What Is Decenter On Eye Prescription

Pantoscopic Tilt Angle – Angle of a spectacle frame tilted towards the cheek and away from the eyebrows. Correct pantoscopic tilt allows for better vision through the lens and a more pleasing cosmetic alignment. Parameter – A constant or variable whose value determines the precise form or performance of an object or procedure. Paraoptometric – Works under the direct supervision of a licensed doctor, collects patient data, administers routine technical tests of the patient’s visual capabilities and assists in office management.

These skills permit the individual to develop the concepts of left, right, front, back, up, and down. Specific Gravity – This measurement of weight is expressed in grams per cubic centimeter.

Eyeglass Lenses

Different eye conditions resulting in night blindness or poor night vision include pupils that become smaller with age, cataracts, nearsightedness, retinitis pigmentosa, or Vitamin A deficiancies. Nodal Point – The point on the optical axis to which entering and emerging rays are directed. Nominal Power – The nominal curve of a semifinished lens marked in diopters by the product manufacturer.

Uniform Density Lens – A lens with luminous transmittance which does not vary significantly over the entire section of the lens. Unilateral – Discussing one side of the top, face or body.

What Is Prismatic Effect?

geometric center; usually expressed in 0.1 mm utilizing a caliper. B “B” Box Measurement – In lens measurement, the longest vertical distance from the uppermost point to the lowermost point of a shape. Back Focal Length – The length from the trunk surface of a lens to the image of an infinitely distant object.

• Because the lens is rotated by rotating the cup, any decenter in the lens may cause the focusing beam to diverge and trace out a circle of radius Δ at the rear focal plane .
• Chiasm – The low portion of the brain at which point both optic nerves intersect.
• U Ultex Bifocal – A one-piece bifocal having an arced top, wider in diameter than a round segment.
• Occluder – An opaque plastic spatula device used to cover one eye during examination.
• Corneal Topography – Mapping or examination of the surface of the cornea.