Guidance [Health Devices Apr 1993;22(4):195-204]

To provide readers with insight into how to select and purchase suitable LSE for the surgical environment, we evaluated 48 models of the most popular LSE offered by 11 manufacturers for use with the most widely used surgical laser wavelengths: 10,600 nm (CO₂, invisible), 1,064 nm (Nd:YAG, invisible), and 532 nm (green). However, some surgical lasers (e.g., argon, dye) that are not commonly used for general surgery still require the use of LSE protection, and many of the following considerations apply to LSE designed for these wavelengths as well.

Sorting through the bewildering amount of LSE sales information, information on protective ability, user needs, and other factors can be confusing. Below, we provide an outline of LSE selection, purchasing, and use considerations to help users make informed decisions.

The primary purchasing consideration is the OD determined to provide protection against a specific laser wavelength. In our study, we took a conservative approach to determining potential exposures by using the maximum power for each of the three laser wavelengths used in our study, assuming that the laser energy would be directed at someone's face from no closer than 25 cm (the worst-case exposure). For other wavelengths, the OD must be determined by the hospital's LSO, who should carefully choose LSE that adequately attenuates specific laser energy and reduces any potential exposure below the MPE for that wavelength. (The MPE for a particular wavelength is determined by evaluating the duration of possible exposure and looking up the MPE on charts and tables in ANSI Z136.1.)

Several surgical lasers deliver two or more wavelengths (e.g., a 532/1,064 nm combination) to provide different therapeutic effects. LSE that protects against more than one laser wavelength requires that an OD be determined for each. Multiwavelength LSE can be cost-effective and convenient, eliminating the need to change eyewear when switching wavelengths. Also, if only two or three wavelengths are used in a facility, its use cuts the purchase cost and eliminates confusion over which LSE should be used for what laser. However, depending on the wavelengths, this choice may cause an unneeded loss of color perception or other vision effects (see below).

Given the variety of LSE, choosing the best model for specific situations can be a complicated process. OD for a specific wavelength is easy to calculate, but the assumptions about the exposure situation on which the calculation is based are not always clear. For example, while direct exposure to laser energy during endoscopic procedures is unlikely, endoscopic use of fiber-delivery lasers does present a hazard for long-term exposure. This exposure situation requires LSE with an OD of at least 2 for visible-light (e.g., 532) surgical lasers.

Also, fiber breakage and loss, which produce a highly directional, yet dispersed, beam from the fiber end that can emit energy damaging to the eyes, can occur during use of fiber-delivery lasers. In an OR darkened for video use, the pupil of the eye will be wide, increasing the exposure risk. If the laser operator is quick and aware of the situation, exposure time would be very short before the laser would be shut off. The 0.25 sec blink reflex, triggered by the visible (e.g., 532 [green]) or aiming (e.g., HeNe [red]) laser beam, could be sufficient to prevent eye injury. An ambient energy detector may reduce the risk by shutting off the laser the instant a fiber breaks. The LSO must decide whether scenarios like this warrant increased or decreased protective measures.

Several types of lasers and some endoscopic systems have automatic shutters that are inserted in the viewing optics when the laser is activated to protect the viewer's eyes when LSE cannot be used. Accidental exposure can result if the shutter is not operating properly, and several eye injuries have been reported that were caused by faulty shutter operation. Therefore, shutter systems must be properly maintained and periodically checked for proper operation. As the shutter and laser activation timing are very fast, special instruments are needed to verify proper operation. Some clinicians use a monocular device rather than the shutters or filters in the viewing system. Although this device allows clear vision with one eye while protecting the other, using it poses the risk that the clinician may accidentally use the unprotected eye for viewing through the optics during laser activation.

Protection for windows and doors. Because the NHZ for surgical lasers can be large enough to encompass the entire OR and beyond, precautions are needed to prevent laser energy from exiting the OR through windows or doors. To reduce any transmitted energy to levels below the MPE, the latest draft of ANSI Z136.1, section 4.6.3, requires that laser-blocking barriers, laser safety curtains, and/or laser safety screens be used on windows in rooms where lasers are used. Also, section 4.6.4 recommends using such devices at entrances to rooms where lasers are used to prevent laser energy from exiting the room at levels above the MPE. These devices must withstand diffuse and direct beams based on the potential exposures and should not burn or emit toxic products when exposed to laser energy.

