Contrast sensitivity through hybrid diffractive, Fresnel, and refractive prisms.

Area of Science:

• Optometry and Vision Science
• Ophthalmic Optics
• Visual Performance

Background:

• Prisms, including Fresnel and refractive types, are clinically used for diagnosis and therapy.
• This study investigates the impact of prisms on contrast sensitivity, expanding on previous visual acuity research.

Purpose of the Study:

• To evaluate and compare the contrast sensitivity function (CSF) through membrane Fresnel, refractive, and novel hybrid diffractive prisms (ComPrisms).
• To assess the effect of varying prism powers (20Δ, 30Δ, 40Δ) on contrast sensitivity.

Main Methods:

• Contrast sensitivity was measured using Vistech CSF charts in 21 (monocular) and 20 (binocular) subjects.
• Measurements were taken without prisms (unaided) and with Fresnel, refractive, and ComPrisms at 20Δ, 30Δ, and 40Δ.

Main Results:

• Significant effects of prism type, power, and measurement condition (monocular/binocular) on contrast sensitivity were found.
• ComPrisms demonstrated a slower rate of contrast sensitivity reduction compared to refractive and Fresnel prisms as power increased.
• The area under the CSF curve was reduced by all prisms, but less so with ComPrisms.

Conclusions:

• ComPrisms provided significantly better contrast sensitivity than refractive or Fresnel prisms of equivalent power.
• All prism types reduced contrast sensitivity relative to the unaided condition.
• Significant binocular summation in contrast sensitivity was observed across all conditions, including with prisms.