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The influence of dry eye and office
environment on visual functioning
Mirjam VAN TILBORG a 1 ,Prof. Helianthe KORT a
Prof. Paul MURPHY b, Dr.Katharine EVANS c
a
University of Applied Sciences HU, research group Demand driven care
b University of Waterloo Optometry and Visual Sciences
cSchool of Optometry & Vision Sciences, Cardiff University
a
Abstract. Environmental factors, such as high airflow and low relative humidity,
are known to promote dry eye symptoms during reading tasks in office workers.
These symptoms are associated with an adverse impact on daily activities at work.
This study reports on the relationship between eye symptoms and environmental
factors in 294 employees at one office location.
Keywords. Humidity, indoor temperature, digital environment
Introduction
Dry eye, a disease of the tears and ocular surface, is characterised by tear film
hyperosmolarity and ocular surface inflammation. The prevalence of Dry Eye Disease
(DED) in the general population varies between 3.5 to 33.7%, depending on age and
diagnostic criteria [1]. The two main aetiologies of DED are insufficient tear
production or excessive tear evaporation. For the office worker, changes in their
environment that promote tear evaporation are therefore problematic Both causes are
typically treated with artificial tears, and although other treatment modalities are
equally or more effective, preventing the development of symptoms is preferable.
Typically referred to as an age-related disease, recent studies show that younger
persons also frequently suffer from DED [2]-[6].
As noted, the environment has an influence on the DED cascade. Environmental
factors, such as high airflow and low relative humidity, can exacerbate the condition,
promoting symptoms such as burning or tearing of the eyes. Symptoms of DED are
associated with an adverse impact on vision-related quality of life, the performance of
daily activities, the ability to work, and emotional well-being [7], [8], even for
mild/moderate dry eye [9].
1 Corresponding Author.
In the published literature, work-related dry eye symptoms often fall under the
diagnosis of Sick Building Syndrome (SBS), which includes a group of symptoms of
unclear aetiology. The group is divided into mucous membrane symptoms related to
the eyes, nose and throat, and dry skin and general symptoms of headache and lethargy
[10]. The term Sick Building Syndrome is only used when the symptoms relate to the
building site and which disappear after leaving the building [10]-[12].
For the eye, work-related dry eye symptoms that develop are similar to those of
age-related dry eye: burning, dryness, gritty, itchy and stinging sensation, soreness,
blurry vision, strain and eye irritation or asthenopia. These all affect the quality of
visual functioning, with the most common complaint being blurred vision. For the
symptoms to be diagnosed as being work-related, they need to be associated with a
work-related indoor environment [13]. For example, significant complaints can occur
even after only two hours of computer work [14]. The figure below shows the main
factors thought to influence dry eye symptoms in a work environment.
Modern offices often incorporate flexible working spaces and high visual demands
from computer screen presenting digital information. The environmental management
for these workspaces modifies air humidity, temperature and air flow, all of which are
known to exacerbate dry eye symptoms and visual functioning during computer tasks
[15] [16], [17].
Dry eye symptoms are a disorder that reduces visual functioning. Visual
functioning is related to the ability of an individual to perform visual dependent tasks,
such as reading and computer work, driving or watching television or using the more
intense video games [18], [19]. Significantly increased symptoms of blurred vision
during reading occur when reading from a computer screen vs reading from a hard
copy [20].
1. Objectives
1.1 Goal
By monitoring subject symptomatology and environmental variables, investigate
their relationship in a cohort of digital information workers within an indoor working
environment.
1.2 Project plan
Recruit subjects from employees working in a modern office building located in
the Netherlands, in which there was a high incidence of dry eye related complaints
reported over several years. Assess subject symptomatology using two comfort
measurements, in combination with environmental metrics for room temperature, air
quality and lighting.
2. Methods
A digital online survey was sent to all employees (n=600) who work in the test
building by email. The survey contained 16 forced-choice Likert scale questions
covering patient demographics, dry eye symptoms, and incidence of DED diagnosis.
Participants could complete the survey within a four-week period: from 16 October
2014 to 14 November 2014. Two environment measurement stands were placed at the
south corner of the building on the second floor from 26 November 2014 to 15
December 2014. The instruments at these locations measured temperature (supplied air,
air temperature, radiation temperature), air quality (CO2, relative humidity (RH),
airflow speed, particle counter), and light (radiation) every hour.
3.Results
(i) Symptomatology
The survey was completed by 294 subjects (49% response rate), with 30%
reporting complaints of dry eye symptoms. Of these, 5% were already diagnosed with
DED. The average age was 42.5 years. Blurry vision, transient vision and irritation of
the eyes were the highest ranked symptoms. The question “Are the symptoms that you
experience inhibiting you in your daily activities at work?” was positively answer by
75% of the employees.
(ii) Environmental
During the recording period, the overall indoor air quality was acceptable,
conforming to the Dutch Build Code Guidelines, the Working Conditions Act (ARBO
wet), and the Ministry of Infrastructure and Environment Guidelines. The RH
measurements were low, but within acceptable limits, and fluctuation during the day
was related to indoor temperature. Greater fluctuation in temperature, humidity and
airflow were seen with outdoor sunshine. A rise in temperature from 5°C to 25°C
produced a drop in humidity from 40% to 22%.
4. Discussion
A considerable proportion of employees were diagnosed with having DED
symptoms. The average age of the employees did not reflect the typical age at which
dry eye symptoms can occur. The test building was found to have low relative humidity
and an air flow effect, which, in combination with high levels of visually-demanding
tasks, such as computer, laptop and smart phone use, stimulated the development of dry
eye sensation in a large proportion of workers. The environmental effects were
accentuated by the south facing aspect of the building promoting an increase in
building temperature from solar heat, with a subsequent increase in airflow rate to
maintain building temperature. This increased airflow further stimulated tear film
changes and worker dry eye discomfort in the office.
5. Conclusions
The study location building air environment had a high impact on eye symptoms,
leading to inhibition in daily work activities. Sunshine further stressed the indoor air
quality and the indoor comfort. Adjustments are needed to create a comfortable indoor
environment for all weather conditions outside, to minimise the development of dry eye
symptoms in workers and good visual functioning.
Acknowledgements
Special thanks to Giel Craenmehr and dr.ir. Marcel Loomans, Technical University
of Eindhoven, for their expertise and measurements.
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