Dispensing and Fitting Procedures Flashcards

Which ANSI Z80.1 tolerance applies to the spherical power of a finished ophthalmic lens with a prescription of -4.00 D sphere?

Answer: ±0.13 D

ANSI Z80.1 allows ±0.13 D tolerance for spherical powers between -3.375 D and -6.375 D.

A patient with anisometropia requires the optical centers of the lenses to be at different heights. This is best described as:

Answer: Slab-off correction

Slab-off (or reverse slab-off) grinds prism into the reading zone of one lens to equalize the vertical imbalance caused by anisometropia.

During frame selection, you notice a patient has a very narrow nose bridge. Which frame feature should you prioritize?

Answer: Adjustable nose pads on pad arms

Adjustable nose pads on pad arms allow precise customization to fit a narrow nasal bridge securely and comfortably.

When fitting a bifocal lens, the standard placement for the flat-top segment top is:

Answer: At the lower limbus of the eye

The standard flat-top bifocal segment top is placed at the lower limbus so it is accessible in downgaze without disrupting distance vision.

A patient experiences swim and distortion when wearing new progressive lenses. Which adjustment is MOST likely to help?

Answer: Adjust pantoscopic tilt to match the prescribed value

Correcting pantoscopic tilt aligns the progressive lens zones to the patient's line of sight, reducing peripheral swim and distortion.

What does the term 'effective diameter' (ED) mean in lens ordering?

Answer: The smallest circle that encloses the entire frame aperture

Effective diameter is the diameter of the smallest circle that circumscribes the frame aperture, used to determine the minimum blank size needed.

Which condition describes lenses that are not level with each other in the finished frame?

Answer: Frame unleveling or tilt

Frame unleveling (tilt) means one side of the frame front is higher than the other, causing the lenses to be at different heights relative to the eyes.