Prevalence and Risk Factors for Symptomatic Dry Eye Disease Based on McMonnies Questionnaire Among Medical Students, Saudi Arabia; a Cross-Sectional Study

Introduction

Dry eye disease (DED) is a disorder of tears and the ocular surface that leads to visual disturbance, symptoms of discomfort, and hyperosmolarity of tear film that results in inflammation and damage to the ocular surface.^1,2 Etiologically, DED is a multifactorial disorder characterized by excessive tear evaporation, decreased tear production, and poor tear quality.³

The affected individuals suffer various symptoms, such as redness, itchiness, burning, irritation, photophobia, dryness, foreign body sensation, and visual disturbances. There is no severe visual impairment or blindness, though DED interferes with daily activities and impacts the vision-related quality of life. In severe cases, there is an increased risk of ocular infection, surface damage, or corneal ulceration.⁴ A recent study documented the negative impact of DED on the productivity of Saudi workers, especially among those having a severe degree of DED.⁵

Dry eye disease is one of the most prevalent ocular diseases worldwide and is a frequently encountered ocular problem in daily ophthalmological practice. The reported prevalence of DED varies from 5% to 50% worldwide.⁶ In Saudi Arabia, according to a recent study, the prevalence of DED is 17.5%.⁷ Additionally, the new lifestyles with increased use of electronic/media devices increased the risk of DED in the younger population.⁸

Many risk factors for DED have been identified, including older age, female gender, and use of estrogen hormone.⁹ Furthermore, some studies have found an association between dry eyes and smoking, wearing contact lenses, and daily screen time.^10,11 Lifestyle, medical and environmental factors, such as low humidity and Asian race, have also been suggested as risk factors for DED.^12,13 A study discussed using a smartphone application “DryEyeRhythm” and revealed that several risk factors, including female gender, using contact lenses, smoking, prolonged periods in front of screens, having collagen disease, hay fever, and depression, can all lead to severe DED-type symptoms.¹⁴

Several questionnaires have been created to evaluate a patient’s personal perception of dry eye symptoms. This is done to generate more reliable and consistent data, which can help improve the management and treatment of patients suffering from dry eye disease. Some of these questionnaires are the National Eye Institute Visual Function Questionnaire-25, Ocular Surface Disease Index, Standard Patient Evaluation of Eye Dryness Questionnaire, Canadian Dry Eye Epidemiology Study, McMonnies questionnaire, and many more.^15–18

It is essential to determine the risk factors associated with increased DED prevalence for possible interventions to control the condition. Therefore, this study aimed to assess the prevalence and risk factors of dry eye disease among medical students at the University of Tabuk using the McMonnies questionnaire, one of the earliest and most widely used questionnaires as a screening instrument for DED with sensitivity reportedly varying between 87% and 98% and specificity between 87% and 97%.^19–21

Materials and Methods

Ethical Considerations

The study protocol was approved by the Faculty of Medicine Ethics Committee, University of Tabuk, Tabuk, Saudi Arabia. Approval number (UT-246-84-2023). Our study complies with the Declaration of Helsinki.

The electronic survey starts with information about the study and “written” consent of participation. First, participants were informed about the study objectives, methodology, risks, and benefits. Participants who agreed to complete the questionnaire implied they decided to participate in the study. The study conserved participants’ privacy. Investigators were responsible for keeping the security of the data. Each subject was given a unique identifier code.

Study Design and Setting

This cross-sectional survey study was conducted at the Faculty of Medicine, University of Tabuk, Saudi Arabia, in January 2023. After obtaining the students’ emails list from the Faculty of Medicine administration, an email was sent by the researchers to all medical students and interns showing the study’s aims and objectives. If they agree to participate, they can use the provided link to fill out the electronic self-administered survey.

Study Population

The duration of medical schools in Saudi Arabia is six years, with an additional internship year that must be completed in order for the students to be considered graduates and obtain their degrees.

