Lens Exposure Research Articles

Central Corneal Thickness of Healthy Lowlanders at High Altitude: A Systematic Review and Meta-Analysis

ABSTRACTPurpose: Central corneal thickness, a marker of corneal hydration and metabolism, was reported to increase at high elevations. This study aimed to assess the effect of chronic high-altitude exposure on the central corneal thickness of healthy lowlanders with unoperated corneas, and determine if a relationship exists between exposure time and corneal edema formation.Materials and Methods: The PubMed, Embase, Scopus, Cochrane Library, and Airiti Library databases were searched up to 2017 January 31 for prospective cohort studies performed above 2500 m in healthy lowlanders with measurements of the central corneal thickness. Subjects with prior eye surgery, contact lens, and non-hypobaric hypoxic exposure were excluded.Results: Seven studies of 207 adults were included. The pooled effect of high-altitude exposure on the central corneal thickness for < 12 hours, 3–5 days, 6–7 days, and > 10 days was a mean difference of 13.4 (95% confidence interval: 5.1–21.6) μm with moderate heterogeneity (p < 0.05, I2 = 59%), 19.3 (95% confidence interval: 9.7–29) μm with low heterogeneity (p = 0.88, I2 = 0%), 20.4 (95% confidence interval: 10.3–30.5) μm with low heterogeneity (p = 0.73, I2 = 0%), and 30.8 (95% confidence interval: 20.4–41.2) μm with low heterogeneity (p = 0.69, I2 = 0%), respectively. Baseline differences between pre-exposure and post-exposure were not statistically significant. Regression analysis revealed a significant linear relation between high-altitude exposure time and corneal edema formation that exceeded 5% after 10 days.Conclusions: High-altitude exposure induces central corneal thickening with significant linear progression over time, whereas it takes over 10 days to reach clinical significance in healthy lowlanders with unoperated corneas, and changes in central corneal thickness are reversible after descent to lower elevations.

Current situations and discussions in Japan in relation to the new occupational equivalent dose limit for the lens of the eye

Since the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye in 2011, there have been extensive discussions in various countries. This paper reviews the current situation in radiation protection of the ocular lens and the discussions on the potential impact of the new lens dose limit in Japan. Topics include historical changes to the lens dose limit, the current situation with occupational lens exposures (e.g., in medical workers, nuclear workers, and Fukushima nuclear power plant workers) and measurements, and the current status of biological studies and epidemiological studies on radiation cataracts. Our focus is on the situation in Japan, but we believe such information sharing will be useful in many other countries.

Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers.

To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water. The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions. GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses. Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk.

Equilibrium study of copper absorption to different types of soft contact lens

To measure binding affinity of copper, one of the heavy metals in particulate matter (PM) was applied to soft contact lenses made of two different materials because contact lenses are readily exposed to PM. Copper binding to ionized silicon hydrogel lens yielded an equilibrium association constant K a,eq value of 14.03 μM without color change of lens, compared to that of 19.16 μM for copper binding to de-ionized hydrogel lenses with color change of lens. The results indicated that the color change of lens is not consistent with the concentration of cooper deposition on lens, and copper bound relatively stronger in ionized silicon hydrogel lens than in de-ionized hydrogel lens. Therefore, the continuous exposure of contact lenses to high PM levels might lead to heavy metal deposition on the lens, which would be detrimental to ocular health.

The effects of simulating a realistic eye model on the eye dose of an adult male undergoing head computed tomography.

