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contact lenses > Soft Lens > Flashcards

Soft Lens Flashcards

1
Q

Clear Clear Clear represents what?

A

Good fit

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2
Q

Clear Blurry Clear represents what?

A

Lens fit flat

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3
Q

Blurry Clear Blurry represents what?

A

Lens fit steep

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4
Q

Lens Fit Assessment (soft)

A

-Contact Lenses should be comfortable immediately
upon placement on the eye

  • CLF should ensure that the
  • Lens is free of foreign particles such as dust or lint
  • Lens is not inverted prior to placement on them eye
  • Allow the lenses to settle on the eyes for approximately 5 to 10 minutes. This allows time for the patient to adapt to the lenses and time for the lens to equilibrate
  • Be aware: Reflex tearing due to an uncomfortable lens may cause the lens to stop moving and give the appearance of a tight fit.
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5
Q

Well Fitted Lens

A
  • Good centration with full corneal coverage in all direction of gaze
  • Sufficient movement to allow tear exchange under the lens during the blink
  • 0.1 to 0.5 mm is generally considered optimal
  • Satisfactory Push Up Test
  • a reliable indicator of a good fit
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6
Q

How is the Push Up Test performed?

A
  • With the patient looking straight ahead, the contact lens fitter will put his or her index finger on the patient’s lower lid margin and gently nudge the edge of the lens upward.
  • Lens will move freely when pushed upward with fingertip pressure and return quickly to its original position.

-Final check is for Good comfort and stable visual
response (with over refraction)

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7
Q

Tight Fitting Lens

A
  • Also known as Steep Lens Fit
  • Insufficient or no lens movement during the blink in primary or upward gaze
  • Unsatisfactory Push Up Test
  • Lens will resist movement.

-On upward nudge the lens may remain
decentered

-Or return slowly to its original position

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8
Q

Flat Fitting Lens

A
  • Also known as a Loose Fitting Lens
  • Reduced comfort
  • Lower lid sensation
  • Poor centration with limbal exposure on exaggerated eye movement
  • Lens edge standoff
  • Excessive lens movement during the blink in primary or upward gaze
  • Unsatisfactory Push Up Test
  • Move easily but may remain decentered or slip under the upper lid
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9
Q

Advantages of Silicone hydrogel lens

A
  • High Dks.
  • Good for prolonged wear.
  • Quick to adapt to.
  • Good for those with vascularization.
  • More hydrating.
  • More rigid which makes it easier to handle.
  • Doesn’t break as easily/can be stretched.
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10
Q

Disadvantages of Silicone hydrogel lens

A
  • Designs are limited.
  • Mostly disposables.
  • High chance of CLIPC.
  • High chance of arcuate staining.
  • More costly.
  • Often shows mucin b
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11
Q

Disadvantages of disposable lenses

A
  • Fittings and powers are limited.
  • Not many options for torics or bifocals.
  • More costly on an annual basis.
  • Uncertain with patient compliance.
  • Cannot check lenses before dispensing.
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12
Q

Advantages of disposable lenses

A
  • It is rare for build up of deposits.
  • Less risk for allergies and infections.
  • Lens cleaning requires very little time and effort.
  • There are always spare lenses.
  • Save on solution.
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13
Q

Ballasted lens

A

Cross-sectional shape with a thicker bottom (prism) to keep the lens from rotating and to weigh it down

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14
Q

Truncated lens

A

Lens is cut at top and bottom to help with design stabilization

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15
Q

Toric Lens

A

Two different radii (BC)

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16
Q

Front surface toric

A

Anterior surface has two base curves and posterior has spherical back

17
Q

Back toric lens

A

Anterior surface spherical posterior has

two base curves

18
Q

Bitoric lens

A

Both anterior and posterior has different

radii

19
Q

Prism Ballast Design

A

Lens will have1.0 or 1.5 prism diopters
base down with a maximum of 3 prism
diopters

•
The thinner portion of the lens lies under the
upper eyelid
•
squeezes the thicker portion of the lens
towards the lower lid
Prism Ballast Design
20
Q

Dynamic Stabilization

A

A technique that depends on the
interaction between the lids and front
surface of the lens

21
Q

Peri ballast

A

the lens has a high minus power
lenticular carrier with superior portion of
the lens edge thinned to produce a
prism like rotational stabilization effect.

22
Q

Truncation

A
  • Truncation used with RGP
  • It works by removing 1 1.5mm chord from the lower edge of the lens
  • excellent stability
  • poor comfort
  • Easy to observe on the eye
  • Not good for oblique astigmatism
  • Not able to mass-produce
  • Not available with Disposable lenses
23
Q

Back Surface Toric

A 
• Back surface toric has a natural
stabilizing effect when placed in side by
side to an equivalently toroidal cornea
because least elastic distortion occurs
when the lens is correctly aligned

• Better stability achieved when used in
conjunction with another stabilizing
design, like prism ballast

contact lenses (4 decks)

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