Total visual experience is multifaceted—it does not just include visual acuity. Contrast sensitivity, spatial awareness, discriminating efficiency, visual endurance, and sensations of visual and physical comfort are all factors that contribute to total visual experience and vision performance.1,2
Light filtering can impact some of the measures of visual performance including:
- Disruption of vision due to bright light, which includes both a temporary impairment of vision and transitory irritation caused by light. These disruptions can reduce vision and give temporary discomfort when exposed to bright light, like engaging in outdoor activities on a bright day
- Chromatic contrast, which can affect how colours are determined in a colourful visual scene, like distinguishing green trees from a blue sky
- Squint response, a coping behaviour that attempts to lower uncomfortable levels of light
- Visual range, which is affected by blue light scatter, like that caused by the atmosphere
Spectral filters can increase tolerance and enhance these performance measures. Light filtering can increase visual comfort during exposure to bright light, and can accelerate photostress recovery (the aftereffect of the exposure).3,4 Filters can also help to reduce squinting and starbursts, and can block the short wavelengths associated with blue haze. The use of spectral filters can help improve spatial vision through better detection of the edges of objects in a scene,5,6 which can positively impact chromatic contrast.
The use of spectral filters has been shown to improve functional vision compared to clear controls in both spectacle and IOL corrections. A recent study has shown meaningful improvement in the same measures for a first-of-its-kind photochromic contact lens.7
ACUVUE® OASYS contact lenses with Transitions™ Light Intelligent Technology™ provide both vision correction and a photochromic filter that helps balance the light entering the eye.
| Measure | Results | Improvement compared with clear lens |
|
Irritation caused by light Temporary impairment of vision |
Significantly improved (P<0.05) with activated photochromic Gray 1 lens vs clear lens, as quantified by both the squint and subjective responses (P<0.05). Significantly improved (P<0.05) with activated photochromic lenses tested vs clear lens.
|
Approximately 20% improvement*
Approximately 13% to 20% improvement |
| Photostress recovery time |
Significantly reduced (P<0.05) recovery time with activated photochromic Gray 1 lens, as quantified by both the squint and subjective responses (P<0.05). |
Approximately 33% improvement in recovery time |
| Chromatic contrast |
Significantly improved (P<0.05) with activated photochromic lenses tested vs clear lens. Improved chromatic contrast indicated when viewed through Gray 1 photochromic lens. |
Approximately 13% to 20% improvement |
*Note this response, as a psychological variable, is nonlinear.
Table 1: Summary of the effect of photochromic spectacle lenses on visual performance.
