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Design Elements ofGP Scleral LensesClarke D. Newman, OD, FAAO

December 8,2013The 30th AnnualCornea,Contact Lens,and ContemporaryVision Care Symposium

Houston,TX

A Story About Joseph Lister Jan’sTowering Intellect

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Paid Consultant◦ B+L◦ AMO◦ GPLI◦ Eye Print

Clinical Research◦ Alcon◦ Alden Optical

ExpertTestimony No Proprietary Interest inAny Subjects

Discussed

Conflict Disclaimer Acknowledgements

I Want to Thank the Following People forHelping Me Get This Lecture Together SoFast:◦ Craig Norman,FCLSA◦ Greg Gemoules,OD◦ George Mera andTru-Form◦ John Edwards and Zeiss Meditech

Introduction “If OnlyWhatWe KnewWasTrue”◦ Corneal Radius of Curvature and Sag◦ Corneal Diameter and Sag◦ Scleral Lenses Don’t Land on the Sclera◦ The Scleral Curvature Myth

Oh My God! NowWhat!?!?!◦ SagAs the Primary Design Element◦ Doctor,Meet the Optic,Haptic,andTransition

Zones◦ Distribute the Load Properly—Zone Specific

Geometry in the Haptics,People!

“…KNOWYOUR ENEMY…”

-SUNTZU

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ANTERIOR SEGMENTIMAGING

Keratometer

Keratometer Scheimpflug Imaging

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Coherence Tomography “Normal Corneas” and Sag For “Normal” Patients, Copilevitz, et al

Found:◦ Average Sagittal Depth at 10.0mm Chord Is: 1,740 μ

◦ Average Sagittal Depth From 10.0—15.0mmChord Is: 1,992 μ

◦ Average Sagittal Depth from Apex to 15.0mmChord is: 3,735 μ◦ Average Corneal Scleral Angle Is: 38.4°

“Abnormal Corneas” and Sag For Keratoconic Patients,Anchon-Coan,et al, Found:◦ Average Sagittal Depth at 10.0mm Chord Is

Roughly 215 μ Deeper than Normals◦ Average Sagittal Depth From 10.0mm—

15.0mm Chord Is Almost the Same As Normals at Just under 2,000 μ◦ Average Sagittal Depth from Apex to 15.0mm

Chord is 200 μ Deeper◦ Average Corneal Scleral Angle Is Roughly the

Same As Normals At Roughly 38°

Corneal Curvatures and Sag Caroline,et al,Found that:◦ Different“K” Readings Do Not CorrelateWith

Sagittal Differences◦ Different Corneal EccentricityValues Do Not

CorrelateWith Sagittal Differences◦ Generally,Larger Corneal Diameters Mean

Larger Sagittal Depths,But NotAlways◦ Scleral Sagittal DepthsAreVery Consistent◦ “CornealAngle” at 10.0mm Chord Depth Is the

Best Predictor of Sagittal Depth◦ HigherAngles = Greater Sagittal Depths◦ LowerAngles = Lesser Sagittal Depths

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Example of the CornealAngle Not Predicting Greater Sag Scleral Sag

Scleral Sag

Scleral Sag Zone

Corneal Angle

Scleral Sag Zone

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Corneal Angle

10.0mm Chord

Scleral Sag Zone15.0mm Chord

Corneal Angle

39°

Scleral Sag Zone

Scleral Lenses Land on the…

Bulbar Conjunctiva!! The Bulbar Conjunctival Epithelium Is 10-

15 Layers Over a Loose Stromal Layer

The Bulbar Conjunctiva

ThisTissue Is Compressible◦ Average IsAround 100 μ

This Compression Must BeAccounted For Allow the Diagnostic Lens to“Settle” into

the Conjunctiva◦ Changes the Clearance—Especially in the

Periphery◦ Changes the Edge Impingement Compression

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Limbal / Scleral Transition Shape

Limbal / Scleral Curvature Limbal / Scleral Transition Curvature

Scleral Spur

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Limbal / Scleral Transition Curvature

