IPoster: Ocular Surface Imaging to Assess Tear Film Dynamics Associated with Contact Lens Wear

Purpose: To evaluate the use of ocular surface imaging on pre-corneal tear film (PCTF) and pre-lens tear film (PLTF) dynamics associated with contact lens wear. To quantify changes in the PLTF on contact lens surfaces differing in material composition. To assess possible visual effects of PLTF changes during the course of a 6 hour period using high and low contrast visual acuity.

Methods: 5 clinically normal subjects were fit into 2 contact lens designs, delefilcon A and etafilcon A. Lipid layer thickness measurements of the PCTF were acquired using the Stroboscopic Video Color Microscope prior to lens insertion. The PLTF was assessed 15 minutes after lens insertion, and after 6 hours of lens wear. High and low contrast logMAR acuities were measured at each time interval. Average lipid layer thickness and logMAR acuity were averaged between the right and left eye and compared using paired t-tests.

Results: A trend towards decreased lipid layer thickness was found after 6 hours of contact lens wear when compared to the baseline PCTF, -6.2 ± 7.7 nm (p = 0.14) in delefilcon A and -9.6 ± 13.8 nm (p = 0.19) in etafilcon A. From 15 minutes to 6 hours of contact lens wear, there was an average decrease in lipid layer thickness of -3.0 ± 7.9 nm (p = 0.44) in delefilcon A and -9.2 ± 14.8 nm (p = 0.24) in etafilcon A. After 6 hours in delefilcon A, there was no significant change in high (p = 0.24) or low contrast (p = 0.11) logMAR acuity. After 6 hours in etafilcon A, there was no difference in high contrast acuity (p=0.41), but a significant decrease in low contrast acuity, 0.10 ± 0.6 logMAR (p = 0.02).

Conclusion(s): Ocular surface imaging is useful in assessing tear film dynamics associated with contact lens wear, where quantifiable changes in lipid layer thickness can be identified over the course of a wearing cycle. Low contrast acuity may be a more sensitive marker than high contrast acuity for vision changes associated with PLTF dynamics.