Safety Spectacles Research Articles

Fundamentals of ophthalmic dispensing 20: Personal eye protection 1

Eye injury remains a significant cause of monocular visual impairment, and blindness in monocular patients. This is the first of two articles in which Peter Black and Tina Arbon Black explore personal eye protection and prescription safety spectacles. (C78821 suitable as one distance learning CET point for optometrists and dispensing opticians)

Reduced field of view under the surgical microscope due to personal protective equipment: lessons learned during the COVID-19 pandemic.

During the coronavirus disease 2019 (COVID-19) pandemic, neurosurgeons all around the globe continue to operate in emergency cases using new self-protective measures. Personal protective equipment (PPE) use is recommended in all surgeries. The authors have experienced varying degrees of field of view (FOV) loss under the surgical microscope with different PPE. Herein, they aimed to investigate the effects of different PPE on FOV while using the surgical microscope. Fifteen neurosurgeons and neurosurgery residents participated in this study. Three kinds of PPE (safety spectacles, blast goggles, and face shields) were tested while using a surgical microscope. FOV was measured using a 12 × 12-cm checkered sheet of paper on which every square had an area of 25 mm2 under the microscope. The surgical microscope was positioned perpendicular to the test paper, and the zoom was fixed. Each participant marked on the test sheet the peripheral borders of their FOV while using different PPE and without wearing any PPE. A one-way repeated-measures ANOVA was performed to determine if there was a significant difference in FOV values with the different PPE. FOV was significantly different between each PPE (F[3, 42] = 6339.845, p < 0.0005). Post hoc analysis revealed a significant decrease in the FOV from the naked eye (9305.33 ± 406.1 mm2) to blast goggles (2501.91 ± 176.5 mm2) and face shields (92.33 ± 6.4 mm2). There were no significant FOV changes with the safety spectacles (9267.45 ± 410.5 mm2). While operating under a surgical microscope safety spectacles provide favorable FOVs. Face shields increase the eye piece-pupil distance, which causes a severe reduction in FOV.

COVID-19 Pandemic: Survey of future use of personal protective equipment in optometric practice

PurposeThe aim of this project was to evaluate which personal protective equipment (PPE) eye care practitioners (ECP) will use during the next months and also what they will ask the patient to use in clinical practice. MethodsA social-media survey was carried out, asking 257 optometrists and opticians in Germany, Austria and Switzerland (i) which PPE they intended to use in the future (after lockdown and before herd immunity and / or vaccine availability) and (ii) what they would ask the patient to do in terms of this. Results75 % of the ECPs planned on wearing masks during refractions and 69 % when fitting contact lens. 62 % of the ECPs also expected their patients to wear masks in these tasks. This number is higher than for distance tasks such as fitting frames. Around 90 % of the ECPs would, in addition to hand washing, disinfect their hands and around 80 % expected their patients to do so too. Less than one third of ECPs favoured wearing safety spectacles, gloves and / or protective facial shields. 73 % planed on disinfecting frames after they would have been tried on by customers. ConclusionsIn summary, most ECPs planed on continuing to use higher standards of PPE. Those, who intended to wear masks themselves, would ask their patients to also do so, combined with hand disinfection.

Selection of Earmuffs and Other Personal Protective Equipment Used in Combination.

In a work environment, in addition to noise, people may be exposed to other harmful factors. Therefore, they wear both hearing protectors and other personal protective equipment (OPPE). Incorrect use of such a combination may increase the risk of hearing loss. The aim of this study was to determine whether the simultaneous use of earmuffs and other personal protective equipment could affect the effectiveness of hearing protection. The study was carried out under laboratory conditions using an acoustic test fixture. This fixture replicated the anatomical shapes of the head and the pinnae, and was also equipped with ear simulators. The study was carried out for five models of earmuffs and eight models of other personal protection equipment. We found that a change in the sound pressure level (SPL) under the earmuffs when using a full face respirator could reach up to 40 dB. On the other hand, the use of a half respirator had practically no adverse impact on the efficiency of hearing protection. In the selection process, it is recommended to consider safety spectacles equipped with thin temples, and half respirators equipped with band adjustment elements positioned on the facial part, rather than the back, of the user’s head.