A variety of laser filter media, including laser safety screens and laser safety curtains, laser-absorbing glass and plastics, and laser-blocking barriers, are available. The materials used in these devices are similar in structure and materials to LSE and interact similarly with laser energy. These devices can be small panes of glass or large sheets of material that are rigid or flexible, as well as fixed or movable. Manufacturers of laser filter media can determine the product specifications (e.g., OD, size, shape, cost) based on the hospital's specific situation. In addition to being lasersafe, laser safety screens for use in the OR should be easy to clean and should resist damage from disinfectant solutions. Laser safety screens with multiwavelength protection should be considered if several types of lasers are used.

The specific lasers to be used and the need for windows in the OR should be evaluated. For example, if only CO₂ lasers are used, window coverings are not necessary because glass absorbs energy at the 10,600 nm wavelength. However, it does not absorb significant amounts of the 1,064 nm and 532 nm wavelengths. Thus, use of Nd:YAG and 532 lasers should be restricted to windowless ORs. As an alternative, opaque laser-blocking barriers, such as Masonite, Sheetrock, or venetian blinds, could be used to cover or replace the window glass if these wavelengths are used. If observation is important, the manufacturers listed below can provide laser safety screens to shield OR windows.

A door and external safety measures (e.g., warning signs, available LSE) may not provide adequate protection for personnel entering the area, especially if education about the hazards and adherence to safety procedures has been poor or inadequate. The proposed draft of ANSI Z136.1 requires additional doorway protection. If, on evaluation by the LSO, an exposure risk exists, the risk may be lessened if the operating table and surgical laser can be placed in positions that reduce or eliminate the possibility of emitting laser energy in the direction of the OR entrance. For example, the surgeon may be able to operate with his or her back to the OR door, reducing the likelihood that the laser would be pointed toward the door. If this positioning cannot be accomplished (e.g., because of room layout or patient modesty), use of a laser safety screen, laser safety curtain, or laser-blocking barrier is suggested in the proposed draft of ANSI Z136.1. Such devices should allow easy movement through the entrance for personnel and equipment and, preferably, be transparent to most of the visible spectrum or be positioned to prevent bumping accidents. Because it may be difficult to put effective screening devices in place that do not interfere with OR procedures (e.g., room access), deferring implementation of such measures until the standard is finalized may be a good idea. Consult ECRI's Health Devices Sourcebook for a list of current manufacturers of laser filter media.

Some hospitals use signs that say "YAG Laser in Use. Wear Green Glasses." However, LSE color is not currently an indicator of which model to wear for a specific laser. The evaluated CO₂ LSE came with pink and green, in addition to clear, lenses. The Nd:YAG lenses were mostly green, but we have seen yellow-orange and clear Nd:YAG lenses in our work with lasers. 532 lenses were generally orange, but pink and yellow are also available. Frames cover a wider range of colors than the lenses and do not often correspond to the color of the lens they contain. Thus, someone could choose "Green Glasses" for Nd:YAG surgery, based on the color of either the lens or frame, that are designed to protect against CO₂ or 532 laser energy, not Nd:YAG.

Also, color does not indicate the degree of protection provided. Samples of LSE that were similar in appearance had labeled ODs ranging from 3 to greater than 10. So a green lens specified for use at the outer periphery of the NHZ far from the laser aperture could be mistakenly worn near the inner periphery of the NHZ, placing the wearer at risk. Users should be instructed to check for the OD and wavelength on the LSE by a sign that says, for example, "Nd:YAG Laser in Use. Use Eyewear Marked OD 5 or greater for 1,064 nm."

However, in the future, color could be an indicator of proper protection. The proposed draft of ANSI Z136.1 recommends that a color-coding system be used in multilaser environments. Currently, Surgimedics is the only manufacturer that does have color-coded eyewear; a unique color frame or marking is used for each wavelength with color-coded storage cases and warning signs. However, this is helpful only if a hospital standardizes on Surgimedics LSE. Using other manufacturers' LSE in addition to the Surgimedics products would confuse and complicate selection of the appropriate model. If the industry would agree on a specific color-coding system, similar to the Compressed Gas Association's system for marking gas cylinders, selection errors would be greatly reduced.

The MPE for many lasers of different wavelengths is lower under anesthetized conditions because the eye may be immobilized or the pupil larger than normal, or the blink reflex, which protects the eye from bright light, may be lacking. The surgical staff must ensure that the patient's eyes are adequately protected by some means that will not injure the patient or pose a risk to the staff.

