RLX Coating

Scratch-Resistant coating.

Roll and Polish

A rolled edge is created when the edge of a lens is beveled down to reduce edge thickness. Edge is then polished for cosmetic purposes. Getting an edge polished is strictly the wearer’s preference.

Roll Edge

Same as above without the polish.

Safety Glasses

Protective eyeglasses with a minimum lens thickness of 3.0mm (1mm thicker than conventional lenses). Special (stronger) frames must be used instead of conventional dress frames.

Scratch Protection Plan

A warranty which ensures that if the coating does not prevent scratches it will be replaced at no additional charge.

Scratch Resistant Coating

Many lenses manufactured today automatically come with a basic scratch resistant coating. Although scratch resistance does not mean 100% scratch proof, it can help to prevent minor scratches that can occur with daily wear. This is different from the Scratch Protection Plan offered by Davis Vision.

Single Vision Lenses

See Lens, Single vision.


See Lens Size.

Slab Off

Used when there is a significant difference in powers for each eye on a patient’s prescription. Used when patient experiences a prismatic effect or image displacement due to anisometropia.

Specialty Lenses (Myodisc, Lenticular Grind, Double Sided Grind)

See Lens, Specialty.


Another term for eyeglasses. An ophthalmic device consisting of two ophthalmic lenses and a supporting frame to position and retain the lenses in proper optical alignment with the eyes.


The prescription power, in diopters, that corrects for hyperobia or myopia.

Subjective Examination

An eye test using patients’ responses to help determine the prescription for glasses.


The part of the frame attached to the frame front that runs along the side of the face and rests over the ears. Consists of the shaft, the bend and the earpiece.


Normal tints that can be added to lenses to block between 5% and 20% of light. A darker tint is also available, which blocks up to 88% of light. The UV coating is always recommended with a sunglass tint. The most common tint colors are grey, green and brown.

Tint, Gradient

Tint is darker at the top and gradually lightens towards the bottom.

Tint, Solid

A lens dyed or coated with pigment of uniform color and density, which causes rays of light to be refracted.


Photochromic lenses that turn dark when exposed to the ultraviolet rays of the sun.

Trifocal Lens

See Lens, Trifocal.


Lens that offers similar lightweight and impact resistant characteristics like polycarbonate but offers better clarity then poly due to higher Abbe value.