SCLERAL Consultant CONTACT LENSES - smcos. · PDF file1889: The first scleral contact lenses were made from blown glass in Germany 1940s: Scleral lenses were made of low ... Facial

2/29/16

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SCLERAL CONTACT LENSES

Fitting, Troubleshooting, and Future Advancements

Pam Satjawatcharaphong, OD, FAAO, FSLS Assistant Clinical Professor

Cornea & Contact Lens Residency Chief Mentor UC Berkeley School of Optometry

[email protected]

DISCLOSURES

�  Consultant �  Bausch + Lomb

�  Allergan

�  Scleral Lens Education Society �  Fellowship Chair

LECTURE OBJECTIVES �  History

�  Indications

�  Diagnostic Fitting

�  Assessment of Scleral Lenses

�  Application & Removal

�  Care Regimen / Solutions

�  Patient Management

�  Advanced Troubleshooting

�  Scleral Lenses in the Literature

�  Future Advancements

HISTORY �  1508: Leonardo da Vinci comes up with

the concept of neutralizing the cornea using an enclosed liquid reservoir

�  1889: The first scleral contact lenses were made from blown glass in Germany

�  1940s: Scleral lenses were made of low oxygen transmissible polymethylmethacyrlate (PMMA) material. Impression molds of the surface of the eye were used to shape these lenses, but with poor reproducibility

�  1980s: Scleral lenses were first made using rigid gas permeable lens materials, and using repeatable computer-assisted lathes

�  2000s: Modern day scleral lenses popularized

INDICATIONS �  Irregular Corneas

�  Primary ectasia: Keratoconus, Pellucid Marginal Degeneration, Keratoglobus

�  Secondary ectasia: Post-surgical corneas (RK, PKP, Intacs, LASIK, PRK, LASEK)

�  Post-infection or post-traumatic corneas

�  Therapeutic: Ocular Surface Disease

�  Exposure Keratitis

�  Facial Nerve/Bell’s Palsy

�  Atopic Keratoconjunctivitis �  Sjögren’s Syndrome

�  Grave’s Disease

�  Stevens-Johnson Syndrome

�  Graft Versus Host Disease

�  Cicatricial Pemphigoid

�  Neurotrophic Corneal Disease

INDICATIONS

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�  Other Uses �  Regular corneas

�  High refractive error, presbyopia (multifocal modality) �  Athletes, occupation, recreational activities �  Corneal GP lens intolerance or ejection

�  Cosmesis �  Ptosis �  Aniridia �  Prosthesis

INDICATIONS GP LENS CATEGORIES

Eef van der Worp, A Guide To Scleral Lens Fitting, 2010

Scleral Lens Education Society

  Larger diameter lenses tend to have wider scleral/landing zones which can support a thicker tear reservoir   Start smaller/simpler and move to larger if necessary using topography as a guide

GP LENS CATEGORIES GENERAL SCLERAL LENS

DESIGN

Photo courtesy of Scleral Lens Education Society

CHOOSING YOUR DIAGNOSTIC LENS

1. Measure HVID   <12.00 mm choose smaller OAD (<16.00 mm)

  ≥12.00 mm choose larger OAD (≥16.00 mm)

2. Choose BC between average and steep K or the manufacturer’s recommended sagittal height

�  Use topography as a guide – note apex location

3. Allow to settle for 30-40 minutes, then use a vault reduction method until desired clearance is achieved


Corneal Topography

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Differences in transition profiles

from cornea to sclera result

different clearances for the same scleral

lens.

The nasal sclera is shorter and flatter causing scleral lenses to

decenter temporally. Lenses also tend to decenter inferiorly due to weight/center of gravity.

So why not fit empirically?


�  Scleral fitters must consider sagittal depth, not just corneal curvature

�  Both of these lenses have the same base curvature, but they have different diameters.

�  The larger diameter lens has a deeper sagittal depth than the smaller diameter lens.

Which of these two lenses has the steeper base curve?


