Ophthalmic Optics Flashcards

What is the purpose of an anti-reflective (AR) coating on spectacle lenses?

Answer: To reduce surface reflections and improve light transmission

AR coatings reduce surface reflections through destructive interference, increasing the amount of light transmitted through the lens and reducing glare.

Which lens design divides the lens into two zones — distance on top and near on the bottom — with a visible dividing line?

Answer: Bifocal lens

A bifocal lens has a visible flat-top or round segment for near vision at the bottom and the distance prescription in the main lens above.

What does base curve refer to in ophthalmic lens fabrication?

Answer: The curve on the front surface of the lens

The base curve is the curvature of the front (convex) surface of a lens, which influences the overall form and optical performance of the finished lens.

Polycarbonate lenses are preferred for children and safety eyewear primarily because of their:

Answer: Lightweight and high impact resistance

Polycarbonate is highly impact-resistant and lightweight, making it the preferred material for safety eyewear and children's glasses.

A prism prescribed as '2Δ base up OD' would displace the image in which direction for the right eye?

Answer: Downward

Base-up prism displaces the image downward, which is used to correct hyperphoria (eye deviating upward).

What is chromatic aberration in ophthalmic lenses?

Answer: The separation of white light into its component colors by the lens

Chromatic aberration occurs because a lens refracts different wavelengths of light by slightly different amounts, causing colored fringes at the edges of objects.

What is the primary optical advantage of a lenticular lens design?

Answer: Improved cosmetic appearance for very high prescriptions

Lenticular lenses place the optical correction in a central 'bowl' surrounded by a carrier lens, reducing edge thickness and weight for very high prescriptions.