In head computed tomography, radiation upon the eye lens (as an organ with high radiosensitivity) may cause lenticular opacity and cataracts. Therefore, quantitative dose assessment due to exposure of the eye lens and surrounding tissue is a matter of concern. For this purpose, an accurate eye model with realistic geometry and shape, in which different eye substructures are considered, is needed. To calculate the absorbed radiation dose of visual organs during head computed tomography scans, in this study, an existing sophisticated eye model was inserted at the related location in the head of the reference adult male phantom recommended by the International Commission on Radiological Protection (ICRP). Then absorbed doses and distributions of energy deposition in different parts of this eye model were calculated and compared with those based on a previous simple eye model. All calculations were done using the Monte Carlo code MCNP4C for tube voltages of 80, 100, 120 and 140 kVp. In spite of the similarity of total dose to the eye lens for both eye models, the dose delivered to the sensitive zone, which plays an important role in the induction of cataracts, was on average 3% higher for the sophisticated model as compared to the simple model. By increasing the tube voltage, differences between the total dose to the eye lens between the two phantoms decrease to 1%. Due to this level of agreement, use of the sophisticated eye model for patient dosimetry is not necessary. However, it still helps for an estimation of doses received by different eye substructures separately.

Seeing with a Filmmaker’s Eyes: Glimpses of Mobilized Landscapes in Stan Brakhage’s The Wonder Ring (1955) and Visions in Meditation #2: Mesa Verde (1989)

In this paper I present various ways in which Stan Brakhage’s The Wonder Ring (1955) and Visions in Meditation #2: Mesa Verde (1989) tend to challenge the concept of American landscape by means of cinematic conventions traditionally associated with phantom rides, city symphonies and contemporary road movies. It seems that Brakhage’s works do not only employ non-standard editing, camera movement and extended shot to reproduce a continuous flow of motion, but they also exploit the dynamics between the spectactor’s “mobilized virtual gaze” (Friedberg, Window 2) and passing views by evoking a distorted experience of sensational and meditative voyages, hence questioning panoramic perception and an idealized image of American (film) landscape intrinsically bound with the natural and technological sublime. Particularly, both films draw on rapid handheld camerawork, superimpositions, anamorphic lens, bright or dim exposures, fades, odd angles, softened focus and other techniques to defamiliarize and objectify the protagonist’s journey and thus document Brakhage’s perception and extra-objective reality.

Ocular Radiation Threshold Projection Based off of Fluoroscopy Time During ERCP.

Current international guidelines for ocular radiation exposure suggest a threshold of 20 millisieverts (mSv)/year. Although endoscopists wear lead aprons, use of protective eye wear is optional. This study was conducted to analyze the lens radiation exposure during endoscopic retrograde cholangiopancreatography (ERCP) for endoscopists to determine the time of fluoroscopy needed to warrant using lens protection during ERCP. ERCP patients were prospectively enrolled. Indications, interventions, fluoroscopy time, dose, and attending ± fellow involvement were recorded. Radiation exposure was collected from body dosimeters and dosimeters placed between the eyes. Cumulative radiation doses were obtained at study completion and averaged over the total fluoroscopy time to determine the mSv/hour exposure. A total of 187 cases were included. Attendings and fellows wore lens dosimeters in 178 and 126 cases, respectively, and body dosimeters in 174 and 128 cases, respectively. Attendings and fellows wore lens dosimeters throughout 15.89 and 11.24 h of fluoroscopy, respectively. The cumulative radiation dose absorbed per lens dosimeters was 5.35 mSv for attendings and 2.55 mSv for fellows. The projected lens absorption by the body dosimeters was 19.03 mSv for attendings and 5.21 mSv for fellows. The hourly fluoroscopy lens exposure was 0.34 mSv/hour for attendings and 0.23 mSv/hour for fellows. The amount of fluoroscopy hours needed to reach the currently suggested lens threshold limit (20 mSv/year) was 59.41 h for attendings and 88.17 h for fellows. Radioprotective eye wear should be worn by physicians with yearly fluoroscopy times in similarly structured practices that meet or exceed these thresholds.

Indatuximab Ravtansine (BT062) in Combination with Low-Dose Dexamethasone and Lenalidomide or Pomalidomide: Clinical Activity in Patients with Relapsed / Refractory Multiple Myeloma

Indatuximab Ravtansine (BT062) in Combination with Low-Dose Dexamethasone and Lenalidomide or Pomalidomide: Clinical Activity in Patients with Relapsed / Refractory Multiple Myeloma

Efficacy of Lens Protection Systems: Dependency on Different Cranial CT Scans in The Acute Stroke Setting.

