Prevalence of dry eye disease among visual display terminal office users in Uyo, Nigeria

Context: Dry eye disease (DED) results from loss of tear film homeostasis. Increase use of visual display terminals (VDT) by individuals and professionals increases the risk of DED. Objective: This study is aimed to determine the prevalence of dry eye disease among office workers who use visual display terminals in Uyo. Methods: A descriptive, cross-sectional study of VDT office workers aged 19-65 years. Multi-stage sampling technique was used to recruit participants. Self-administered Impact of Dry Eye on Everyday Life (IDEEL) questionnaire and ocular examination was done to gather data; such data was analyzed using SPSS version 22.0 Results: Prevalence of dry eye disease (DED) was 5.8% (95% CI 3.44 - 8.16). Mean Schirmer’s 1 was 21.60 ± 9.29mm, mean TBUT was 9.74 ± 2.48s, mean IDEEL score was 76.15 ± 25.47. There was a statistically significant association between DED and educational level 7.56(p-value 0.02), hours of visual display terminal use per day 10.72(p-value 0.013), and use of air conditioning 7.66(p-value 0.006). Multivariate regression analysis to identify predictors of dry eye was statistically significant for module 1(Symptom bother) of the dry eye questionnaire (p-value 0.01, odds ratio 12.71,), tear break up time in the left eye (p-value 0.00, odds ratio 38.67), and Schirmer 1 test in the right eye (p-value 0.00, odds ratio 30.83)`. Conclusion: The prevalence of DED increases with the number of hours spent on VDT Periodic medical and psychological evaluation of VDT users to identify office workers most at risk should be carried out by employers of labour.


Introduction
Tear makes up an important part of the ocular surface.It aids in lubrication of the cornea and conjunctiva to provide ocular surface comfort and provide oxygen to the superficial layers of the cornea.Together with the cornea, it makes up the major refractive surface of the eye and provides both mechanical and humoral protection to the 1,2 eye.The cornea, conjunctiva, lids, tear forming glands and the nerves connecting them make up the 3 lacrimal functional unit (LFU).The lacrimal functional unit is important in tear secretion and 3 maintenance of normal ocular surface homeostasis.Disruption of the normal homeostasis is what causes 1 Dry Eye Disease (ED).An unstable tear film is unable to maintain the normal functioning of the ocular surface leading to a cycle of ocular surface inflammation with resulting pain.Dry eye disease is a multifactorial disease of the tears and ocular surface resulting in symptoms of visual disturbance, ocular discomfort, tear film instability with potential damage to the ocular surface.It is associated with hyperosmolarity of the tear film and sub-acute inflammation of the ocular 4 surface (DEWS Ocul Surf 2007) .Any of the structures including the cornea, conjunctiva, the main or accessory lacrimal glands or the meibomian glands may be affected in dry eye disease.Dry Eye Disease (DED) is classified broadly into two main groups, the aqueous deficient dry eye disease and the evaporative dry eye disease.This classification is not mutually exclusive, since dry eye disease is chronic and no matter the etiological factor, features of both reduced tear quality and quantity may be 1 seen.Visual display terminal (computer display) is a computer output surface and a projecting mechanism that shows texts and images to the computer user and includes the screen and the Society's Dry Eye Workshop (TFOS DEWS II) on population studies reported a world-wide prevalence of 5-50% based on symptoms with or without signs but when only signs were taken into account, the prevalence went up to 75%.Females were noted to have a higher prevalence of dry eye disease than males and this was said to increase with each passing decade.East Asians were also reported to have a higher prevalence compared to the rest of ).Permission letters were written to the management of various offices in the city.Written informed consent was obtained from all the participants and the study adhered to the Helsinki Declaration on studies involving human subjects.

