FITTING TOOLKIT
®
CONTACT LENSES
FOR KERATOCONUS
& ALL IRREGULAR CORNEAS
www.kerasoft.co.uk
MoRoCCo VA
UltraVision International Ltd, Commerce Way, Leighton Buzzard, Beds, LU7 4RW
UK Freephone 0800 585115 Tel: +44 (0)1525 381112 Fax: +44 (0)1525 370091
Registered in England and Wales No. 1408851 VAT Registered Number: GB 322 5509 81
®
Fitting Toolkit: Contents
This Fitting Toolkit is best used in conjuction with KeraSoft IC Online Training.
To register, please visit www.kerasoft.co.uk/training.
Kerasoft® IC Design - Outlines the design of the KeraSoft® IC lens and gives the parameters and materials available to order.
Natural Ectasia Corneal Shape Recognition Chart - This chart shows how to use information from refraction and corneal curvature measurement to identify
corneal shape.
Corneal Profile Chart - How to observe and identify the corneal profile to assist in classifying the corneal shape to be fitted.
First Choice Fitting Lens Guide - When the corneal shape has been identified, this guide suggests which lenses from the Fitting Set to use as a starting point.
MoRoCCo Introduction and Dynamic Assessment Routine - Introduction to the fitting methodology for the KeraSoft® IC lens which uses the MoRoCCo
fitting system.
MoRoCCo Hints and Tips - How to use MoRoCCo to differentiate between optimal, tight and flat fitting lenses.
KeraSoft® IC Fit Assessment Guide -
This guide explains how to use the MoRoCCo fit characteristics to assess the lens on eye using a simple, colour coded
system.
Periphery Options - This guide explains how to change the whole periphery of the KeraSoft® IC lens.
KeraSoft® IC SMC Design - An introduction to Sector Management Control (SMC). Up to two sectors of the KeraSoft® IC lens can be changed independently and at
any angle.
KeraSoft® IC Fitting Examples -
These examples show how to work through a KeraSoft® IC fitting from first assessment of corneal shape to interpreting the
MoRoCCo characteristics. An example of each type of peripheral change is given.
®
The KeraSoft® IC Lens for Keratoconus and all Irregular Corneas
The KeraSoft® IC is a front surface toric design with a large Back Optic Zone (BOZ) of 12.50.
The periphery can be manipulated
independently of the base curve, up to 4
steps flatter or steeper.
Up to two sections of the periphery can
be modified independently, the location
of which is decided by the practitioner.
The peripheries in these sections can be
flattened, steepened or remain as
standard.
Specification Table
Base Curve
7.40mm to 9.40mm (0.20 steps)
Diameter *
14.50mm as standard
Lens Design
Front surface Asphere or Aspheric Toric prism
ballasted with balanced overall thickness
Wavefront aberration control
KeraSoft® IC Lens with STD Periphery
Periphery
Options
The whole periphery can be steepened or
flattened independently of the overall base curve,
additionally, up to two sectors of the periphery
can be modified independently of each other
(Sector Management Control).
Standard, STEEP1, STEEP2*, STEEP3*, STEEP4*
(*Reverse Geometry), FLAT1, FLAT2, FLAT3,
FLAT4
Power Range
Material
DK
Pack Size
Sphere: +30.00DS to -30.00DS
Cylinder: -0.50 to -15.00DC (in 0.25 steps)
Axis: 1° to 180° (in 1° steps)
Filcon V3, 74% Water, 3 Monthly replacement
2
Filcon II 2, 77% Water, 12 Monthly replacement
1
1
2
1
2
60 x 10-11 (cm2/sec)[ml02/(ml x mmHg)]
53 x 10-11 (cm2/sec)[ml02/(ml x mmHg)]
Single Lens, 2-pack
Single Lens
* Diameters of 14.00, 15.00 and 15.50 can be manufactured to order.
Record No. 301
Issue 2
01.07.11
Kerasoft® is a Registered Trademark
Fitting Set Parameters
BCOR
DIA
PERIPH
POWER
7.80
14.50
STD
Plano
8.00
14.50
STD
Plano
8.20
14.50
STD
Plano
8.40
14.50
STD
Plano
8.60
14.50
STD
Plano
8.80
14.50
STD
Plano
8.20
14.50
FLT2
Plano
8.60
14.50
STP2
Plano
The Fitting Set is supplied in standard Hydrogel
(Filcon II 2), 77% Water
Ordering KeraSoft® IC
The following information should be
provided to Customer Services when
ordering KeraSoft® IC:
• Base Curve
• Diameter
• Periphery (STD, STP or FLT)
• Power of Fitting Lens
• Over refraction
Additional information required:
• BVD of all lenses
(including all cyl lenses)
• Laser mark rotation and direction
It is important to specify the material
required:
• SiH, 74% Water
• Standard Hydrogel, 77% Water
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
®
Natural Ectasia Corneal Shape Recognition Chart
For Natural Ectasias, unaffected by scarring or contact lens wear, the charts below assist in understanding the Corneal Shape being fitted. The relationship between spectacle
refraction, visual acuity and K readings are influenced by the location of the steepest area of the cornea. This relationship does not hold true for post surgical corneas as they no
longer have a natural shape.
