CL Review Flashcards
A diffuse throws out a large illumination. This is good for general survey of the cornea.
t/f
true
Direct illumination is used for a sharp focus of 2mm or less.
t/f
true
A 1-2mm beam gives a parallel piped section that separates the anterior and posterior cornea.
t/f
true
A narrow slit, called an optical section, allows the observer to see individual layers of a transparent structure.
t/f
true
Direct illumination is best used for... opacities endo deposits scratches on the lens surface all of the above
all of the above
Optical section is used to determine which layer of the cornea is involved, detect irregular topography, and to view the lens/cornea relationship.
t/f
true
Specular reflection is used for detecting hazy lenses, fine epithelial edema, endo cells, and the surface of the crystalline lens.
t/f
true
Indirect beam is very useful for inspecting opaque structures such as lids and lashes, scleara and conjunctiva.
t/f
true
Retro is used for viewing corneal vascularization and scarring, edema and myocists, deposits on the contact lens or cornea.
t/f
true
Sclerotic Scatter produces a halo effect, and is used for detecting opacities, central corneal clouding or patch edema.
true
Keratometer mires, va, and retinoscopy reflex blurry but clear immediatly after blink indicates a ____ fit.
loose
tight
well
tight
Circumcorneal injection and indention and good initial comfort are a indication of a ____ fit
well
tight
loose
tight
Poor centration, excessive movement, and edge stand off are an example of a ____ fit.
tight
loose
well
loose
Keratometer mires, va, and retinoscopy reflex clear but blur immediately after blink is an example of a ____ fit.
loose
tight
well
loose
With the rule, flattest K at 90
t/f
true
Flattest K at 90 is ATR.
t/f
true
Oblique is flattest k between 30 and 60 or 120 and 150.
t/f
true
Irregular is when the flattest and steepest meridians are noticeably more or less 90 apart.
t/f
true
Lenticular/internal astigmatism is created by a surface other than the anterior surface of the cornea.
t/f
true
Total/refractive astigmatism found in the spectacles rx.
t/f
true
Residual astigmatism is wha remains after a contact lens is fit to the cornea.
t/f
true
Calc. residual astig.
- Determine the amount and type of astig.
- with the rx in (-) cyl, determine amount and type of refractive astig.
- If they’re the same, subtract. If they’re opposite, add.
If we find more than 1.00D of residual astigmatism, the pt will usually require a front surface toric lens.
t/f
true
If the flattest and steepest meridians differ by more than 3.00D, the pt will usually require a back surface or bitoric design.
t/f
true
Peripheral limbal staining at 3:00 and 9:00 is a result of exposure causing limbal dryness.
t/f
true
A contact lens wearer may experience edema of the cornea because of a absorption of tears into the cornea.
t/f
true
The subjective symptom of edge flare or reflection with a contact lens is aggravated by tearing.
t/f
true
A stinging and burning sensation which occurs each day after several hours of wear may be caused by a contact lens which has a stagnation of fluid build up behind the lens.
t/f
true
A ______ is used to check for lens warpage.
radiuscope
lensometer
measuring magnifer
measuring magnifer
If fogging occurs immediatly upon insertion, the lenses were not cleaned properly.
t/f
true
Bubbles trapped under a rigid lens may result in _____.
dimple veiling
stippling stains
stippling stains
F/U K readings on an adapted rigid lens should be with-in ____ from the original readings.
.50
1.00
.75
.50
Rose K is the latest design for keratoconus.
t/f
true
A patient has a possible acuity of 20/25 but has anaridia and photophobia, would a opaque cosmetic lens with optics be used?
t/f
true
Corneal scars benefit from an X-chrom or Ruby Red lens.
t/f
true
A prism ballast RGP lens requires 0.75-1.50D prism for proper orientation.
t/f
true
Prism ballast, double slab off, and peri ballast are all used for soft toric lens designs.
t/f
true
A segmented is an example of a translating bifocal design.
t/f
true
A bifocal lens where the power gradually changes from the central area of the lens to the periphery is known as an aspheric lens.
t/f
true\
When fitting a rigid back surface toric, appox. _____ % of the corneal toricity may be placed on the posterior lens surface.
75
66
50
66%
What type of illumination is best used for checking lens postion & movement, TBUT, corneal staining, and blinking reflex?
Diffuse
direct
sclerotic
diffuse
