Fluorescein Patterns

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Fluorescein Patterns
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General Information

• Hydrostatic forces from the tear film holds the
  CL to the eye
• Fluorescein shows us where there are tears
  between the lens and cornea
• Fluorescein turns green when a cobalt blue or UV
  light hits it
• Variations in the intensity of the green will
  tell us where the lens is close to and far from
  the corneal surface
• These variations appear as fluorescein patterns
  that tell us how the lens is fitting

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Viewing the Fluorescein Pattern

• Instill a small amount of fluorescein into the
  tears
• Wet the strip with saline
• Shake off excess fluid from strip
• Lightly touch the strip to the inferior palpebral
  or bulbar conjunctiva
• Do not swab or paint the conjunctiva
• Do not touch the cornea
• Have the patient blink 2-3 times to distribute
  the fluorescein

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Viewing the Fluorescein Pattern

• Use the cobalt blue filter in the slit lamp
• Use a yellow (Wratten 12) filter
• In front of the objective or ocular
• Not in front of the light source
• Use low mag 10x
• Use a wide beam
• Slit beam to see FP profile in one meridian
• Alternatively, use a Burton lamp
• Does not work if the RGP material has a UV
  blocker Boston materials

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Viewing the Fluorescein Pattern
Cobalt blue filter without yellow filter
Cobalt blue filter with yellow filter
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Viewing the Fluorescein Pattern

• Minimum tear thickness visible 0.0022 mm
• If tear film is thinner than this, FP appears
  black
• A thin tear film is almost always present between
  lens and cornea, so some green will be visible
  even where lens is closest to the cornea
• Gradation of 0.02 mm visible as changes in FP
  green intensity

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Viewing the Fluorescein Pattern

• Too much fluorescein will obscure the true FP
• Front surface fluorescein
• Artificially thick post-lens tear film
• Wait for most of the Fl to dissipate
• Too little will not reveal true FP
• Will appear alignment even if not

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Viewing the Fluorescein Pattern
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Pattern Relationships

• Alignment
• Back surface of lens matches the corneal
  curvature
• Clearance
• There is space between the lens and cornea
• Touch
• The lens is close to the cornea compared to
  another part of the lens

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Pattern Locations

• Apical
• Central portion of the FP
• Area under the optic zone
• Mid-peripheral
• Area under the intermediate curves
• Determines lens positioning and movement patterns
• Peripheral
• Area under the peripheral curve
• Determines tear exchange

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Pattern Dynamics

• Static pattern
• FP when the lens is centered on the cornea
• If lens decenters, must manually center lens
  using patients lids
• Gives true apical relationship
• Dynamic pattern
• FP when the lens is in its normal resting
  position
• May be different from static pattern
• Pattern not as flat as when centered because
  peripheral cornea is flatter

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Pattern Dynamics
Dynamic pattern Normal resting position
Static pattern Lens in central position
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Patterns

• Apical alignment (AA)

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Patterns

• Apical clearance (AC)

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Patterns

• Apical touch (AT)

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Patterns

• Mid-peripheral alignment

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Patterns

• Mid-peripheral touch

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Patterns

• Mid-peripheral clearance

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Patterns

• Peripheral clearance

Minimal / none
Moderate / medium
High / excessive
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Toric Patterns

• With-the-rule

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Toric Patterns

• Against-the-rule

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Toric Patterns

• 1 D corneal toricity

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Toric Patterns

• 2 D corneal toricity

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Toric Patterns

• 3 D corneal toricity

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Toric Patterns

• 4 D corneal toricity

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Toric Patterns

• Alignment, clearance and touch patterns

Apical touch On Flat K
Apical alignment Splitting K
Apical clearance On Steep K
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Toricity and Lens Position

• With-the-rule corneas
• Superior or inferior position
• Good for LA but poor if inferior
• Steeper fits tend to center better
• Against-the-rule corneas
• Temporal or nasal position
• Poor comfort when decentered laterally
• Difficult to stabilize
• Steeper fits tend to center better

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Changes in FP with Decentration

• FP is not as flat as when centered
• Central cornea is steeper than periphery
• Mid-peripheral arcuate pooling
• Companion touch in periphery
• In direction of decentration

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Changes in FP with Decentration
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Toricity and Lens Movement