LSE can be used for patient eye protection, especially with conscious patients. Goggles fit closely on the face, providing good peripheral protection all around the eyes (see below). Spectacles and wraps should not be used, as they generally lack peripheral protection along the lower edge and corners, posing a risk to direct eye exposure, especially to a supine patient, who may be exposed from below the eyes. Because the quality of vision during surgery is not a concern for the patient and because exposure risks to the patient may be greater than for the surrounding staff, we recommend use of LSE with an OD higher than that required for the staff.

Other devices and techniques are available for use in place of LSE. Special laser safety extra-ocular shields, also known as laser eye shields or laser eye cups, are useful during head and neck surgery in the vicinity of the patient's eyes when LSE might be in the way. When using eye shields, care must be taken to protect the patient's eyes from other irritation or injury by using ophthalmic lubricating ointments, with judicious use of anesthetic eye drops if the patient is awake or semiconscious, and in limiting the time the shields are in place to prevent oxygen deprivation of the eyes. Shields that heat easily and retain heat may cause thermal eye injury. Wet gauze or sponges taped over the eyes have also been used, but these must be kept wet to prevent accidental ignition of the material by laser energy. An adherent foil mask with padded eye areas is available, but is not recommended because the foil can reflect laser energy, creating other risks (e.g., ignition of drapes), and the adhesive can cause patient discomfort when removed.

The amount of laser energy that lenses can withstand without being damaged while still protecting the wearer is another facet of the protective ability of LSE. When a lens is severely damaged, its OD may no longer attenuate the laser energy it was designed to protect against. In other words, a high OD is good, but meaningless if the LSE is easily physically penetrated at low irradiance levels. Also, an exposure that severely damages LSE may also cause eye or skin injury or ignite other materials, such as cloth and paper.

The damage threshold levels (i.e., the lowest irradiance at which the LSE lens is visibly changed) for most of the LSE lenses we tested were generally far below irradiances that caused severe damage to the eyewear, although LSE with glass lenses had a higher damage tolerance. For most surgical laser systems, our measured LSE lens damage threshold is closer than 25 cm from the laser aperture; thus, an LSE lens would have to be unrealistically close to the laser aperture to be damaged.

Although LSE with glass lenses had a higher damage tolerance than those with plastic lenses, glass lenses tend to crack, sometimes minutes after the exposure, creating the risk of patient or user injury from glass fragments. Most 532 LSE lenses were constructed of orange glass that shattered with mechanical impact or when overexposed to laser energy. Shatterproof plastic 532 LSE should be more widely available. (Schott, the major manufacturer of all types of specialty glass in the United States and Europe, provides glass for many LSE lenses and can provide shatterproof glass.)

Plastic-laminated lenses can reduce this hazard. Some of the evaluated LSE (notably some Uvex models) had plastic attached to the eye side of the lens to protect the wearer from glass fragments. Because glass is typically resistant to laser damage, such LSE would be a good choice if direct exposure is the primary risk. Also, glass is more difficult to scratch than plastic, although some hard plastics provide almost the same degree of scratch resistance. (Plastic lenses are also considerably lighter in weight than glass lenses and are more comfortable to wear. Because comfort is critical to LSE use, this may be an overriding consideration.)

LSE is not necessarily impact safe simply because it meets ANSI Z136.1 requirements. If "ANSI Z87" is marked on the lens, then the lens has met the impact and other safety requirements of that standard. To fully meet Z87, the lens and frame must be tested according to the standard. As noted, plastic laminated to glass helps the lens meet the standard by preventing glass fragments from entering the eye. However, as we saw in our durability tests, quite a few LSE models with glass lenses did break when dropped in an accidental manner; none of the plastic LSE broke when dropped. Impacts directed at the edge of the lens or exacerbated by the frame design can break glass lenses. Therefore, purchasing plastic or impact-resistant glass lens LSE is a wise choice.

Choosing between the three types of LSE—goggles, spectacles, and wraps—depends on both the amount of peripheral protection desired, the FOV, the user's face and head shape, and whether the user is wearing vision-correcting spectacles. Although frontal protection is the most important consideration, peripheral protection is also important, especially to provide protection when the user's face is facing away from the laser and to reduce exposure to diffuse energy, a consideration during long-term laser use.

