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Fluorescein Patterns. 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

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general information
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
viewing the fluorescein pattern
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
viewing the fluorescein pattern4
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
viewing the fluorescein pattern5
Viewing the Fluorescein Pattern

Cobalt blue filter without yellow filter

Cobalt blue filter with yellow filter

viewing the fluorescein pattern6
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
viewing the fluorescein pattern7
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
pattern relationships

Flat

Steep

Aligned

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
pattern locations
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
pattern dynamics
Pattern Dynamics
  • Static pattern
    • FP when the lens is centered on the cornea
    • If lens decenters, must manually center lens using patient’s 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
pattern dynamics12
Pattern Dynamics

Dynamic pattern:

Normal resting position

Static pattern:

Lens in central position

patterns
Patterns
  • Apical alignment (AA)
patterns14
Patterns
  • Apical clearance (AC)
patterns15
Patterns
  • Apical touch (AT)
patterns16
Patterns
  • Mid-peripheral alignment
patterns17
Patterns
  • Mid-peripheral touch
patterns18
Patterns
  • Mid-peripheral clearance
patterns19
Patterns
  • Peripheral clearance

Minimal / none

Moderate / medium

High / excessive

toric patterns
Toric Patterns
  • With-the-rule
toric patterns21
Toric Patterns
  • Against-the-rule
toric patterns22
Toric Patterns
  • 1 D corneal toricity
toric patterns23
Toric Patterns
  • 2 D corneal toricity
toric patterns24
Toric Patterns
  • 3 D corneal toricity
toric patterns25
Toric Patterns
  • 4 D corneal toricity
toric patterns26
Toric Patterns
  • Alignment, clearance and touch patterns

Apical touch:

On Flat K

Apical alignment:

Splitting K

Apical clearance:

On Steep K

toricity and lens position
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
changes in fp with decentration
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