A Study on Dry Eye and Its Associated Risk Factors Among Patients with Pterygium.

Pterygium is a common degenerative and proliferative disorder of the ocular surface characterized by a triangular or wing-shaped fibrovascular growth of conjunctival tissue extending onto the cornea. It is one of the most frequently encountered external eye diseases, particularly in tropical and subtropical regions, where environmental exposure plays a significant role in its development.¹ Although pterygium is often considered a cosmetic concern, progressive lesions can induce significant corneal astigmatism, obscure the visual axis, reduce visual acuity, and cause chronic ocular irritation, thereby adversely affecting the patient's quality of life.²

 

The exact pathogenesis of pterygium remains incompletely understood and is believed to be multifactorial. Chronic exposure to ultraviolet (UV) radiation, especially UV-B rays, is regarded as the most important etiological factor. Other environmental risk factors include prolonged exposure to dry, dusty, windy, and sunny conditions, particularly among individuals engaged in outdoor occupations.³ In addition to environmental factors, inflammation, oxidative stress, limbal stem cell dysfunction, and genetic susceptibility have also been implicated in the development of pterygium.

 

Dry eye disease (DED) is a multifactorial disorder of the ocular surface characterized by loss of tear film homeostasis, accompanied by ocular symptoms such as burning, foreign body sensation, irritation, fluctuating vision, and redness. Tear film instability, hyperosmolarity, ocular surface inflammation, and neurosensory abnormalities contribute to the pathophysiology of dry eye disease.

 

Several studies have reported an association between pterygium and tear film abnormalities. One proposed mechanism suggests that tear film instability and ocular surface dryness lead to localized desiccation of the conjunctiva and cornea, making the ocular surface more susceptible to ultraviolet-induced damage and subsequent pterygium formation. Conversely, the presence of pterygium may disrupt normal tear film distribution and stability, thereby contributing to dry eye symptoms.⁴ However, the causal relationship between pterygium and dry eye disease remains controversial, and it is still unclear whether tear dysfunction precedes pterygium development or occurs as a consequence of the disease.

 

Assessment of dry eye among patients with pterygium is therefore important for understanding disease pathogenesis, improving symptom management, and optimizing surgical outcomes. The present study is undertaken to evaluate the prevalence of dry eye among patients with pterygium and to identify the factors associated with dry eye in these patients attending a tertiary care hospital.

 

Aim

To study the prevalence of dry eye among patients with pterygium attending the Department of Ophthalmology at Department of Ophthalmology

Fathima Institute of Medical Sciences, Kadapa, Andhra Pradesh.

 

Objectives

1.             To determine the proportion of dry eye among patients diagnosed with pterygium attending the Department of Ophthalmology,Fathima Institute of Medical Sciences, Kadapa, Andhra Pradesh.

2.             To identify the demographic, environmental, and clinical factors associated with dry eye among patients with pterygium.

Study Design

Hospital-based cross-sectional observational study.

 

Study Setting

Department of Ophthalmology, Fathima Institute of Medical Sciences, Kadapa, Andhra Pradesh.

 

Study Population

Patients clinically diagnosed with pterygium attending the Outpatient Department of Ophthalmology, Fathima Institute of Medical Sciences, Kadapa.

 

Study Period

18 months.

 

Sample Size

The sample size was calculated using the formula:

n = 4pq/d²

Where:

•              p = Prevalence of dry eye among patients with pterygium = 50%, based on the study by Roka N et al.

•              q = 100 − p = 50

•              d = Clinically allowable error (20% of prevalence) = 10%

Accordingly,

n = 4 × 50 × 50 / 10² = 100

Considering possible non-response or incomplete data, an additional 10% may be included, if required.

Study Tools

•              Pre-tested structured questionnaire

•              Visual acuity assessment

•              External ocular examination under torchlight

•              Slit-lamp biomicroscopy

•              Direct ophthalmoscopy

•              Schirmer Test I (with and without topical anesthesia)

•              Tear Film Break-Up Time (TBUT)

•              Tear Meniscus Height (TMH) assessment

•              Measurement of pterygium size using slit-lamp biomicroscopy

 

Inclusion Criteria

•              Patients aged 18 years and above with a clinical diagnosis of pterygium.

•              Patients willing to participate and provide written informed consent.

 

Exclusion Criteria

•              Patients with acute ocular infections or inflammatory conditions associated with excessive watering, pain, or itching.

•              Patients with previous ocular surgery within the preceding one month.

•              Patients scheduled for ocular surgery during the study period.

•              Patients using topical medications (other than lubricants) that may alter tear film parameters.

•              Patients with systemic diseases or autoimmune disorders known to cause dry eye, where applicable.

 

Methodology

After obtaining approval from the Institutional Ethics Committee and written informed consent, eligible patients fulfilling the inclusion criteria were enrolled consecutively.