Record No. 296
Issue 2
16.06.2011
Kerasoft® is a Registered Trademark
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
®
Natural
Ectasias
Corneal Profile Chart
Topography
Normal
Mild
Moderate
Advanced
Central
Keratoconus
The Corneal Profile gives important information about
the overall corneal shape (in the vertical meridian),
especially if topography is unavailable or difficult to
interpret.
Natural Ectasia
The corneal shape in natural ectasias is influenced by
the location of the thinnest area of the cornea. The
Corneal Profile Chart shows the characteristic shapes
found in central and decentred/low cones and Pellucid
Marginal Degeneration and can be used, in conjunction
with the Natural Ectasia Corneal Shape Recognition
Chart, to help identify the corneal type being fitted.
Steep Periphery
Central
Keratoconus
Post Surgical
Flat Periphery
Corneas which have undergone one or more surgical
procedures no longer have a natural shape. Observing
the Corneal Profile, however, is a very useful tool,
especially in determining whether the cornea is a
reverse geometry shape.
Decentred/Low
Cone
To observe the Corneal Profile
Move the illumination system to the side, ask the patient
to look straight ahead and open the beam to the widest
setting.
Observe the anterior cornea, in profile, from the same
side as the illumination system, using the side of the
patient’s nose as a background.
Pellucid
Marginal
Degeneration
P
Post Surgical
Corneal Profile
O
S
T
S
U
R
G
I
C
A L
Post surgical corneas are often reverse geometry in
shape but this is by no means a general rule.
Example of Corneal Profile
Kerasoft® is a Registered Trademark
Ultravision International Limited, Commerce Way
Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
Record No. 302
Issue 1
15.06.11
®
First Choice Fitting Lens Guide
The Natural Ectasia Corneal Shape Recognition Chart and the Corneal Profile Chart in the KeraSoft® IC Toolkit assist in identifying the corneal shape being fitted. The guide below
suggests the Fitting Lens to be used as the first choice for each corneal shape.
If there is limited information as to the corneal shape, it is suggested to begin with the 8.20:STD Fitting Lens and assess using the MoRoCCo characteristics.
Note: Care should be taken not to confuse a mobile tight fitting lens with a flat fit. Therefore, if fitting one step steeper results in a more mobile lens, try fitting flatter base curves.
Condition
Central
Keratconus Steep
Periphery
Central
Keratoconus Flat
Periphery
Decentred/Low
Cone
Pellucid Marginal
Degeneration
Post Surgical
Topography
Corneal
Profile
MILD
MODERATE
ADVANCED
Hints and Tips
7.60 BC and 7.40 BC are also available on request but should
only be necessary in very Advanced cases.
8.60:14.50:STD
8.40:14.50:STD
8.00:14.50:STD
Due to the corneal shape, STP1 peripheries may also be
required in some cases.
8.60:14.50:STD
8.60:14.50:STD
8.60:14.50:STD
8.60:14.50:STP2
8.20:14.50:FLT2
8.40:14.50:STD
8.40:14.50:STD
8.00:14.50:FLT2
(Not in Fitting Set)
Mild, Moderate and Advanced cases may all require FLT
periphery Fitting Lenses with the appropriate base curves.
These can be ordered as required from Customer Services.
For more information view the Advanced Fitting – Natural
Ectasia online training module.
8.20:14.50:STD
In cases where all Fitting Lenses persist in dropping
significantly, it may be necessary to use SMC, steepening
lenses in the inferior sector only.
For more information view the Advanced Fitting - Natural
Ectasia online training module.
May require SMC
In Advanced cases the SMC design that is applied will usually
require a superior FLT sector and inferior STP sector to reflect
that these corneas are rotationally non-symmetrical.
For more information view the Advanced Fitting - Natural
Ectasia online training module.
In Post Surgical cases, if there is limited information as to the corneal shape, begin with the 8.60:14.50:
STD lens. These types of corneas may require STP periphery Fitting Lenses with the appropriate base
curves. Tilted grafts or Post Refractive surgery ectasias may require an SMC design. For more information
view the Advanced Fitting – Post Surgical online training module.
KeraSoft® IC Online Training can be accessed at www.kerasoft.co.uk/training
Record No. 276
Issue 6
15.06.11
Kerasoft® is a Registered Trademark
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
MoRoCCo Introduction and Dynamic Assessment Routine
Successful fitting of the KeraSoft® IC lens is based on observing the characteristics of the lens behaviour on eye.