�  There is a wide range of reported clearance in the literature �  Typically aim for 150-250 µm once

settled

�  Keep in mind scleral lenses tend to settle down ~100 µm with longer wear time, which can result in a thinner tear reservoir

�  The amount of clearance may vary throughout the lens (describe both apical and central)

CHOOSING YOUR DIAGNOSTIC LENS ASSESSMENT OF SCLERAL LENSES

1. Corneal Clearance   Apical Clearance (AC)   Central Clearance (CC)

2. Limbal Clearance (LC) 3. Scleral Alignment 4. Centration 5. Over-refraction

ASSESSMENT OF SCLERAL LENSES

Some practictioners use an anterior segment OCT to evaluate central clearance and scleral alignment

Photos courtesy of Greg Gemoules and the Scleral Lens Education Society


�  Step One: Corneal Clearance �  Does the lens vault or touch the cornea?

48.00 D 46.00 D 44.00 D 42.00 D

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�  Using an optic section, assess the ratio of the tear reservoir thickness to the central thickness of the contact lens �  Ex: 1:1 TL:CL ratio.

Known lens center thickness is 0.35mm (350 µm), so tear lens reservoir is 350 µm

�  Ex: 1:2 TL:CL ratio. Known lens center thickness is 0.35mm (350 µm), so tear lens reservoir is 175 µm

�  If possible assess the lens after 20-30 minutes of settling


�  Step One: Corneal Clearance

�  Options to increase vault: �  Steepen base curve

�  Steepen corneal or limbal curve (oblate or reverse geometry)

�  Increase diameter


�  Step Two: Limbal Clearance �  Does the lens clear or touch the limbus?

Small areas of limbal touch (<20% of limbal circumference) that cannot be fixed with fit changes may be acceptable


�  Step Two: Limbal Clearance

�  Options to improve limbal clearance �  Increase diameter

�  Steepen limbal curve

Both these adjustments increase sagittal depth, so may need to compensate for this if want to maintain central corneal clearance


�  Step Three: Scleral Alignment �  Evaluate the landing curves for proper scleral alignment

�  The peripheral curves should land softly and distribute weight and pressure evenly



�  Restriction of blood flow causes “blanching”

�  Blanching around majority of lens requires adjustment

�  Focal or sectoral blanching may not require an adjustment

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�  Step Three: Scleral Alignment �  Impingement (+conjunctival NaFl pooling)

�  Excessive bearing or pinching of outer scleral curve

�  Compression (-conjunctival NaFl pooling, +limbal hyperemia) �  Excessive bearing of inner scleral curve; “hinge effect”


�  Step Three: Scleral Alignment �  Options to improve alignment:

�  Impingement (+conjunctival staining) �  Excessive bearing on outer scleral curve – landing too steep = flatten PC

�  Compression (-conjunctival staining, +limbal hyperemia); “hinge effect” �  Excessive bearing on inner scleral curve – reduce the hinge = may need to

flatten limbal curve or steepen inner PC

�  Can also consider increasing width of PCs to better distribute pressure and weight

Photo courtesy of cornea.org



�  Slight edge lift can allow for minimal tear exchange �  Excess edge lift can cause bubbles or lens awareness �  Steepen PC to reduce edge lift


�  Step Four: Over-refraction �  Spherical over-refraction first to determine BCVA with

sphere alone �  Spherocylindrical over-refraction second

Residual astigmatism may be caused by:

  Lens Flexure – increase center thickness by 0.1-0.2 mm or use back surface toric periphery

  Lenticular Astigmatism / Posterior Keratoconus - can order front surface (F1) toric or design overlay glasses

  Generally should try with spherical design before moving to F1 toric



If necessary perform over-keratometry or topography

Flexure would be seen in the 180° meridian

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Sample Fit Description: AC (350 um) / CC (525 um) / LC 360 / Good scleral alignment, (-) blanching 360 / Slight inferotemporal decentration

Once you have found your best fitting diagnostic lens and have performed your over-refraction, you are ready to order. Do not forget to vertex SOR if needed.

