Changes in the ocular surface and tear film during 30 days of daily use of hydrogel and silicone hydrogel soft contact lens

Abstract

Morphological and physiological changes induced by contact lens (CL) are mainly due to hypoxia, mechanical trauma and toxicity associated with time of use of CL. <em><strong>Objective:</strong></em> To determine changes in the ocular surface and tear film during 30 days of daily use of hydrogel and silicone hydrogel CL. Materials and <em><strong>Methods:</strong></em> 20 individuals, novices in the use of CL signed an informed consent and were adapted with Lotrafilcon A and Vasurfilcon A. Conjunctival hyperemia, Schirmer I, TBUT, corneal staining and comfort were assessed before adaptation and during each check-up (4 and 8 hours, day 3, 7, 11, 15, 19, 23, 27 and 30). The Wilcoxon rank test (IC 95 %), the Mann/Whitney test (IC 95 %) and the Spearman correlation were used. <em><strong>Results:</strong></em> Alterations were evident in all tests studied after 4 hours of use of the two lenses. The greatest decrease (p < 0.05) in the tear film quality was on day 3 of use of Lotrafilcon A and Vasurfilcon A (4.5 s and 5.5 s, respectively) and in the quantity of the tear film was on day 30 (12 min/5 min and 9 min/5 min, respectively). There was a gradual increase in the percentage of patients with corneal staining and with conjunctival hyperemia during the 30 days. There were no statistical differences (p > 0.05) or clinically significant differences between the two groups of lenses. Conclusions: Soft CL with high and low Dk/t during 30 days of daily use cause significant changes in the ocular surface and tear film, without showing any differences among the changes generated by the two types of lenses.