Attenuation of earmuffs used simultaneously with safety spectacles in exposure to impulse noise

Impulse noise is particularly hazardous to the hearing of exposed individuals. In many real-life scenarios, the only protective measure used to reduce the level of impulse noise is hearing protectors. These scenarios include firing ranges. Aside from hearing protectors, shooters use personal safety spectacles. The purpose of this paper was to determine the effect of the simultaneous use of earmuffs and safety spectacles on the sound attenuation of earmuffs during exposure to impact noise. The research was completed with the MIRE method and included the determination of sound attenuation changes in five different models of earmuffs, used simultaneously with three different models of safety spectacles and prescription glasses. The impulse noise source used was a starting pistol, which generated C-weighted peak sound pressure level at a mean of 136.7 dB. The tests demonstrated that the simultaneous use of safety spectacles and earmuffs reduces the impulse noise attenuation of the earmuffs by up to 9 dB. Such sound attenuation changes occurred during simultaneous use of earmuffs with safety spectacles, which feature temples with a rectangular cross-section. The tests also demonstrated that the effect of prescription glasses on sound attenuation was unusually high; prescription glasses reduced the impulse sound attenuation of earmuffs by as much as 18 dB. Keywords: acoustics, noise protection, impulse noise, hearing protectors, earmuffs, noise attenuation

Protective equipment for small-scale laboratory explosive hazards. Part 2. Shielding materials, eye and face protection

A range of commercially available protective equipment including face shields, safety spectacles and safety screens, was tested against detonating explosive charge masses of up to 7.5 g with a short stand-off. The explosive charges were placed in representative fragment sources such as glass round bottom flasks or porcelain Buchner funnels. The firings were evaluated using test article recovery and high speed video footage. Complete protection was possible at the 0.3 g and 1.0 g scales.

Quality control of injection molded eyewear by non-contact deflectometry

Occupational eye wear such as safety spectacles are manufactured by injection molding techniques. Testing of the assembled safety spectacle lenses in transmission is state of the art, but there is a lack of surface measurement systems for occupational safety lenses. The purpose of this work was to validate a deflectometric setup for topography measurement, detection of defects and visualization of the polishing quality, e.g. casting indentations or impressions, for the production process of safety spectacles. The setup is based on a customized stereo phase measuring deflectometer (PMD), equipped with 3 cameras with f’1,2 = 16 mm and f’3 = 8.5 mm and a specified measurement uncertainty of ± 3 µm. Sixteen plastic lenses and 8 corresponding injection molds from 4 parallel cavities were used for validation of the deflectometer. For comparison an interferometric method and a reference standard (&lt; λ/10 super polished) was used. The accuracy and bias with a spherical safety spectacle sample was below 1 µm, according to DIN ISO 5725-2.2002-12. The repeatability was 2.1 µm and 35.7 µm for a blind radius fit. In conclusion, the PMD technique is an appropriate tool for characterizing occupational safety spectacle and injections mold surfaces. With the presented setup we were able to quantify the surface quality. This can be useful and may optimize the quality of the end product, in addition to standardized measuring systems in transmission.

Guidance on the use of respiratory and facial protection equipment

Infectious micro-organisms may be transmitted by a variety of routes, and some may be spread by more than one route. Respiratory and facial protection is required for those organisms that are usually transmitted via the droplet/airborne route, or when airborne particles have been artificially created, such as during ‘aerosol-generating procedures’. A range of personal protective equipment that provides different degrees of facial and respiratory protection is available. It is apparent from the recent experiences with severe acute respiratory syndrome and pandemic (H1N1) 2009 influenza that healthcare workers may have difficulty in choosing the correct type of facial and respiratory protection in any given clinical situation. To address this issue, the Scientific Development Committee of the Healthcare Infection Society established a short-life working group to develop guidance. The guidance is based upon a review of the literature, which is published separately, and expert consensus.

Theoretical model for design and analysis of protectional eyewear

IntroductionProtectional eyewear has to fulfill both mechanical and optical stress tests. To pass those optical tests the surfaces of safety spectacles have to be optimized to minimize optical aberrations. Material and MethodsStarting with the surface data of three measured safety spectacles, a theoretical spectacle model (four spherical surfaces) is recalculated first and then optimized while keeping the front surface unchanged. Next to spherical power, astigmatic power and prism imbalance we used the wavefront error (five different viewing directions) to simulate the optical performance and to optimize the safety spectacle geometries. ResultsAll surfaces were spherical (maximum global deviation ‘peak-to-valley’ between the measured surface and the best-fit sphere: 0.132mm). Except the spherical power of the model Axcont (−0.07m−1) all simulated optical performance before optimization was better than the limits defined by standards. The optimization reduced the wavefront error by 1% to 0.150 λ (Windor/Infield), by 63% to 0.194 λ (Axcont/Bolle) and by 55% to 0.199 λ (2720/3M) without dropping below the measured thickness. ConclusionThe simulated optical performance of spectacle designs could be improved when using a smart optimization. A good optical design counteracts degradation by parameter variation throughout the manufacturing process.