To evaluate the dose-reduction potential with different lens protectors for patients undergoing cranial computed tomography (CT) scans. Eye lens dose was assessed in vitro (α-Al2O3:C thermoluminescence dosemeters) using an Alderson-Rando phantom® in cranial CT protocols at different CT scanners (SOMATOM-Definition-AS+®(CT1) and SOMATOM-Definition-Flash® (CT2)) using two different lens-protection systems (Somatex® (SOM) and Medical Imaging Systems® (MIS)). Summarised percentage of the transmitted photons: (1) CT1 (a) unenhanced CT (nCT) with gantry angulation: SOM = 103%, MIS = 111%; (2) CT2 (a) nCT without gantry angulation: SOM = 81%, MIS = 91%; (b) CT angiography (CTA) with automatic dose-modulation technique: SOM = 39%, MIS = 74%; (c) CTA without dose-modulation technique: SOM = 22%, MIS = 48%; (d) CT perfusion: SOM = 44%, MIS = 69%. SOM showed a higher dose-reduction potential than MIS maintaining equal image quality. Lens-protection systems are most effective in CTA protocols without dose-reduction techniques. Lens-protection systems lower the average eye lens dose during CT scans up to 1/3 (MIS) and 2/3 (SOM), respectively, if the eye lens is exposed to the direct beam of radiation. Considering both the CT protocol and the material of lens protectors, they seem to be mandatory for reducing the radiation exposure of the eye lens.

Occupational Exposure of the Eye Lens in Interventional Procedures: How to Assess and Manage Radiation Dose

Occupational exposure from interventional x-ray procedures is one of the areas in which increased eye lens exposure may occur. Accurate dosimetry is an important element to investigate the correlation of observed radiation effects with radiation dose, to verify the compliance with regulatory dose limits, and to optimize radiation protection practice. The objective of this work is to review eye lens dose levels in clinical practice that may occur from the use of ionizing radiation. The use of a dedicated eye lens dosimeter is the recommended methodology; however, in practice it cannot always be easily implemented. Alternatively, the eye lens dose could be assessed from measurements of other dosimetric quantities or other indirect parameters, such as patient dose. The practical implementation of monitoring eye lens doses and the use of adequate protective equipment still remains a challenge. The use of lead glasses with a good fit to the face, appropriate lateral coverage, and/or ceiling-suspended screens is recommended in workplaces with potential high eye lens doses.

Eye lens radiation exposure in greek interventional cardiology personnel

Introduction The exposure of the radiosensitive eye lenses to ionizing radiation can lead to radiation-induced cataract, which is usually detected earlier than the age-related cataract. Purpose In the framework of the study, measurements of the eye lens doses of Interventional Cardiologists (ICs) were performed. An attempt was made to calculate retrospectively their eye lens doses and compare them with the probability for radiation-induced cataract. Materials and methods The study included ICs from different health centers of Athens and unexposed workers. Each participant underwent two clinical eye examinations and the detected lens opacities (nuclear, cortical or posterior subcapsular) were classified according to LOCS III protocol. Moreover, the lens doses of the ICs were measured using special designed eye dosemeters. Results 43 ICs (mean age = 48.8 ± 6.7 years) and 22 unexposed workers (mean age = 48.2 ± 5.0 years) participated at the study. The mean dose to the eye lenses of the ICs per month was 0.74 ± 0.53 mSv, while the maximum annual dose was calculated 28 mSv/yr, much higher than the occupational annual dose limit of 20 mSv/yr. Regarding the lens opacities, the two groups did not differ significantly in the prevalence of either nuclear or cortical lens opacities, whereas 4 ICs where detected with early stage subcapsular sclerosis. Conclusion Though no statistically significant difference was observed in the cohort, the measured doses and the cumulative ones indicate that the ICs receive high eye lens doses. In order to minimize the radiation induced risk at the eye lenses, the use of radioprotective equipment and appropriate training on this issue is highly recommended.

