Transcript Introduction to scleral Contact lenses

Dr. Desinee Drakulich O.D.
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I do not have any affiliations nor am I paid by
any of the companies that are used in this
presentation.
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Historical overview of scleral lens
Detailed review of structure and design
Detailed process of fitting
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Introduction of sagittal depth
Peripheral curves
Edge lift
Diameter
Slit Lamp images
OCT images
Why and when we use scleral lenses
Advantages and Disadvantages
 Comparing other RGPs
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The scleral contact lens was the first contact
described in medical literature.
In 1888, Adolf Fick developed the first blown
glass scleral contact.
Also in 1888, Eugene Kalt started using blown
glass scleral contacts for the treatment of
keratoconus.
In 1889, August Mueller made himself a
ground glass scleral lens for his high myopia
and used it for his doctorial dissertation.
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Scleral CLs never really progressed much after
that due to the poor oxygen permeability of
glass.
Re-introduced in 1900’s with the advent of
PPMA material. More oxygen permeable than
glass but still not great. Fenestration was
added to try to increase oxygen permeability.
Developers started making lenses small to
allow the tear to flow under the CL and
increase oxygen.
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In 1970, scleral lens were re-introduced again in
Rigid Gas Permeable materials.
Lens were difficult to fit and intimidating due
to there relative size.
With the recent focus on Dry Eye Disease
contact lens companies have began promoting
scleral lenses as a suitable solution for dry eye
patients who want to remain in contacts.
PPMA Material
RGP Material
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Glass = 0 Dk/t
PPMA = 0 Dk/t
Boston EO = 31-61 Dk/t
Boston XO = 61-100 Dk/t
Fluoroperm 151 = 151-200 Dk/t
Air Optix Night and Day = 140 Dk/t
Scleral Lenses = 10 - 36.7 Dk/t in center
17.4 – 62.6 Dk/t in peripheries
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The Jupiter Scleral Lens has two designs – 15
mm diameter and the 18 mm diameter.
Both are true scleral lenses, meaning they bear
on the sclera and vault the cornea.
Both have 5 curves organized in 3 zones
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The Corneal Zone – the central corneal curve
and the Aspheric peripheral corneal curve.
The Limbal Zone – the Aspheric scleral curve.
The Scleral Zone – the Aspheric scleral curve
and the Aspheric edge curve.
Central Corneal Curve
Aspheric peripheral curve
Aspheric Scleral
Curve
Aspheric
Scleral Curve
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The Jupiter Standard – central and peripheral
curves in Zone 1 are the SAME.
The Jupiter Advanced Keratoconic – central
curve STEEPER than peripheral curve.
The Jupiter Reverse Geometry – central curve
FLATTER than the peripheral curve.
There is a fourth design – Toric Scleral Zone –
front toric with double slab off ballasting.
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Base Curve – any
Diameter – 13.5 mm to 24.0 mm
BV power - +50.00 D to -75.00 D in 0.25 steps
Cylinder power - -0.25 D to 15.00 D in 0.25
steps
Axis – 1˚ to 180˚ in 1˚ steps
Diagnostic lenses – 14 pre-designed lenses for
each 3 configurations.
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Standard RGPs and Soft CLs rely heavily on
Base Curve and Diameter to fit them properly.
Scleral CLs rely heavily on Corneal Sagittal
Depth and Diameter.
With the use of an anterior segment OCT scan
one can easily calculate the sagittal depth of the
cornea and what the sagittal depth of the
contact would be needed for that patient.
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When fitting you need to ensure adequate
corneal clearance.
What is adequate?
For 18 mm design – 40 to 200 um
For 15 mm design – 50 to 200 um
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An OCT makes fitting Scleral CLs easier;
however it is not necessary.
If you have the pachymetry reading of your
patients cornea you can use that as a guide to
estimate the corneal clearance of the scleral
contact in the slit lamp.
If clearance is too low you need to either
increase sagittal depth by steeping the base
curve or increasing the diameter.
For example:
Fluoress clearance
~ ½ the corneal thickness
Corneal Clearance ~ 270 um
Corneal thickness = 540
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I always start steep and back down from there
approximately 1.00 D STEEPER than patients
STEEPEST curvature.
I have learned from me own fitting experience
that it is important on initial fit that you leave
about 400 um clearance.
The reason for this is the scleral elasticity of
every person is different.
These lens can settle any where between 50 um
to 250 um in a 4h period and can continue to
settle up to 8h.
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Limbal clearance – complete and generous
limbal clearance insures good tear circulation.
If there is very little limbal clearance you must
pick a large diameter lens.
If there is too much limbal clearance large
bubbles will form and a smaller diameter
should be uses.
Examples:
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Peripheral Curves need to be adjusted to either
tighten or loosen the fit of the CL.
If the PCs are to tight this can lead to vessel
blanching, hyperemia, difficulty removing the
lens, fogging and discomfort for the patient.
If the PCs are to loose seal off can not be
maintained and the lens will not stay on the
cornea.
Examples:
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Dry Eye
Ocular Surface disease
Keratoconus
High refractive error
Irregular Corneas
Post Lasik
 Post RK
 Post PKP
 Injury/Scarring
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Advantage – since the scleral contact is filled
with preservative free saline the cornea is
constantly bathed in fluid throughout the day.
Advantage – since the scleral contact is vaulted
over the cornea instead of touching the cornea
it does not compromise the integrity of the
corneal surface.
Disadvantage – lenses are large and difficult to
handle.
Disadvantage – cost ~ 300 dollars per lens
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Keratoconus is a progressive thinning of the
cornea secondary to the loss of the collagen
fiber integrity. Thinning causes a bulging of
the cornea resulting in an irregular corneal
surface.
Treatment for keratoconus:
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Rigid Gas Permeable contacts
Hybrid Contacts (Duette)
Specialty Contacts (Rose K, Rose K2IC, Rose K Post)
Scleral Contacts
Surgery (Corneal Cross-linking, Intacs, PKP)
Keratocnusooooooooooo
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Advantage – corneal vaulting reduce risk of
corneal scarring since the lens does not touch
the cornea.
Advantage – excellent visual outcome even
with advanced keratoconic patients.
Disadvantage – difficult to handle
Disadvantage - cost
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Advantage – wide range of available powers
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BV power - +50.00 D to -75.00 D in 0.25 steps
Cylinder power - -0.25 D to 15.00 D in 0.25 steps
Axis – 1˚ to 180˚ in 1˚ steps
Disadvantage – difficult to handle
Disadvantage - Cost
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Advantage – wide range of powers
Advantage – does not compromise corneal
integrity
Advantage – gives excellent visual outcome
Disadvantage – difficult to handle
Disadvantage - Cost
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Scleral lenses are not difficult to fit if you
follow some simple rules.
Scleral lenses have improved materials and
oxygen permeability to make them safe to fit.
They can be a life saver for that difficult dry
eye patient or irregular cornea.
They are difficult to handle due to their large
size
They are no inexpensive, but worth it for the
right patient.