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The information about dry eye epidemiology in Saudi Arabia is few in literature.
To estimate the prevalence and identify determinants of dry eye symptoms (DES) in Al-Ahsa, Saudi Arabia.
Using a multi-stage proportionate sampling technique, Saudis of both genders from 6 urban and 4 rural Primary Health Care centers in Al-Ahsa were enrolled. They were interviewed to gather data on sociodemography, symptoms of dry eye, factors potentially related to dry eye, and chronic comorbidities. If one or more of DESs present often or constantly, we labeled the person with DES.
We examined 1858 Saudi adults with mean age of 39.3 ± 14.1 years. The age-adjusted prevalence of DES was 32.1% (95% confidence interval [CI] = 30.0–34.3). Multivariate logistic regression analysis showed that female gender (adjusted odds ratio [aOR] = 2.1, 95% CI = 1.7–2.6), older age (>56 years; aOR = 1.5, 95% CI = 1.0–2.1), current smoking (aOR = 1.4, 95% CI = 1.1–1.8) and history of diabetes mellitus (aOR = 1.5, 95% CI = 1.2–2.0) were significantly associated with DES. Nonsignificant variables included residence (urban/rural); work status; wearing contact lenses; multivitamin use; caffeine use; history of trachoma, hypertension, bronchial asthma, coronary artery disease, thyroid disease, arthritis, hemolytic blood diseases (sickle cell-thalassemia), gout, and osteoporosis.
DES are highly prevalent among the adult population of Al-Ahsa. Females, persons more than 55 years of age, smokers and diabetics were associated to DES.
“Dry eye is multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface.” In spite of the fact that this condition rarely leads to loss of vision, it may reduce the quality of life when its symptoms occur.
Dry eye is a common ocular condition and a major reason for visits to ophthalmologists. Its prevalence varies widely among epidemiological studies depending on how the disease is defined and diagnosed, and which population is surveyed. It is estimated to be 7.4%–33.7%.[2,3,4] Definitions of the dry eye based on symptoms have been often used to define dry eye prevalence in population-based studies because they are more repeatable and reliable than the objective clinical tests in identifying dry eyes. The validated six-item questionnaire of ocular symptoms related to dry eye[6,7] is a widely used effective tool to assess the presence of dry eye.
Some environmental and epidemiological risk factors are thought to put Al-Ahsa population at a great risk for dry eye. As in most of Saudi regions, Al-Ahsa has a hot desert climate with a temperature reaching more than 50°C in the summer months. To cope with this, almost all of its population use air-conditioning at their homes and cars. Trachoma was endemic in this district of Saudi Arabia with a prevalence of 100% in 1955–1970 surveys.
The aim of this study was to evaluate the prevalence and identify risk factors related to dry eye symptoms (DESs) in Al-Ahsa, Saudi Arabia.
This population-based cross-sectional study was carried out between May and August 2016 in Al-Ahsa Governorate, Eastern Province of Saudi Arabia; located about 60 km from the coast of the Arabian Gulf, 350 km from the capital Riyadh, and populated by about 1.1 million, composed of three main regions; urban, populated by around 60% of the total population, rural (43 villages representing 35% of the population) and “Hegar” or Bedouin scattered communities making up the remaining 5%. The Ministry of Health provides primary care in Al-Ahsa through 54 Primary Health Care (PHC) Centers.
Epi-Info™ version 7.2 was used to calculate the required sample size. According to 2010 Census by General Authority for Statistics in the Kingdom of Saudi Arabia, Al-Ahsa population >16 years old is 787,506. Assuming a prevalence of DESs of 27.5% and the worst acceptable prevalence of 25.0%, applying a margin of error of 5% (95% confidence interval [CI]), a minimal sample size of 1224 was required. After adding 20% for potential nonresponse, the final sample size was estimated to be 1469.
An updated list of PHC centers was obtained and a multistage proportionate sampling technique was used. In the first stage, 10 PHC centers were randomly selected from the updated list (six urban and four rural, proportionately; those at Hegar [Bedouin] areas were excluded due to transportation difficulties). In the second stage, with considering a female to male ratio of 1.5:1 among attendees of PHC centers in Al-Ahsa, a suitable sampling fraction was used to estimate the required sample according to male/female and urban/rural distribution.
