Questions and Answers
What is comprised of the same tissue as the cornea, but is opaque instead of transparent?
Sclera
The ability of the crystalline lens to change shape and therefore focus is called?
Accommodation
Soft contact lenses are also known as?
Hydrogel
Which type of lens design corrects astigmatism by providing more than one power throughout the lens?
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A break in the corneal epithelium that will often result in pain, light sensitivity, and excessive tearing is a?
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Which lens modality is the only one not approved for use with solutions?
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The average horizontal corneal diameter is?
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What piece of equipment is used to measure the base curve of a GP contact lens?
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What are the two basic scales used on a corneal topographer?
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If fitting an apical alignment lens 0.50D later than flat K, what would the base curve be in the K reading of 42.00 @ 180/ 43.00 @ 90?
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A progressive, non-inflammatory condition in which the cornea thins and bulges forward is called?
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The crystalline lens is responsible for approximately how much refractive power?
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Which lens tint is used to aid in handling only and doesn't alter the patient's natural eye color?
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Two-thirds of the eye's refractive power is provided by?
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A build-up of fluid in the cells is called?
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In order to reduce the risk of damaging a GP lens during modification because of heat, it is important to?
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If a GP lens is fit 1.00D flatter than flat K and the RX is -3.50 -2.50 x 180, what would be the power of the lens?
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At what point do contact lens powers need to be vertexed?
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At what point should a toric lens be considered for a soft lens candidate?
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The evaluation of a contact lens fit is done with which of the following pieces of equipment?
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How much overlap onto the seller should there be in every direction for a well-fitted soft lens?
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Scleral indentation is an indication of what type of lens fit?
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What can be used to evaluate the blends of a GP lens?
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The corneal topographer is based on the principles of the?
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In a fluorescein pattern, areas of bright green indicate?
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When converting diopters to mm of radius, every 0.25D equals approximately?
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The lens treatment that increases the mass at its bottom in order to prevent rotation for toxic and bifocal contact lenses is called?
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The K reading 43.00 @ 180 / 46.00 @ 90 reflects what type of astigmatism?
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What is the term used for soft contact lenses that are worn overnight?
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The total refractive power of the average eye?
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Which layer of the cornea is regenerated every three to seven days?
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What type of modifications can not be made in an office?
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The K reading 45.00 @ 180/ 44.00 @ 90 reflects what type of astigmatism?
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The specific gravity of a material is the same as its?
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What was added to rigid materials to increase the amount of oxygen transmitted through the lens?
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The lining of the eyelids is called the?
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When a person can see at 20 feet what a normally sighted person can see at ____ feet, they are said to have 20/40 vision.
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Study Notes
Contact Lens and Eye Anatomy Facts
- Sclera, made of the same tissue as the cornea, is opaque instead of transparent.
- Accommodation refers to the ability of the crystalline lens to change shape for focusing.
- Soft contact lenses are commonly referred to as Hydrogel.
- Toric lens designs correct astigmatism by incorporating multiple powers.
Eye Conditions and Measurements
- A corneal abrasion is a break in the corneal epithelium resulting in pain, light sensitivity, and excessive tearing.
- The average horizontal corneal diameter measures 14.0mm.
- Keratoconus is a progressive condition leading to corneal thinning and bulging.
Contact Lens Types and Fitting
- Disposable lenses are the only type not approved for use with solutions.
- Base curve for an apical alignment lens fitted 0.50D steeper than flat K readings of 42.00 @ 180/ 43.00 @ 90 is 41.50D.
- Two basic scales on a corneal topographer are absolute and normalized.
Light Sensitivity and Refractive Power
- The crystalline lens contributes approximately 15.00D to 16.00D of refractive power.
- Two-thirds of the eye’s refractive power is provided by the cornea.
Handling and Evaluating Contact Lenses
- Visibility tints help in handling lenses without altering natural eye color.
- Slit Lamp is the equipment used for evaluating the fit of contact lenses.
- Areas of bright green in fluorescein patterns indicate space between the cornea and contact lens.
Modifications and Lens Characteristics
- Scleral indentation indicates a tightly fitted soft lens.
- Use ample water and polish to reduce damage risk during GP lens modifications.
- Modifications that increase overall diameter cannot be performed in an office setting.
General Knowledge on Eyes and Lenses
- The total refractive power of the average eye is 60 diopters.
- The cornea's epithelium layers regenerate every three to seven days.
- Every 0.25D of diopter change approximates a 0.05mm change in radius when converting to mm.
- Prism ballast is used to increase the mass at the bottom of bifocal contact lenses to prevent rotation.
- The term "continuous wear" refers to soft contact lenses that can be worn overnight.
Studying That Suits You
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Description
Test your knowledge of key terms and concepts from the Optied NCLE study materials. This quiz covers important vocabulary related to the eye's anatomy and contact lenses, including definitions and functions. Perfect for anyone preparing for the NCLE exam.