These characteristics can be remembered by using the acronym MoRoCCo which represents Movement,
Rotation, Centration and Comfort, all of which when optimal, give the best Visual Acuity.
All of these characteristics are related to each other and have EQUAL IMPORTANCE when assessing the fit of the
lens on an irregular cornea.
If only two or three of the MoRoCCo characteristics are optimal, it will reduce the chance of the final ordered lens
behaving as expected.
Optimal Lens Fit Characteristics
Up to 3mm movement
These lathe cut lenses naturally move more than disposable lenses and up to 3mm post blink movement is acceptable, as long as the patient is
comfortable.
Vertical Laser mark
Rotation of the KeraSoft® IC is a strong indicator that the fit is not correct, unlike normal soft toric lenses where rotation can easily be accounted for by
changing the cylinder axis.
Central
The centration of the lens can be easily determined by observing the Front Optic Zone and is a very useful indicator in assessing flat fits. An optimal
fitting lens will be central.
Comfortable
KeraSoft® IC lenses should be comfortable. General discomfort can indicate the lens is flat and discomfort on one position indicates the lens is tight at
that point.
Stable
It is important that visual acuity is assessed before and after the blink. If VA is clearer after blink this indicates a TIGHT fit and if VA is worse AFTER blink,
this indicates a FLAT fit.
Dynamic Assessment Routine
Observe the lens within 5 minutes of the lens being inserted.
Mo
Ro
The Dynamic Assessment Routine uses the slit lamp to observe three of the MoRoCCo characteristics;
Movement, Rotation and Centration.
These three characteristics are observed in STRAIGHT AHEAD and UPWARD gaze.
Lag is assessed on lateral excursions in the straight ahead position.
C
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Movement is observed during the natural blink cycle. The push-up test is NOT used to assess movement.
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
Record No. 303
Issue 1
15.06.11
Hints and Tips
Mo
Ro
LENSES THAT FIT VERY TIGHTLY CAN MIMIC A FLAT FIT AND VICE VERSA.
The KeraSoft® IC Online Training Module ‘Dynamic Assessment Routine’ shows
how to differentiate between these fits.
UP TO 15 DEGREES ROTATION IS ACCEPTABLE, IF NO OTHER FITTING LENS
GIVES LESS ROTATION.
The most common reason for an ordered lens not behaving like the Fitting Lens
is that the initial fit was not optimal.
OPTIMAL
Mo
Record No. 304
Issue 1
15.06.11
UP TO 3mm
TIGHT
FLAT
LESS THAN 1mm
GREATER THAN 3mm
ROTATION that is STABLE
ROTATION that is UNSTABLE
Conjunctival indentation
Lens may flute
Ro
VERTICAL
Laser mark
In straight ahead and upward gaze
C
CENTRAL
CENTRAL
Co
COMFORTABLE
VA
STABLE
or rotates on upwards gaze
DECENTRED
FOZ drops to or below limbus
COMFORTABLE INITIALLY
UNCOMFORTABLE
CLEARER AFTER BLINK
WORSE AFTER BLINK
gradually becomes uncomfortable in one area
Kerasoft® is a Registered Trademark
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
Rotation
Centration
Optimal Fit
(Green)
Re-assess Fit
(Amber)
Incorrect Fit
(Red)
1-3mm Vertical Post Blink
<1 or >3mm
Too Mobile OR Immobile Lens that
Moves with Push-up
Up to 3mm acceptable if patient is
comfortable
<1mm - try one step flatter
>3mm - try one step steeper
If lens too flat - try 2 steps steeper
If lens too tight - try 2 steps flatter
Laser Mark - Vertical
15 - 20 Degrees
>20 Degrees
Up to 15 degrees stable rotation acceptable
if fitting 1 lens steeper or flatter does not
reduce the angle
Erratic swing on blink - Flat fit
Limited swing on blink - Tight fit
Erratic swing on blink - Flat fit
Limited swing on blink - Tight fit
Central
Decentres on Straight Ahead Gaze /
FOZ Drops to Limbus on Upward Gaze
FOZ Edge Drops Below Limbus on
Upward Gaze
Minimal decentration acceptable if visual
acuity is good
Try lens 1 step steeper
Try lens at least 1 step steeper
Good Comfort
General Discomfort
Very Uncomfortable
Consistently good comfort
Lens feels edgy - Flat fit
Discomfort in one location - Tight fit
Comfort does not improve with time
No Fluctuation
Fluctuation with Blink
Very Poor Vision
Visual acuity should not fluctuate on blink
Worse after blink - Flat fit
Clearer straight after blink - Tight fit
Poor vision not improved by any
over-refraction
Comfort
VA
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
Movement
Select and insert initial Fitting Lens using First Choice Fitting Lens Guide
Assess within 5 minutes
If it is in RED zone, remove lens then select next Fitting Lens 1-2 steps steeper or flatter
If fit is in GREEN or AMBER zone, begin over-refraction while the lens settles further
If VA is in RED zone, remove and reconsider first lens choice
If VA is in AMBER zone, determine whether fit is steep or flat, then adjust fit by 1 step
When an optimal GREEN fit is achieved, allow to settle for 15-20 minutes then finalise
over-refraction and take note of BVD
Kerasoft® is a Registered Trademark
MOVEMENT ROTATION CENTRATION COMFORT
VISUAL ACUITY (MOROCCO = BEST VA)
•
•
•
•
•
•
•
Record No. 275
Issue 5
15.06.11
KeraSoft® IC
Fit Assessment Guide
®
Periphery Options
When to use FLAT peripheries
In cases of Irregular Cornea where STD periphery lenses do not provide an optimal
fit, the periphery of the KeraSoft® IC can be steepened or flattened independently of
the base curve.