Measurement of conversion coefficients beteen free-in-air kerma and personal dose equivalent for RQR spectra to be used in monitoring of the eye lens in nterventional radiology

Introduction The recommended operational quantity to monitor eye lens exposure in interventional radiology is personal dose equivalent in 3 mm depth: H p (3). However, there are no conversion coefficients suggested in international standards. Purpose The aim of this study was to calculate the air kerma (K a ) to H p (3) conversion coefficients for a cylindrical phantom based on measurements with the radiation qualities RQR2 to RQR10 that provide better approximation of X-ray spectra used in interventional radiology, especially compared to narrow spectra applied for calibration of personal dosemeters. Materials and methods The conversion coefficients h p,k (3) were determined using the formula h p , k ( 3 ) = H p ( 3 ) K a = μ en ρ air mat BSF · PDD The backscatter factors, BSF, were measured using LiF:Mn,Ti thermoluminescent detectors on a homogeneous cylindrical phantom and free in air kerma. RQRs radiation qualities were reproduced in the Secondary Standards Dosimetry Laboratory – Sofia, Bulgaria. Data for dry air and ICRU soft tissue were taken from NIST. Results The Percentage Depth Dose, PDD, for RQR2 to RQR10 were calculated, BSFs were measured and conversion coefficients h pK (3, RQR,0°) were determined for the new cylindrical phantom. The results are in good agreement with those published by Principi et all. Conclusions The conversion coefficients from the air kerma (K a ) to H p (3) for radiation qualities RQR 2 to RQR 10 can be used in occupational dosimetry for interventional radiology.

The influence of operator position, height and body orientation on eye lens dose in interventional radiology and cardiology: Monte Carlo simulations versus realistic clinical measurements

ObjectiveThis paper aims to provide some practical recommendations to reduce eye lens dose for workers exposed to X-rays in interventional cardiology and radiology and also to propose an eye lens correction factor when lead glasses are used. MethodsMonte Carlo simulations are used to study the variation of eye lens exposure with operator position, height and body orientation with respect to the patient and the X-ray tube. The paper also looks into the efficiency of wraparound lead glasses using simulations. Computation results are compared with experimental measurements performed in Spanish hospitals using eye lens dosemeters as well as with data from available literature. ResultsSimulations showed that left eye exposure is generally higher than the right eye, when the operator stands on the right side of the patient. Operator height can induce a strong dose decrease by up to a factor of 2 for the left eye for 10-cm-taller operators. Body rotation of the operator away from the tube by 45°–60° reduces eye exposure by a factor of 2. The calculation-based correction factor of 0.3 for wraparound type lead glasses was found to agree reasonably well with experimental data. ConclusionsSimple precautions, such as the positioning of the image screen away from the X-ray source, lead to a significant reduction of the eye lens dose. Measurements and simulations performed in this work also show that a general eye lens correction factor of 0.5 can be used when lead glasses are worn regardless of operator position, height and body orientation.

Surgeon's and Patient's Radiation Exposure Through Vertebral Body Cement Augmentation Procedures: A Prospective Multicentric Study of 49 Cases

Vertebral body cement augmentation as a treatment option for osteoporotic or traumatic fractures has become increasingly popular during the past decade. However, these surgical procedures require numerous fluoroscopic examinations, resulting in high radiation exposure for the patient and the surgical team. The aim of this study was to evaluate the level of radiation exposure of the spine surgeon and the patient during these percutaneous procedures. Forty-nine patients admitted for single- or 2-level vertebral compression fracture were prospectively included and treated with vertebral body cement augmentation. For each procedure, radiation dose was measured on the surgeon's whole body, lens, and extremities as well as patient irradiation. Each surgeon wore 2 thermoluminescent dosimeters to measure lens and extremities radiation exposure and 1 electronic personal dosimeter. Patient clinical and surgical data, effective dose to patient, and surgeon were analyzed. Mean operative time was 31.5 ± 11.7 minutes. The average fluoroscopic time was 61.0 ± 27.1 seconds. The average whole-body radiation dose per procedure was 1.4 ± 2.1 μSv. The average equivalent dose to lens and extremities were 44 μSv and 59 μSv, respectively. Values of radiation doses for surgeon and patient were lower than those reported in the previous literature. The recommended annual dose limit is set to 500mSv for extremities and 150 mSv for lens. According to our results, the exposure dose to the eye exceeds the annual limit after 3500 procedures. However, there is increasing concern among surgeons about radiation exposure, and there is still a need for solutions as preventive measures.