Results
A total of 377 participants who met the inclusion criteria participated in the study.The response rate was 100% and total number of eyes examined was  1 shows that of the 377 participants, 136(36.1%)were male and 241(63.9%)were female, giving a male to female ratio of 1:1.8 (Table 1).Most participants had tertiary (n=180; 47.7%) and post graduate education (n= 109; 28.9%).Most study participants had normal TBUT (n=458; 60.7%).The mean TBUT for all eyes was 9.74±2.5s.Most of the participants were married (n= 277; 73.5%), while divorced persons (n=3; 0.8%) made up the least number.Table 1 also shows that most people had worked at their current employment for at least 10 years (201; 53.3%) while the least number (n=25;6.6%) of persons had worked for over 30 years.Table 1 also shows that most participants had used visual display terminals (VDT) for at least 20 years (n=360; 95.5%).Regarding the number of hours spent per day using VDT, most participants spent 4 hours or less per day (n=190; 50.4%); this is closely followed by persons who spent more than 4 hours a day using the VDT (n=187; 49.6%).Most of the participants (n=218;57.8%)did not use airconditioners in their offices.Table 2 shows the average relative humidity and temperature during the study period.The indoor relative humidity and temperature was based on the room allocated to the research team.December 2019 had recorded the lowest values with an average relative humidity indoors of 56.4 ± 1.2%, indoor temperature of 26.5 ± 3.10C and 60 ± 1.4% relative humidity and 27.1 ± 2.60C outdoors.Indoor and outdoor average temperatures were the same in January and February 2020.There was a statistically significant difference (F-ratio 616.6; p-value 0.00) between outdoor temperature in December (27.1 ± 2.60C), January and February (31.0 ± 1.80C).There was also a statistically significant difference (Fratio 11.9; p-value 0.00) between relative humidity in December (60.0 ± 1.4%), January (78.2 ± 1.6%) disease studies.This result may have been because most of the participants were younger than 50 years, while those in other studies were 50 years 18 or older.Mostafa et al in Egypt even reported that the prevalence of dry eye disease in those 45 years and older was more than those younger than 45 years.There was no statistically significant association between dry eye disease and smoking in this study 30 (p = 0.99), similar to Moss et al in the USA who found no association between dry eye disease and smoking.The probable reason for the result in this study could be because smokers only made up 1.3% (n = 5) of the study population thus making no 31 impact on the study population.However, Lee et al 28 in Indonesia and Bukhari et al in Saudi Arabia found an association between dry eye and smoking.This study found a statistically significant association between dry eye disease and the time spent on the visual display terminal per day (p=0.013).This study used two hours as the minimum accepted amount of time spent per day, 32 and a maximum of over six hours.Kojima et al in Japan found that visual display workers who used visual display terminals for four or more hours had reduced tear meniscus height, significant dry eye 33 disease and visual symptoms.Patil et al in India found that increased duration of computer use was associated with an increased risk of dry eye disease.There was no statistically significant association between duration in years of visual display terminal use and dry eye disease; this was in contrast to 34 Akkaya et al in Turkey who found that increased duration of visual display terminal use was associated with an increased risk of dry eye disease.This may be the case because many Nigerians only began using visual display terminals about two 35 decades ago with the introduction of the internet, while developed countries have been using visual display terminals for a much longer time.

Conclusion
The prevalence of DED increases with the number of hours spent on VDT but has no gender preference.Workers who use visual display terminals (VDTs) for more than 4 hours, had better education and work with air conditioning were found to have a higher risk of dry eye disease.This study did not however show that dry eye disease was associated with the duration of VDT use in years.It is recommended that regular eye healthcare consultations should be enforced by any office or department where there is intense use of VDT.Mandatory periodic medical and psychological evaluation at offices to identify workers most at risk in order to boost productivity by employers is advocated.The use of humidifiers by offices using air conditioning to improve relative humidity, screen glare filters and other ergonomic practices is also advocated.

5 device
that gives information to the screen.These visual display terminals include personal computers 6 (desktops), laptops, tablets and smartphones.Persons who use visual display terminals typically develop evaporative dry eye (EDE) caused by reduced blinking, increased palpebral fissure height which encourages tear evaporation and working in 1 cool dry environments with low relative humidity.The prevalence of Dry Eye Disease according to a meta-analysis by the Tear Film and Ocular Surface 11 1

Figure 2 :
Figure 2: Prevalence of dry eye disease.
six months, those on topical medication, contact lens or oral antihistamines Data collection was done with use of selfadministered IDEEL questionnaire, ocular examination was done during which Schirmer 1 test and tear break up time (TBUT) were performed.Random blood sugar was also carried out.Indoor temperature and relative humidity were measured using a combined digital thermometer and hygrometer.Outdoor temperature and relative humidity readings were taken using online accuweather.com.This was done by checking the temperature and relative humidity of Uyo at this website each day (between 9-11am) samples were taken, then finding the average at the end of every month.Diagnosis of Dry Eye Disease was made by into four parts.A simple random sampling was carried out to select Wellington Bassey and Oron roads.Cluster sampling was done at the next stage.The area between Wellington Bassey way and Oron road was divided into ten clusters.Each cluster containing 30 buildings.Balloting was then used to select four clusters in order to achieve the sample size.Office buildings within the selected clusters with at least three people using computers were recruited and permission was sought.Eligibility criteria included participants who have worked on a visual terminal device for at least six months and at least two hours or more per day and have not used topical medication for at least two months before commencement of the study.Exclusion criteria were persons younger than 18 years or older than 65 years, known diabetic, anyone with gross lid abnormality or have done eye surgery in the last 13 combining the positive test results.DED was d i a g n o s e d b y t h e p r e s e n c e o f I D E E L questionnaire's Module 1 of greater than ≥40, Schirmer 1 test of <10mm, and tear break up time (TBUT) <10s.Respondents with only one or two criteria were classified as normal.Both eyes for each participant were tested.All data generated was entered into a pro-forma and data analysis was