The inclusion criteria were to enroll medical students of all six years and the interns at the University of Tabuk aged 18 years and older, both genders, who received the invitation email and replied with an agreement to participate in this study and complete the questionnaire. We excluded the medical students and interns who did not consent to participate in the study. To minimize selection bias, we attempted to include medical students of both genders in all academic grades (from the first to the sixth years, and house officers “interns”).

Sample Size

The sample size was calculated using “The Raosoft program”. With a 5% margin of error, 95% confidence level, and 550 students and interns as the total population, the required sample size was 227, to be recruited randomly from all male and female medical students at the University of Tabuk.

Data Collection Tool

We collected data from medical students using the validated self-administered McMonnies questionnaire, which was adopted according to our study objectives.^19–23 It included information regarding socio-demographics (age, gender, and grade), behavior (contact lens wearing, daily hours in front of screens), medical history (symptoms “such as soreness, scratchiness, dryness, grittiness, burning” and treatment of dry eye, the effect of different irritants on the eye “cigarette smoke, smog, air conditioning, central heating, chlorinated fresh water, drinking alcohol” and medications “antihistamines, diuretics, tranquilizers, oral contraceptives, antihypertensives”, dryness of other mucus membranes “nose, mouth, throat, chest, or vagina”, relation to sleep and other medical disorders “arthritis and thyroid diseases”), history of allergy or previous refractive surgery, and family history of eye dryness or use of eye drops or other treatment for dry eye.

Statistical Analysis

The data were imported into SPSS Ver 22 (IBM Corp. USA). Categorical data were expressed as numbers and percentages. Subjects considered in our study as “Dry eye disease patients” are those who stated having at least one of the five self‐reported symptoms (soreness, scratchiness, dryness, grittiness, burning) reported as often or constantly. Subjects considered as “having no DED” were those with no reported symptoms, or they reported symptoms as “sometimes present”. Univariate analysis was performed using Chi-Square or Fisher’s Exact tests as appropriate. Variables that showed significant association with DED in the univariate analysis were entered in a multivariate logistic regression analysis to show the significant risk factors for DED. P<0.05 was considered statistically significant.

Results

Demography

After emailing all medical students and interns at the University of Tabuk (550 students), 247 replied to the sent email that they agreed to participate in the study, and the remaining (303 students) either did not respond to the invitation email or did not agree to participate were all excluded from the study. So, our study included 247 medical students and house officers from the University of Tabuk, Saudi Arabia, who completed a self-administered questionnaire for dry eye disease. The highest percentage of the participants were females (n=176, 71.3%) (Table 1).

Table 1 Demographic Characteristics of the Study Participants (N=247)

Prevalence of DED Among the Medical Students at the University of Tabuk

The prevalence of DED among the medical students at the University of Tabuk was 18.2%, with a 95% CI of 13.61% to 23.61%. The diagnosis of DED was based on constantly or often experiencing at least one symptom of the disease, according to the validated McMonnies questionnaire. The prevalence of each symptom alone or in association with other symptoms is illustrated in Table 2.

Table 2 Prevalence of Self-Reported Symptoms of Dry Eye Disease

Symptomatic Features of DED Among the Medical Students at the University of Tabuk

The most commonly reported symptom of DED was dryness (63.1%), followed by scratchiness (59.5%) and soreness (51.4%). Alternatively, less frequent symptoms included burning (44.1%) and grittiness (22.7%).

Risk Factors for DED Among the Medical Students at the University of Tabuk

Univariate analysis revealed that a significantly higher percentage of subjects with DED reported wearing soft lenses than those not having the disease (17.8% versus 5.4%, p=0.027). However, other variables, including age, gender, family history of DED, the number of hours in front of the screen, and history of corrective eye surgery, did not show a significant association with the presence of DED (p>0.05), as shown in Table 3.

