1. science
2. physics
3. optics

Hybrid Contact Lenses
Past, Present, and Future
Victoria Butcko, O.D., FAAO
Jesse Brown VAMC
820 S Damen Ave
Chicago, IL 60612
History of Hybrid Lenses
• Hybrid lenses
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Rigid gas permeable optic zone
Hydrogel peripheral zone
Have been available for 18 years
Their use in keratoconus was first described
by Little in 1971.
SoftPerm (Wesley Jensen)
• Original design by Precision-Cosmet
– Marketed as Saturn II lens -1983
• Design fuses styrene-based RGP center with low water
hydroxyethyl methacrylate (HEMA) soft-lens skirt
– Ideal was to provide good comfort but have optic of RGP for best
quality vision
• Performance limitations with Saturn lens
– Redesigned and marketed as SoftPerm Lens- 1985
• Softperm offered larger OAD, larger central central optic
zone and RGP pcs allowed wider range of applications
SoftPerm Lens
• Originally considered ideal s/p PKP, KCN,
irregular corneas
• Larger OAD allowed better centration
– Excellent stability and moderated astigmatism
correction
• Negatives:
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Limited oxygen transmission
Tendency to adhere
Lens breakage- major issue
Flexure of RGP
SoftPerm
• Resulted in:
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corneal edema
neovascularization
epithelial erosion
acute red eye
infiltrative keratitis
graft rejection
• Limited wear time for patient
SoftPerm
Table 1. The properties and parameters of the SofiPerm TM lens, as stated by the manufacturer .
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Properties
Material
Oxygen permeability (at 35°C)
Synergicon A (non-ionic)
14.0 x 10 -n rigid optic zone*
5.5 × 10 -11 hydrogel peripheral zone*
Water content 25%
hydrogel peripheral zone
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Parameters
Back optic zone radii
7.10 to 8.10 mm
Back optic zone diameter
7.00 mm
Diameter of rigid optic zone
8.00 mm
Total diameter
14.30 mm
center thickness of the rigid center (3.00 D) 0.08 mm
skirt thickness
0.20 mm.
steepest BC
6.5 mm
*Units of oxygen permeability are (cm2/s) (mlO2/ml × mmHg).
Overcoming Limitations
• Quarter Lambda Technologies, Inc. of
SanMarcos, CA
– commenced a focused research and
development program September 2001 to create
an improved hybrid contact lens.
• October 2003- company received IRB
approval to begin with four of the
SynergEyes products.
Synergeyes
• Rigid Lens Component:
Diameter: 8.4 mm OZD: 7.8 mm
• Oxygen permeability of 100 X 10 (-11) (cm2/sec) (mL
O2/mL mm Hg).
• RGP center thickness is 0.15 mm for the 3.00 D back
vertex power
• The soft skirt extends to 14.5 mm with a water content of
27% and a permeability of 9.3 X 10(-11) (cm2/sec) (mL
O2/mL mm Hg).
• The mean thickness of the skirt is 0.16 mm.
Synergeyes
• Employs a continuous aspheric base curve from lens
center to periphery
• Available with base curve radii as steep as 5.7 mm.
• Patent pending technology to produce a lens that is more
than 10 times stronger at junction zone
• Multiple skirt radii are available for each base curve
radius, 0.7 to 1.6 mm flatter than the central radius, in 0.3
mm steps.
TABLE 1.