A pre-tested structured questionnaire was used to collect demographic and clinical information, including age, sex, occupation, dietary habits, smoking status, duration of symptoms, and ocular complaints.

 

Schirmer Test I (Without Anesthesia)

Schirmer Test I was performed using Whatman No. 41 filter paper strips. The strip was folded at one end and placed in the lower conjunctival fornix at the junction of the medial two-thirds and lateral one-third of the lower eyelid. Patients were instructed to keep their eyes gently closed or blink normally during the test. After 5 minutes, the strip was removed and the length of wetting was recorded in millimetres.

 

Schirmer Test I (With Anesthesia)

Following instillation of topical anesthetic drops, excess tears were gently wiped away. The Schirmer strip was similarly placed in the lower fornix and removed after 5 minutes. The wetting length was measured in millimetres to assess basal tear secretion.

 

Tear Film Break-Up Time (TBUT)

A fluorescein strip moistened with sterile saline was applied to the inferior conjunctival sac. The patient was instructed to blink several times and then keep the eyes open. Using the cobalt blue filter of the slit lamp, the interval between the last blink and the appearance of the first dry spot on the cornea was measured in seconds. Three readings were obtained, and the average value was recorded.

 

Tear Meniscus Height (TMH)

TMH was measured at the central lower lid margin using slit-lamp biomicroscopy by aligning the graticule with the lower tear meniscus.

 

Diagnostic Criteria for Dry Eye

Dry eye disease was considered to be present if one or more of the following criteria were observed:

•              Schirmer Test I (without anesthesia): <10 mm in 5 minutes

•              Tear Film Break-Up Time (TBUT): <10 seconds

•              Tear Meniscus Height (TMH): <0.5 mm

 

Outcome Measures

Primary Outcome

•              Proportion (prevalence) of dry eye among patients with pterygium.

Secondary Outcomes

•              Association of dry eye with age, sex, occupation, smoking status, dietary habits, and pterygium size.

•              Relationship between severity of pterygium and tear film parameters (Schirmer test, TBUT, and TMH).

 

Statistical Analysis

Data will be entered into Microsoft Excel and analyzed using IBM SPSS Statistics version 22.0.

Descriptive statistics will be presented as mean ± standard deviation for continuous variables and frequency with percentages for categorical variables. Associations between categorical variables will be analyzed using the Chi-square test or Fisher's exact test, wherever appropriate. Continuous variables will be compared using the Student's t-test or Mann–Whitney U test, depending on the distribution of data.

 

A p-value ≤ 0.05 will be considered statistically significant.

TABLE 1: Distribution of study participants by sex, age, occupation, and smoking.

 

TABLE 2: Distribution of study participants by diet, diabetes, hypertension.

 

TABLE 3: Distribution of study participants according to dry eye tests.

 

Table 4: Number of Patients with different types of Pterygium.

Type 1: < 2 mm over cornea Type 2: 2 – 4 mm over cornea Type 3: > 4 mm over cornea

 

Table 5: Mean values of Dry eye tests of the study population.

 

 

Table 6. Association between Right Eye Pterygium and Dry Eye Tests (n = 100)

 

 

Table 7. Association between Left Eye Pterygium and Dry Eye Tests (n = 100)

 

 

 

Table 8. Association between Bilateral Pterygium and Dry Eye Tests (n = 100)

 

Table 9. Pearson's Correlation between Pterygium and Dry Eye Parameters

 

Table 10. Association between Age and Dry Eye Parameters (n = 100)

 

 

Table 11. Association between Gender and Dry Eye Parameters (n = 100)

 

Table 12. Association between Occupation and Dry Eye Parameters (n = 100)

 

 

 

 

 

Table 13. Association between Smoking and Dry Eye Parameters (n = 100)

 

Table 14. Association between Diabetes Mellitus and Dry Eye Parameters (n = 100)

 

Table 15. Association between Hypertension and Dry Eye Parameters (n = 100)

 

 

Table 16. Summary of Association between Risk Factors and Dry Eye Parameters

Risk Factor	Schirmer Test	TBUT	TMH
Age	Significant (p = 0.007)	Significant (p = 0.050)	Not Significant (p = 0.235)
Gender	Not Significant (p = 0.705)	Not Significant (p = 0.533)	Not Significant (p = 0.840)
Occupation	Not Significant (p = 0.452)	Not Significant (p = 0.466)	Not Significant (p = 0.637)
Diet	Not Significant	Not Significant	Not Significant
Menopausal status	Not Significant	Not Significant	Not Significant
Smoking	Not Significant (p = 0.129)	Not Significant (p = 0.253)	Not Significant (p = 0.745)
Diabetes mellitus	Not Significant (p = 0.429)	Significant (p = 0.014)	Not Significant (p = 0.555)
Hypertension	Not Significant (p = 0.601)	Not Significant (p = 0.706)	Not Significant (p = 0.463)

 

Pterygium is a common ocular surface disorder in tropical and subtropical regions and is strongly associated with chronic exposure to ultraviolet (UV) radiation, dust, wind, and dry environmental conditions. Tear film instability has been proposed as an important factor in the pathogenesis of pterygium, although it remains unclear whether dry eye predisposes to pterygium or develops secondary to it. Abnormal tear film exposes the ocular surface to environmental damage, resulting in inflammation and fibrovascular proliferation.

