Comparative Assessment of Tear Function Tests, Tear Osmolarity, and Conjunctival Impression Cytology between Patients with Pterygium and Healthy Eyes

PURPOSE: To compare histologic abnormalities of tear film and tear osmolarity between normal eyes and eyes with pterygium. METHODS: This was a prospective, hospital-based, case–control study involving 95 patients (65 men, 30 women) with unilateral pterygium. The tear meniscus height (TMH), Schirmer's test-1 (SCH-1) score, Rose Bengal staining (RBS) score, tear film breakup time (TBUT), tear osmolarity (TO), and conjunctival impression cytology (CIC) were assessed in both eyes. The Chi-square and Student's t-tests were used to compare the results between the two groups. P values <0.05 were considered statistically significant. RESULTS: The mean patient age was 50.9 years, with the largest age group being the 45–55 year-old bracket across both genders. Most patients (82.1%) had nasal pterygium, and 80% were involved in outside activities. The mean assessment values in the case and control groups were as follows: TMH, 0.21 vs. 0.24 mm; SCH-1, 13.2 vs. 17.8 mm; RBS, 4.38 vs. 2.51 points; TBUT, 8.7 vs. 13.2 seconds; TO, 306 vs. 299 mOsm/L (P < 0.001 in all cases). The proportions of abnormal assessment values in the case and control groups were as follows: TMH, 82.1% vs. 3.16%; SCH-1, 20% vs. 2.1%; RBS, 30.53% vs. 4.22%; TBUT, 61.05% vs. 6.3%; TO, 10.52% vs. 1.05%; CIC, 33.7% vs. 7.37% (P < 0.05 for all comparisons). CONCLUSION: This study showed that the quantity and quality of tear film, as well as the number of goblet cells, decreased, but the tear osmolarity increased in eyes with pterygium. Furthermore, the TMH, RBS results, TBUT, and CIC have more precise state of the patient's tear condition with the disease of the pterygium.