Anti-reflective coatings reflect ultraviolet radiation

Area of Science:

• Ophthalmology
• Materials Science
• Optical Engineering

Background:

• Anti-reflective (AR) coatings enhance spectacle lens visual performance.
• AR coatings typically focus on visible light, neglecting ultraviolet (UV) spectrum reflectance.
• UV radiation reflected from spectacle lens back surfaces poses a risk to wearer's eyes.

Purpose of the Study:

• To evaluate the UV reflectance and transmittance properties of spectacle lenses with and without AR coatings.
• To assess the impact of lens materials, coatings, and frame parameters on UV radiation exposure.
• To determine optimal eyewear designs for mitigating UV radiation risks.

Main Methods:

• Spectrophotometric analysis of lens transmittance and reflectance across UV and visible spectra.
• Testing of various clear and tinted lens materials with and without AR coatings.
• Evaluation of eyewear configurations, including frame wrap and lens base curve.

Main Results:

• AR coatings confirmed to improve visible light transmittance.
• Most tested AR coatings reflected unacceptably high levels of UV radiation.
• Tinted lenses showed similar issues with UV reflectance.
• High wrap frames with high base curve lenses effectively blocked UV radiation.

Conclusions:

• Standard AR coatings may increase ocular UV exposure due to back-surface reflectance.
• Eyewear design (high wrap, high base curve) is critical for UV protection.
• Clear, flat lenses, even with tints, are insufficient for long-term sun protection.