Socrative Flashcards
A prism ballast GP lens requires how much prism for proper orientation?
0.75 to 1.50D (She says in most cases)
In against-the-rule astigmatism, the short/ steepest corneal meridian:
At or near 180
In with-the-rule astigmatism, the longest/flatest corneal meridian:
At or near 90
What is the term for the condition in which there is loss of vision without any apparent disease to the eye?
Amblyopia
is the absence of an iris
Aniridia
What should be suspected when there are large fluctuations in a patient’s refractive error?
In diabetics, the sudden shift in blood sugar levels can cause changes in the refractive error
Corneal edema, a sensation of soreness. injection, foggy vision and ghost images usually indicate:
A lens that prevents tear exchange and elimination of corneal debris and metabolic waste products may cause corneal edema which could be due to a tight-fitting lens
What does it mean when we say the soft lens must equilibrate on the eye?
The polymer of the lens must reach the same temperature as the tear film 98.6 degrees
Punctal occlusion may be most beneficial for?
Tear deficient dry eye, occlusion of the lacrimal drainage apparatus simply increases tear volume by slowing the rate of outflow.
In a GP lens, a poorly finished transitional zone between the optic zone and the lens edge can be evaluated by:
Profile analyzer which helps in evaluating the quality of the peripheral blends of a GP lens.
A patient will have a much greater awareness of a loose lens and may experience a constant foreign body sensation when wearing a lens that…
Is too loose
Soft lenses fit steeper than K
A soft lens that is fit steeper than K will vault the cornea centrally and seal off around the periphery. Vision will fluctuate with each blink
It is important that the practitioner inform the patient not to use lotions, creams, make-up, sprays and all cosmetics (before/after) lens insertion.
before
Things to be documented with a patient:
the care system the patient is using and any systems they had problems with, as well as lens parameters and materials are all vital pieces of information to have documented in the patient’s permanent record.
With a rigid contact lens in place, a fluorescein pattern shows a concentration of fluorescein inferiorly and superiorly beneath the lens. Which one of the following types of astigmatism is represented by this pattern?
With the rule astigmatism: the flattest corneal curvature is horizontal and steepest curvature is vertical.
Fluorescein will be absent or minimal where the cornea is (flatter/steeper), and pool or collect where the cornea is (flatter/steeper).
Flatter
Steeper
Astigmatism that is inside the eye and not on the cornea.
lenticular/residual astigmatism
The base curve of a rigid lens was ordered 7.84mm and was received measuring 7.94mm. this lens is ________than ordered.
0.50 flatter
Every 0.05mm of radius equals approximately 0.25 diopters. The lens ordered was 43.00D, but was received as a 42.50D
Which of the following modifications to a gas permeable lens can be made in the office?
Blending of peripheral curves
Polishing lens surface
Addition of minus power
Which of the following modifications to a gas permeable lens can not be made in the office?
Changing the base curve
Application of fluorescein should be used in…
Evaluations of gas permeable lens fit
The main purpose of a rigid lens wetting solution is to:
Convert the hydrophobic surface of a rigid lens to one that is temporarily hydrophilic
If a soft contact lens is not properly neutralized, how does residual hydrogen peroxide affect the cornea?
It is likely to cause epithelial damage
contact lenses that have a non-spherical back surface are called:
Aspheric lenses