Initial Lens Selection Overall KeraSoft® IC Irregular Cornea Fitting

7/31/2013
Disclosure Statement:
New Soft Lens Designs for the
Keratoconic Cornea
Joel A. Silbert, OD, FAAO
Professor of Optometry
Director, Cornea & Specialty Contact Lens Service
The Eye Institute at Salus University
#aaoptom13
• Faculty of the Pennsylvania
College of Optometry (Salus
University) for the past 39 years
• Clinical Director of the Cornea &
Specialty Contact Lens Service of
the Eye Institute
• Private practice of optometric
medicine in Woodbury Heights, NJ
for 39 years
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Conventional Soft Lens Applications for
Irregular Astigmatism and Keratoconus
Course Objectives
• To appreciate the benefits
of “piggybacking” GP
lenses over soft lenses
for correction of irregular
astigmatism
• To know when to consider
“hybrid” lenses for better
optical centration,
including various lens
designs in this category
#aaoptom13
• To learn about the two
newest “entirely soft”
specialty lenses designed
for keratoconic corneas
and irregular astigmatism,
with their respective
design attributes, fitting
requirements and
problem-solving
approaches
#aaoptom13
• Soft lenses may delay the onset of scarring, but
scarring may occur as part of the keratoconic condition
whether a lens is used or not (CLEK Study)
• Many keratoconics are currently functioning with soft
spherical or toric lenses, but are experiencing poor
vision quality
• GP lenses, hybrids (GP with soft skirt), and piggyback
systems will provide good acuity due to presence of a
rigid lens worn over an irregular cornea
• Newest soft lens designs can provide both
good VA, and comfort while maintaining a
healthy corneal epithelium
• Soft lenses have always been an option for
these patients when evidence of irregular
astigmatism has been minimal and acuity can
been satisfactorily achieved
• Stiffer and/or thicker lenses have some
advantage here:
– First generation SiHy lenses with with stiffer
modulus of elasticity
– Toric soft lenses can also be employed as needed
Piggyback Lenses
• Piggybacking has been
and continues to be an
excellent approach in
improving comfort for
patients who can be
satisfactorily fit with GP
lenses for keratoconus,
irregular astigmatism,
or post-PK, but who
cannot tolerate comfort
Courtesy Patrick Caroline, COT, FAAO
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7/31/2013
Piggyback lens
• Easiest and most effective approach is to first
fit the best GP lens possible, and then add a
disposable lens with minimal power (and
steepest BCR) to be worn under the GP lens
• Reduces discomfort at
least 50% and may allow
normal GP adaptation to
proceed
• Use of peroxide
disinfection can be used
for both types of lenses;
otherwise two separate
systems need to be used
• Use of daily disposables
or a 2 week disposable is
easiest
Flexlens®
FLEXLENS® Tricurve Keratoconus Lens
Flexlens® Materials (X-CEL Group)
• The “Tricurve Keratoconus Lens” is a
completely soft contact lens that incorporates
3 peripheral curves on the back surface of the
lens.
• It also provides a thicker center that ranges
from 0.45mm thick to 0.65mm.
• Diameter 15.0
Posterior OZ 7.5mm
• Toric powers are not available in this lens
Standard Flexlens material is 49% hioxifilcon.
However Flexlens products are also available
in 59% hioxifilcon or 55% methafilcon and in
the newest Contamac Definitive SiHy material:
Definitive™ 60Dk - 74% water Silicone-Hydrogel
FLEXLENS® TRI-CURVE KERATOCONUS LENS
Front View
Sectional View
FLEXLENS® PIGGYBACK lens
Lens Design