Purchasers should strongly consider buying LSE that does not unduly restrict FOV (i.e., either peripheral or vertical vision). In the operative setting, FOV is important considering that ORs are often crowded, and bumping an unperceived object or person could cause serious injury to the staff or patient and violate sterile technique. Significantly reduced vision interferes with the work of the surgical staff. When wearing LSE with severely reduced FOV, several of our volunteers bumped into people and objects just outside of their FOV or had difficulty performing routine work functions. Also, the reduced FOV seen with some goggles caused fatigue because the wearer had to hold and move his or her head in unaccustomed ways to allow desired viewing. Unfortunately, with much LSE, increased FOV is obtained by sacrificing peripheral protection.

Face shape is also a factor because some LSE fits better on some face shapes than others. For example, deep-set eyes are protected by facial structure and need less peripheral protection than prominent eyes or eyes that are set in thin, triangular faces, on which LSE can leave significant gaps in protection on the sides and lower edges.

Goggles may provide the best peripheral protection, but often sacrifice FOV and comfort. Spectacles without side shields provide inadequate peripheral protection; for spectacles with side shields, peripheral protection and FOV depend on the design of the LSE and how it fits on the face. Wraps can provide adequate peripheral protection, although not as good as that provided by goggles; they are also comfortable and provide good FOV.

LSE that is uncomfortable or ill fitting will not be worn. Most laser eye injuries occur because users are not wearing LSE. An examination of the present collection of LSE in a hospital would likely reveal that the most comfortable models are the ones that are most frequently used. Users should be consulted about LSE suitable to their needs so that problems can be uncovered and corrected; they should be able to try a variety of LSE to find the one that fits them best. Adjustable LSE that can conform to particular face shapes increases comfort and compliance, as well as protection. Straps available with some spectacles may help hold eyewear in place when wearing caps and masks or prevent the LSE from falling off the wearer's face.

Before being exposed to laser energy, users should check for proper fit and wear the LSE during a trial period to check for any problems of fit or inadequate ventilation. Antifogging coatings and rub-on solutions, similar to those used with swim goggles, are available from some LSE manufacturers to reduce fogging. Some goggle users may always experience fogging regardless of the model; switching to spectacles or wraps will eliminate this problem.

Many people believe that vision-correcting prescription eyeglasses are laser safe; however, they are not. Some will attenuate CO₂ laser energy, but the frames and lens shape of most eyeglasses do not completely protect the eyes from all direct laser beams or reflected energy. Other laser wavelengths are not attenuated by vision-correcting prescription eyeglasses. Those who use only their prescription eyeglasses during laser surgery are risking an eye injury.

To placate insistent LSOs and to try to meet safety requirements, some people wear LSE spectacles or wraps over their vision-correcting prescription eyeglasses. While these types of LSE offer some protection from direct front exposure, the peripheral protection is never as good as wearing LSE alone, and the combination of LSE and eyeglasses is ill fitting. Goggles are designed to be worn over eyeglasses and provide frontal protection and good peripheral protection, albeit with some discomfort.

Some users who need vision-correcting prescription eyeglasses may not be comfortable using goggles over the eyeglasses or may experience fogging. These users may require vision-correcting prescription LSE (i.e., LSPE), available from most LSE manufacturers, or they can wear contact lenses with appropriate spectacles or wraps. Using LSPE that provides laser protection, good fit and comfort, and proper vision is a good solution. Also, FDA requires that LSPE meet the ANSI Z80 and Z87 standards, which define impact resistance. LSPE that meets Z80 and Z87 will be so marked on the lens and the frame. LSPE is not recommended for routine, nonlaser use because of its effects on vision or its susceptibility to loss of protective ability.

Another consideration is whether, or how, LSE alters color perception. Clinicians need to be able to properly evaluate patients and interpret equipment information. LSE that alters color perception very little is the best choice because it does not interfere with patient observations (e.g., cyanosis), anatomical structure identification (e.g., veins versus arteries), or monitor reading (e.g., red warning lights). Although CO₂ lenses, which are often clear, do not usually affect color perception, some clinicians may prefer dark lenses to reduce the white light produced when tissue is vaporized.

Some Nd:YAG and 532 lenses alter the colors seen on color computer monitors and significantly dim the green of monochrome monitors. Tinted or colored lenses in LSE not only significantly alter the wearer's perception of true colors, but may induce the wearer to remove them at hazardous times. Display lights may need to be set to maximum or otherwise adjusted to compensate for the darkening or reduced luminous transmission caused by LSE use.

