Fluorescein PatternsFluorescein Patterns

General InformationGeneral Information

• Hydrostatic forces from the tear film holds the CL to Hydrostatic forces from the tear film holds the CL to the eyethe eye

• Fluorescein shows us where there are tears between Fluorescein shows us where there are tears between the lens and corneathe lens and cornea– Fluorescein turns green when a cobalt blue or UV light hits itFluorescein turns green when a cobalt blue or UV light hits it

• Variations in the intensity of the green will tell us Variations in the intensity of the green will tell us where the lens is close to and far from the corneal where the lens is close to and far from the corneal surfacesurface

• These variations appear as “fluorescein patterns” that These variations appear as “fluorescein patterns” that tell us how the lens is fittingtell us how the lens is fitting

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

• Instill a small amount of fluorescein into the Instill a small amount of fluorescein into the tearstears– Wet the strip with salineWet the strip with saline– Shake off excess fluid from stripShake off excess fluid from strip– Lightly touch the strip to the inferior palpebral or Lightly touch the strip to the inferior palpebral or

bulbar conjunctivabulbar conjunctiva– Do not swab or paint the conjunctivaDo not swab or paint the conjunctiva– Do not touch the corneaDo not touch the cornea– Have the patient blink 2-3 times to distribute the Have the patient blink 2-3 times to distribute the

fluoresceinfluorescein

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

• Use the cobalt blue filter in the slit lampUse the cobalt blue filter in the slit lamp

• Use a yellow (Wratten 12) filterUse a yellow (Wratten 12) filter– In front of the objective or ocularIn front of the objective or ocular

– Not in front of the light sourceNot in front of the light source

• Use low mag: 10xUse low mag: 10x

• Use a wide beamUse a wide beam– Slit beam to see FP profile in one meridianSlit beam to see FP profile in one meridian

• Alternatively, use a Burton lampAlternatively, use a Burton lamp– Does not work if the RGP material has a UV blocker: Does not work if the RGP material has a UV blocker:

Boston materialsBoston materials

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

Cobalt blue filter without Cobalt blue filter without yellow filteryellow filter

Cobalt blue filter with Cobalt blue filter with yellow filteryellow filter

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

• Minimum tear thickness visible = 0.0022 mmMinimum tear thickness visible = 0.0022 mm– If tear film is thinner than this, FP appears blackIf tear film is thinner than this, FP appears black– A thin tear film is almost always present between A thin tear film is almost always present between

lens and cornea, so some green will be visible lens and cornea, so some green will be visible even where lens is closest to the corneaeven where lens is closest to the cornea

• Gradation of 0.02 mm visible as changes in Gradation of 0.02 mm visible as changes in FP green intensityFP green intensity

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

• Too much fluorescein will obscure the true FPToo much fluorescein will obscure the true FP– Front surface fluoresceinFront surface fluorescein– Artificially thick post-lens tear filmArtificially thick post-lens tear film– Wait for most of the Fl to dissipateWait for most of the Fl to dissipate

• Too little will not reveal true FPToo little will not reveal true FP– Will appear “alignment” even if notWill appear “alignment” even if not

Viewing the Fluorescein PatternViewing the Fluorescein Pattern

Pattern RelationshipsPattern Relationships

• AlignmentAlignment– Back surface of lens matches the Back surface of lens matches the

corneal curvaturecorneal curvature

• ClearanceClearance– There is space between the lens There is space between the lens

and corneaand cornea

• TouchTouch– The lens is close to the cornea The lens is close to the cornea

compared to another part of the compared to another part of the lenslens Flat

Steep

Aligned

Pattern LocationsPattern Locations

• ApicalApical– Central portion of the FPCentral portion of the FP– Area under the optic zoneArea under the optic zone

• Mid-peripheralMid-peripheral– Area under the intermediate curvesArea under the intermediate curves– Determines lens positioning and Determines lens positioning and

movement patternsmovement patterns

• PeripheralPeripheral– Area under the peripheral curveArea under the peripheral curve– Determines tear exchangeDetermines tear exchange

Pattern DynamicsPattern Dynamics

• Static patternStatic pattern– FP when the lens is centered on the corneaFP when the lens is centered on the cornea– If lens decenters, must manually center lens using If lens decenters, must manually center lens using

patient’s lidspatient’s lids– Gives true apical relationshipGives true apical relationship

• Dynamic patternDynamic pattern– FP when the lens is in its normal resting positionFP when the lens is in its normal resting position– May be different from static patternMay be different from static pattern– Pattern not as flat as when centered because Pattern not as flat as when centered because

peripheral cornea is flatterperipheral cornea is flatter

Pattern DynamicsPattern Dynamics

Dynamic pattern:Dynamic pattern:Normal resting positionNormal resting position

Static pattern:Static pattern:Lens in central positionLens in central position

PatternsPatterns

• Apical alignment (AA)Apical alignment (AA)

PatternsPatterns

• Apical clearance (AC)Apical clearance (AC)

PatternsPatterns

• Apical touch (AT)Apical touch (AT)

PatternsPatterns

• Mid-peripheral alignmentMid-peripheral alignment

PatternsPatterns

• Mid-peripheral touchMid-peripheral touch

PatternsPatterns

• Mid-peripheral clearanceMid-peripheral clearance

PatternsPatterns

• Peripheral clearancePeripheral clearance

Minimal / noneMinimal / none Moderate / mediumModerate / medium High / excessiveHigh / excessive

Toric PatternsToric Patterns

• With-the-ruleWith-the-rule

Toric PatternsToric Patterns

• Against-the-ruleAgainst-the-rule

Toric PatternsToric Patterns

• 1 D corneal toricity1 D corneal toricity

Toric PatternsToric Patterns

• 2 D corneal toricity2 D corneal toricity

Toric PatternsToric Patterns

• 3 D corneal toricity3 D corneal toricity

Toric PatternsToric Patterns

• 4 D corneal toricity4 D corneal toricity

Toric PatternsToric Patterns

• Alignment, clearance and touch patternsAlignment, clearance and touch patterns

Apical touch:Apical touch:On Flat KOn Flat K

Apical alignment:Apical alignment:Splitting KSplitting K

Apical clearance:Apical clearance:On Steep KOn Steep K

Toricity and Lens PositionToricity and Lens Position

• With-the-rule corneasWith-the-rule corneas– Superior or inferior positionSuperior or inferior position– Good for LA but poor if inferiorGood for LA but poor if inferior– Steeper fits tend to center betterSteeper fits tend to center better

• Against-the-rule corneasAgainst-the-rule corneas– Temporal or nasal positionTemporal or nasal position– Poor comfort when decentered Poor comfort when decentered

laterallylaterally– Difficult to stabilizeDifficult to stabilize– Steeper fits tend to center betterSteeper fits tend to center better

Changes in FP with DecentrationChanges in FP with Decentration

• FP is not as flat as when centeredFP is not as flat as when centered– Central cornea is steeper than peripheryCentral cornea is steeper than periphery

• Mid-peripheral arcuate poolingMid-peripheral arcuate pooling• Companion touch in peripheryCompanion touch in periphery

– In direction of decentration In direction of decentration

Changes in FP with DecentrationChanges in FP with Decentration

Toricity and Lens MovementToricity and Lens Movement