Modified optical coherence tomography enabled dynamic evaluation of minute contact lens movements and ocular surface contours, according to a study.
“Combining the ultrahigh-resolution and ultralong-scan-depth OCT devices for the determination of the lens movement may provide a new, different and practical approach to evaluate contact lens movement at the micrometer scale and provide useful information in the characterization of the lens fitting,” the study authors said.
The study included 10 subjects with a mean age of 31.2 years. Four different types of commercially available soft contact lenses were tested on subjects’ left eyes.
Investigators used a custom-built spectral-domain ultrahigh-resolution and ultralong-scan-depth OCT system to image ocular surface contour and contact lens edges at primary, temporal and nasal gazes. Inferior lens edges were imaged constantly to track vertical movements during blinking.
Excursion lag, the distance between the location of the lens edge while gazing forward and its location immediately after the eye is turned nasally or temporally, was also evaluated. Lag results when inertia of the lens causes the lens to move more slowly than the eye, the authors said.
Patients were tested after 10 a.m. to obviate effects on the tear film induced by sleep.
Study results showed that excursion lag at the horizontal meridian was 366 μm at temporal gaze and 320 μm at nasal gaze.
Lens uplift at the vertical meridian was 342 μm after blinking. Blink-induced lens uplift lowered by 104 μm and lifted 342 μm after the blink.
Different lenses varied significantly in terms of horizontal lag and vertical movement (P
< .05), the authors said.