Assessment of prevalence of dry eye among medical students using ocular surface disease index questionnaire – Is COVID-19 to be really blamed?

Abstract

Purpose:

An undergraduate research conducted during the pre-covid times, to highlight the importance of screen time and its association with dry eye in medical students. The aim was to study the prevalence of dry eye among medical students using the ocular surface index (OSDI) questionnaire.

Methods:

This was a cross-sectional study. This study was conducted among medical students using an OSDI questionnaire in the pre-covid times. Based on the pilot study, the minimum sample size calculated was 245. A total of 310 medical students participated in the study. These medical students answered the OSDI questionnaire. The OSDI score was used to categorize students with dry eye as mild (13–22 points), moderate (23–32 points), and severe (33–100 points). In addition, the associations between the OSDI score and possible risk factors such as gender, contact lens/spectacle wear, laptop/mobile usage, and duration of exposure to air conditioners were also studied.

Results:

The analysis of the study revealed that out of 310 students, dry eye was seen in 143 (46.1%) and severe dry eyes were seen in 50 (16.1%). A high OSDI score (>13 points) was associated with the usage of a laptop/mobile for more than 6 h in 40 (52.6%) (P < 0.001).

Conclusion:

The prevalence of dry eye among medical students was 46.1% in the present study. Longer duration of usage of visual display units (laptop/mobile) was the only factor that showed a statistically significant association with dry eye in our study.

“Dry eye is a multifactorial disease of the ocular surface manifested by ocular symptoms in which tear film instability, hyperosmolarity, ocular surface inflammation, and neurosensory abnormalities play etiological roles”.[1] Dry eye disease (DED) is influenced by various factors such as geographical area, exposure to sunlight, windy conditions, contact lens use, exposure to air conditioners, ametropia, usage of drugs like cyclosporine, isotretinoin, excessive screen time.[2,3] Symptoms of DED include watering, grittiness, foreign body sensation, sensitivity to light, red eye, and burning sensation.

In the pre-covid era, there were very few studies on the prevalence of dry eye in medical students as compared to engineering students. The reason for fewer dry eye studies in medical students was that the prevalence of DED in engineering students was expected to be more due to the longer duration of exposure to visual display units.[4-6] However, during the covid pandemic, researchers expected more screen time among medical students as well; thus, many dry eye studies were conducted among medical students with varied results on the prevalence of DED.[7-10]

Because of the variable prevalence of dry eye among medical students, we conducted this ocular surface disease index (OSDI)-based dry eye study among our medical students during the pre-covid era.

Methods

A cross-sectional study was conducted in a medical college in South India in the year (January to June) 2019 to study the prevalence of dry eye in medical students. The institutional ethical committee clearance was obtained. The chief author was a medical student who conducted the survey. As there were no similar studies of dry eye in only medical students in the Indian scenario, a pilot study including 30 students was conducted using the OSDI questionnaire. Of the 30 students, 10 students suffered from dry eye. Hence, anticipating 33% of the students to have dry eye symptoms with a relative precision of 20% at a 95% confidence level, a minimum of 246 students were required for the study. Accounting for a “non-response” of 20%, a sample size of 308 students was suggested by the biostatistician. Hence, 310 medical students were included in the study.

The study was conducted in the classroom of the medical college. The students who were willing to participate in the study were included. The questionnaire was given out to the students at the end of the lecture by the chief author and was collected back within 10 min. [OSDI questionnaire Appendix 1] We have defined and graded dry eye based on OSDI Questionnaire only. The 12 variables of the OSDI questionnaire were graded on a scale of 0–4, where 0 indicates none of the time; 1, some of the time; 2, half of the time; 3, most of the time; and 4, all the time. The total OSDI score was then calculated based on the following formula: OSDI = [(sum of scores for all questions answered) × 100]/[(total number of questions answered) ×4]. The OSDI score was calculated on a scale of 0–100, with higher scores representing greater disability. According to the OSDI score, DED was classified as mild (13–22 points), moderate (23–32 points), or severe (33–100 points).