Scleral Spur

Limbal / Scleral Transition Curvature

Some More Numbers

Average Central Radius Is 7.80mm Average Peripheral Radius is 9.10mm AverageAnterior Scleral Radius is

12.40mm (van derWorp,2010)

More on Scleral Curvature

The Nasal Sclera is Significantly Flatter Than theTemporal Sclera (Choi,Tang,Kim,2012)◦ Average Nasal Curvature—13.30mm◦ AverageTemporal Curvature—12.52mm◦ ReferenceAverage Corneal Curvature—

7.8mm◦ Reference Peripheral Corneal Curvature Is

9.10mm

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Scleral Shape Study Spiral of Tillaux

Average Corneal Diameter 11.80 mm The Maximum Diameter of a Scleral Lens

IsAbout 25.00mm (Pullum and van derWorp)

UsingWhatWe Know…

DESIGN ELEMENTS

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The Three Zones The Three Zones

Optic Zone

The Three Zones

Optic Zone

Transition Zone

The Three Zones

Optic Zone

Haptic Zone

Transition Zone

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Another Way to Look at It

Courtesy of Greg Gemoules,OD

Okay, Sometimes,All Bets Are Off

Scleral Design: First Principle

AcceptThatYouAre in theVision Correction Business and Not the Contact Lens Business◦ Some PatientsAre Surgical◦ OthersAre Great Spectacle Candidates◦ OthersAre Great Soft Lens Candidates

The First Rule of Scleral Lens Prescribing Is Prescribing Scleral Lenses for Scleral Lens Candidates

Think inTerms of Sag and Clearance

For Large Scleral Lenses (18.0mm to 25.0 mm) the Desired Clearance Is 200-300 μ

For Small Scleral Lenses (15.0mm to 18.0mm) the Desired Clearance Is 100 μ

For Corneo-Scleral Lenses (13.0mm to 15.0mm)the Desired Clearance Is 20-30 μ (DeNayer,2010)

Newman Says,“The More the Better—to aPoint.” Too Much Clearance Has BeenShown to Be More Prone to InsertionBubbles,andThere Is Some Evidence thatLargeVaultsAffect Corneal Oxygenation(Michaud,2012)

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Using the Coherence Tomographer Using the Coherence Tomographer

The Slit Lamp Technique A Closer Look

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Happy CamperWith a Lot ofClearance Very Important Point

Haste MakesWaste Allow the Lenses to Equilibrate for at

Least 20 Minutes—the Longer the Better EspeciallyTrue If:◦ Smaller Corneo-Scleral Lenses◦ IfYouAre DealingWith Significant Corneal

ShapeAlterations,Like Post-RK and Intacs®

IfYou Don’t Wait…

You Over-Estimate the Clearance You Under-Estimate the Haptic

Impingement

Looking at Haptic Alignment Conjunctival Compression◦ Evidenced byVascular Blanching or Blood

Column“Segmenting” Conjunctival Impingement◦ Distal Haptic—Edge ImpingementWill Cause

Edge Staining◦ Proximal Haptic—Impingement in theTransition

Zone / Haptic Zone BoundaryWill Cause Bulbar Conjunctival Hyperemia◦ Edge Standoff Circumferential Sectoral Meridional

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Non-Rotationally Symmetrical Haptics Toric Haptics Quadrant Specific Haptics Custom Elevation Haptics◦ Mathematical Modeling◦ Actual Modeling

Use Technology

Use TechnologyIn theTrenchesWays toAssess HapticAlignment InsertWith Saline Use the Red Free Filter The Push InTest Do Over-Keratometry Do Follow-UpVisitsAfter Several Hours

of LensWear◦ Look For Indentation Rings and Staining

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Well,That’s Obvious… Don’t Wait to Change Gears

Fifteen Hours a Day Every Day

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.,

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Conclusions Understand the Shape of the Cornea Understand the Shape of the LensesYou

Are Using EnsureYou Get EnoughVault Make SureYou Get Proper Haptic

Alignment Use NewTechnologies toAccomplish

These Goals Don’t Fix Nuthin’ThatAin’t Broke

, // ' . . -·/

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cdnewman@earthlink.net

THANKYOU!

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