How to calculate the periphery change
In such cases, one STD periphery Fitting Lens will give the best overall fit in terms of
rotation and movement but a different one will give the best VA.
During the fitting process, record the Fitting Lens that gives the best fitting
characteristics, Best Peripheral Fit (BPF)
Flattening the periphery allows the lens to
correctly drape over the central cornea.
When to use STEEP peripheries
Then record the Fitting Lens that gives the best possible VA, Best Central Fit (BCF).
The difference in base curves is then calculated: BPF-BCF and the Kerasoft® IC
Table (fig. 1), indicates the periphery required.
Each periphery step is equivalent to a 0.20 change in base curve.
NB. When a periphery change is made, it affects the diameter of the Back Optic Zone
(BOZ). The Front Optic Zone (FOZ) is not affected.
Examples
If all STD lenses give stable rotation,
this implies the periphery of the
cornea is flat compared to the centre.
e.g., Nipple Cones.
When STD lenses show central
bubbles, general poor vision or VA
clearer after blink and flattening the
base curve improves VA but gives flat
fit characteristics.
Examples
When STD lenses show fluting or
unstable rotation and steepening the
base curve improves the fit but gives
VA clearer after blink.
Such cases include:
Post Refractive surgery.
Central Keratoconus with steep
periphery.
Post Graft corneas showing a reverse
geometry Corneal Profile.
Examples
BPF-BCF
Periphery to order
-0.80
STP4
-0.60
STP3
-0.40
STP2
-0.20
STP1
STD
STD
+0.20
FLT1
+0.40
FLT2
+0.60
FLT3
+0.80
FLT4
Figure 1
Record No. 299
Issue 3
05.07.2011
1 The best possible VA is found using an 8.00 Fitting Lens but shows tight fitting characteristics. This base curve is recorded
as the Best Central Fit (BCF).
The base curve giving optimal rotation and movement is found to be 8.20, however, the VA is now worse after blink. This
base curve is recorded as the Best Peripheral Fit (BPF).
BPF - BCF = 8.20 - 8.00 = +0.20 which gives a periphery value of FLT1 from the table.
This would be ordered as 8.00:FLT1
2 The best possible VA is found using an 8.40 Fitting Lens but shows flat fitting characteristics. This base curve is recorded as
the Best Central Fit (BCF).
The base curve giving optimal rotation and movement is found to be 7.80, however, the VA is now clearer after blink. This
base curve is recorded as the Best Peripheral Fit (BPF).
BPF - BCF = 7.80 - 8.40 = -0.60 which gives a periphery value of STP3 from the table.
The required lens would be ordered as 8.40:STP3
KeraSoft® is a Registered Trademark
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®
Sector Management Control
For more irregular corneas, up to two sectors of the periphery can be modified
independently of the base curve and customised to the specification of the Practitioner.
When to use Sector Management Control
Sector 1
1. A good fit cannot be obtained with an STD lens or by changing the whole
periphery. Such cases include:
A2
A2
A1
A3
A4
• Low cones and PMD
• Very irregular Post Graft cases
A1
Blended
Area
Blended
Area
A3
Sector Management Control is typically used in cases where:
A4
2. Lenses, that are otherwise a good fit, persistently decentre or drop
significantly on upward gaze.
3. The optimal fitting STD periphery lens consistently provides ghosting or
shadowing of images. Using SMC in these cases can significantly improve
Visual Acuity.
4. Decentred cones where the resultant corneal shape consistently causes all
lenses to decentre.
Sector 2
How to define the SMC Sector Angles
Classic SMC Design Sector Angles
Angles are recorded anti-clockwise around the lens circumference as A1, A2, A3 and A4.
This design can be used for most corneas that have a natural ectasia.