CL parameters for the Softperm and SynergEyes
hybrid contact lenses:
Lens
SoftPerm
Overall diameter (mm)
14.3
Rigid overall diameter (mm)
8.0
Rigid optic zone (mm)
7.0
Soft skirt water (%)
25
Soft skirt Dka
5.5
Rigid Dka
14.0
Power (D)
-3.00
Center thickness (-3.00 D) (mm) 0.08
Mean skirt thickness (mm)
0.20
SynergEyes
14.5
8.4
7.8
27
9.3
100
-3.00
0.15
0.16
Synergeyes
Rigid optics give optimal visual acuity
• Soft skirt material is dimensionally stable and
expansion-free
– Increased stability for consistent, predictable
vision
• Hydrophilic, non-ionic soft skirt
– Retains water content for all-day comfort;
delivering a low-soiling lens
•
Synergeyes
• Rotationally symmetrical platform
– Requires no orientational positioning in eyes
having near equal refractive and corneal
astigmatism
• High oxygen transmission
– Excellent physiological response
Synergeyes
• Precise optics centered over visual axis
– Ability to correct refractive errors ranging from 20.00D to +20.00D (with great reduction in glare, halo
and starbursts)
• Exclusive HyperBond™ junction
– Much stronger than other marketed hybrid lenses[1]
• Proprietary HydrolEyes™ surface science
– Outstanding in vivo wetting provides excellent all-day
comfort and optical clarity
Fitting Synergeyes Lenses
• Synergeyes A
– 20 lenses
• 10 BC, 2 SC each
• Synergeyes KC
– 24 lenses
• 8 BC, 3 Skirt Curves each
Fitting Synergeyes Lenses
• Synergeyes A and KC
– Diagnostic fitting
• Initial selection should be 1.00D to 1.50D steeper
than flat K
• Each 0.1mm of BC change requires 0.50D power
adjustment
– SAM and FAP
• Goal is to fit the steepest BC that is free of central
bubble
• Focus on BC selection before fine tuning skirt
curve
Synergeyes A and KC
• Can not use regular Sodium Fluorescein
due to the soft lens skirt
– Large Molecule Fluorescein used to evaluate
fit
– Fluorescein is placed in bowl of lens prior to
inserted lens
– Interpretation can be difficult
• not as effective as regular fluorescein
Synergeyes A and KC
• Goal is to achieve apical clearance
– Pooling of fluorescein will be noted centrally in the
lens
• Lens movement
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Should be slight lag in up gaze
No scleral impingement
Free of “edge fluting”
Free to move with “push up” test
Lenses need to settle 10-15 minutes to properly assess
movement
• Lenses will tighten over time
Synergeyes A and KC
• Skirt Curve Radius
– If “Heavy bearing or a heavy ring of touch” is
noted at the junction of the skirt curve and the
RGP:
• Plan: steepen the SCR
• Example: change SCR from 8.5mm to 8.2mm
– If edge fluting is noted also steepen SCR
– Steeper skirts will reduce the bearing at the
corneal apex
Figure 1:
Pt in down gaze with
superior pooling.
Figure 2:
Central pooling noted
with light touch
midperipheral zone.
Two additional
examples
using high molecular
weight fluorescein
with Synergeyes A fit.
Synergeyes A/KC Fitting
• Fitting is Counter-intuitive
– Tight fitting lenses- steepen BC or SCR
– “Heavy Bearing” at junction- steepen SCR
• Never prescribe flatter than or “on” Flat K
• Lenses are 6 month replacement
Synergeyes
• Also available from Synergeyes
– Synergeyes Multifocal
– Synergeyes PS (post surgical)
• Syn A marketed for normal astigmats,
myopes and hyperopes
• Syn KC marketed for KCN, PMD, more
corneal irregularity
Care and Cleaning of
Synergeyes Lenses
• Digital rubbing is extremely important!
• Multipurpose solutions:
– Opti-free
– Renu Multipurpose
– Clear Care Solution
• 6 month replacement schedule
Over refraction
• After achieving proper fit, proceed to over
refraction
– Begin with spherical over refraction
– If necessary incorporate cylindrical over refraction
– If over refraction >2.00D cyl, pt may be experiencing
lens flexure
• Perform over Ks to see if they correlate
• Can order enhanced profile design, increased central
thickness to prevent flexure.
References
• Bennett, Edward S., Vinita, Henry; Clinical Manual of Contact
Lenses
• Philidelphia: Lippincott Williams & Wilkins, 2000;
• http://www.synergeyes.com
• Rubinstein, MP, Sud, S; "The use of hybrid lenses in the management
of the irregular cornea." Contact Lens Anterior Eye; 1999; 22(3); 8790