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Greg W. Michael - One of the best experts on this subject based on the ideXlab platform.
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the effect of the eye s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of Photochemistry and Photobiology B-biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The effect of the eye’s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of photochemistry and photobiology. B Biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
Benjamin J. Birt - One of the best experts on this subject based on the ideXlab platform.
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the effect of the eye s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of Photochemistry and Photobiology B-biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The effect of the eye’s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of photochemistry and photobiology. B Biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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Evaluation of the contribution of reflected UVR to the inner Canthus' total dose
2007Co-Authors: Benjamin J. BirtAbstract:Basal cell carcinoma is a form of a non-melanoma skin tumour, that commonly forms over the sun exposed regions of the head and neck. Investigation of the rate of occurrence at different sites on face and neck shows considerable variation from site to site. The inner Canthus has a disproportionate number when compared to more exposed sites. The eye brow ridge, cheek bone and nose limit the field of view of the inner Canthus, thus it is expected to receive less radiation than other more exposed regions. To explain the disproportionate rate, it is hypothesised that a portion of radiation incident onto the eye is reflected to the inner Canthus. The aim of this thesis is to investigate the contribution that the radiation reflected off the surface of the eye makes to the overall dose on the inner Canthus. The inter reflections between the eye and inner Canthus were studied through the use of the ray tracing program Zemax. Zemax was used to trace rays in a non sequential mode incident onto a model eye and periorbital region. To obtain the models of the eye and periorbital region, both magnetic resonance imaging and a casting process was investigated, with the later being superior for our uses. With the model obtained, it was used in a series of three dimensional ray tracing programs. On a macroscopic scale there is a small increase in the irradiance on the inner Canthus (2 % over a 1 cm2 area). Peaks of high irradiance (19 % increase in irradiance above direct irradiance) were discovered over the surface when the detector was divided into 200 mm elements. It was concluded that these increases above the direct irradiance in these small regions, increases the possibility of the occurrence of a Basal cell carcinoma. Individual facial geometry, will greatly effect the location and size of these peaks and as a result an experimental method to measure the dose distribution across the inner Canthus was proposed. Initially it was planned to use polysulphone film to measure the erythemal dose on the inner Canthus. Results from the modelling indicated that any measurements made had to be at a high spatial resolution. Polysulphone film was found to be inadequate for this, due to its large uncertainties. An alternative method was investigated so that a population study could be performed in future studies using visible radiation and high dynamic range images gave a simple and effective clinical assessment tool. The high dynamic range images showed hot spots in the irradiance across the inner Canthus agreeing with the model. The small spots of high relative irradiance may not be the only reason for the increased rate in this region. Greater skin sensitivity and absence of sun screen use at this site are other possibilities. It is believed however that the irradiance distribution across the inner Canthus on a microscopic scale goes a long way to increasing the risk for certain people.
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The Effect of Measurement Area on Modelling UVR Dose to the Inner Canthus
Journal of Light & Visual Environment, 2006Co-Authors: Benjamin J. Birt, Ian Cowling, Steven CoyneAbstract:People are exposed to varying amounts of UVR throughout their life from both natural and artificial light sources. The dose and rate of UVR exposure required for the formation of non-melanoma skin cancers is inconclusive. Certain regions on the face appear to exhibit a high rate of occurrence of Basal Cell Carcinomas (BCCs) in relation to the perceived dose of UVR. One of these regions is the inner Canthus located on the medial side of the eye. The inner Canthus appears to be well protected from large direct doses of ultraviolet radiation (UVR). Facial features such as eyelids, eye brow ridge, nasal bridge and cheek, combine to limit the solid angle of the field of view of the inner Canthus to UVR from overhead sources. To explain the unexpected high rate of BCCs it is hypothesized that a percentage of the radiation incident on the eye is reflected onto the inner Canthus. This paper showed that a portion of the radiation incident onto the eye was reflected towards the inner Canthus. The percentage increase above the direct dose was only 2% across the whole region. As the detector elements decrease in size it is observed on a cellular level that some of the cells dose increased by 30% when the reflections were considered.
Ian Cowling - One of the best experts on this subject based on the ideXlab platform.
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the effect of the eye s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of Photochemistry and Photobiology B-biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The effect of the eye’s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of photochemistry and photobiology. B Biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The Effect of Measurement Area on Modelling UVR Dose to the Inner Canthus
Journal of Light & Visual Environment, 2006Co-Authors: Benjamin J. Birt, Ian Cowling, Steven CoyneAbstract:People are exposed to varying amounts of UVR throughout their life from both natural and artificial light sources. The dose and rate of UVR exposure required for the formation of non-melanoma skin cancers is inconclusive. Certain regions on the face appear to exhibit a high rate of occurrence of Basal Cell Carcinomas (BCCs) in relation to the perceived dose of UVR. One of these regions is the inner Canthus located on the medial side of the eye. The inner Canthus appears to be well protected from large direct doses of ultraviolet radiation (UVR). Facial features such as eyelids, eye brow ridge, nasal bridge and cheek, combine to limit the solid angle of the field of view of the inner Canthus to UVR from overhead sources. To explain the unexpected high rate of BCCs it is hypothesized that a percentage of the radiation incident on the eye is reflected onto the inner Canthus. This paper showed that a portion of the radiation incident onto the eye was reflected towards the inner Canthus. The percentage increase above the direct dose was only 2% across the whole region. As the detector elements decrease in size it is observed on a cellular level that some of the cells dose increased by 30% when the reflections were considered.