Experimental assessment of eye protection efficiency against high speed projectiles

IntroductionWork in hazardous zones with the risk of mechanical injuries requires protection with safety spectacles. Mechanical eye injuries with metal foreign bodies are often caused by rotational material machining or production processes with high pressure or high velocity moving parts. Normative regulations restrict to tests with small and fast flying objects (e.g. 6mm ball). The literature does not provide any information about protection capabilities against larger objects with high mass and arbitrary shape.The purpose of this study was to test the protection efficiency of safety spectacles against flying objects. The scope of this paper is to present a new test setup for mechanical impact resistance testing of personal protective eyewear against objects with arbitrary shape and mass. Material and MethodsThe setup is based on a catapult platform, accelerating a sliding carriage on a rail. A pull rope system allows velocities up to 62±2 m·s-1. A photo sensor was used for velocity measurement. The carriage can be loaded with projectiles of up to 30mm×30mm×40mm in size with arbitrary orientation, depending on the carriage insert. Testing and validation was done with projectiles such as 7g metal chips and fragments with approximate dimensions of 10mm×15mm. Samples were standard occupational safety spectacles mounted on a test head. The projectile impact was captured with a monochrome high speed camera. ResultsThe aiming accuracy test showed deviations of approximately 1mm of two impacts on the same spectacle surface with a free flight distance of 150mm. All tests with slow, medium and high speed projectiles showed no contact with the eye medium. Objects with velocities from 10 m·s-1 to 62 m·s-1 fired the spectacle off from the test head. The medium speed test cut off one side of the spectacle frame. The high speed test with 62±2 m·s-1 cracked the polycarbonate shield. DiscussionWe describe a method for accelerating arbitrary objects up to 62 m·s-1 and for aiming these objects on safety eyewear, mounted on a test head. The setup allows a variety of projectile shapes, orientations and velocities. The accuracy of velocity measurement is ± 2 m·s-1 for high velocity (< ± 5%). Further studies will address optimization of this setup due to signs of wear and gliding properties of the carriage, wireless ignition and higher velocities.

Influenza A(H1N1) and infection control guidelines for optometrists

The emergence of a novel influenza A virus (Influenza A[H1N1]), which has not circulated previously in humans, has led to the first global influenza pandemic in 41 years. Influenza A(H1N1), commonly called ‘swine flu’, is a novel influenza virus made up of porcine, avian and human genes, and preferentially infects younger people. Although Influenza A(H1N1) does not appear to be likely to cause as many fatalities as previous influenza pandemics, attempts to contain it are necessary because people whose health is already compromised through underlying chronic medical conditions are at risk of death if they contract the virus. In addition, pregnant women who become infected are at increased risk of complications.This paper provides figures on the number of cases of Influenza A(H1N1) and deaths associated with this virus in Australia (using World Health Organization and Australian Government figures) and discusses infection control measures that optometrists should put in place for themselves, their staff and their patients, in the event that there is suspicion of Influenza A(H1N1) infection. Measures include isolating those who display symptoms indicative of influenza, use of surgical masks (P2 [N95]) by the infected person, frequent hand‐washing, appropriate cough and sneeze etiquette, disposal of used tissues and rescheduling of non‐urgent appointments for those thought to be infected. Any staff members who need to be closer than one metre to the infected person should also use personal protective equipment (for example, surgical masks, goggles or safety spectacles, gowns and gloves). The current evidence indicates that Influenza A(H1N1) should be treated by optometrists as another type of flu. As with other forms of influenza, following basic infection control guidelines will help reduce the spread of infection in optometric practices and within the community.