A1 and A2 define beginning and end of the first sector.
A3 and A4 define beginning and end of the second sector.
Each sector can be ordered as either STD, STP 1-4 or FLT 1-4.
A1 = 30
A3 = 220
A2 = 150
A4 = 320
Blend areas are automatically set once sector angles are defined.
There must be a minimum of 30 degrees between each sector.
For cases where tightening in the inferior sector only is required, keep the
superior sector STD and steepen the inferior sector by STP1. Post graft
corneas may require a more customised design.
Example 1: Classic SMC - Low Cone/PMD
Example 2: Customised SMC - Fluting on Post Graft cornea
A1
This SMC would be ordered as:
A2 = 150
A3 = 220
A1 = 30
A4 = 320
8.40:14.50:
FLT1: A1:30 A2:150
STP1: A3:220 A4:320
Using the Classic SMC design.
A4
A2
A3
Record No. 305
Issue 2 05.07.11
Kerasoft® is a Registered Trademark
If the lens requires tightening in
the area between 20 and 290
degrees, the order would be
written as:
8.60:14.50
STD: A1 = 110 A2 = 210
STP2: A3 = 290 A4 = 20
Ultravision International Limited, Commerce Way, Leighton Buzzard, Bedfordshire, LU7 4RW, United Kingdom
®
History
Fitting Toolkit Example: Decentred Cone
STD
Diagnosed with Keratoconus 14 years ago. RGP wearer ever since (VA this eye 6/12). The
cornea had central scarring and significant staining with fluorescein. Due to the current discomfort,
the patient elected to go without a lens until the cornea had demoulded.
Identifying Corneal Shape
In this case, the spectacle refraction has
been affected by central scarring
Spectacle Rx: +1.25/-6.25 x 50 VA 6/15
Sim Ks: 6.13/5.39
Steepest curvature: 4.75
Flattest curvature: 9.30
Curvature of ‘green area’: 7.50
Corneal Astigmatism: -7.58D ax 11 at 3mm
-6.56D ax 41 at 5mm
Corneal Shape Recognition Chart
Decentred/Low
Keratoconus
Moderate
The normal relationship between refraction and corneal shape has been changed due to central
scarring. Decentred cones often demonstrate oblique axes, which can be a useful clue if
topography is not available. This cornea demonstrates a very flat periphery on topography but
this may not, in fact, mean the corneo-scleral junction is flat.
Conclusion: This corneal shape is consistent with moderate decentred/low Keratoconus.
First Choice Lens
For decentred cones, the suggested choices are: 8.20 or 8.40:STD. As there were significantly flat areas on this cornea, the
8.40:STD lens was tried first.
MoRoCCo findings for 8.40:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
3mm post blink movement
15 degrees anti-clockwise
Lens was decentred 2 mm nasally and dropped to limbus on upward gaze
Lens felt edgy
Over Rx is +1.00/-6.00 x 60 6/12 with ghosting, VA worse after the blink
Conclusion:
Action:
Lens was fitting flat
This lens was removed and the 8.20:STD inserted
MoRoCCo findings for 8.20:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
3mm post blink movement
5 degrees anti-clockwise, unstable rotation, especially on upward gaze
Lens was decentred 0.5 mm nasally and dropped to limbus on upward gaze
Comfortable
With same over refraction, VA was 6/9+ still slightly worse after the blink
Conclusion:
Action:
This lens was still fitting slightly flat
This lens was removed and the 8.00:STD inserted
MoRoCCo findings for 8.00:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
1-2 mm post blink movement
Vertical
Centred
Comfortable
With same over refraction, VA was 6/7.5+ stable before and after the blink
Conclusion:
Action:
Lens had all parameters in optimal range from Fit Assessment Chart
This lens was now optimal and was ordered
ULTRAVISION INTERNATIONAL LIMITED, COMMERCE WAY, LEIGHTON BUZZARD, BEDFORDSHIRE, LU7 4RW, UNITED KINGDOM
Telephone: +44 (0)1525 381112 Fax: +44 (0)1525 370091 UK Order Line (Freephone): 0800 585115
Email: [email protected] Web: www.ultravisiongroup.com
Fitting Toolkit Example: Decentred Cone (Cont’d)
Discussion:
• The flattest and steepest areas on a topography can be very misleading, therefore it is always wise to look at
the corneal profile and also start fitting with STD lenses from the Fitting Set rather than order flatter Fitting
Lenses
• Remember one is fitting the whole cornea, not just the steepest area. In this case, it might have been tempting
to go straight to the 7.80 lens. If this had been done, the following MoRoCCo characteristics would have been
found:
Movement:
Rotation:
Centration:
Comfort:
VA:
1mm post blink movement
Vertical
Centred with no drop on upward gaze
Comfortable
6/9 and slightly clearer after the blink
If this had been the only lens tried, then it may well have been tempting to order this lens, thus missing the opportunity of
better VA with the 8.00:STD lens.
