RGPs - troubleshooting Flashcards

1
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- Fogging (late) (2)

A

Tight/dirty lens

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2
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- Photophobia (3)

A

Tight lens
Lens too flat
FB stain

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3
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- Difficulty looking up (2)

A

Improper edge (too steep)
Lens too small

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4
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- Hazing, haloes or fogging (2)

A

Inadequate tear exchange
dirty lenses

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5
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- Flare (2)

A

Optic zone in pupil area
Decentred lens

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6
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- General lens discomfort initial (2)

A

Spherical lens on toric cornea
Pt inability to adapt to lens wear

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7
Q

What are the probable causes for an RGP lens when SUBJECTIVE:
- General lens discomfort late (3)

A

Damaged/warped lens
Lenses in wrong eyes
Lens Deposits

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8
Q

What are the probable causes for an RGP lens when:
- Excessive movement/too loose (3)

A

BC too flat or steep
Edge lift too flat
Lens too small

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9
Q

What are the probable causes for an RGP lens when:
- No movement (3)

A

BC too steep
Edge lift too steep
Lens too large

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10
Q

What are the probable causes for an RGP lens when:
- Displaced by lids (2)

A

Thick edge profile (high minus)
Lens too flat

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11
Q

What are the probable causes for an RGP lens when:
- Bubbles under standard lens (4)

A

Excessive clearance under lens
BC too steep
Steep fit (central bubbles)
OZ too large (mid periph bubbles)

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12
Q

What are the probable causes for an RGP lens when:
- Bubbles under KCN lens (3)

A

Excessive clearance
Steep fit (central bubbles)
OZ too large (mid periph bubbles)

NB: If bubbles w central touch - steepen BC, if bubbles without central touch, flatten BC

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13
Q

What are the probable causes for an RGP lens when:
- Central pooling (1)

A

Excessive clearance (so flatten BC in response)

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14
Q

What are the probable causes for an RGP lens when:
- Excessive Edge Standoff (1)

A

Peripheral curve too flat or wide

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15
Q

What are the probable causes for an RGP lens when:
- Fine stippling/spk (3)

A

Normal in adaptation
Poor tear circulation
BC or periph curves too tight

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16
Q

What are the probable causes for an RGP lens when:
- Zig-zag corneal staining

A

FB under lens

17
Q

What are the probable causes for an RGP lens when:
- 3 and 9 o’clock staining (under lens) (3)

A

Periph too flat or steep
Inappropriate size
Decentred inferiorly

18
Q

What are the probable causes for an RGP lens when:
- 3 and 9 o’clock staining past lens edge (1)

A

Front surface profile abrupt - mostly high minus rx (should reduce front optic size and incr lens diameter)

19
Q

What are the probable causes for an RGP lens when:
- Deep corneal stain w pain (1)

A

Corneal ulcer or uveitis

20
Q

What are the probable causes for an RGP lens when:
- Sudden unusual change in refraction (2)

A

Lenses in wrong eyes
Lenses damaged/warped

21
Q

What are the probable causes for an RGP lens when:
- gradual change in refraction (2)

A

Lenses slowly distorting
Pt Rx changing

22
Q

What are the probable causes for an RGP lens when:
- mucus on lens (3)

A

Poor hygiene
scratches on surface
deposits on lens

23
Q

What are the probable causes for an RGP lens when:
- lens falls out in fitting (3)

A

Lens too small
Lens too flat
Lens too steep

24
Q

What are the probable causes for an RGP lens when:
- lens falls out after continued wear (2)

A

Lens damaged
Wrong lens in wrong eye

25
Q

What are the probable causes for an RGP lens when:
- Lens rides to side (2)

A

against the rule astig
lens too small

26
Q

What are the probable causes for an RGP lens when:
- Lens rides under top lid (2)

A

Lens is too flat
Lens too small