Shielding Effect of Lead Glasses on Radiologists' Eye Lens Exposure in Interventional Procedures.

To study the shielding effect of radiologists' eye lens with lead glasses of different equivalent thicknesses and sizes in interventional radiology procedures. Using the human voxel phantom with a more accurate model of the eye and MCNPX software, eye lens doses of the radiologists who wearing different kinds of lead glasses were simulated, different beam projections were taken into consideration during the simulation. Measurements were also performed with the physical model to verify simulation results. Simulation results showed that the eye lens doses were reduced by a factor from 3 to 9 when wearing a 20 cm2-sized lead glasses with the equivalent thickness ranging from 0.1 to 1.0 mm Pb. The increase of dose reduction factor (DRF) was not significant whenever increase the lead equivalent of glasses of which larger than 0.35 mm. Furthermore, the DRF was proportional to the size of glass lens from 6 to 30 cm2 with the same lead equivalent. The simulation results were in well agreements with the measured ones. For more reasonable and effective protection of the eye lens of interventional radiologists, a pair of glasses with a lead equivalent of 0.5 mm Pb and large-sized (at least 27 cm2 per glass) lens are recommended.

Radiation exposure to eye lens and operator hands during endovascular procedures in hybrid operating rooms

The purpose of this study was to evaluate the radiation exposure of vascular surgeons' eye lens and fingers during complex endovascular procedures in modern hybrid operating rooms. Prospective, nonrandomized multicenter study design. One hundred seventy-one consecutive patients (138 male; median age, 72.5 years [interquartile range, 65-77 years]) underwent an endovascular procedure in a hybrid operating room between March 2012 and July 2013 in two vascular centers. The dose-area product (DAP), fluoroscopy time, operating time, and amount of contrast dye were registered prospectively. For radiation dose recordings, single-use dosimeters were attached at eye level and to the ring finger of the hand next to the radiation field of the operator for each endovascular procedure. Dose recordings were evaluated by an independent institution. Before the study, precursory investigations were obtained to simulate the radiation dose to eye lens and fingers with an Alderson phantome (RSD, Long Beach, Calif). Interventions were classified into six treatment categories: endovascular repair of infrarenal abdominal aneurysm (n = 65), thoracic endovascular aortic repair (n = 32), branched endovascular aortic repair for thoracoabdominal aneurysms (n = 17), fenestrated endovascular aortic repair for complex abdominal aortic aneurysm, (n = 25), iliac branched device (n = 8), and peripheral interventions (n = 24). There was a significant correlation in DAP between both lens (P < .01; r = 0.55) and finger (P < .01; r = 0.56) doses. The estimated fluoroscopy time to reach a radiation threshold of 20 mSv/y was 1404.10 minutes (90% confidence limit, 1160, 1650 minutes). According to correlation of the lens dose with the DAP an estimated cumulative DAP of 932,000 mGy/m(2) (90% confidence limit, 822,000, 1,039,000) would be critical for a threshold of 20 mSv/y for the eyes. Radiation protection is a serious issue for vascular surgeons because most complex endovascular procedures are delivering measurable radiation to the eyes. With the correlation of the DAP obtained in standard endovascular procedures a critical threshold of 20 mSv/y to the eyes can be predicted and thus an estimate of a potential harmful exposure to the eyes can be obtained.

AIR KERMA TO Hp(3) CONVERSION COEFFICIENTS FOR IEC 61267 RQR X-RAY RADIATION QUALITIES: APPLICATION TO DOSE MONITORING OF THE LENS OF THE EYE IN MEDICAL DIAGNOSTICS.

