Purpose:
To compare the visual performance of scratched CR39 spectacle lenses with different antireflective (AR) coatings.
Methods:
20 subjects (mean age=28y) were tested monocularly while wearing two different plano CR39 lenses. The tested lenses were AR coated with either: (A) Crizal Avancé with Scotchgard Protector or (B) leading competitor AR. All the lenses used were subjected to the same Bayer abrasion test before use. The mean scores were 12 for lens A and 5 for lens B. The subjects were either emmetropic or corrected with contact lenses. Visual performance was tested in the presence of glare in an environment simulating nightime driving conditions, by measuring resolution thresholds of a tumbling "E" at 5 different contrast levels (~6% to ~100%) at a distance of 10M. Targets were presented by using a Cambridge Research Systems Ltd. ViSaGe on a SONY GDM-F20 CRT. A 4AFC linear staircase procedure was used.
Results:
Significant improvements in visual performance were seen at all contrast levels tested. The mean differences were 0.04 LogMAR (about half a VA line) (p<0.01)
Conclusions:
The improved scratch resistance of the new AR coatings can provide significant visual benefits in visually challenging environments such as during night driving. There could be potential implications on safety when lenses get abraded after long periods of use.
Keywords: visual acuity • spectacle lens