what is with all these soft contacts!? krystle kennedy, o.d
TRANSCRIPT
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 DESIGNAvaira 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 DesignThe 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.
