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Fluorescein Patterns

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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Fluorescein Patterns

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  1. Fluorescein Patterns

  2. 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

  3. 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

  4. 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

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

  6. 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

  7. 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

  8. Viewing the Fluorescein Pattern

  9. 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

  10. 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

  11. 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

  12. Pattern Dynamics Dynamic pattern: Normal resting position Static pattern: Lens in central position

  13. Patterns • Apical alignment (AA)

  14. Patterns • Apical clearance (AC)

  15. Patterns • Apical touch (AT)

  16. Patterns • Mid-peripheral alignment

  17. Patterns • Mid-peripheral touch

  18. Patterns • Mid-peripheral clearance

  19. Patterns • Peripheral clearance Minimal / none Moderate / medium High / excessive

  20. Toric Patterns • With-the-rule

  21. Toric Patterns • Against-the-rule

  22. Toric Patterns • 1 D corneal toricity

  23. Toric Patterns • 2 D corneal toricity

  24. Toric Patterns • 3 D corneal toricity

  25. Toric Patterns • 4 D corneal toricity

  26. Toric Patterns • Alignment, clearance and touch patterns Apical touch: On Flat K Apical alignment: Splitting K Apical clearance: On Steep K

  27. 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

  28. 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

  29. Changes in FP with Decentration

  30. Toricity and Lens Movement

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