Record No. 306
Issue 2
06.07.11
®
History
Fitting Toolkit Example: Central Keratoconus
STP
Diagnosed 4 years previously with keratoconus, L>R. She started to wear RGP lenses but could not tolerate
them for more than 4 hours. She lost them 6 months later and did not bother to replace them. She was able
to wear a disposable soft lens in the right eye and wanted a specialist soft lens for the left eye.
Identifying Corneal Shape
Spectacle Rx: +0.25/-2.75 x 105 VA 6/15
Sim Ks: 7.32/6.78
Steepest curvature (Inf): 6.34
Flattest curvature: 7.93
Curvature of ‘green area’: 7.30
Corneal Astigmatism: -4.98 x 141@ 3mm
-3.48 x 143 @ 5mm
Corneal Shape Recognition Chart
Central Keratoconus
Steep Periphery
Mild
This cornea demonstrates reasonably normal K readings with a low spectacle Rx but affects
the central acuity significantly. This is typical of mild central ectasias, as any distortion on the
visual axis impacts on VA.
The topography has a pattern reminiscent of low cones/PMD (’crab claws’ pattern) but the
central location of the steep area confirms keratoconus. The curvature of the “green” area and
the flattest curvature value show that this cornea has a relatively steep periphery.
Conclusion: This corneal shape is consistent with mild central keratoconus with a steep
periphery.
First Choice Lens
Even though this is mild keratoconus, the cornea has a relatively steep overall profile. The suggested First Choice lenses for
this type of cornea are 8.00:STD and 7.80:STD. Therefore the first lens tried in eye was the 8.00:STD Fitting Lens.
MoRoCCo findings for 8.00:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
3mm+ post blink movement
10CW unstable
Centred but drops to limbus on upward gaze
Comfortable
OR Plano/-2.50 x 135 VA 6.7.5+. Stable after the blink
Conclusion:
Action:
This lens is behaving flat based on movement, centration and rotation
This lens was removed and a 7.80:STD inserted
MoRoCCo findings for 7.80:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
2mm post blink movement
Vertical
Centred on straight ahead and upward gaze
Comfortable
VA slightly clearer after the blink with same over refraction
Conclusion:
Action:
This lens gives good peripheral fit but is tight centrally, based on VA results
Order lens with 8.00 base curve, STP1 periphery and above over refraction
MoRoCCo findings for powered 8.00:STP1
Movement:
Rotation:
Centration:
Comfort:
VA:
Lens assessed within the first 5 minutes
2mm
Vertical
Centred on straight ahead and upward gaze
Comfortable
VA 6/7.5+
ULTRAVISION INTERNATIONAL LIMITED, COMMERCE WAY, LEIGHTON BUZZARD, BEDFORDSHIRE, LU7 4RW, UNITED KINGDOM
Telephone: +44 (0)1525 381112 Fax: +44 (0)1525 370091 UK Order Line (Freephone): 0800 585115
Email: [email protected] Web: www.ultravisiongroup.com
Fitting Toolkit Example: Central Keratoconus (Cont’d)
Discussion:
In this case, the decision to steepen the periphery was guided by the fact that the laser mark was vertical with the 7.80
lens and all other fit characteristics were optimal except for vision being clearer after the blink. However, flattening the base
curve introduces too many flat characteristics. Therefore combining the central fit of the 8.00 lens with the peripheral fit of
the 7.80 provided the optimal fit and visual acuity.
It should be noted that it is not advised to steepen the periphery in order to tighten a fit; this action may improve the fit
inferiorly and cause the fit to become tight superiorly due to the majority of natural ectasic corneas being steeper inferiorly.
Therefore, always try the next steepest base curve in the eye first, this will normally resolve the issue.
It should also be noted that increasing just the diameter may work to tighten ‘normal’ lenses but tends to change the whole
fit when applied to irregular corneas.
Record No. 307
Issue 1
15.06.11
®
History
Fitting Toolkit Example: Refit from RGP
FLT
Patient had been wearing RGP lenses for 18 years and had lost tolerance to them. Suffering from extreme
photophobia with reduced wear time of only a few hours hence she wished to be refitted with soft lenses. It
was explained that it might take several months for the cornea to demould. RGP has power of -12.50 (VA
6/9) and showed central touch with resultant central punctuate staining.
