Contact lenses are thin discs made of transparent material that are shaped to correct vision. There is debate around wearing contact lenses at work due to risks like dust, chemicals, gases or vapors getting trapped behind lenses and irritating or damaging the cornea. Contact lenses are not meant as protective equipment and should not replace proper personal protective equipment if required. The risks of wearing contact lenses depend on the work environment and factors like chemicals, heat, dust, vapors, and whether adequate hygiene and eye protection are available. Contact lenses may not be advisable in certain settings like welding due to risk of irritation.

1. Contact Lenses and Work

2. What are contact lenses?
 Contact lenses are small, thin discs made of a transparent material.
 The outer surfaces are custom-shaped to correct or improve vision and the
inner side is carefully formed to fit the surface of the cornea (the clear, front
covering of the eye including the iris and pupil).
 Today, the lenses are typically soft (flexible) but hard (rigid) are still available.

3. What is the controversy about wearing contact
lenses at work?
 Dusts or chemicals can be trapped behind the lens and cause irritation or
damage to the cornea or both.
 Gases and vapours can cause irritation and excessive eye watering.
 Chemical splash may be more injurious when contact lenses are worn. This
increased risk is related to the removal of the lenses. If removal is delayed, first
aid treatment may not be as effective and, in turn, the eye's exposure time to the
chemical may be increased.

4.  The critical point to remember is that contact lenses are not intended to be used
as protective devices
 They are not a substitute for personal protective equipment (PPE)
 If eye and face protection is required for certain work operations then all workers,
including contact lens wearers, should wear the proper protective devices.
 Safe work conditions for all workers are only possible when basic occupational
health and safety practices and procedures are followed.

5. Are there situations where it may be
hazardous to wear contact lenses?
 Soft lenses are made from a type of plastic that contains a large proportion of
water.
 The soft lense adheres more tightly to the cornea and does not have as much
fluid motion as the hard contact lens.
 For these reasons, some researchers think the soft lens offers some, but not
total, protection against entrapment of foreign substances between the contact
lens and the cornea.

6.  The major risks for soft contact lens wearers are from chemical splashes and from
hot, dry environments. Because of the high water content of the soft contact lens,
some chemicals can pass through the lens and be held against the cornea by the
lens itself.
 Hot, dry environments can lead to problems because they can cause the tear layer
(upon which the lens 'sits') to dehydrate. This situation results in eye discomfort.

7. What are some other possible concerns when
wearing contact lenses?
 The concern about the use of contact lenses with respirators or personal
protective hoods arose because it was believed that dislodgement or sudden
loss of a contact lens while wearing a respirator could lead to two potential
problems.
 First, it is impossible to adjust or replace a contact lens while wearing such
equipment in a hazardous environment. Secondly, the dislodged contact lens
could become trapped in a part of the equipment that prevents its proper
functioning.

8. Can you wear contact lenses when welding?
 The CSA(CANADIAN STD ASSOCIATION) Standard W117.2-12 states that contact
lenses should not be worn by welders and welding personnel because foreign
bodies in the eye can cause excessive irritation.
 Contact lenses do not provide protection from ultraviolet radiation and flying
objects. Welders must wear appropriate eye protection according to the
circumstances.

9.  Reports of contact lenses being "welded" to the cornea (or lens of the eye) as a
result of exposure to an arc flash have been proven to be incorrect. It is impossible
for contact lenses to become "welded" to the cornea.
 Note that in Canada, Prince Edward Island's Occupational Health and Safety Act
Regulations (E.C. 180/87) Section 45.11 specifically bans wearing contact lenses
while welding.

10. Your Role…
 To determine whether contact lenses are advisable in a specific environment,
consider the effect of the various risk factors both on the eye and in the
individual who is not wearing contact lenses.
 Once you determine this, you can evaluate the risk using the known physical
parameters and physiological effects of the contact lens.

11.  There may or may not be laboratory studies, epidemiological data or well
documented case reports to support or refute your theoretical conclusions. An
extensively referenced review of contact lens use in a large range of environments
is available
 Some particular factors to consider: any toxic physical or chemical agent, any
mechanical hazards, raw materials and byproducts, potential for exposure,
protective equipment (provided/available/ worn) and other protective measures.
 Also, consider hygiene facilities, health personnel on staff and factors that affect
compliance.

12. Additional Risks
 Barometric pressure. Extremes of barometric pressure occur at high altitudes and
under water. Bubble formation occurs in haptic lenses at altitudes greater than
5,400m (more than 17,000 feet).
 Corneal thickening response with soft lenses increases with altitude. Bubbles
may also form under gas permeable and soft lenses during decompression from
hyperbaric exposure.
 Even so, contact lenses have been safely used for various high altitude and
underwater activities. One precaution: A potential microbial hazard from
Pseudomonas aeruginosa has been reported in pressure chambers.

13.  Vibration stress. This may be encountered while operating machinery, such as
pneumatic drills or chain saws, or while travelling in or on modes of
ranging from low-capacity motorcycles to aerospace vehicles. Visual acuity is
impaired at vibration between 6 and 8Hz. This effect occurs with spectacles,
contact lenses and the naked eye. Soft lenses are not dislodged regardless of
vibration level.

14.  Acceleration stress. We might expect high G forces to cause a contact lens to
dislodge from the cornea. However, contact lenses are not displaced by more
a few millimeters under high acceleration forces. Indeed, combat pilots have
contact lenses when exposed to forces up to +12G. Zero gravity of space flight
has little negative effect on the cornea-contact lens relationship

15.  Humidity. The optimum range for comfort is 40% to 60%. Ambient temperature
and humidity have not been found to be important factors for contact lens
wearers, except for those wearing very thin high-water-content lenses. Wear of
such lenses in very dry condition (i.e., low humidity) can result in slight corneal
desiccation or aggravation of an existing dry eye conditions.

16.  Wind. Wind can be expected to have two effects in the eye: drying and stimulation
of tearing. So, whether an individual worker in these and similar occupations can
safely and comfortably wear contact lenses can only be evaluated by trial.

17.  Computers. The computer user who wears contact lenses has fewer surface
reflections and perhaps fewer aberrations than spectacle lens wearers. These
advantages are offset by several potential disadvantages. Myopic wearers require
a presbyopic addition earlier. Low levels of astigmatism may contribute to video
display terminal (VDT) user discomfort. Also, computer tasks requiring
concentration may reduce the blink rate, which in turn reduces lens movement
and increases drying effects.

18.  Commercial office buildings. In offices in which poor air quality contributes to so-
called sick building syndrome, we can anticipate that factors such as temperature,
relative humidity, air movement, CO2 levels, and airborne pollutants could
adversely affect contact lens wear in a variety of ways.

19.  Military. Some occupations do not allow an individual to adhere to wearing
schedules or lens care protocols. There may also be a lack of hygiene facilities and
an increased level of chemical, mechanical, physical, microbial and biological
hazards. This became apparent to the U.S. military during various deployments
since the 1990s.

20.  Recent events and reports have revealed non-compliance with USCENTCOM FHP
(United States Central Command Force Health Protection) policy. According to
USCENTCOM, due to the risks associated the lack of adequate hygiene, dust and
dirt, of the deployed environment, lens wearers have experienced documented
eye infection, damage, and loss of combat capability

21. THANK YOU