The impact of toric contact lens correction upon functional near visual performance with digital devices

Although it is well known that astigmatism correction with toric contact lenses improves clinical vision measures, their effects on real-world visual performance using digital devices such as smartphones are less well understood. This study aimed to examine how toric soft contact lenses impact functional near visual performance with a smartphone, in comparison to spherical equivalent contact lenses.

Fifteen healthy young adults (mean age 23.6 ± 2.8 years) with low to moderate astigmatism (-0.50 D to -1.50 D) participated in this prospective, repeated measures randomised crossover trial. Either toric or best sphere soft daily disposable contact lenses (lens material Verofilcon A) were worn during two separate study visits. At each visit, near visual acuity (VA) was assessed, and participants performed a reading task on a smartphone with both high and low contrast text displays. A mobile eye tracker was worn during the reading task to track objective measures of visual fatigue such as palpebral aperture height and near focusing demand.

Both high and low contrast near VA were significantly better with the toric correction compared to the best sphere (p = 0.001). While reading on a smartphone, the average reading speed was not significantly different between the sphere and toric lenses (p = 0.18). Significantly fewer errors were made while reading with the toric lens compared to the best sphere lens for the low contrast (p = 0.04), but not for high contrast text (p = 0.4). For measures of palpebral aperture height, and focusing demand, a significant lens by time interaction was found (both p < 0.05), with a significantly greater focusing demand and a narrower palpebral aperture observed towards the end of the reading task with the best sphere lens.

Significant visual and functional benefits were found for digital near visual tasks associated with toric contact lens correction.