Steven Coyne - One of the best experts on this subject based on the ideXlab platform.
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the effect of the eye s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of Photochemistry and Photobiology B-biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The effect of the eye’s surface topography on the total irradiance of ultraviolet radiation on the inner Canthus
Journal of photochemistry and photobiology. B Biology, 2007Co-Authors: Benjamin J. Birt, Ian Cowling, Steven Coyne, Greg W. MichaelAbstract:Basal cell carcinoma is the most commonly occurring skin cancer in sub tropical climates. The link between ultraviolet radiation (UVR) and basal cell carcinomas (BCC) is strong. Numerous studies have investigated the spatial distribution of BCCs over the head and neck region and the relative UVR dose, with little or no correlation found between the UVR dose and occurrence rates. This is particularly noted in the inner Canthus region. The inner Canthus' field of view is restricted by the eye brow ridge, eye orbit and the cheek bone. Yet, the occurrence rate here of BCC's when compared to other regions that are more directly exposed to the environment is significantly higher. A possible causal effect for the increase in occurrence rate in this region is the focussed reflection of UVR from the tear film surface associated with the eye not previously considered in earlier studies. This paper investigates the potential for the surface topography of the eye to reflect focussed radiation towards the inner Canthus using a ray tracing programme where the analysis is conducted at a cellular level. Defined hot spots, or striations, of increased irradiation were evidenced across the surface of the inner Canthus. This increase in irradiation was not observed with macroscopic detectors which also possibly explain why this increased dose has not previously been detected during environmental measurements with large detectors on manikins or humans.
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The Effect of Measurement Area on Modelling UVR Dose to the Inner Canthus
Journal of Light & Visual Environment, 2006Co-Authors: Benjamin J. Birt, Ian Cowling, Steven CoyneAbstract:People are exposed to varying amounts of UVR throughout their life from both natural and artificial light sources. The dose and rate of UVR exposure required for the formation of non-melanoma skin cancers is inconclusive. Certain regions on the face appear to exhibit a high rate of occurrence of Basal Cell Carcinomas (BCCs) in relation to the perceived dose of UVR. One of these regions is the inner Canthus located on the medial side of the eye. The inner Canthus appears to be well protected from large direct doses of ultraviolet radiation (UVR). Facial features such as eyelids, eye brow ridge, nasal bridge and cheek, combine to limit the solid angle of the field of view of the inner Canthus to UVR from overhead sources. To explain the unexpected high rate of BCCs it is hypothesized that a percentage of the radiation incident on the eye is reflected onto the inner Canthus. This paper showed that a portion of the radiation incident onto the eye was reflected towards the inner Canthus. The percentage increase above the direct dose was only 2% across the whole region. As the detector elements decrease in size it is observed on a cellular level that some of the cells dose increased by 30% when the reflections were considered.
Heidi B. Donnelly - One of the best experts on this subject based on the ideXlab platform.
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Canthal Rotation Flap: Analysis of Flap Mechanics.
Dermatologic Surgery, 2020Co-Authors: Zain U. Syed, Nichelle Madden, Heidi B. DonnellyAbstract:BACKGROUND Surgical defects of the medial Canthus lack reconstructive options that are reproducible, precise, and uncomplicated. The canthal rotation flap is a simple rotation flap that respects the geometry of this anatomic location. OBJECTIVE To describe the authors' experience with reconstructive planning, flap mechanics, and geometric analysis of the medial Canthus to achieve the best cosmetic outcome when using the canthal rotation flap. METHODS A retrospective review of 16 cases performed at Dayton Skin Care Specialists and Skin Care Specialty Physicians between 2016 and 2018 was completed with a blinded visual analog score (VAS). RESULTS Sixteen patients with Mohs defects in the medial Canthus were reconstructed using the canthal rotation flap. Defect diameters ranged from 0.8 to 2.7 cm. Patient ages ranged from 17 to 88 years. The mean flap dimensions were 4.8 cm by 2.15 cm. No major complications were noted. The VAS scar rating at 2 to 5 months follow-up was available for 10 of 16 patients; the mean VAS was 2.1. CONCLUSION The canthal rotation flap is a reliable, single stage repair for small defects of the medial Canthus that is optimized for the unique geometry of the medial Canthus. This repair technique adds to the paucity of reconstructive options for the medial Canthus.