Objectives: Contact lens wettability is an important issue for patients and practitioners as it has an impact on comfort and visual performance. In vivo wettability can be assessed by various means and evaluating the use of the point spread function (PSF) as a surrogate for lens wettability presents one option that may have advantages over other methods of assessment. One of the functions of the HD Analyser instrument is to record PSFs over 20 seconds to derive the objective scatter index (OSI). The aim of this paper is to explore the feasibility of using this instrument to evaluate in vivo contact lens wettability.

Methods: The OSI was measured in one subject wearing six different daily disposable contact lens materials in one eye on different days. Measurements were performed 5 minutes after application of the contact lens and again 3 hours later. For the purpose of comparison, the OSI data were fitted with trend lines.