The Piggyback Lens incorporates a central
circular depression into the anterior surface of
the soft lens carrier.
The design recesses the GP lens within the soft
lens eliminating upper lid dislodgement and
maintaining centration of the GP optics over
the pupil.
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FLEXLENS® PIGGYBACK lens
FLEXLENS® PIGGYBACK LENS
Front View
Courtesy Patrick Caroline, COT, FAAO
Sectional View
Indications
FLEXLENS® PIGGYBACK LENS
Basic Fitting information
PMD
Nipple Cone
Lasik
RK
Sagging Cones
Post PK
Trauma
Soft lens base curve
• The Piggyback Lens fitting criteria is identical to
any soft lens, with movement and centration the
primary factors. The initial lens selection should
be 1.0mm flatter than the patient’s flattest
keratometric value (in mm).
• There should be good lens centration with 1.0 to
1.5mm of limbal draping, and lens movement
should be minimal, 0.25 to 0.50mm in primary
position with normal blink.
Soft lens evaluation
EXAMPLE:
“K’s” 52.00D @ 180 / 57.00D @ 090
Flat “K” 52.00D = 6.49mm
BC = 6.50 + 1.0 = 7.50 mm
Diagnostic lens 7.50 mm Base Curve
Recommended lens: 7.50 mm Base Curve,
14.5mm Diameter, Plano Power
Push up test
• If the soft lens centers well, a simple “pushup” test will verify if the base curve is
appropriate for the patient.
• If the soft lens decenters up, down, left or
right, the base curve is most likely too flat and
the next steeper base curve should be
evaluated.
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GP Insert Design
Keratometry is performed over the central
depression of the soft contact lens and a
standard GP lens is designed as if it were being
fitted onto the cornea.
GP Base curve is selected on “K” or .10mm steeper
than the flat “K”.
GP lens diameter should be selected at least
1.0mm smaller than the anterior cut-out
boundaries to facilitate lens movement and tear
exchange.
FLEXLENS® PIGGYBACK
Example: If the anterior cut-out is 10.2mm, the largest
GP lens diameter would be 9.2mm. This will
mimic the final weight and lid-to-lens
interaction, allowing for a better evaluation
NOTE: The soft lens skirt should be inserted first,
followed by the GP lens being inserted on top of the
soft lens.
- The GP lens is removed from the central cut-out
with a standard GP suction device.
FLEXLENS® PIGGYBACK
Parameter availability
• BASE CURVE 5.0 to 11.0mm in 0.1mm steps
• DIAMETER
8.0 to 16.0mm in 0.1mm steps
• ANTERIOR CUT-OUT DIAMETER
6.5 to 12.5mm in 0.1mm steps
• POWER
Plano
• Available as a Monthly Replacement,
in 6 and 12 packs.
Hybrid Lenses for Keratoconus
SynergEyes® KC
Hybrid Lenses
• As this topic is
extensive and
involves optics that
are rigid lens in
nature, we will only
touch briefly on the
dynamics of lens
movement and
fluorescein
assessment
Courtesy Patrick Caroline, COT, FAAO
• A successful
SynergEyes® KC fit
demonstrates total apical
clearance. A well-fit lens should
come to a soft landing where the
base curve joins the skirt curve,
with minimal touch in the rigid
portion of the lens.
• The steeper skirt curve radius will
add sagittal depth to the lens and
lift the bearing point to produce a
lighter landing. This step will
improve comfort and prevent late
onset tightening.
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View with high molecular weight
fluorescein and a Wratten filter
• Many corneas with emerging or
moderate keratoconus may be
actually be fit with the SynergEyes®
A lens design.
• SynergEyes® KC is required with
significant ectasia and high
eccentricity. It is similar to the