Identifying Corneal Shape
Spectacle Rx: -10.00/-1.50 x 103 VA 6/24
Sim Ks: 5.93/5.58
Steepest curvature (Inf): 5.93
Flattest curvature: 7.70
Curvature of ‘green area’: 6.47
Corneal Astigmatism: -3.50 x 162 at 3mm
-2.59 x 165
Corneal Shape Recognition Chart
Central Keratoconus
Flat Periphery
Moderate
The spectacle refraction, spectacle VA, and K readings all suggested a moderate central
keratoconus. The topography suggested that there might be some peripheral flattening, as
did observation of the corneal profile. However, long term RGP wear had moulded the
cornea and placido topography did not give full peripheral information. The behaviour of the
Fitting Lenses on eye gave the final clues as to corneal shape.
Conclusion: This corneal shape is consistent with moderate central keratoconus.
First Choice Lens
For central ectasias, the First Choice lens suggestion is an 8.00:STD, 7.80:STD or 8.20:FLT2 lens. If there is any doubt on the
peripheral cornea shape then it is advised to start with the 8.00:STD lens.
MoRoCCo findings for 8.00:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
Very little movement, air bubble at nasal, inferior position
15CW stable on straight ahead and upward gaze
Centred
Good comfort
Over Refraction was -11.50/-1.00 x 180 VA 6/12 Clearer after the blink
Conclusion:
The stable rotation indicated the lens was a tight fit and the position of the bubble suggested it was
tight at the periphery, rather than centrally. This then confirmed the suspicion that the peripheral
cornea was relatively flat compared to the central area.
NB: The bubble disappeared after 10 minutes wear. As up to 15 degrees rotation is acceptable for a
good fit, this vital clue that the lens was tight in the periphery may have been missed if the lens had
not been assessed straight away.
Removed this lens and inserted the 8.20:FLT2 lens in the Fitting Set. This lens design is intended for
this type of cornea.
Action:
MoRoCCo findings for 8.20:FLT2
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
3mm post blink. No bubble in the periphery
Vertical
Decentred 0.50 downwards on straight ahead/Dropped to limbus on upward gaze
Felt slightly edgy
With same over refraction, VA 6/9 slightly worse after the blink
Conclusion:
Fit and acuity was now much better, so that this configuration confirmed as a better fit. However,
decentration, comfort and VA showed the lens was now slightly flat. The logical course of action was
to fit tighter centrally, keeping the periphery as FLT2.
An 8.00:FLT2 Plano Fitting Lens was ordered
Action:
ULTRAVISION INTERNATIONAL LIMITED, COMMERCE WAY, LEIGHTON BUZZARD, BEDFORDSHIRE, LU7 4RW, UNITED KINGDOM
Telephone: +44 (0)1525 381112 Fax: +44 (0)1525 370091 UK Order Line (Freephone): 0800 585115
Email: [email protected] Web: www.ultravisiongroup.com
Fitting Toolkit Example: Refit from RGP (Cont’d)
MoRoCCo findings for 8.00:FLT2
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
2mm post blink movement
Vertical
Lens centred in straight ahead and upward gaze
Comfortable
6/9+2. Stable after blink
Conclusion:
Action:
This lens was now an optimal fit
An 8.00:FLT2 lens was ordered with a power of -10.00DS for the patient to use while the cornea
demoulded.
Follow Up:
She was assessed 3 months later and reported that during this time her vision
had fluctuated but now seemed to be much more settled.
Topography showed a generalised flattening of the cornea:
Central K readings were now 6.16/6.00 and the flattest part of the topography
was now reading 8.50.
MoRoCCo findings with patients own 8.00:FLT2
Movement:
Rotation:
Centration:
Comfort:
VA:
0.50mm post blink movement
5CW
Lens was centred
Comfortable
VA 6/12. Clearer after the blink
Conclusion:
Action:
This lens was now a tight fit
The 8.20:FLT2 Fitting Lens was inserted and assessed
MoRoCCo findings for 8.20:FLT2
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
1.5mm post blink movement
Vertical
Lens was centred
Comfortable
Over Refraction was now -13.50/-2.00 x 40 VA 6/9+2 stable after the blink
Conclusion:
Action:
This lens was now an optimal fit
This lens ordered with power -11.50/-1.75 x 40
Discussion:
• Demoulding can result in a cornea steepening or flattening dependent on the RGP lens fit.
• Even if information is not available as to the peripheral corneal shape, clues can be found in the way the Fitting
Lenses behave.
• Often it is best to give a spherical lens while the cornea is demoulding.
o This avoids the visual disturbance of changing astigmatism.
o It is easier to assess over refraction.
• Only change the power of the lens when the corneal demoulding has slowed or stopped.
Record No. 308
Issue 2
06.07.11
®
History
Fitting Toolkit Example: Low Cone
SMC
Diagnosed with Pellucid Marginal Degeneration 4 years ago and had a Corneal Collagen Cross linking
(CXL) procedure 6 months prior to assessment. He had not used his RGP lenses since Cross Linking and
now wished to be refitted with soft lenses.
