What is with all these Soft
Contacts!?
Krystle Kennedy, O.D.
History of SCL
• Publication about SCL first appeared in 1960s, by
Czech doctors.
• Best VA 20/40
• In March 1971, B&L had the entire soft lens system
approved by FDA
• Sales top $10 million by the end of the year
• 1979 The first toric SCL is developed
• In 1999, PureVision, the world’s first silicone
hydrogel is introduced
Soft Lens Material
• HEMA =Hydroxyethylmethacrylate backbone
material in almost all SCL
Dk?
– Permeability/Thickness
– Higher DK more permeable to oxygen
– As water content increases the more permeable the
lens is but doesn’t necessarily mean it delivers more
oxygen to the eye-> high water thicker lens
– The thicker the lens, the less oxygen transmission
– The higher the water content, the great oxygen
transmission
– Thinner=healthier
– Problem: thin lenses can be difficult to handle or tear
easily
How practitioners decides
(not in any order)
– Cost
– Availability
– Visual requirements
– GPC
– Deposits
– Familiarity
– Tints
– Durability
– Physiological requirements
Silicone Hydrogels
– Water content not high
– Took long time to develop b/c it is hard to combine
silicone with anything
– Silicone is oxygen permeable. So silicone hydrogel
lenses use both their water and polymer content to
transmit oxygen to the eye.
– Silicone hydrogel contact lenses contain less water
than traditional hydrogel lenses. As a result, they
aren't as prone to dehydration while you're wearing
them. For some people who wear their lenses for long
days, this can mean better end-of-day comfort.
Aspheric Lenses
• More recently, manufacturers have designed
"aspherics" to correct for spherical aberration
(SA) of the lens and/or the eye.
Extended Wear
– The initial heyday of 30-day wear was in the
1980s, but that ended due to health and safety
concerns
– Two brands — Air Optix Night & Day by CIBA
Vision, and PureVision from Bausch + Lomb — can
be worn for up to 30 days.
– Four other silicone hydrogels — Acuvue Oasys, Air
Optix, and CooperVision's Biofinity — are
approved for overnight wear of six nights
consecutively.
One-Day
• fresh start every day with a new, clean pair of lenses
for the healthiest and most convenient way to wear
contact lenses
Toric Contact lenses
– Toric contact lenses are made from the same
materials as regular ("spherical") contact lenses
– Toric lenses have two powers in them, created
with curvatures at different angles. There is also a
mechanism to keep the contact lens relatively
stable on the eye when you blink or look around.
To provide crisp vision, toric contact lenses cannot
rotate on your eye.
The Accelerated Stabilization Design (ASD) of
ACUVUE®OASYS® for ASTIGMATISM delivers clear, stable
vision beyond the chair. The unique lens design has four
zones of stability, compared to the single zone of ballast
design lenses.
OPTIMIZED BALLAST DESIGN
Avaira Toric’s consistent horizontal thickness and wide
ballast improve lens stability, reduce rotation, and
enable a consistent fit across the power range—
providing exceptional vision, regardless of prescription
Lo Torque Design
The unique Lo-Torque design of
SofLens For Astigmatism contact
lens clearly means stability, visual
acuity, comfort, and ease of fit.
• Optimal Lens Design
• PureVision Toric lenses combine material and design innovations to
deliver:
• Exceptional rotational stability enabled by a proven prism ballasting
geometry with a 360° comfort chamfer (1) and a balanced vertical
thickness profile (2).
• High-quality vision, with refined optic zones (3) and next-generation
spherical aberration correction with unique anterior aspheric optics
(4).
Multifocal
– Multifocal contact lenses have a range of powers
– Concentric rings type of bifocal contact lens features
a prescription in the center and one or more rings of
power surrounding it. If there are multiple rings, they
alternate between the near and distance prescription.
– Aspheric multifocal contact lens designs work more
like progressive eyeglass lenses, where the different
prescriptive powers are blended across the lens.
Unlike eyeglasses, however, aspheric contact lenses
are simultaneous vision lenses, so your visual system
must learn to select the proper prescription for the
moment.
Thanks!
• Any questions?
• doctorkrystle@hotmail.com