The eligibility criteria were the medical students of age 18–26 years from the medical college who gave consent for the study. Exclusion criteria included those students who did not give consent and those who were suffering from ocular diseases like allergic/infective conjunctivitis during the period of study. Those students suffering from any systemic disease and on any medications were not included in the study as well.

In addition to the OSDI questionnaire, the other details included were gender, presence of refractive errors (duration of refractive errors, usage of spectacles or contact lens for the same), exposure to an air conditioner, and the usage of visual display units (laptop/mobile).

The duration since the diagnosis of refractive error and correction of refractive errors with spectacle/contact lens use was assessed as less than 2 years, 2–7 years, or more than 7 years. Exposure to air conditioner was assessed based on the duration of exposure of less than 3 h, 3–6 h, or more than 6 h per day, and laptop/mobile usage was assessed as less than 3 h, 3–6 h, more than 6 h per day.

Among contact lens users, in addition to the duration of usage, regularity of usage (regular or during special occasions) was also asked.

The data was statistically analyzed using the Chi-square test. A P-value of less than 0.05 was considered clinically significant for the variable associated with DED.

Results

The OSDI questionnaire was administered to 310 medical students. The students included in the study were from various states of India studying in a medical college in South India. Of the 345 students who were approached, 35 students refused to participate in the study.

According to the OSDI grading, dry eye was seen in 46.1% (143/310) of students, of whom mild dry eye was seen in 20.3% (63/310), moderate dry eye in 9.6% (30/310), and severe dry eye in 16.1% (50/310) students [Table 1].

Table 1.

Prevalence of dry eye in medical students as per OSDI grading

Grade of dry eye	No of students	Percentage
Normal	167	53.9
Mild	63	20.3
Moderate	30	9.7
Severe	50	16.1

The prevalence of dry eye in females was 46.4% (84/181), and in males was 45.7% (59/129) (P > 0.05). A total number of students wearing spectacles were 218 (70.32%), of whom 117 (53.7%) did not have dry eye, 48 (22%) had mild, 18 (8.3%) had moderate, and 35 (16.1%) had a severe dry eye. Statistical analysis for the association between spectacle wear and dry eye had a P value of 2.5. Among the students who wore spectacles, 45 (20.64%) wore contact lens also. Of the contact lens wearers, 21 (46.6%) suffered from dry eye. The details of the subjects who had dry eyes with the use of contact lenses were as follows: 6 (13.3%) had mild, 3 (6.7%) had moderate, and 12 (26.7%) had severe dry eyes. This association was not statistically significant (P = 5.3).

There was no significant association between dry eye and exposure to the air conditioner (P = 3.5). OSDI score >13 seen among those with long usage of visual display units (laptop/mobile) for more than 6 h was 52.6% (40/76) (P < 0.001) [Table 2].

Table 2.

Association of dry eye and visual display units (laptop/mobile phones)

Visual display unit (laptop/mobile) usage	Ocular Surface Disease Index (OSDI)
	Normal	Mild	Moderate	Severe
<3 h
No. of students	46	30	15	13
% With laptop/mobile usage	44.2	28.8	14.4	12.5
3-6 h
No. of students	85	22	8	15
% With laptop/mobile usage	65.4	16.9	6.2	11.5
>6 h
No. of students	36	11	7	22
% With laptop/mobile usage	47.4	14.5	9.2	28.9, (P<0.001)
Total
No. of students	167	63	30	50
% With laptop/mobile usage	53.9	20.3	9.7	16.1

Discussion

DED is one of the most prevalent ophthalmic disorders and may have an adverse impact on the quality of life. A dry eye can cause a burning sensation, gritty sensation like the feeling of a foreign body, sensitivity to light, easy fatigability of eyes after reading even for a short time, redness, and intense eye pain in some patients. In addition to causing various disabling symptoms, it may also compromise the results of corneal, cataract, and refractive surgical procedures.[11]