Recent studies highlight the fact that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens monitoring could be required for these workers. The recommended operational quantity for monitoring of eye lens exposure is the personal dose equivalent at 3 mm depth Hp(3) (ICRU 51). However, there are no available conversion coefficients in international standards, while in the literature coefficients have only been calculated for monoenergetic beams and for ISO 4037-1 X-ray qualities. The aim of this article is to provide air kerma to Hp(3) conversion coefficients for a cylindrical phantom made of ICRU-4 elements tissue-equivalent material for RQR radiation qualities (IEC-61267) from 40 to 120 kV and for angles of incidence from 0 to 180°, which are characteristic of medical workplace. Analytic calculations using interpolation techniques and Monte Carlo modelling have been compared.

Study of the Protection of the Operators Against Radiation during Surgical and Endovascular Procedures

Bifurcated aortoiliac 47 (11e112) 103 (1 Branched iliac 134 (50e359) 395 (1 FEVAR 1310 (31e3066) 4004 (1 TEVAR 93 (86e100) 192 (7 Chimney 745 1720 operational room equipped with a Siemens Arcadis Avantic or Siemens CIOS Alpha mobile arch. The evaluation of the exposure was carried out with the thermoluminescent LiF dosimeters (Mg, P, Cu) calibrated in Hp(0.07) with usual X-ray energies (Emax 1⁄4 70 keV). For all the persons intervening in operating room (main operator, assistants, paramedical staff, radiology technician, and anesthesiologist) these dosimeters were positioned on the level of the temples, for the evaluation of the exposure of the crystalline lenses, and on the level of the hands and the ankles. Whole body HP(10) dosimetry was evaluated directly with the means of the operational dosimeters carried under the lead apron. The clinical and dosimetry data were recorded for each procedure (age of the patient, weight, size, BMI, duration of fluoroscopy, dose area product, air kerma). We also made a study of the dosimetry of the patient by means of radiochromic films to measure the maximum amount delivered to the skin. Results: The results of the clinical and dosimetry data are summarized in Table I and those of the dose equivalents measured for the main operator in Table II. Conclusion: This study showed very good practices of the surgical team to optimize the protection against radiation during the procedures, making it possible to limit the intensity of the diffused radiation which was directly demonstrated by the values of the maximum dose delivered to the skin of the patients, who were always < 2 Gy, i.e. really lower than the values reported in the literature. This study also showed the limits of the conventional operating room suites for this type of interventions. Hybrid rooms offer better conditions of

The value of protective head cap and glasses in neurointerventional radiology

BackgroundProtection of the head and eyes of the neurointerventional radiologist is a growing concern, especially after recent reports on the incidence of brain cancer among these personnel, and the revision...

TH-AB-201-08: Eye Lens Dose Reduction of Radiologists in Interventional Procedures with Lead Glasses

Purpose: To study and compare the shielding effect of radiologists’eye lens exposure with lead glasses of different equivalent thickness and size in interventional procedures. Methods: Using the human voxel phantom and MCNPX code, eye lens doses of the radiologists were simulated under different conditions of wearing lead glasses and beam projections, and measurements were performed with the physical model by using eye lens dosimeters to verify simulation results. Results: Simulation results show that the eye lens doses were reduced by a factor from 3 to 9 when wearing a 20 cm 2 sized led glasses with the equivalent thickness ranging from 0.1 to 1.0 mm Pb. The dose reduction factors (DRF) not only depend on the lead equivalent, but also the beam projection of X-rays. However, the increase of DRF was not significant whenever the lead equivalent of glasses was larger than 0.35 mm. Furthermore, the DRF was proportional to the size of glass lens from 6 cm 2 to 30 cm 2 with the same lead equivalent. Conclusion: For more reasonable and effective protection of the eye lens of interventional radiologists, a pair of glasses with a lead equivalent of 0.5 mm and large-sized lens is recommended.