ABO Industry Standards Flashcards

In ophthalmic lens standards, what is the 'optical center' of a single vision lens?

Answer: The point on the lens where prismatic effect is zero

The optical center is the point on a lens through which light passes without being deviated (zero prismatic effect).

What is the standard pupillary distance measurement method used when fitting progressive addition lenses?

Answer: Monocular PD measured from each pupil to the bridge

For PALs, monocular PD is the preferred method, measuring from the center of each pupil to the bridge of the nose independently.

According to FDA regulations, which lens material is exempt from the standard dress impact (drop-ball) test requirement?

Answer: Glass lenses over 3mm thick

FDA regulations exempt glass lenses that are at least 3mm thick at their thinnest point from the drop-ball impact test.

What does the 'Abbe value' of a lens material indicate?

Answer: The degree of chromatic aberration (color dispersion)

The Abbe value (V-number) measures chromatic aberration; a higher value means less color fringing and better optical clarity.

Which organization publishes the ANSI Z80 series of ophthalmic standards in the United States?

Answer: The American National Standards Institute

ANSI (American National Standards Institute) publishes and maintains the Z80 series, which includes standards for ophthalmic lenses, frames, and instruments.

Under ANSI Z80.1, the distance power tolerance for lenses with power greater than ±6.50D is:

Answer: ±2% of the power

For lenses with powers greater than ±6.50D, ANSI Z80.1 specifies a tolerance of ±2% of the specified power.

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

Answer: To reduce surface reflections and improve light transmission

AR coatings use thin-film interference to cancel surface reflections, increasing visible light transmission and reducing glare.