The form used by the interviewers includes 16 items: Five items for sociodemographic profile, six items about DESs, four items about factors potentially related to dry eye and one item to ask about chronic comorbidities.
The presence of a symptom was further graded as rarely (at least once in 3–4 months), sometimes (once in 2–4 weeks), often (at least once a week), or constantly (all the time).
The initial questionnaire was constructed in English, which was translated into Arabic by an expert, and then back translated into English by another independent expert to assure the validity of constructs to be assessed. This form was tested on random subjects (n = 62) attending two nearby PHC centers beyond the sample size with the following objectives:
Saudis of both genders above age of 15 years attending the previously 10 selected PHC centers were invited to a personal interview. Those with difficulties in communications due to neurological/cognitive conditions were excluded. Trained, Arabic-speaking medical interns interviewed the participants, explained the objectives of the study, and collected data using a pretested questionnaire.
Total forms eligible for final analysis were 1858; those with missing of ≥two items were discarded (n = 71). Data analysis was performed using Statistical Package for the Social Sciences software, version 19.0 (SPSS Inc, Chicago, IL, USA). For categorical data, frequency, proportions, and percentage were used for reporting, and Chi-square test was used for comparisons. For continuous variables, mean and standard deviation were reported, and t-test was used for comparison. The value of P < 0.05 was used to indicate statistical significance. Odds ratio with 95% CI were calculated to study the association between potential risk factors and DESs. Significant variables at the univariate analysis were used to generate adjusted logistic regression analysis.
The presence of one or more of the six dry symptoms often or constantly was considered to be positive. Age-adjusted prevalence was derived using the 2010 population census of Saudi Arabia as the reference standard.
The study protocol was approved by Research Ethics Committee at our institution. Permissions were obtained from the local health authorities. Participants were provided with a full explanation of the study with the emphasis on the right of the subject not to participate. Forms of informed consent were obtained, and data confidentiality was maintained all through.
Table 1 demonstrates sociodemographic profile of the study population and factors possibly related to DESs. The sample was composed of 1858 patients, 892 (48%) were males and 966 (52%) were females. The age was from 16 to 78 years with a mean of 39.3 ± 14.1 years. Urban participants represented 56.8% of the population. Among the participants, 65.1% were working, 15.3% were smokers, 8.3% wore soft or hard contact lenses, 3.8% had a history of trachoma, 19.2% used multivitamin, and 45.3% consumed caffeine almost daily.
Most frequent DES among the study population was grittiness (21.3%), followed by burning (20.9%), redness (17.8%), crusts (14.9%), dryness (13.5%), and stuck shut (11.6%). Figure 1 demonstrates the distribution of each DES by the frequency of participant responses (rarely, sometimes, often, or constantly). Nearly 17.2%, 8.4%, 4.1%, 1.6%, 0.7%, and 0.1% of the participants reported 1, 2, 3, 4, 5, and 6 of the six DESs often or constantly, respectively. The overall prevalence of one or more of the six DESs often or constantly was 32.1% (22.9% among men and 40.6% among women). Age-adjusted prevalence rates to the Saudi 2010 population census was similar.
Sociodemographic characteristics, factors possibly related to dry eye and chronic comorbidities of participants (n = 1858) were explored as potential risk factors for DESs often or constantly [Tables [Tables22 and and3].3]. Multivariate logistic regression analysis showed that female gender (adjusted odds ratio [aOR] = 2.10, 95% CI = 1.71–2.58, P = 0.001), older age (>56 years; aOR = 1.46, 95% CI = 1.03–2.05, P = 0.012), current smoking (aOR = 1.40, 95% CI = 1.06–1.85, P = 0.017), and history of diabetes mellitus (aOR = 1.51, 95% CI = 1.16–1.95, P = 0.001) were associated with significantly higher likelihood for DESs often or constantly. Nonsignificant variables included residence (urban/rural); work status; wearing contact lenses; multivitamin use; caffeine use; and history of trachoma, hypertension, bronchial asthma, coronary artery disease, thyroid disease, arthritis, hemolytic blood diseases (sickle cell-thalassemia), gout, and osteoporosis.
