ABO PRACTICE TEST - When discussing thick lenses, the factors which...

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ABO PRACTICE TEST

EXAM WITH CORRECT SOLUTIONS.

When discussing thick lenses, the factors which are considered

in computing the lens power are:

• front curve, thickness and index
• back curve, thickness and index
• front curve, back curve and thickness
• front curve, back curve, thickness and index - correct

answer- d. front curve, back curve, thickness and index

Toric transposition shows:

• lens thickness
• power in principal meridians
• the power of the ADD
• the lens diameter - correct answer- b. power in principal

meridians

Increasing the diameter of a minus power lens always

increases its:

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• vertex power
• center thickness
• weight
• refractive index - correct answer- c. weight

The optical center of a round segment is located:

• at the very top of the segment
• in the geometric center of the segment
• 5 mm from the top of the segment
• at the very bottom of the segment - correct answer- b. in the

geometric center of the segment

The base curve of any multifocal lens is found on the surface

containing the:

• cross curve
• cylinder surface
• segment
• ocular curve - correct answer- c. segment

Normal slab-off (bicentric grind) is ground on the lens whose

vertical meridian has the: 2 / 4

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• strongest curves
• most plus power
• least plus power
• least minus power - correct answer- c. least plus power

The refractive error indicated by the Rx +1.75 -2.75 x 090 is:

• compound hyperopic astigmatism
• compound myopic astigmatism
• simple myopic astigmatism
• mixed astigmatism - correct answer- d. mixed astigmatism

Tempering a lens by heat treating results in a lens being:

• less resistant to impact
• more resistant to impact
• more resistant to surface scratching
• impossible to break - correct answer- b. more resistant to

impact

A slab-off lens is for the correction of: 3 / 4

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• astigmatic errors
• excessive weight of lens
• excessive prism imbalance at the reading level
• exotropia - correct answer- c. excessive prism imbalance at

the reading level

Chem-tempering makes a glass lens more impact resistant by placing the lens in a potassium nitrate bath. The lens

undergoes a process known as:

• ion exchange
• iron oxide activation
• silver halide transfer
• thermal bleaching - correct answer- a. ion exchange

Which wavelengths of light have been indicated as possible contributors to the onset of cataracts?

• 400-520 nm
• 520-635 nm
• 350-400 nm
• 635-750 nm - correct answer- c. 350-400 nm
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