 

In the present study, dry eye was evaluated using Schirmer's test, Tear Film Break-Up Time (TBUT), and Tear Meniscus Height (TMH). Based on Schirmer's test, dry eye was observed in 20.5% of eyes with pterygium, while 33.5% showed abnormal TBUT and 59.5% had reduced TMH. These findings indicate that tear film instability was more frequently detected by TBUT and TMH than by Schirmer's test.

 

The mean Schirmer test values (16.94 mm right eye and 17.85 mm left eye) and TBUT values (10.14 seconds right eye and 10.72 seconds left eye) were comparable to reports from previous studies. Several investigators, including Roka et al.,5 Amer et al.,6 and Kampitak et al.,7 have demonstrated significantly reduced TBUT and, in many studies, reduced Schirmer values among patients with pterygium, suggesting tear film dysfunction.

 

However, other investigators such as Goldberg et al.8 and Jie et al.9 reported no significant association between dry eye and pterygium. Thus, the available literature remains inconsistent.

 

In the present study, only right-eye TBUT showed a statistically significant association with the presence of pterygium (p = 0.024), whereas Schirmer's test and TMH did not show significant associations. Similarly, no significant association was observed between bilateral pterygium and any of the dry eye parameters. These findings are consistent with the observations of Goldberg et al., Balogun et al.,10 and Jie et al., but differ from studies by Roka et al., Mithal et al.,11 Ishioka et al., and Lekhanont et al.,12 which reported a strong association between pterygium and dry eye.

 

Correlation analysis demonstrated only weak or negligible correlations between pterygium size and dry eye parameters, indicating that increasing pterygium size was not associated with worsening tear film function. This finding agrees with Kampitak et al., who also reported no correlation between pterygium size and Schirmer or TBUT values. In contrast, strong positive correlations were observed between corresponding dry eye test values of the right and left eyes, indicating good inter-eye agreement.

 

Age was significantly associated with abnormal Schirmer test (p = 0.007) and TBUT (p = 0.050), suggesting that tear film function deteriorates with advancing age. This observation is consistent with reports by Hashemi et al.,13 and other epidemiological studies showing increased prevalence of dry eye in older individuals.

 

No significant association was observed between dry eye and gender, occupation, smoking, hypertension, diet, or menopausal status. Similar findings regarding gender and occupation have been reported by Roka et al. Although outdoor exposure is a recognized risk factor for pterygium, it did not independently influence dry eye parameters in the present study.

 

Diabetes mellitus showed a significant association only with TBUT (p = 0.014), indicating increased tear film instability among diabetic patients. This finding agrees with studies by Aljarousha et al.,14 Gupta et al.,15 Yoon et al.,16 and Ozdemir et al.,17 who reported significantly reduced TBUT in diabetic individuals. However, no significant association was observed between diabetes and Schirmer's test or TMH in the present study.

 

Overall, the present study suggests that although tear film abnormalities are common among patients with pterygium, a statistically significant association was demonstrated only for TBUT in the right eye and for diabetes with TBUT. The findings support the role of tear film instability in pterygium but also indicate that the relationship between pterygium and dry eye is complex and may vary across populations and study methodologies. Further prospective studies with larger sample sizes and objective tear film assessments are required to clarify this relationship.

This cross-sectional study assessed the prevalence of dry eye among patients with pterygium using Schirmer's test, Tear Film Break-Up Time (TBUT), and Tear Meniscus Height (TMH).

 

At least 26% of eyes with pterygium (unilateral or bilateral) had evidence of dry eye based on one or more diagnostic tests. The prevalence of dry eye varied according to the assessment method, being 20.5% by Schirmer's test, 33.5% by TBUT, and 59.5% by TMH.

 

No statistically significant association was observed between the presence or size of pterygium and dry eye, except for a significant association between right-eye pterygium and reduced TBUT. Correlation between pterygium size and dry eye parameters was weak or negligible.

 

Among the risk factors studied, advancing age was significantly associated with abnormal Schirmer's test and TBUT, while diabetes mellitus showed a significant association with reduced TBUT. No significant associations were found between dry eye and gender, occupation, smoking, menopausal status, diet, or hypertension.

 

Overall, the study suggests that tear film abnormalities are common in patients with pterygium, particularly tear film instability, although a consistent statistical association between pterygium and dry eye could not be demonstrated. Further longitudinal studies with larger sample sizes are recommended to better define the relationship between pterygium and dry eye disease.

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