Fit Char Flashcards

1
Q

Sag GREATER: (steeper/flatter), (tighter/looser) (stable/unstable)

-how about when sag is decreased?

A

steeper; tighter; stable (but suction cup!)

decreased: flatter, looser, unstable (rocking effect!)

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2
Q

T/F: it is possible to match sagittal depth with the corneal surface (an ideal fit)

A

false. Aspheric corneas don’t match spherical sags - close as possible is the only option

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3
Q

U____ distributed tear thickness gives the greatest adhesional forces

A

uniform - IDEAL tear-lens thickness = 5-10microns

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4
Q

flat = LESS curved = (longer/shorter) radius of curvature

A

LONGER - remember; they’re inverse!

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5
Q

What is the most stable fitting relationship?

A

alignment

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6
Q

STEEP fit results in a (thicker/thinner) tear layer in the central portion of the lens

A

thicker centrally - edges and pushing it up!

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7
Q

if the patient is tearing excessively, how will that affect the lens fit?

A

will make it fit LOOSER than actual; give ‘em proparacaine to decrease reflex tearing

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8
Q

T/F: if a LA fit is desired, it’s ok to let the lens rest slightly superior to the upper limbus (since it’s under the upper lid anyway)

A

FALSE. Lid attachment should only be attempted with the upper lid actually covers the sup limbus slightly in NORMAL straight-ahead gaze. Should position superior, but not THAT superior

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9
Q

Movement - interpalpebral - describe it.

What’s the difference w/ LA mvmt?

A

interpalpebral - down w/ blink, up a LITTLE when completely closed, pulled up w/ opening, slight drop when completely open (centers itself)

LA - follows the motion of the lid. Down on downgaze, STAYS down w/ complete closure, follows it up on upgaze

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10
Q

T/F: lens is still acceptable if it goes slightly past limbus on lid closure w/ a LA fit

A

true - as long as it’s not excessive

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11
Q

Lens should move (with/against) motion of eye when moving laterally. What happens in a tight fit?

A

AGAINST (slightly)

- too tight? lens isn’t falling behind slightly

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12
Q

which way does the lens usually ROTATE when blinking? (compare temporal to nasal)

-what aspect of lens characteristics is rotation an issue?

A

temporal aspects move DOWN, nasal move up. RE goes CC when looking @ pt, LE goes clockwise

bifocals, torics (rotation matters!)

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13
Q

Does the lens rotate more with the upper or lower lid? In which way does it rotate w/ lid closing? Opening?

A

LOWER lid - upper contributes very little (inf lens edge moves w/ lower lid)
Closing - inferior edge moves nasal
opening - inf. edge moves temporal

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14
Q

Which type of dynamic stability is usually observed with novice GP wearers?

A

KICK - eye lid twitches and kicks it down

other types: normal (static position), loose (inferior drop or to the sides - fix it)

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15
Q

moderate to high ____ lenses tend to automatically want to lid attach

-what’s a pseudo-lid attachment? What does it indicate?

A

minus (minus lenticulars) - most comfortable initially

lens stays up when UL pulled away (should fall). Indicates a) flat lens or b) WTR cornea

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16
Q

what type of edge design would you want for an interpalpebral fit?
-which type of lids is IP ideal for?

A

thin - UL must traverse sup. lens w/ each blink!

-tight lids, extremely LOOSE lids (UL can’t hold it up), high upper lid

17
Q

what happens to the lens in a lower lid fit?

  • which type of lenses cause this to happen?
  • is this comfortable? When is it required?
A

drops to lower lid b/w blinks

  • prism-ballasted, KConus, post-surgical, etc.
  • No, no it’s not. Bifocal GPs require it though.