The results of this population based study in Al-Ahsa has found that the age-adjusted prevalence of DESs often or constantly is 32.1% (95% CI = 30.0–34.3) using a validated six-item questionnaire of ocular symptoms related to dry eye. After adjusting for confounders, DESs were found to be significantly associated with older age (≥56 years), female gender, current smoking, and history of diabetes.
Comparisons between population based studies evaluating dry eye prevalence are difficult due to differences in the choice of dry eye questionnaire and objective clinical tests, the definition of dry eye, and selection of study population [Table 4]. The prevalence of dry eye is estimated to be 7.4%–33.7%[2,3,4] depending on how the disease is diagnosed and which population is surveyed. Moreover, the definition of dry eye is still under continual revision, and the lack of a single diagnostic tool challenges ophthalmologists worldwide. The 2007 Report of International Dry Eye Workshop recommended to combine subjective symptoms with objective clinical tests to confirm dry eye diagnosis.
The Salisbury Eye Evaluation study (SEE study) using the same six-item questionnaire to evaluate and define DESs, found 14.6% of participants reported one or more of the six DESs often or constantly. The prevalence decreased to 2% when rose Bengal tests were added. In spite of the fact that the participants of the SEE study were 65 years or older, the prevalence of DESs in our study population 56 years or older were more than twice as high (36.9%). Another population-based study in Taiwan has found that 33.7% of population >65-year-old reported one or more of DESs often or all the time. The prevalence is still higher among the older age participants of our study.
A population-based study conducted in Indonesia using the same validated questionnaire on subjects >21-year-old, found 27.5% of participants reported one or more of the six DESs often or constantly, which is less than the prevalence in our study population. Pterygium and current smoking were independent risk factors identified in that study, and DESs increased with age and male gender. The same association of current smoking and older age with DESs was found in the study; however, we identified female gender as an independent risk factor for DESs. Other epidemiological studies suggest the same relationship between female gender and dry eye.[2,4,19,16]
Possible explanations of higher prevalence of DESs in the study population compared to the previous studies using the same questionnaire are that Saudi Arabia has a hot desert climate with a temperature reaching more than 50°C in the summer months; and as a result, almost all of Saudis use air-conditioning at their homes and cars. Both factors, the climate and air-conditioning, are known to increase the likelihood of having dry eye.[20,21] In addition, trachoma was endemic in Al-Ahsa with a prevalence of 100% in 1955–1970 surveys. This may explain the high prevalence of DESs among participants ≥56 years. However, trachoma was not found to be significantly associated with DESs in the current study. This can be justified by the relatively small number of participants who reported or “knew” that they had this condition, and a larger number is needed to establish a more reliable result. Similarly, thyroid disease is a documented risk factor in studies evaluating dry eye, and no relationship was found in this study perhaps due to a few number of participants who reported this condition.
The Beaver Dam Eye Study suggested several risk factors for dry eye after controlling for age and gender. These factors included current and past smoking; caffeine use; multivitamin use; history of arthritis, thyroid disease, gout, and diabetes. In this study, none of these factors, except current smoking and diabetes, were significantly associated with DESs often or constantly, either in univariate or multivariate analysis.
To the best of our knowledge, this is the first population-based study regarding prevalence and risk factors of DESs in Saudi Arabia. This study used a validated six-item questionnaire to study DESs which has been used in other population-based studies. Trained, Arabic-speaking medical interns interviewed the participants and administered the study questionnaire, a factor that reduced reporting bias.
This study did not combine subjective tools with objective clinical tests to determine the prevalence and risk factors of dry eye in Al-Ahsa. Despite the subjective nature of self-reported symptoms, they are more repeatable and reliable than objective clinical tests in identifying dry eye. Objective clinical studies of dry eye commonly include Schirmer's test, rose bengal staining, tear meniscus height, and tear break-up time; however, these tests lack sensitivity and underestimate dry eye, or sometimes overestimate by giving false positive results, compared with self-reported symptoms.[4,7,14,17,22]
DESs are highly prevalent in Al-Ahsa, Saudi Arabia, as 32.1% of the population are symptomatic. This prevalence is higher than that of the other studies using the same six-item questionnaire of DESs. In this study, female gender, age ≥56 years, current smoking, and history of diabetes mellitus are independent risk factors for DESs often or constantly.
There are no conflicts of interest.