A design, just steeper values)
• Use of a Wratten filter is helpful in
viewing fluorescein patterns.
ClearKone (SynergEyes®)
• Works on basis of
saggital depth fitting
• Has a “reverse –
geometry” design that
works better in cases
of significant ectasia
• Improves centration
• Improves ability to
vault over the cone
UltraHealth (SynergEyes®)
• Newest iteration of hybrid design
• Similar to ClearKone but has higher Dk
130 Dk rigid gas permeable center
84 Dk silicone hydrogel soft skirt
Class II UV blocker: >80% of UVA
and >95% of UVB radiation
• Vault Values
50, 100, 150, 200, 250, 300,
350, 400, 450, 500, 550
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7/31/2013
Newest soft lenses for the
fitting of keratoconic and
irregular astigmatic corneas
Kerasoft IC (B+L)
NovaKone (Alden)
Note: Clinical certification is required for fitting these lenses
Kerasoft® IC (B+L)
8 Lens Kerasoft® IC Fitting Set
Indications
• Keratoconus
• Pellucid marginal degeneration
• Post-laser refractive surgery
• Other irregular corneal astigmatic conditions
Features
–
–
–
–
Front surface asphere or aspheric toric
Two sectors of independent modifiable periphery
Silicone hydrogel material
8 lens diagnostic fitting set
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Lens Parameters
• BC range 7.40mm to 9.40 (0.20mm steps)
• Diameter: 14.5mm std (custom 14, 15, 15.5mm)
• Power: Sph +20D to -20D
Cyl -0.50D to -12D (0.25D steps)
Axis: 1 to 180 degrees (1 degree steps)
Material: Etrofilcon A, 74% water
(Definitive Tm ) Contamac
Dk 60 x 10-11 (cm2/sec) [ml O2/ (ml x mm Hg)]
Lens Design Features
•
•
•
•
•
•
•
Back surface is spherical with tricurve geometry
Front surface aspheric or toric aspheric
Front optic zone 8 mm diameter
Back OZD is 12.5 mm for a std. 14.5 diameter
Vertical laser marks at 6 o’clock
Full line for right lens; broken line for left lens
Dot on right side of laser mark (Dr. view for
inversion check)
• Stabilization via prism ballast with balanced
thickness
Initial Lens Selection
Overall KeraSoft® IC Irregular Cornea Fitting
Flow
1. Aim to fit all cases with STD periphery lenses
2. Only change the periphery of the lens if it is
clinically indicated from the STD lens fit
3. Use Sector Management Control for specific
clinical cases, only when certain it is required
4. Typically start with 8.20mm BC w/std
periphery and assess using “MoRoCCoVA”
method
Periphery Options
• Periphery can be steepened or flattened,
independently of the BC
• Up to 2 sectors in the periphery can also be
modified, independently of each other when
clinically necessary(Sector Management
Control)
Peripheries: Standard, Steep 1, 2, 3, 4
Flat 1, 2, 3, 4
Corneal Shape Fitting Guidelines
Central KC w/steep periphery: 14.5, std periph
Mild 8.60BC; Moderate 8.40 BC Advanced: 8.20mm BC
Central KC w/flat periphery: 14.5, std or FLT2 periphery
Mild 8.60mm Std, Mod 8.20mm FLT2, Adv 8.00mm FLT2
Decentered, Low Cone: 14.5, std periphery
Mild 8.60mm, Mod 8.40mm, Adv 8.20mm
Steep inferior sector may need to be ordered here if all lenses
drop on the eye
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7/31/2013
Fitting Assessment Procedure
Pellucid: 14.5 diameter Mild 8.60, Mod 8.40 STD
Because of shape of PMD corneas, may need a FLT
sector superiorly, and STP sector inferiorly
Select and insert initial fitting lens
• Assess within 5 minutes to determine which MoRoCCo
fitting characteristics below are being achieved
(GREEN, YELLOW, RED)
Post-surgical eyes (oblate): start 8.60 14.5 STP2
May require SMC in cases of tilted grafts
