed. Patients in this study were operated on before their late teens and had greater than 1-year follow-up including serial photographic documentation. Nasal growth was determined by comparing anthropometric measurements preoperatively, perioperatively, and postoperatively. Patient satisfaction was determined through a questionnaire that addressed memory, donor-site morbidity, and nasal perception. Independent, blinded skilled observers who reviewed frontal and lateral photographs of the preoperative, perioperative, and postoperative intervals assessed nasal aesthetics. Thirty-two patients who underwent 38 rib graft reconstructions of the nasal dorsum and tip at an average age of 8.8 years constitute the study population. Six patients underwent secondary augmentation. The average interval between initial nasal reconstruction and evaluation for this study was 7.9 years. Comparative anthropometric measurements before and after surgery documented increases in both tip projection (2.3 percent) and nasal length (3.0 percent) and a decrease in nasolabial angle (1.9 percent). Patient satisfaction interview response rate was 100 percent of those whom we were able to contact (28 of 32). The average age at interview was 17.2 years. Most patients recalled the operation and denied recollection of pain. Donor-site long-term morbidity was not an issue for 86 percent of patients. Sixty-four percent of patients remembered their preoperative nasal appearance and 89 percent of these preferred the postoperative change and were not concerned with nasal scars or texture. Almost two-thirds of the patients had fixation screws removed from the nasal dorsum because of skin erosion, easy palpability, or visibility. Although several patients expressed a desire to make minor additional changes to their nose, only one of these elected offered presurgical consultation and none have had such surgery. The postoperative nasal appearance compared with that preoperatively was rated as improved for 66.3 percent of responses, 26.5 percent as unchanged, and 7.2 percent as deteriorated. Cantilevered autogenous chondro-osseous rib graft reconstruction of the nasal dorsum is an effective means of reconstruction for the hypoplastic nose in childhood with respect to morphometric measurements, patient self-perception, and the assessment of nasal appearance by others.     

Long-term results after microlymphaticovenous anastomoses for the treatment of obstructive lymphedema

Over the last 14 years, 134 patients with obstructive lymphedema have been treated with microlymphaticovenous anastomoses. Ninety patients were available for long-term follow-up study. Of these, 52 patients were treated by microlymphatic surgery only and 38 of them also had segmental or radical reduction surgery, either at the same time or secondarily. Objective assessment was undertaken by volume and circumferential measurements. Initially, lymphangiography was used, but a study demonstrated increased edema immediately following the investigation in one-third of the patients and it was abandoned, both preoperatively and postoperatively. In the microlymphaticovenous anastomoses only group (N = 52), subjective improvement occurred in 38 patients (73 percent). Objectively, volume changes showed a significant improvement in 22 patients (42 percent), with an average reduction of 44 percent of the excess volume. In the microlymphaticovenous anastomoses and reduction surgery, usually segmental, group (N = 38), subjective improvement occurred in 30 patients (78 percent) and objective improvement occurred in 23 patients (60 percent), with an average reduction of 44 percent of the excess volume. Of those followed up, 67 patients (74 percent) have been able to discontinue the use of conservative measures, with an average follow-up of 4.0 years and average reduction in excess volume of 26 percent. There was a 58 percent reduction in the incidence of cellulitis following surgery. In those patients who were improved, drainage resulted in increased softness of the limbs. Edema of the hand diminished considerably in most patients, although this was difficult to measure. These long-term results indicate that microlymphaticovenous anastomoses have a valuable place in the treatment of obstructive lymphedema and should be the treatment of choice in these patients. Reduction surgery can be used as an adjunct in some of these patients, especially in the posteromedial aspect of the upper arm. Liposuction has been used in failed cases or in patients in whom no lymphatics could be found. Improved results can be expected with earlier operations because patients referred earlier usually have less lymphatic disruption.     

Long-term follow-up of the effectiveness and safety of inferior turbinectomy.

The long-term effectiveness and safety of inferior turbinectomy were assessed in 186 patients who were interviewed and examined 10 to 15 years after surgery (mean 12.3 years). Relief of nasal obstruction was reported by 82 percent of the patients; rhinoscopy showed wide, clean nasal airways in 88 percent. Rhinorrhea was still a problem for 34 percent of patients, and 19 percent were receiving medical treatment for this symptom. Smell acuity had improved in 52 percent of the patients. Before turbinectomy, 32 patients had suffered from bronchial asthma; postoperatively, there was an improvement in 16, and no change in 13; 3 patients reported exacerbation of asthmatic attacks. Atrophic changes of the nasal mucosa and chronic purulent infection were not observed in any of the patients.     

Nest covering in plovers: How modifying the visual environment influences egg camouflage

Camouflage is one of the most widespread antipredator defences, and its mechanistic basis has attracted considerable interest in recent years. The effectiveness of camouflage depends on the interaction between an animal's appearance and its background. Concealment can therefore be improved by changes to an animal's own appearance, by behaviorally selecting an optimal background, or by modifying the background to better match the animal's own appearance. Research to date has largely focussed on the first of these mechanisms, whereas there has been little work on the second and almost none on the third. Even though a number of animal species may potentially modify their environment to improve individual‐specific camouflage, this has rarely if ever been quantitatively investigated, or its adaptive value tested. Kittlitz's plovers (Charadrius pecuarius) use material (stones and vegetation) to cover their nests when predators approach, providing concealment that is independent of the inflexible appearance of the adult or eggs, and that can be adjusted to suit the local surrounding background. We used digital imaging and predator vision modeling to investigate the camouflage properties of covered nests, and whether their camouflage affected their survival. The plovers' nest‐covering materials were consistent with a trade‐off between selecting materials that matched the color of the eggs, while resulting in poorer nest pattern and contrast matching to the nest surroundings. Alternatively, the systematic use of materials with high‐contrast and small‐pattern grain sizes could reflect a deliberate disruptive coloration strategy, whereby high‐contrast material breaks up the telltale outline of the clutch. No camouflage variables predicted nest survival. Our study highlights the potential for camouflage to be enhanced by background modification. This provides a flexible system for modifying an animal's conspicuousness, to which the main limitation may be the available materials rather than the animal's appearance.     