Identifying Corneal Shape
Spectacle Rx: +1.50/-8.00 x 120 VA 6/19
Sim Ks: 6.55/5.68
Steepest curvature (Inf): 6.61
Flattest curvature: 8.80
Curvature of ‘green area’: 7.00
Corneal Astigmatism: -7.81 x 128 @ 3mm
-6.80 x 131 @ 5mm
Corneal Shape Recognition Chart
Decentred/Low
Keratoconus
Moderate
The topography map is a classic PMD “crabs claw” pattern and the Spectacle Acuity also
indicates this. However, in this case, the steepest area of curvature is relatively high and is thus
better described as a low cone. This is also suggested from the central K readings and the poor
Spectacle Acuity, which is caused by the rapid changes of curvature within the pupil area. It is
often difficult to distinguish between Low Cones and PMD and the fitting indications are often
quite similar. Observing the Corneal Profile will often confirm the position of the steepest area.
Conclusion: This corneal shape is consistent with moderate low cone.
First Choice Lens
Deciding on the first choice lens for Low Cones/PMD is challenging as often there are extremes of flatness and steepness
within the same cornea. The suggested first choice for Low Cone is either 8.40:STD or 8.60:STD and for PMD is 8.20:STD.
This is influenced by the fact the lens has to fit the steeply curved inferior area. In this case, as the cornea had characteristics
of both conditions, it was decided to start with the 8.40:STD lens.
MoRoCCo findings for 8.40:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
1mm post blink movement
Vertical but rotated clockwise and then anti-clockwise on blinking and upward gaze
Centred but dropped towards limbus on upward gaze
Initially good but patient began to feel the lens superiorly
6/15 - 6/12. Variable and clearer after the blink and letters ghosted
Conclusion:
Action:
Lens is showing a mixture of tight and flat characteristics
Explored the fit of base curves either side of the 8.40:STD
MoRoCCo findings for 8.20:STD
Lens assessed within the first 5 minutes
Movement:
Rotation:
Centration:
Comfort:
VA:
Very little movement
Vertical and stable on straight ahead and upward gaze
Centred
Uncomfortable at top edge of lens
6/19+. Variable and clearer after the blink
Conclusion:
Although the lens appeared to be a good fit inferiorly, other characteristics indicated the lens to be
fitting steep.
An 8.60 lens was inserted into the eye
Action:
MoRoCCo findings for 8.60:STD
Movement:
Rotation:
Centration:
Comfort:
VA:
Lens assessed within the first 5 minutes
2mm post blink movement
10 degrees anti-clockwise and very unstable
Sat low on straight ahead gaze and dropped to limbus on upwards gaze
Could feel lens at bottom edge
6/9 but still ghosted
ULTRAVISION INTERNATIONAL LIMITED, COMMERCE WAY, LEIGHTON BUZZARD, BEDFORDSHIRE, LU7 4RW, UNITED KINGDOM
Telephone: +44 (0)1525 381112 Fax: +44 (0)1525 370091 UK Order Line (Freephone): 0800 585115
Email: [email protected] Web: www.ultravisiongroup.com
Fitting Toolkit Example: Low Cone (Cont’d)
Conclusion:
This cornea would benefit from a Sector Management Control (SMC) lens. The best VA was with
the 8.60 base curve but the lens was unstable at the bottom. The least rotation was with the 8.20
base curve but the lens was tight at the top. A lens was designed combining the fits of these two
lenses.
Action:
An SMC plano trial lens was ordered with parameters: 8.60:STD:STP2 (each step is equivalent to
a change in base curve of 0.20).
The classic SMC design was used: A1=30 A2=150 A3=220 A4=320.
Therefore, the lens ordered was: 8.60:14.50:STD A1=30 A2=150 STP2 A3=220 A4=320.
MoRoCCo findings for 8.60:STD:STP2
Movement:
Rotation:
Centration:
Comfort:
VA:
Lens assessed within the first 5 minutes
2mm post blink movement
Vertical and stable on straight ahead and upward gaze
Centred
Comfortable
6/7.5 with +1.00/-9.00 x 125 Over Refraction. Stable before and after the blink and no ghosting
Discussion:
• The poor acuity with STD lenses was due to tear pooling under the lens, either because steeper lenses were
too tight or flatter lenses were to loose in different locations. By using a relatively flat base curve and then
‘tucking in’ the inferior periphery, the best of both lens fits was obtained.
150
30
The classic SMC works well even if the steepest area of the cornea is decentred, as
in this case. This is because the periphery of the lens is fitting to the sclera rather
than to the cornea and the aim is to make sure the lens touches down properly in
the inferior.
The exception to this general rule is when fitting post-graft corneas with tilted grafts
or horizontally decentred cones.
220
Record No. 309
Issue 2
06.07.11
320
Extra Fitting Lenses incorporating SMC can be ordered when required.