Table 3 Demographic Factors Associated with Dry Eye Disease (N=247)

Furthermore, a history of taking sleeping antihistamine tablets, antihistamine drops, or tranquilizers was frequently reported by the subjects having DED (p=0.018). High percentages of individuals with DED stated having previous prescriptions of eyedrops or other treatments for dry eyes than their counterparts (75.6% and 46.0%, respectively, p<0.001). When swimming in chlorinated fresh water, redness and irritation of the eyes were more significantly described by those having DED (35.6%) than the healthy ones (14.4%), p=0.005. Sleeping with partially opened eyes was significantly detected in subjects with DED (17.8%), p<0.001. Reporting eye irritation when waking up from sleeping was more frequent among the diseased than the healthy subjects (8.9% versus 1.0%, p<0.001). The univariate analysis revealed non-significant relation between the prevalence of DED and arthritis, thyroid abnormalities, dryness of the nose, mouth, throat, chest, or vagina, history of allergic diseases, eye dryness and irritation the day after drinking alcohol, eye sensitivity to cigarette smoking, smog, air conditioning, or heating (p>0.05) (Table 4).

Table 4 Clinical Factors Associated with Dry Eye Disease (N=247)

Binary logistic regression analysis revealed that irritation of the eyes when waking up from sleeping (OR=19.315), sleeping with partially opened eyes (OR=19.105), redness and irritation of the eyes when swimming in chlorinated fresh water (OR=7.863), and having previous prescriptions of drops or other treatment for dry eyes (OR=3.083) were significant risk factors for the DED (Table 5).

Table 5 Binary Logistic Regression for Risk Factors of Dry Eye Disease

Discussion

This study revealed a DED prevalence rate of 18.2% among the medical students at the University of Tabuk using a validated McMonnies questionnaire of ocular symptoms related to dry eye. Furthermore, DED was found to be significantly associated with the presence of irritation of eyes when waking up from sleeping, sleeping with partially opened eyes, redness and irritation of the eyes when swimming in chlorinated fresh water, and having previous prescriptions of drops or other treatment for dry eyes. Early detection of dry eyes is important because it can indicate the presence of systemic diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Sjogren’s syndrome.²⁴ However, in the present study, there was no significant association between a history of rheumatoid arthritis or thyroid abnormalities and the presence of DED. This might be attributed to the young ages of the involved participants.

A history of taking sleeping antihistamine tablets, antihistamine drops, or tranquilizers was frequently reported by the subjects having DED. This is in line with previous researchers who stated that antihistamines and psychotropics might be associated with dry eye.²⁵ Also, a higher percentage of individuals with DED stated having previous prescriptions of eyedrops or other treatments for dry eyes than their counterparts (75.6% and 46.0%, respectively, p<0.001). This suggests high awareness of the studied medical students about the disease.

Patient education is essential in managing DED, and avoiding exacerbating factors is an integral part of the treatment plan.³ Therefore, this study investigated the risk factors significantly associated with DED among the studied medical students.

The diagnosis of dry eye is based on subjective self-reported symptoms questionnaires and objective clinical tests. Though there is no “gold standard” for the diagnosis, no single clinical test is universally accepted as a standard criterion for the diagnosis.²⁶ One of the methods used to diagnose DED is measuring central corneal thickness (CCT) and thinnest corneal thickness (TCT) using various investigative methods, including Pentacam and anterior segment coherence optical tomography (ASCOT), which were found to be significantly different in assessing the corneal morphology.²⁷ Additionally, a study utilized the smartphone app “DryEyeRhythm” to create a reliable system for categorizing and displaying individual and diverse subjective symptoms of dry eye disease (DED). This system aims to establish a basis for future predictive, preventive, personalized, and participatory medicine in managing DED.²⁸

In the current study, the diagnosis of DED was based on the often or constant presence of at least one of the DED symptoms listed in the McMonnies questionnaire. Symptoms-based diagnosis has been very effective as a screening tool that can discriminate the presence of DED.²⁹ Additionally, several studies have reported that the McMonnies questionnaire is effective in accurately detecting Dry Eye Disease (DED) with high levels of sensitivity and specificity.^30–32 The questionnaire-based diagnosis is also more applicable and a favorable option for diagnosing dry eye in research based on large populations. Nonetheless, some studies reported a poor and inconsistent relation between patient-reported symptoms and clinical signs, with higher prevalence rates of symptom-based diagnosis than for both symptoms and signs-based diagnosis.^33,34

