# Daytime Changes in Tear Film Parameters and Visual Acuity with New-Generation Daily Disposable Silicone Hydrogel Contact Lenses—A Double-Masked Study in Symptomatic Subjects

## TL;DR

This study compared how two types of contact lenses affect tear film stability and vision over the course of a day in people with dry eye symptoms.

## Contribution

The study introduces the use of dynamic topography to evaluate tear film changes and highlights the SRI index as a sensitive tool for dry eye assessment.

## Key findings

- Both lenses showed similar performance in visual acuity and tear film stability with no significant differences.
- Dynamic topography detected temporal changes in the tear film, with SRI being more sensitive to lacrimal destabilization.
- Fluctuations in tear film parameters were observed throughout the day in symptomatic subjects.

## Abstract

This prospective, double-masked, contralateral study aimed to analyze and compare daytime changes in pre-lens tear film (PLTF) stability and optical quality in symptomatic subjects wearing two contact lenses (CL). A secondary goal was to assess the performance of the PLTF by using dynamic topography techniques and analyzing surface asymmetry and irregularity indexes (SAI and SRI, respectively). Measurements were conducted on 20 symptomatic subjects (OSDI score > 13). Participants were fitted contralaterally and randomly with spherical Delefilcon A and Stenfilcon A CLs and underwent a series of measurements over 3 consecutive days: three in the morning (after 1–2 h of CL wear) and three in the afternoon (after 7–9 h of CL wear). High- and low-contrast visual acuity (HCVA and LCVA, respectively), pre-lens NIBUT, and dynamic topography were assessed. The contralateral fit of the two lenses allowed a direct and better comparison between them since they were exposed to the same conditions during the day. Consequently, both lenses demonstrated similar performance in HCVA, LCVA, and PLTF stability, with no statistically significant differences between them, although some fluctuations were observed throughout the day. Dynamic topography proved sensitive in evaluating temporal changes in the PLTF. The SRI index showed greater sensitivity to topographic changes due to lacrimal destabilization, making it potentially valuable for evaluating dry eye patients.