SCLERAL CONTACT LENSES Fitting, Troubleshooting, and Future Advancements

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1 DISCLOSURES SCLERAL CONTACT Fitting, Troubleshooting, and Future Advancements Consultant Bausch + Lomb Allergan Scleral Lens Education Society Fellowship Chair Pam Satjawatcharaphong, OD, FAAO, FSLS Assistant Clinical Professor Cornea & Contact Lens Residency Chief Mentor UC Berkeley School of Optometry psatjawat@berkeley.edu LECTURE OBJECTIVES History Care Regimen / Solutions Indications Patient Management Diagnostic Fitting Advanced Troubleshooting 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 Assessment of Scleral Lenses Application & Removal Scleral Lenses in the Literature Future Advancements 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 INDICATIONS 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 1

2 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 GP LENS CATEGORIES GENERAL SCLERAL LENS DESIGN 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 Photo courtesy of Scleral Lens Education Society CHOOSING YOUR DIAGNOSTIC LENS 1. Measure HVID <12.00 mm choose smaller OAD (<16.00 mm) mm choose larger OAD ( mm) CHOOSING YOUR DIAGNOSTIC LENS Corneal Topography 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 minutes, then use a vault reduction method until desired clearance is achieved 2

3 CHOOSING YOUR DIAGNOSTIC LENS So why not fit empirically? 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. CHOOSING YOUR DIAGNOSTIC LENS Which of these two lenses has the steeper base curve? 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. CHOOSING YOUR DIAGNOSTIC LENS There is a wide range of reported clearance in the literature Typically aim for 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) 1. Corneal Clearance Apical Clearance (AC) Central Clearance (CC) 2. Limbal Clearance (LC) 3. Scleral Alignment 4. Centration 5. Over-refraction Some practictioners use an anterior segment OCT to evaluate central clearance and scleral alignment Step One: Corneal Clearance Does the lens vault or touch the cornea? D D D D Photos courtesy of Greg Gemoules and the Scleral Lens Education Society 3

4 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 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? Step Two: Limbal Clearance Options to improve limbal clearance Increase diameter Steepen limbal curve Small areas of limbal touch (<20% of limbal circumference) that cannot be fixed with fit changes may be acceptable 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 Step Three: Scleral Alignment Evaluate the landing curves for proper scleral alignment Restriction of blood flow causes blanching Blanching around majority of lens requires adjustment Focal or sectoral blanching may not require an adjustment 4

5 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 Step Three: Scleral Alignment Evaluate the landing curves for proper scleral alignment 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 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 5

6 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. Sample Fit Description: AC (350 um) / CC (525 um) / LC 360 / Good scleral alignment, (-) blanching 360 / Slight inferotemporal decentration APPLICATION AND REMOVAL APPLICATION AND REMOVAL CARE REGIMEN & SOLUTIONS The fluid inside the lens should be a preservativefree saline solution. Preservatives sitting in the tear reservoir can cause a toxic reaction. CARE REGIMEN & SOLUTIONS GP lenses made with high Dk material and that are plasma treated are generally not compatible with abrasive cleaners. Acceptable Solutions: NaCl 0.9% saline is preferred because it is both preservative free and buffer free, and comes in single-dose vials 6

7 PREPARING THE PATIENT AT DISPENSE PREPARING THE PATIENT AT DISPENSE A mild impression ring after lens removal without bulbar injection may be acceptable. 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. PREPARING THE PATIENT AT DISPENSE PREPARING THE PATIENT AT DISPENSE Poor surface wetting can cause reduced vision 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 PREPARING THE PATIENT AT DISPENSE 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 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 Recommend take-home handout with pictures of acceptable solutions, resources and videos for application and removal, places where can buy more solutions and plungers 7

8 PATIENT MANAGEMENT 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 FOLLOW-UP SCHEDULE 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 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 minutes to evaluate 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. Photo courtesy of University Hospital Antwerp (Belgium) 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. 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. Peripheral Bearing Pellucid marginal degeneration or inferior displaced cones may require an oblate or reverse geometry design to vault the midperipheral area of bearing. 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. 8

9 Pingueculae may cause localized hyperemia and require notching of the lens. 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 Severe conjunctival prolapse can cause neovascularization and may require fit adjustment or a resection procedure. Conjunctival Prolapse Mild conjunctival prolapse is generally inconsequential. 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 Publications Since present Graph courtesy of Muriel Schornack, OD, FAAO, FSLS SCLERALS IN THE LITERATURE Publications Since Graph courtesy of Muriel Schornack, OD, FAAO, FSLS 9

10 SCLERALS IN THE LITERATURE 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 Graph courtesy of Muriel Schornack, OD, FAAO, FSLS SCLERALS IN THE LITERATURE Michaud et al CL Ant Eye 2012 Theoretical model Central and limbal Dk/t To Prevent Hypoxic Stress: 1. Use highest Dk available (>150) 2. Max lens CT of 250 um 3. Max TF thickness of 200 um The Oxygen Transmissibility Conundrum Resistance to oxygen in series Compañ et al IOVS 2014 Clinical Trial 8 patients measuring CCT changes Results: 1. Shallow TF (150 um) showed 1.59% swelling 2. Thicker TF (350 um) showed 3.86% swelling 3. Physiologic: 4% Jaynes et al CL Ant Eye 2015 Theoretical model Entrapped po2 (oxygen tension) To Achieve Sufficient PO2 (100 mmhg) 1. Lens Dk of Lens CT of 300 um 3. TF thickness of 50 um (Best case scenario) 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 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) 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! 10

11 QUESTIONS? RESOURCES Eef van der Worp. A Guide to Scleral Lens Fitting 2 nd edition. Scleral Lens Education Society Gas Permeable Lens Institute 11