The Nd:YAG LSE we evaluated all had some tinting that altered color perception. Clear or slightly tinted Nd:YAG LSE should be more commonly available. The orange glass of which most 532 LSE lenses were constructed significantly altered color perception while they were being worn and, in some cases, for some time after being removed (some of our volunteers experienced a yellow tint in their vision for 5 min or so after removing the LSE). True color perception on 532 LSE may not be practical until technology improves.

Knowing beforehand how the LSE will affect color perception (e.g., by observing monitors to ensure that all displayed information can be seen through the LSE) can allow the clinician to compensate to maintain the standard of care and proper eye protection. Some clinicians choose color-balanced lenses, in which the colors are equally altered and usually darkened, over lenses that alter only a particular color.

LSE must be available and worn to protect personnel from laser eye injuries. Also, OSHA refers to the ANSI standards in ruling on laser issues in healthcare facilities and has cited hospitals for using LSE that did not meet these standards. Thus, adequate LSE for all personnel involved with lasers is required, but can be expensive. Management should take steps to ensure personnel safety, protect its investment in LSE, and avoid hospital liability.

As defined in ANSI Z136.1 and Z136.3, all facilities that use surgical lasers should have an LSC (laser safety committee) and an LSO (laser safety officer) who determines the conditions of use of laser and laser-protective equipment, defines laser hazards, and requires safety precautions, including the use of LSE. The LSO's directives should be rigorously followed by all personnel, including surgical and service staff.

Part of the laser safety program should be instruction on the proper care and use of LSE. ECRI recommends, and the proposed ANSI Z136.1, section 4.6.2.7 requires, that the LSE be periodically inspected and cleaned according to the manufacturer's instructions and replaced if necessary. The use of protective storage cases is recommended. Many manufacturers believe that, with proper care, their LSE can last up to 5 yr and that plastic LSE would have a shorter life than glass. As long as "proper care" is adequately defined, this life span is reasonable. Manufacturers should supply inspection, cleaning, and disinfection information. If this information is not provided, users should apply the procedures outlined below in "Inspection and Cleaning of LSE" to each pair of LSE.

Also required in ANSI Z136 are eye examinations to establish baseline eye health and to identify those placed at risk by chronic exposure to laser energy (e.g., users on photosensitizing medications) and after any suspected exposure. The exams are detailed in Z136.1, Appendix E, and include ocular history, visual acuity, color vision, and a detailed examination of the ocular fundus. The baseline exam allows the amount of injury to be determined in the event of an accidental exposure. ECRI recommends that an additional eye exam be made on termination of employment to confirm the absence of injury as a result of laser use while working at the facility. The termination exam is primarily to protect the employer from unwarranted claims after the employee leaves a job.

Because eye exams are expensive, the LSO should determine the necessity and level of examination for the various personnel who deal with lasers. For example, a circulating nurse who is outside the zone of highest irradiance may not need a full examination as described in Z136.1, whereas a clinical engineer who services the laser may.

All laser safety requirements and concerns apply to laser service personnel, as well as to surgical staff. Servicing lasers sometimes requires that normal protective features be bypassed and that beams with high irradiance be exposed, placing service personnel at even greater risk of laser injury than the surgical staff. This makes training, vigilance, and LSE use particularly important. Numerous eye injuries have been suffered by service people because they were not following safe procedures and were not wearing LSE. The LSO should evaluate potential laser exposure under service conditions and define the required protective measures, including laser operation procedures and use of protective equipment. Generally, LSE with at least the same OD required during surgery should be used by service personnel.

In some cases, such as during alignment of visible-wavelength lasers, it may be necessary to use alignment LSE with a lower OD to allow the technician to see the beam. The wearer must be instructed to use only low powers, to not place himself or herself in a dangerous position, and to not allow dangerous reflections from an open optical bench (the apparatus that directs, focuses, and aligns the laser beam). Wearing alignment eyewear is certainly better than wearing no eyewear because it attenuates the beam somewhat and may give some sign that the wearer is being exposed (e.g., a light flash). Also, with outside contractors for laser service, a hold-harmless clause should be part of the service contract to protect the hospital from liability for service-related injuries. An attorney familiar with these types of arrangements should review laser service contracts.

