Tear Osmolarity and Ocular Changes in Pterygium

Purpose: To determine abnormalities in tear osmolarity (TO), tear function, and impression cytology in patients with pterygium and to assess the relationship between the variables. Methods: Thirty eyes from 30 patients with primary nasal pterygium and 30 eyes from 30 volunteers without ocular pathologies or dry eye symptoms were enrolled in the present study. TO test, tear ferning test, fluorescein tear breakup time, Schirmer test, and impression cytology of the conjunctiva were performed. Analysis of variance was applied for intergroup comparisons, and Pearson correlation was used to calculate the strength of relationships between the variables. A statistical significance level of P < 0.05 was considered. Results: Pterygium patients had significantly higher TO, lower crystallization percentage, and lower goblet cell density (GCD) than control patients. A weak but significant negative correlation seems to exist between TO and crystallization percentage (r = -0.425, P < 0.01) and between TO and GCD (r = -0.295, P < 0.05). Conclusion: There is evidence to suggest that pterygium appears to induce unfavorable conditions of increasing TO that could trigger alterations in tear crystallization and GCD. Being aware of TO changes seems essential to understand the complex relationship among pterygium, tear film functions, and ocular surface changes.