In our study, OSDI questionnaire was used to assess DED among medical students. This questionnaire has a shorter completion time, easy comprehension by students, and no additional cost, making it ideal for screening.[12]

The OSDI is perhaps the most frequently used survey instrument for the assessment of ocular surface disease severity in dry eye research. The OSDI is specific for DED. It enquires into the presence and frequency of specific symptoms and their impact on vision-related functioning. The OSDI has good to excellent reliability, validity, sensitivity, and specificity.[13]

The global prevalence of dry eye is about 11.59%.[14] In a study of Medical Students of Gandaki Medical College, Pokhara, Nepal among 200 students, 146 (73%) were males and 54 (27%) were females. The mean age of patients was 21.73 ± 1.42 years. The prevalence of dry eye was 46%, of whom 19.5% had mild, 1% had moderate, and 13.5% had severe dry eyes.[15] In our study, the prevalence of dry eye is 46.1%, which is similar to the above study.

Many studies have found that the occurrence of dry eye was common among females. Anshu Sahai et al. in their study screened 500 patients above 20 years of age randomly for dry eye. Dry eye was significantly higher (P = 0.024) in females (22.8%) than in males (14.9%).[2]

In a cross-sectional study where McMonnies’ index and OSDI questionnaires were used to estimate the prevalence of dry eye among 400 consecutive patients aged >40 years attending the ophthalmology outpatient department, it was found that the women investigated were more likely to have dry eyes than the men (27% v. 12%).[16] In our study too though not statistically significant, the prevalence of dry eye was seen relatively more among females than males. Our study showed no significant association between dry eye and refractive error. Anshu Sahai et al.[2] showed that dry eye was commonly seen among ametropes compared to emmetropes. In our study, 70.32% (218) were ametropes and 46.4% of them had dry eyes. This result was statistically not significant (P = 2.5). In our study, there was no significant association between contact lens users and dry eye (P = 5.3). The possible reason may be that less number of students used contact lenses 45/310. In total, 46.6% (21/45) of the students wearing contact lenses suffered from dry eyes. This association was not statistically significant (P > 0.5). Begley et al. and Doughty et al. reported a significant association between dry eye and contact lens usage; 50% of contact lens wearers in their study showed symptoms of dry eye.[17,18] The dry eye in contact lens wearers is due to reduced oxygen supply to the cornea. Hence, the use of contact lenses was a contributing factor along with other factors, but not the main nor the only cause. This relates well with our study with a dry eye prevalence of 46.6% among contact lens wearers. This was comparable to the occurrence of dry eye in spectacle users (46.4%).

Air-conditioned (AC) room has a negative impact on tear film by causing desiccation of the eye.[19] Our study did not find a significant association between AC exposure and dry eye. The reason probably is the shorter duration of AC exposure, as most of them were exposed to AC only during class hours of at most four hours in a day. As per studies, there was a significant association between dry eye and laptop usage.[3,6,20] The results of these studies showed varying rates of prevalence of dry eye.[3,6,20] A study conducted by Lograj et al. showed that the prevalence of dry eye was 81.9% (176/215) among engineering students and 78.6% (158/201) among medical students.[6] Along with the usage of laptops, they also studied ergonomic factors like the level of the top of the display screen, viewing distance from the screen, the position of the AC, the brightness of the room, use of antiglare filters, regular breaks, etc.[6] In our study, the association between dry eye and visual display unit usage (52.6% among laptop usage of 6 h or more) was statistically significant with a P value < 0.001.