Concerning the prevalence of DED, wide variations have been found among different population-based studies. The observed discrepancy is related to different factors, including the selected population, the etiological factors, the definition, and the methods used for DED diagnosis.³⁵

Several studies have assessed the accuracy of the McMonnies questionnaire in identifying DED among ophthalmic outpatients. In one study conducted in China, the questionnaire revealed a DED prevalence rate of over 90% among outpatients, which is significantly higher than the rate documented in our study. This differentiation might be attributed to the difference in the studied populations, as the Chinese study included approximately 28,000 patients with dry eye symptoms.³⁰

A population-based study from Al-Ahsa, Saudi Arabia, estimated a prevalence of dry eye symptoms of 32.1% among Saudi adults, with older females (>56 years), current smoking, and a history of diabetes mellitus significantly associated with dry eye.³⁶ A more recent study involving the coastal population of the eastern province of Saudi Arabia found a higher prevalence of 65.4%.³⁷ A study in Jeddah, Saudi Arabia, found that 93.2% of healthy people have dry eyes. Those with autoimmune diseases or on long-term medications should see an ophthalmologist. People should be educated that dry eyes could be a sign of chronic diseases.³⁸ There was also a high prevalence (59%) among the Jordanian population.³⁵

The Ocular Surface Disease Index survey of students, staff, and faculty members of Mohammed Bin Rashid University and the staff at Mediclinic City and Parkview Hospitals in Dubai, United Arab Emirates, revealed a high prevalence of 62.6%. Female gender, daily screen time of more than six hours, and the use of contact lenses were found to be associated with dry eyes.³⁹

A large hospital-based study included 3128 adult patients recruited from the Ophthalmology Outpatient Clinic of the Sohag University Hospital, Egypt, and reported a prevalence of 22.8% depending on both symptoms and signs.⁴⁰ Another corresponding study from Singapore detected a 12.3% prevalence of DED among participants aged 15 to 83 years based on McMonnies’ dry eye questionnaire. Further, there were significant associations between DED and female gender, contact lens wearing, previous treatment for dry eye (OR=2.09), taking medication (OR=1.84), unusual sensitivity of eyes (OR=3.04), and irritation on waking (OR=2.38).⁴¹

In China, DED prevalence among senior high school students was 23.7%, depending on a previous clinical diagnosis of DED or severe symptoms (both dryness and irritation constantly or often). In addition, inadequate refractive correction, frequent self-administered topical ophthalmic medications, and poor sleep quality were significant risk factors.⁴² Alternatively, another study included Chinese people aged 5–89 years showed a prevalence of 13.55%.⁴³

A study of the residents of a rural area in Japan reported a prevalence of 21.6% in women and 12.5% in men, with a significant difference. The DED in this study depended on a composite of clinically diagnosed DED or severe symptoms of dryness and irritation, either constantly or often. Contact lenses were a common dry eye risk factor in both genders.⁴⁴ Furthermore, a population-based study in Sumatra, Indonesia, detected a 27.5% prevalence of one or more of the six dry eye symptoms often or all the time adjusted for age, and pterygium was a possible independent risk factor.¹³

A study that investigated the overall prevalence of DED among a representative population of the United States has explored a rate of 5.28%. The annual prevalence from 2005 to 2012 was increasing, highlighting a growing health problem that necessitates continued research and therapeutic development.⁴⁵

Our study could be limited by the self-reported responses, which could result in misclassification or recall bias. Also, the responses were not validated by performing the ophthalmic examination, which may affect the observed prevalence of dry eye disease among medical students at the University of Tabuk.

Conclusion

Our study was conducted among medical students at the University of Tabuk, it was discovered that a significant proportion of 18.2% suffered from dry eye disease (DED). Furthermore, the study also unveiled various risk factors that are associated with the development of DED. Given the relatively high prevalence of DED, it is imperative to emphasize the significance of early diagnosis and prompt treatment to prevent further complications. Therefore, it is crucial that individuals remain vigilant and seek medical attention if they experience any symptoms of DED.