• If any of the MoRoCCo characteristics are in the RED zone,
remove lens, then select next fitting lens 1-2 base curves,
steeper or flatter
• If any of the MoRoCCo characteristics are in the GREEN or
YELLOW zone, begin over-refraction while the lens settles
further
• When an optimal GREEN fit is achieved, allow to settle for
15-20 minutes then finalize over-refraction and make
allowance for vertex distance
Optimal Fit
Reassess Fit
Change the Fit
Optimal Fit
Reassess Fit
Change the Fit
VERTICAL
1.0mm - 2.0mm
VERTICAL POST BLINK
Up to 2.0mm acceptable
If patient is comfortable
<1.0mm or >2.0mm
MOBILE may be too
TIGHT OR too FLAT.
Reassess fit.
Mo
(Movement)
CENTERED
>10° rotation
Stable: lens is tight – remove and
try progressively flatter lenses
Unstable: Try a BC 0.40mm steeper
(Rotation)
Reassess Fit
Change the Fit
DECENTERED
SIGNIFICANTLY DECENTERED
Minimal decentration is
acceptable if visual acuity is
stable and acceptable. VA
clearer after the blink
indicates a TIGHT fit
Laterally on straight ahead gaze
Drops to limbus on upward gaze.
Indicates a FLAT fit,
Try 0.20mm BC steeper
Lateral decentration with
significant lag; FOZ drops
BELOW limbus on up gaze
MoRo Co
Try 0.40mm BC steeper
(Centration)
ROTATION
RoCCo
Optimal Fit
COMFORTABLE
C
ROTATION
Up to 10° stable rotation
acceptable if 0.20mm BC flatter
does not rectify problem.
Unstable rotation indicates
a flat fit. Try 0.20mm BC
steeper in this instance
<1.0mm - try one step flatter
Lens too flat - try 0.40mm
>2.0mm - try one step steeper
BC steeper
Lens too tight - try 0.40mm
BC flatter
MoRoCCo
Optimal Fit
Laser mark should sit at
6 o’clock position and be
stable or return rapidly to
position post blink
Consistently
good comfort
Reassess Fit
Change the Fit
NON-SETTLING
DISCOMFORT
SIGNIFICANT
DISCOMFORT
General edge awareness= FLAT
fit. Try 0.20mm BC steeper
TIGHT fit. Try base curve
0.20mm BC flatter
Co
MoRoC
(Comfort)
STATIC = TIGHT – Remove and
fit 0.40mm BC FLATTER
MOBILE may be too TIGHT OR
Too FLAT. Reassess fit.
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7/31/2013
Optimal Fit
Reassess Fit
STABLE VISION
Change the Fit
UNSTABLE VISION VERY POOR VISION
No fluctuation
between preand post blink acuity
VA
Worse after the blink=FLAT fit
Clearer after the blink = TIGHT fit
Try 0.20mm BC steeper or
flatter accordingly
Usually caused by tears
pooling under the lens.
Most frequent cause,
very flat corneal
periphery
Sector Management Control
From: Silbert J. Soft lenses for Irregular Corneas: Yes we can.
REVIEW OF CORNEA & CONTACT LENSES | APRIL 2013 pp. 22-26
Sector Management Control
• The periphery of the Kerasoft IC is unique in that it can
be steepened or flattened, independent of the base
curve
• Up to two sectors in the periphery can be modified
when necessary, such as with post-graft corneas that
require flatter base curves but need peripheral
steepening.
• Also, low cones and PMD corneas may require SMC
steepening of the inferior sector and possibly flattening
of the superior sector.
• Lens sector angles (quadrants) are designated and
specified as either STD or STP 1-4 or FLT 1-4
NovaKone™
(Alden Optical)
Sector Management Control
NovaKone™
NovaKone™
• NovaKone uses lens thickness to neutralize
corneal irregularity
• The optical design is then employed to
correct for normal spherical and residual
astigmatic refractive errors
• Dual Elliptical Stabilization™ for rotational
stability and controlled thickness
• Cease GP lens wear for at least 1 week prior
to fitting NovaKone
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7/31/2013
18 lens Diagnostic Fitting Set