Testing safety eyewear: How frame and lens design affect lens retention

Purpose The aim of this study was to determine the role that frame and lens design play in lens retention during high-impact testing of safety eyewear that advertises conformance to the performance-based ANSI Z87.1-2003 standard. Methods A total of 75 Z87 safety eyeglass frames (3 each of 25 frame models) were used in this study, procured from 5 of the leading U.S. safety frame manufacturers. Frames were fitted by an independent laboratory with 2.0-mm plano polycarbonate lenses in compliance with ANSI Z87.1-2003. Finished spectacles were sent to a subsequent laboratory testing facility where each frame was subjected to both high-mass and oblique-incidence high-velocity impacts to determine frame characteristics that were most highly associated with testing failure. Among the frame and lens parameters that were considered in this analysis were the A and B dimensions, effective diameter, distance between lenses, bridge type, frame material, bevel type, and frame cost. Certain variables were controlled for by maintaining consistency among all spectacle pairs, e.g., lens prescription, center thickness, and edge thickness. Multiple logistic regression was used to control potential confounding variables and to develop the best combination of them for predictive value. Results Of 25 separate frame models assessed, 10 passed both high-mass and high-velocity impact testing, i.e., none of the 3 frame/lens samples failed. Of the models that failed, 13 failures were caused by high-velocity testing, 1 by high-mass testing, and 1 failed both high-mass and high-velocity testing. None of the 15 spectacles with the SprinGuard™ (Hilco, Plainville, Massachusetts) bevel design failed, although these were proprietary to 1 manufacturer and included only 5 frame models. Two spectacle designs (6 individual frames) incorporated an inverted bevel design of which 3 of the frames failed impact testing. Controlling for drop ball velocity among the 54 remaining standard “V” bevel spectacle pairs, the odds of failure were about 8 to 9 times higher for metal frames than Zylonite frames (odds ratio [OR], 8.5; 95% confidence interval [CI], 1.4 to 52.3; P = 0.02), and the odds of failure were about 4 times higher for lens effective diameters of less than 50 mm than for lens effective diameters more than 50 mm (OR, 4.1; 95% CI, 1.2 to 14.8; P = 0.03). Conclusion Among our sample of safety spectacles, failure from high-mass impact resistance testing rarely occurred. No spectacles with the SprinGuard bevel design failed in our analysis, but this was limited to a small sample size from a single manufacturer. Among our sample of 54 spectacle pairs with a v-bevel design, metal frame material and an effective diameter of less than 50 mm were the strongest predictors of failure relative to high-velocity impact testing with a 45° temporal angle projectile.

Optical radiation hazards of welding arcs.

Welding, a widely used industrial process, is one of the most intense artificial sources of optical radiation. Each type of welding process emits a different spectrum and intensity of optical radiation. For most processes, ultraviolet and visible radiation are the main components of the emission. Such factors as arc current, shielding gas, and base metal influence the emission spectrum. Adverse effects are confined to the skin and eyes, with welders suffering from a higher proportion of optical radiation associated eye conditions than do non-welders. Erythema is a common skin condition among welders, but conditions like skin cancer are rare. An evaluation of optical radiation from welding consists of determining an effective irradiance and a maximum permissible exposure duration, which can be very short (from seconds to minutes). Control measures include the use of screens to localize the hazards, and the use of personal protective equipment, such as protective clothing, safety spectacles, and welding helmets. Recent studies indicate that optical radiation can infiltrate into helmets and workers may be exposed to excessive levels. Overall, further investigation into adverse health effects and safety equipment design is warranted.

Eye protection in ear, nose and throat surgery.

The aim of this study was to quantify the risk of blood splashes to the conjunctiva during ear, nose and throat surgery. Two hundred and sixty consecutive operations by three surgeons were assessed for contamination of safety glasses and other factors. We found that 15 per cent of operations resulted in blood droplet contamination of safety glasses. In 92 per cent of these, contaminations were on the exterior of the glasses and eight per cent were on both sides. We concluded that about one and a half per cent of operations would result in droplet contamination of the conjunctiva and that safety spectacles reduced the risk by a factor of about 10. This study generally concurs with that of previous research in the areas of general and orthopaedic surgery and necropsies. We substantiate the need for eye protection for all ear, nose and throat procedures. Spectacles do provide a reasonable degree of protection but where absolute protection is needed i.e. in high risk groups, goggles should be used in preference to safety spectacles.

Should eye protection be worn when performing necropsies?

One hundred necropsies were performed by four junior pathologists wearing safety spectacles. The number of blood splashes on the spectacle surfaces were counted after each necropsy. Splashes were found after 22 necropsies (range 10-34%), with higher numbers being seen among the more junior grades of pathologist. This suggests that the use of safety spectacles should be considered by all pathologists performing necropsies.

