Contact Lens Design & Materials
New Introductions in the Daily Disposable Modality
By Neil Pence, OD, FAAO
The summer of 2012 has seen the introduction of two new daily disposable contact lenses: a single vision entry with some unique properties and a multifocal lens, only the second in the market.
The Biotrue Oneday (Bausch + Lomb [B+L]) single vision lens incorporates spherical aberration correction that B+L says is customized for every 0.25D step. The lens is currently available in powers from −0.25D to −9.00D, with plus powers to follow. It has a 14.2mm diameter, one base curve, and a UV blocker.
One unique aspect of Biotrue Oneday compared with existing daily disposables is its water content. According to B+L, it has the highest water content of any daily disposable on the market—78 percent, which is generally accepted as the water content of the cornea. B+L refers to this new high-water-content hydrogel lens material as a “HyperGel.”
Historically, high-water-content lenses, especially thin designs, have good initial comfort, but such lenses are prone to pronounced dehydration as wearing time progresses. Biotrue Oneday lenses combat this dehydration in a relatively novel manner. B+L says that the liquid polymer contains a surfactant, which migrates to the lens surface during the manufacturing process. This creates an outer surface layer that helps lock in moisture to prevent dehydration, much as the tears' own lipid layer prevents dehydration, according to the manufacturer. By combating dehydration, the lenses are designed to maintain more consistent comfort and acuity throughout the day.
Proclear 1 Day Multifocal
The Proclear 1 Day Multifocal (CooperVision) lens is only the second multifocal daily disposable contact lens on the market. The lens is manufactured in the company's Proclear material, which is known for its low dehydration properties. The design has an annular center-near configuration.
The Proclear 1 Day Multifocal lens has one standard add power that is said to be effective for patients needing near adds up to 1.00D. CooperVision says that for these patients, the initial lens selection for both eyes is the best distance power for each eye, vertexed if necessary. For adds from 1.25D and above, the fitting suggestion is to add 0.75D to the distance power of the nondominant eye. Some patients who require 2.00D and greater add powers may need 1.00D extra near power rather than 0.75D. Initial powers can then be adjusted using handheld trial lenses on each eye. Patients should keep both eyes open during this over-refraction.
Many would refer to this approach as modified monovision. While the powers are not perfectly balanced at all distances, the binocular summation with low amounts of blur is better than what might be expected. Patients who are fitted in this manner see binocularly at most of the viewing distances common in daily living.
Two more daily disposable contact lenses in the marketplace are welcome additions. A lens with different surface properties that corrects spherical aberration brings some new attributes to our fitting options. Having a second daily disposable multifocal increases the number of patients who may benefit from the comfort, convenience, and safety of daily disposable lenses.
These two new daily disposable options will soon be joined by a second silicone hydrogel daily disposable lens—Alcon's Dailies Total1. This lens is being launched in various global markets at present, with a U.S. launch thought to be planned for later this year. Stay tuned. CLS
|Dr. Pence is the associate dean for Clinical and Patient Care Services, Indiana University School of Optometry in Bloomington, Indiana. He is also a consultant to B+L, J&J Vision Care, and Alcon. You can reach him at firstname.lastname@example.org.|