APPLICATION AND REMOVAL

“The comfort of a soft lens with the vision of a gas

permeable lens.”



CARE REGIMEN & SOLUTIONS

�  The fluid inside the lens should be a preservative-free saline solution. Preservatives sitting in the tear reservoir can cause a toxic reaction.

NaCl 0.9% saline is preferred because it is both preservative free and buffer free, and comes in single-dose vials

CARE REGIMEN & SOLUTIONS

�  GP lenses made with high Dk material and that are plasma treated are generally not compatible with abrasive cleaners.

�  Acceptable Solutions:

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A mild impression ring after lens removal without bulbar injection may be acceptable.

PREPARING THE PATIENT AT DISPENSE

An impression ring with bulbar injection or limbal congestion indicates a tight and/or sealed-off fit,

or may be caused by excessive lens flexure.


Mild, transient rebound redness upon lens removal is acceptable, but excessive and persistent redness and limbal

congestion is indicative of a tight fit/seal off.


Use of extra strength cleaners can improve surface quality Switching materials may also improve wettability


Poor surface wetting can cause reduced vision

Many patients (50%) need to remove/clean lens at least once during the day Solution “cocktail” of saline + Celluvisc or Oasis Tears may reduce clouding


Tear reservoir clouding can occur if debris accumulates under the lens

PATIENT MANAGEMENT �  Always prepare your patient ahead of time – no surprises:

�  Solution to fill scleral bowl should be preservative free to avoid toxic reactions

�  May need to remove, clean, refill, and reapply lens once during the day

�  Transient rebound redness or an impression ring may occur after lens removal, and depending on degree, may not present a problem

�  Recommend take-home handout with pictures of acceptable solutions, resources and videos for application and removal, places where can buy more solutions and plungers

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�  Considerations to discuss with patient prior to fitting:

�  Cost (fitting + lenses) – can bill as medically necessary with some insurances

�  Time investment – will require multiple visits

�  Application & Removal – may be difficult for patients with poor fine motor skills or dexterity, or anatomically small palpebral apertures

PATIENT MANAGEMENT FOLLOW-UP SCHEDULE

�  The patient should wear lenses 3-4 hours prior to all follow-up appointment to ensure lenses have settled

�  Instill a generous amount of fluorescein with the lens on to determine whether there is fast or slow tear exchange (with or without push-up)

�  The tear reservoir can be evaluated with white light, but if it is difficult to visualize, remove the lens and add fluorescein directly into the lens bowl and wait 20-30 minutes to evaluate

Typical Follow-up Schedule: 1.  Dispense with application &

removal training 2.  2 week follow-up after initial

dispense 3.  Every 2 weeks until finalized 4.  2 month progress check 5.  6 month progress check

TROUBLESHOOTING TIPS

Photo courtesy of University Hospital Antwerp (Belgium)

Toric Sclera As you move further from the limbus, the sclera becomes

more toric. Larger overall diameter scleral lenses may require a toric periphery (back-surface toric) design to achieve

appropriate alignment.

Air bubbles are most often a product of improper lens application technique, but can also be caused by improper scleral alignment/excessive edge lift. Bubbles can cause discomfort and interfere with vision. Lenses with bubbles

must be removed and reinserted.


Peripheral Bearing Pellucid marginal degeneration or

inferior displaced cones may require an oblate or reverse geometry design to vault the

midperipheral area of bearing.

TROUBLESHOOTING TIPS Lens drop is an area of tear reservoir thinning

or absence, typically in the superior nasal quadrant, and is due to lens decentration.

It can be caused by very heavy and/or steep lens, or by tight upper lid or small palpebral

aperture pushing the lens downward.

This is generally not a problem unless the area of bearing is harsh enough to cause SPK.

Have patient look down to see if there is harsh or light

touch.


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Pingueculae may cause localized hyperemia and require notching of the

lens.