Increased screen time is associated with infrequent and incomplete blinking leading to the evaporation of tears resulting in dry eyes. The hypothesis that digital screens lead to dry eye by affecting blinking is supported by several studies showing that blinking dynamics are altered when participants use digital screens.[21,22] Blink rates during reading tasks on digital devices have been found to be reduced when compared to rest conditions.[23-25]

An early study by Tsubota and Nakamori reported that the mean rate of blinking in 104 office workers was 22 blinks per minute for a relaxed condition, 10 per minute while reading a book at a table, and 7 per minute while viewing text on a video screen.[23] The blink rate has also been found to decrease during an active computer task compared to the blink rate found when participants were engaged in relaxed conversation.[22]

Cardona et al.[21] found the percentage of incomplete blinks increased compared to the baseline during video game playing. Among the pre-Covid dry eye studies, a Korean study on dry eye symptoms and their association with psychological stress in medical students showed that 27.1% had dry eye; Lograj et al. showed 78.6% of dry eye among medical students. Our study showed a 46.1% prevalence of dry eye in medical students.[4-6]

Very few studies were conducted on dry eye in medical students prior to the Covid pandemic. However, during and post-Covid times, multiple studies have reported varied prevalence of dry eye among medical students all over the world.[7-10]

With the increased usage of gadgets among the student population, the younger generation is prone to develop dry eye; hence, we have included them in our study so that we can detect and treat dry eye early. We looked into OSDI scores only and no other dry eye tests, which can be considered a limitation of our study. However, since it was undergraduate questionnaire-based research and more focused on dry eye prevalence among medical students, we felt that using OSDI was sufficient.

Conclusion

In conclusion, the prevalence of dry eye was 46.1% among medical students. There was a significant association between dry eye and longer duration of visual display unit usage of more than 6 h (52.6%, P < 0.001). Irrespective of the Covid situation, DED has been shown to be associated more with increased screen time.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Appendix 1 OSDI Questionnaire

Ocular Surface Disease Index (OSDI) Questionnaire

Semester:

Gender:

Age:

A. Have you experienced any of the following during the last week?

	All of the time	Most of the time	Half of the time	Some of the time	None of the time
1.Eyes that are sensitive to light?	4	3	2	1	0
2.Eyes that feel gritty?	4	3	2	1	0
3.Painful or sore eyes?	4	3	2	1	0
4.Blurred vision?	4	3	2	1	0
5.Poor vision?	4	3	2	1	0

Subtotal score for answers 1 to 5

B. Have problems with your eyes limited you in performing any of the following during the last week

	All of the time	Most of the time	Half of the time	Some of the time	None of the time
6.Reading?	4	3	2	1	0	n/a
7.Driving at night?	4	3	2	1	0	n/a
8.Working with computer or ATM?	4	3	2	1	0	n/a
9.Watchig TV?	4	3	2	1	0	n/a

Subtotal score for answers 6 to 9

C. Have your eyes felt uncomfortable in any of the following situations during the last week

	All of the time	Most of the time	Half of the time	Some of the time	None of the time
10.Windy climate?	4	3	2	1	0	n/a
11.Places with low humidity (very dry)?	4	3	2	1	0	n/a
12. Areas that are air conditioned?	4	3	2	1	0	n/a

Subtotal score for answers 10 to 12

Add subtotals A,B,and,C to obtain D (D=sum of scores for all questions answered)

Total number of questions answered (do not include questions answered N/A)

Additional questions

13.How many hours do you use your laptop/phone

• ◻ <3 hours

• ◻ 3-6 hours

• ◻ >6 hours

14. Do you wear spectacles?

• ◻ YES

• ◻ NO

If yes,then from how long?

• ◻<2 years

• ◻2-7 years

• ◻>7 years

15. Do you use contact lens?

• ◻YES

• ◻NO

If yes,then how often?

• ◻Everyday

• ◻Special occasions

16. Are you on any of these following medications

• ◻Antihistamines

• ◻Diuretics

• ◻Antidepressants

• ◻Beta blockers

• ◻Isotretinion (acne medication)

If yes, then from how long?............

17. How many hours are you exposed to AC?

• ◻<3 hours

• ◻3-5 hours

• ◻>5 hours

Scoring chart

If OSDI score

• 0-12: Normal

• 12–22:Mild

• 23-32: Moderate

• 33-100: Severe