ANSI Z136.1 specifically states that LSE shall be labeled with the OD and wavelength for which the eyewear provides protection, but it does not specify who should do the labeling. It also recommends color coding in multiwavelength environments. This implies that facilities can do their own labeling. For example, some laser manufacturers have provided their customers with unlabeled LSE on delivery of their lasers. This LSE was most likely adequate in all respects except labeling; yet it was cited by OSHA as presenting a safety violation based on ANSI Z136.1 and Z136.3. If the LSE could be verified as having a certain OD, the user could label the LSE with the measured OD and wavelength and thus meet the standard. However, this requires special measuring devices that are available only in a few nonmanufacturer laboratories. Also, the liability for injuries sustained while using nonmanufacturer-labeled LSE may be shifted to the labeler. We therefore recommend against hospital labeling of eyewear when OD information is not provided by the suppliers.

The cost of LSE varies from about $20 to over $380. CO₂ LSE is typically the least expensive, around $100; Nd:YAG and 532 LSE is mid-range, about $250; and multiwavelength models are the most expensive, around $350. Multiwavelength models may be cost-effective considering the number of users and lasers. Glass lenses are heavier, more damage resistant, and more expensive. Prescription vision-correcting LSE can double the cost of standard LSE, depending on the type of lens required.

• Ensure that the LSE is clearly labeled for the intended use.
• Examine the LSE for signs of laser or mechanical damage that could compromise laser protection (see below).
• Ensure that the LSE fits comfortably and securely on the head and face.

Cleaning and Disinfection:

• Clean LSE with a mild soap and warm-water solution. Avoid using materials that may scratch or chemically attack the lenses (e.g., abrasives, strong solvents) or leave films on the LSE.
• Once gross soil has been removed, disinfect the LSE. Note that isopropyl alcohol (which is found in many antifogging and cleaning solutions) and other disinfectants may damage some LSE, including removal of identifying information. Check with the LSE manufacturer to determine whether alcohol can be used on its LSE.
• Optional: Once clean and dry, apply an antifogging solution to the LSE.

Inspection:

• After cleaning, examine the LSE lenses and frames for signs of damage, including discoloration, melted areas, pits, or cracks.
• Discard and replace LSE that has damaged lenses or side shields. If questionable, the LSO should determine the LSE's acceptability.
• Damage may indicate that the wearer may not have followed laser safety procedures. In this case, institute training or other corrective measures. Scratched or hazy areas on the lenses may hinder viewing and suggest that the LSE has been improperly cleaned or stored.
• Ensure that labeling is intact and clearly readable.
• Check the LSE for mechanical integrity. The lenses should be secure in the frames. Straps should be unfrayed. Strap-adjusting mechanisms should be easy to adjust, but should hold the strap securely. Frames should be pliable if worn against the face and be free of rough areas, holes, tears, cracks, or similar damage. Hard frames and temples should be free of rough areas and cracks. Both pliable and hard frames should be free of bent or distorted areas. Temples should move properly, but should be securely attached to the lens frame. Check for damage that may allow unfiltered energy to be transmitted through protected areas; white light visible through these areas may indicate a problem. If any problems with the LSE are identified, the LSO should determine its acceptability.

Storage:

• Store LSE in its original container or in another device that will protect it from mechanical damage or excess light. It should be stored at normal indoor ambient conditions (e.g., about 72° F and 60% relative humidity). Long exposure to light, especially sunlight, can degrade some absorber materials and plastics. Also, high or low temperatures (e.g., from autoclaving or freezing) can damage plastics.

All of the LSE we evaluated had some drawback to its use in the surgical setting; we found that many models were uncomfortable, offered poor peripheral protection, affected color perception, were hard to clean, or were easily scratched or broken. The ideal LSE design would eliminate or mitigate these drawbacks.

Discomfort is related to LSE weight, ventilation, and how the LSE fits on the head. With plastic technology, weight can be reduced. Because heated air rises, airflow through LSE should allow easy upward inflow and outflow of air. Exhaled air should not cause fogging of the lenses or discomfort to the eyes. Ergonomics can be used to define head shape and improve ventilation and comfort and can also help to define the best peripheral protection, accounting for surgical garb.

Clear lenses are needed to enable clinicians to properly evaluate patients and read monitoring instruments. Some clear lenses exist for traditionally colored LSE (e.g., Nd:YAG); the chemistry and laser physics involved in these lenses should be more widely studied and put to use.

LSE should have smooth designs that have no nooks, pockets, open foam, or other areas that are difficult to clean when soiled. LSE should also be compatible with medical cleaning and disinfecting solutions and methods. Hard, tough materials that resist being scratched or broken exist and should be used in an ideal LSE. LSE manufacturers can improve on the present designs.

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UMDNS Term

Eyewear, Safety, Laser [17-650]