经皮椎体成形术治疗椎体血管瘤疗效观察

目的:评估使用经皮椎体成形术(Percutaneous vertebroplast PVP)治疗椎体血管瘤的临床疗效。方法:回顾性分析2008~2015年诊断为椎体血管瘤并在我院进行PVP手术的46例患者,至少6个月术后随访,获取相关的临床数据和资料。对患者在术后疼痛等症状改善,肿瘤复发,Macnab疗效和治疗安全性等方面进行分析。结果:所有患者均在术后有了明显的疼痛改善(P0.05),并在6个月内随着时间的推移疼痛评分逐步下降。有2例患者出现术后肿瘤复发,但无明显症状,未给予特殊处理。余未出现明显并发症。患者的术后SF-36生存质量评分均较术前有较大提高(P0.05)。在患者术后6月时,对其Macnab疗效进行分析,其优良率为93.5%。结论:经皮椎体成形术治疗椎体血管瘤可以有效的改善疼痛症状,且相对安全,并能实现微创治疗。     

Prospective evaluation of late cosmetic results following breast reconstruction: II. Tram flap reconstruction

Although it is thought that transverse rectus abdominis muscle (TRAM) flap breast reconstruction produces excellent cosmetic results that are maintained over the long term, there is little objective evidence in the literature to support this. One hundred seventy-one consecutive patients who underwent TRAM flap reconstruction were prospectively analyzed over an 8-year period to assess their morbidity and late cosmetic outcome.The early patient complication rate (< 2 months) was 37.4 percent, the late hernia and fat necrosis rates (> 2 months) were 8.8 and 13.5 percent, respectively, and the contralateral symmetrization rate was 33.9 percent. The cosmetic results were evaluated prospectively using an objective five-point global scale. Each patient was scored at each visit once surgery was completed. Follow-up continued until a flap was lost, a patient died, or the point of last patient contact was reached. Six patients died during the study. The actuarial percentage cosmetic outcome remained stable during the study period, with an acceptable result in 96.4 percent of patients at 2 years and in 94.2 percent of patients at 5 years. Only five patients in this series obtained poor cosmetic outcomes, with three due to substantial flap necrosis and two because of poor flap design. Two free TRAM flaps were also lost. Log-rank analysis revealed that neither patient age nor timing of surgery significantly affected the cosmetic outcome. Single pedicle and supercharged (single pedicle) TRAM flaps produced slightly better results than bipedicle and free TRAM flaps. In this prospective longitudinal study, TRAM flap reconstructions were shown to produce aesthetically pleasing results. Moreover, with long-term follow-up, it was demonstrated that these reconstructions maintained their stability.     

Colour change and camouflage in the horned ghost crab Ocypode ceratophthalmus

Species that change colour present an ideal opportunity to study the control and tuning of camouflage with regards to the background. However, most research on colour‐pattern change and camouflage has been undertaken with species that rapidly alter appearance (in seconds), despite the fact that most species change appearance over longer time periods (e.g. minutes, hours, or days). We investigated whether individuals of the horned ghost crab (Ocypode ceratophthalmus) from Singapore can change colour, when this occurs, and how it influences camouflage. Individuals showed a clear daily rhythm of colour change, becoming lighter during the day and darker at night, and this significantly improved their camouflage to the sand substrate upon which they live. Individuals did not change colour when put into dark conditions, but they did become brighter when placed on a white versus a black substrate. Our findings show that ghost crabs have a circadian rhythm of colour change mediating camouflage, which is fine‐tuned by adaptation to the background brightness. These types of colour change can enable individuals to achieve effective camouflage under a range of environmental conditions, substrates, and time periods, and may be widespread in other species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 257–270.     

Dazzle camouflage affects speed perception

Movement is the enemy of camouflage: most attempts at concealment are disrupted by motion of the target. Faced with this problem, navies in both World Wars in the twentieth century painted their warships with high contrast geometric patterns: so-called "dazzle camouflage". Rather than attempting to hide individual units, it was claimed that this patterning would disrupt the perception of their range, heading, size, shape and speed, and hence reduce losses from, in particular, torpedo attacks by submarines. Similar arguments had been advanced earlier for biological camouflage. Whilst there are good reasons to believe that most of these perceptual distortions may have occurred, there is no evidence for the last claim: changing perceived speed. Here we show that dazzle patterns can distort speed perception, and that this effect is greatest at high speeds. The effect should obtain in predators launching ballistic attacks against rapidly moving prey, or modern, low-tech battlefields where handheld weapons are fired from short ranges against moving vehicles. In the latter case, we demonstrate that in a typical situation involving an RPG7 attack on a Land Rover the reduction in perceived speed is sufficient to make the grenade miss where it was aimed by about a metre, which could be the difference between survival or not for the occupants of the vehicle.