The effects of two longpass filters on visual performance

Area of Science:

• Ophthalmology and Optometry
• Visual Science
• Optical Engineering

Background:

• Spectacle filters can modify light transmission to enhance visual performance.
• Understanding the impact of different filter types on visual acuity and contrast sensitivity is crucial for lens design.

Purpose of the Study:

• To compare the visual performance and optical properties of three spectacle filters: a clear control, Standard Drive (STD), and Professional Drive (PRO).
• To evaluate the filters' effects on visual acuity under photopic, mesopic, and glare conditions, as well as contrast sensitivity.

Main Methods:

• Two groups of adults, progressive addition lens (PAL) wearers and single vision lens (SVL) wearers, were tested.
• Optical transmittance was measured using a spectrophotometer.
• Best corrected visual acuity (BCVA) under photopic, mesopic, and glare conditions, and photopic contrast sensitivity (CS) were assessed for each filter.

Main Results:

• Drive filters (STD/PRO) demonstrated improved visual acuity under glare compared to the clear lens for both PAL and SVL wearers.
• Mesopic visual acuity improved significantly for PAL wearers using Drive lenses.
• Contrast sensitivity showed improvements at specific frequencies for PAL wearers with Drive lenses; no significant differences in photopic visual acuity were found.

Conclusions:

• Drive lenses maintain or enhance certain visual functions, particularly in mesopic and glare conditions, compared to clear lenses.
• Improvements are attributed to reduced intraocular light scattering due to light attenuation below the filters' cutoff wavelengths.
• A majority of participants preferred the Drive lenses after a two-week trial period.