History of SCL What is with all these Soft Contacts!? Publication about SCL first appeared in 1960s, by Czech doctors. Best VA 20/40 Krystle Kennedy, O.D. 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 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 nextgeneration spherical aberration correction with unique anterior aspheric optics (4). Lo Torque Design The unique Lo Torque design of SofLens For Astigmatism contact lens clearly means stability, visual acuity, comfort, and ease of fit.
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