Radiation Exposure to Radiologists With Eye Pathology

To the Editor.— I would like to comment on the inquiry by Irvin Deutsch, MD (242:372, 1979), in relation to Irradiation Exposure Hazard to Radiologist With Existing Eye Pathology. As far as exposure for the radiologist to x-rays is concerned, all he need do is wear lead glass goggles during fluoroscopic examination; they reduce the incident radiation to practically zero. The more important factor, in my opinion, is the ultraviolet radiation emanating from standard view boxes. Ever since plastic diffusion panels came into use instead of glass, the ultraviolet light created by the fluorescent tubes strikes the observer. To avoid this, it is necessary for the radiologist to wear glass spectacles. The ordinary safety spectacles now mandated by law are made of plastic and do not absorb the ultraviolet rays. It is imperative that the radiologist use glass spectacles. They can be obtained by requesting safety glasses .

Plastics as Optical Materials

AbstractThe Principal material used in optics is glass. Plastics can only gain acceptance in optics if they have properties not encountered with glass or if a desired article can be produced more rationally from a plastic. An example of the first case is provided by UV light guides consisting of a quartz glass core surrounded by a plastic cladding; there is no glass with a sufficiently low refractive index. Examples of the second case are viewfinder optics for camerás and lenses for sunglasses and industrial safety spectacles.

Safety Spectacles for All?*

Current FDA legislation in America requires all spectacle lenses and all sunglass lenses to be dispensed in specified “safety” materials. The intent of the legislation is to reduce the incidence of eye injuries. The indications and contraindications for this approach are reviewed and compared with some other approaches that may be equally effective or may even show greater cost benefit in the prevention of eye injuries. It is concluded that our existing knowledge is so limited that it is currently not possible to provide any comprehensive, fully researched, scientific basis for this or any other course of action. The analysis therefore ends with a request for additional research by a team of interdisciplinary workers as a sound basis for future action to reduce eye injuries in Australia.

The Introduction of an Eye Protection Programme

The implementation of an eye protection programme into a factory is probably one of the biggest challenges a Management faces in its Safety Programme. This is because, firstly, no-one likes wearing eye protection. With prescription spectacles there is an immediate benefit—with them we can see clearly; without them, vision for certain functions is either blurred or symptoms of discomfort may result. However, with piano safety spectacles, there is not an immediate benefit. The benefit only applies when an eye injury Is prevented. Secondly, supervisors and shop stewards will face a multitude of questions, complaints and reasons why eye protection should not be worn. These questions will need to be dealt with quickly and 1competently and, as we proceed, the need for professional assistance will be obvious. The eye protection programme should be an integral part of the general Safety programme. However, as it is more sophisticated than most other segments of the general programme, e.g., the hard hat, safety shoes or gloves programmes, it is better to leave it until later in the programme when the whole company is more safely orientated in their thinking. Frequently In commencing a safety programme one may be tempted to rush in and provide the whole work force with eye protection; this way, everyone can see that ‘something’ is being done towards safety. However, experience has proven it is much better to wait until the general programme is well established. There are two methods of equipping employees with eye protection. The first is to purchase a quantity of multifit pianos, place them in the general store and then hope employees will requisition them from the store and wear them. Naturally, this idea seldom works. Employees don't wear spectacles and if complaints arise, little reliable information is available to deal with them. The second method Is to implement a comprehensive eye protection programme.

Maintenance of an Eye Protection Programme

The implementing and maintaining of an Eye Protection Programme requires particular attention to those factors which have critical influence on the outcome of the programme. The personal and specialised nature of the programme needs the Initial and continuing involvement of services competent to handle procedures and problems. The major factor concerns the necessity to incorporate the wearing of plano safety spectacles in “eye hazardous” areas as a condition of employment. When a programme is soundly based and gives proper, fair and due regard to the personal requirements of individual employees, union ‘concurrence is certain to be forthcoming. Provision must be made for maintaining the programme in all respects viz: the repair, replacement and issue of eye protectors, continuing sight screening pre-employment procedures, scheduled examination of employees in certain specified operations, the continuing requirements of prescription eye-wear. The standard of discipline in the plant environment is another governing factor. Although the floor supervisor has the direct responsibility all levels of management are involved and have significant effect on the programme. A programme which is implemented and maintained according to the outlined planning and procedures will, with certainty, eliminate serious eye injuries.