TROUBLESHOOTING TIPS Other irregular anatomical

landmarks, like bulbar conjunctival cysts or filtering

blebs, may also require notching.

Can attempt to decrease diameter to land inside of

landmark


Conjunctival Prolapse Mild conjunctival

prolapse is generally inconsequential.

Severe conjunctival prolapse can cause

neovascularization and may require fit adjustment or a resection procedure.


Diffuse pancorneal epithelial erosions are

often indicative of solution toxicity.

Ensure the patient is properly educated on

lens hygiene and proper solution use.


SCLERALS IN THE LITERATURE

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Publications Since 1940

Graph courtesy of Muriel Schornack, OD, FAAO, FSLS


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Interventional Studies

Epidemiology

Prospective Studies

Single Center

Multi-Center

Retrospective Studies

Case Reports

Case Series

Retrospective Reviews



SCLERALS IN THE LITERATURE Questions being answered or that need answering:

  Appropriate amount of wearing time and need for lens removal   Best lens design (spherical vs. toric haptics)   Lens settling   Post-lens fluid reservoir debris   Asphericity of optics (high order abberations)   Efficacy of new instruments   Effect of anatomy and physiology of the eye with scleral lens wear

  Conjunctival prolapse   Corneal epithelial “bogging”   Corneal sensitivity/nerve bundles   Corneal thickness   Keratometry readings   Oxygen transmissibility   Intraocular pressure

SCLERALS IN THE LITERATURE The Oxygen Transmissibility Conundrum

Resistance to oxygen in series

Michaud et al CL Ant Eye 2012

Compañ et al IOVS 2014

Jaynes et al CL Ant Eye 2015

Theoretical model Central and limbal Dk/t

Clinical Trial 8 patients measuring CCT

changes

Theoretical model Entrapped pO2 (oxygen

tension)

To Prevent Hypoxic Stress: 1.  Use highest Dk available

(>150) 2.  Max lens CT of 250 um 3.  Max TF thickness of

200 um

Results: 1.  Shallow TF (150 um)

showed 1.59% swelling 2.  Thicker TF (350 um)

showed 3.86% swelling 3.  Physiologic: 4%

To Achieve Sufficient PO2 (100 mmHg)

1.  Lens Dk of 140 2.  Lens CT of 300 um 3.  TF thickness of 50 um

(Best case scenario)

Clinical experience:   Minimize vault as much as possible while still achieving corneal clearance

  Choose smaller overall lens diameters and thinner center thickness if possible   Choose higher Dk lens materials in cases of high risk (post PKP)

IS EMPIRICAL FITTING IN THE FUTURE?

�  New scleral mapping technology and advancements are becoming available which may make empirical fitting more plausible. �  sMap3D by Visionary Optics

�  Eye Surface Profiler by Eaglet-Eye

�  EyePrintPRO by EyePrint Prosthetics

THE SKY’S THE LIMIT �  Scleral lenses are a useful tool

for a wide range of patients

�  They are incredibly customizable, and you have the ability to get creative � Many available diameters

and curvatures � Oblate/Reverse Geometry �  Front surface toric � Toric or quadrant specific

peripheral curves � Aspheric multifocal �  “Notching” for pingueculae/

cysts/blebs �  ...and more design options

continually being developed!

THE SKY’S THE LIMIT

�  Labs are knowledgeable in how to fit and troubleshoot their own lens designs. Ask for a consultation on your more difficult cases.

�  Fitting these lenses can be very rewarding – have fun!

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QUESTIONS? RESOURCES Eef van der Worp. A Guide to Scleral Lens Fitting 2nd edition. http://commons.pacificu.edu/mono/10/ Scleral Lens Education Society www.sclerallens.org

Gas Permeable Lens Institute http://www.gpli.info/

Documents

SCLERAL Consultant CONTACT LENSES - smcos. · PDF file1889: The first scleral contact lenses were made from blown glass in Germany 1940s: Scleral lenses were made of low ... Facial