is required
NovaKone™ Fitting Set
Fitting Technique
Four Step Process – “from the inside out”
1.
2.
3.
4.
Initial Lens Selection
Determine Base Curve (central)
Determine IT Factor (lens thickness)
Determine Lens Power
Determine Fitting Curve (para-central)
Fit Evaluation
with high molecular weight fluorescein
Average K for CENTRAL 3 to 4 mm
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7/31/2013
Thickness controls vision!
Evaluate “Over K” Mire Quality!
IT = “Index of Thickness” , ranges from 0 to 4.
• Use the lowest IT factor possible
- The more central the cone, the lower IT
factor typically required
- The more irregular or decentered the cornea,
the higher the IT factor to optimize visual acuity
• Verify IT factor with Keratometry or Topography over
the lens.
• If any irregularities are observed, increase the IT to
improve optical stability.
Resnick Guide to selecting IT Factor
of first diagnostic lens
Photo courtesy of Mark Andre, FCLSA, Pacific University
Keratometric mires over the NovaKone lens
will be crisp and clear with the proper IT
factor
Determine Lens Power
(Courtesy Alden Optical and Dr. Susan Resnick –Drs. Farkas, Kassalow, Resnick & Associates, P.C.)
BCVA (manifest)
cone location
20/20
Central (C)
20/20
Decentered (D)
IT Factor
0
0
20/25
C
1
20/25
D
1
20/30
C
1
20/30
D
20/40
C or D
20/50-20/60
C or D
2 or 3 depending upon acuity and cone size
<20/60
C or D
3 or 4 depending upon acuity and cone size
1 or 2 depending upon visual quality with
overrefraction
•
2
• Over-refract and calculate the power of the Rx lens
• Note: Effective Over-Refraction can be obtained using
an AutoRefractor
• Compensate for Vertex distance
• Compensate for rotation
– All Dx lenses have Dual Elliptical Stabilization to assess
rotation
– Dx lenses have no actual cylinder power
• Order total SCOR, compensated for vertex and for any
rotational torsion noted
Please note that this is based upon selecting the thinnest possible profile to acceptable vision
Determine Fitting Curve
The fitting curve should demonstrate typical fitting
characteristics of a standard soft lens fit.
• If the fitting curve is too flat there will be excessive movement and/or
edge lift (order steeper fitting curve)
• Little or no movement and/or edge impingement would indicate the fit
curve is too steep (order flatter fitting curve)
• Alden labels the fitting curve with the actual radius in millimeter,
practitioners should be comfortable with these values in relationship
to a “good” lens fit.
• The fitting curve should be adjusted in a minimum of
0.2mm increments
PMD unsuccessfully
wearing GP semisclerals
Always D/C GP lens wear 1 wk prior to fitting
(one eye at a time so patient can function)
NovaKone Fitting Results:
1) 7.8 BC / 8.4 FC / IT2 / -6.00 (thinning to light
bearing; movement good, comfort good,
OR -2.50 -2.50 x 093
20/25
2) 7.4 BC / 8.4 FC / IT3 / -7.00 (pooling, movement
good, comfort good,
OR -3.00 -2.25 x 105

20/40 (X)
Ordered 7.8/8.4/15.0/ IT2/
-8.50-2.50x093
On Dispense Day

VA 20/32-2
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7/31/2013
Thank you!
1st Lens Follow Up
Initial Dispensed Lens
1)
7.8/8.4/15.0/IT2/-8.50-2.50x093

Wear Time 12 Hr, Minimal Mucus, Improved Comfort, Blur OS

SLE: Cornea Clear, No Staining

20/50 + 2

Re-Ordered
OR +1.25-1.25x113 (20/25+2)
7.8/8.4/15.0/IT2/-7.25-3.50 x100
2nd Lens Follow Up
2) Revised Lens
7.8/8.4/15.0/IT2/-7.25-3.50 x100

WT 15 Hr, No Mucus, Good Comfort & VA

SLE: Cornea Clear, Neg Staining

20/20-1
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