Why You Need Eye-Protectors

Potential ocular hazards, such as flying particles and chemical splashes, should be eliminated or controlled at source. However, if this is not possible, the appropriate type of eye-protection must be provided and worn.
Screens or fixed shields can be used alone or in addition to eye-protectors to guard against potential hazards. People are now becoming more aware of the need to protect their eyes and eye-protectors should not only be provided to fulfill legal obligations at work but also for the many other leisure activities, such as DIY, ski-ing, squash, and ice hockey.

Ideally, an eye-protector must be:

• Constructed to provide the necessary protection against the hazard for which it is designed, e.g. flying particles or radiation;
• Comfortable during wear and not liable to steam up;
• Light-weight and not interfere with movement;
• Compatible with other protective devices, such as ear and respiratory protective equipment;
• Constructed so that it does not impair visual function;
• Durable, non-flammable and non-irritant to the skin;
• Readily replaced at reasonable cost;
• Easily cleansed;
• Of suitable optical quality;
• Cosmetically acceptable.

Eye-protectors may be in the form of spectacles, goggles (cup or box), screens or visor supported by a headband, or in the form of a helmet.

The main advantage of spectacle eye-protectors is that they can be made to fit well, as there is a range of sizes available. Spectacles are not suitable impact protection such as dusts, molten metal or liquid droplets or splashes.

Afocal one piece eye-protector is usually molded in one piece from polycarbonate. This type of protector has the advantage that the lenses cannot be dislodged, as may occur with a spectacle frame. They are suitable for emmetropes, but are usually manufactured in only one size. As the fit required is different for each person, they do not always fit well.

If not fitted correctly, eye-protectors will not provide the necessary protection and eye injury may still occur. Prescription eye-protectors are normally fitted by optometric practitioner or dispensing optician and should be adjusted carefully on collection. It is most unfortunate that afocal eye-protectors are often handed out by safety officers, who do not have the necessary training or the facilities to fit them.

Afocal eye-protectors are often disliked by employees who do not normally wear spectacles and are therefore worn very reluctantly. The employees' complaints can be listed as follows:

1. Restricted field of view, due to the frame.
2. Magnification effect. Afocal lenses can give a small magnification, caused by the shape of the lenses (base curve).
3. Reflections from i.e. the lens surfaces give rise to unwanted ghost images.

Peripheral displacement effects of afocal lenses increase with centre thickness, base curve and angle of ocular rotation. The vertical displacement effect induced on ocular rotation is only a problem if the lenses of a pair have different base curves.

Goggles (cup type) may be used to provide protection against molten metal, flying particles, dust, etc. A good tight fit to the face is required.

Face shields are usually headband-supported visors that cover the face and neck. They are used to provide protection from flying particles, molten metal and chemical splashes and can easily be worn over prescription spectacles or other types of eye-protection, if required. They provide an excellent field of view. The face shield is generally made from either polycarbonate or cellulose acetate. They can also be made so that they can be hand-held, e.g. the arc welding screens, which have a filter as the ocular (i.e. a tinted window). Face shields are also to provide protection in occupations such as motor cycling, cricket and the security industry.

Helmets on the other hand are commonly worn during welding. They provide protection of the face and neck from intense radiation and spatter. There is an ocular containing a filter to prevent harmful radiation from reaching the eyes. The filter may be designed so that it can be flipped up to expose a clear, impact resistant lens, which can be used for grinding and chipping operations. There are some superior variations of this appliance where the window is fitted with a polarizing cell, which darkens to welding density as soon as the arc is struck. These appliances usually have their own air supply, as the gases from welding rods are toxic.

Various types of eye-protectors can offer protection against different types of ocular hazards and it is essential that the hazards are correctly identified so that the appropriate eye-protector can be supplied.