refractive

If the surface is refractive/reflective, recursively shoot one more ray calculating the right direction, with correctly diminished intensity and follow the same process.

Absence of this dopamine cycle may cause the eyeball to be more elongated, leading to refractive errors.

How is this any different than materials that change color or refractive index based on temperature?

As it approaches the smoke point, its refractive index will change and its viscosity will decrease, giving a dimpled appearance.

No explanation of how they do it and: Internal studies show Opternative’s exam performing equally to a traditional refractive eye exam.

But sapphire has a higher refractive index than gorilla glass (1.77 vs 1.5 or thereabouts) and thus reflects more at each surface.

How you see if your mix has the same refractive index as the glass I haven't figured out yet.

The important part is that refractive index is dependent on wavelength and so you get dispersion, which increases with the distance between surfaces.

Such a system can potentially be very small because there's no refractive optics.

No, the speed of light decreases in a medium – in fact, the proportional decrease in speed is the refractive index of the material.

The authors here introduce the study of the glial 'supporter' cells and their refractive indices as wave guides for light to the receptive cells.

If the scratches are on the glass it could work even better to use a liquid with the same refractive index as the glass.

Edit: Their disclaimer at the bottom says: "Opternative’s technology is only intended and suitable for use by licensed eye care professionals to perform online refractive eye exams on patients between the ages of 18-40 and in good health." I am now confused.