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Since silicone hydrogel soft contact lenses were first introduced they have continued to grow in popularity and in market share. Initially, silicone hydrogel lenses were designed to optimise oxygen transmission for extended wear use,1 and ideally to lessen ocular complications. Many changes have occurred in the design and availability of new generation silicone hydrogel lenses. As a result, many practitioners now offer the significant benefits of increased oxygen transmissibility as first choice fit to their daily wear patients too.
The growth of silicone hydrogel lenses since their introduction in the late 1990s is an indication of their popularity and the confidence eye care professionals have gained by prescribing silicone hydrogel lenses for their patients. In 2007, silicone hydrogel lenses accounted for over half of all new soft lens fits in some countries in Europe and in the US.2 In the UK, 24 per cent of daily wear fits are now in silicone hydrogel materials.3
This growth has also been driven by the unmet needs of consumers for better comfort, with up to 70 per cent of wearers still reporting discomfort.4 Some patients can only wear contact lenses for short periods in the day, pointing to an opportunity for increased wearing comfort and oxygen transmission. Others are wearing their lenses regularly and for long hours, increasing the need for healthy lenses. (Figure 1).
The increase in availability of silicone hydrogel lenses from a few spherical choices to nine silicone hydrogel spherical lenses now (Table 1), demonstrates a commitment from contact lens manufacturers to provide a healthy contact lens option, and also proves the large demand from eye care professionals to offer superior lens materials to their customers. In addition to the sphere availability, other designs have now been introduced to help astigmatic patients, presbyopic patients, and patients with high prescription requirements. Table 1 includes three toric options and one multifocal option, as well as a made-to-order (MTO) lens in silicone hydrogel material.
These silicone hydrogel materials have different properties, water contents and oxygen transmissibilities, but all work to increase the amount of oxygen passing through the lens.
In 2005, CIBA Vision introduced Air Optix as a new silicone hydrogel lens for daily wear, and overnight wear for up to six nights, offering high oxygen transmission through the lens. The lens also had a patented, biocompatible plasma surface treatment that resists deposits to contribute to healthy lens wear.5
Air Optix Aqua
CIBA Vision is now launching the new Air Optix Aqua which offers the Aqua Moisture System that:
- Lubricates - a unique moisture agent with hydrophilic properties that binds with the lens surface to create a silky layer that helps the eyelid to easily glide over the lens for comfort upon insertion
- Maintains - Lotrafilcon B, a patented 33 per cent water content lens material that helps maintain moisture by minimising the rate of lens dehydration for all-day-comfort
- Sustains - an ultra-smooth surface with superior wettability to deliver a new level of comfort every day. Better wettability also means excellent deposit resistance, which contributes to comfortable lens wear. New Air Optix Aqua has superior wettability due to its lower initial contact angle, there is a 30 per cent improvement over the original Air Optix.
To quantify the on-eye improvements with Air Optix Aqua, a clinical trial comparing it with Air Optix was conducted. The details were as follows:
Objectives/design
The primary purpose of the trial was to assess the overall performance of Air Optix Aqua lenses compared to Air Optix lenses when worn according to the FDA-approved wearing schedule.
Materials and methods
The trial was a prospective, double-masked, randomised, contralateral trial involving 113 patients at 10 investigational sites in the US. Subjects were randomly assigned to wear Air Optix Aqua in one eye and Air Optix in the opposite eye. This three-month trial had seven scheduled visits. Patients were seen for a baseline/dispensing visit, 24-hour visit, one-week visit, two-week visit, one-month visit, two-month visit and three-month/exit visit.
All subjective comfort ratings were based on a scale from 1 to 10, with 1 being poor and 10 being excellent.
Results
A overall total of 113 patients were enrolled and 103 patients completed the trial as 10 patients discontinued the trial.
Subjective ratings
Subjective ratings for comfort after insertion, end of day comfort and overall dryness were significantly better for Air Optix Aqua compared to Air Optix (p<0.05) (Figure 2).
Preferences
Of subjects with a preference, Air Optix Aqua lenses were significantly preferred over Air Optix lenses for the following variables (p<0.05):
- End of day comfort
- Overall comfort
- Overall handling.
In fact, Air Optix Aqua was preferred by a factor of two to one for overall comfort compared to the original Air Optix.
The superior on-eye performance of Air Optix Aqua in this study may be related to the enhanced surface wettability. The low contact angle measurements with Air Optix Aqua demonstrate that it provides the best surface wettability of the leading silicone hydrogels on the market6 (Figure 3) when compared to Acuvue Oasys, Acuvue Advance, Biofinity, and PureVision.
Conclusion
As manufacturers continue to place emphasis on research and innovation in silicone hydrogel lenses, new contact lenses continue to emerge in the market.
With improvements in manufacturing processes and material properties, and the introduction of comfort agents, eye care professionals are able to offer more of their patients the benefits of this new technology.
With the introduction of Air Optix Aqua, practitioners can now offer their patients a silicone hydrogel lens that offers improvements in insertion, end-of-day and overall comfort over Air Optix. This is achieved by the Aqua Moisture System with a new, unique moisture agent to lubricate on insertion, a 33 per cent water patented lens material to help maintain moisture and an optimised biocompatible plasma surface treatment for superior wettability and deposit resistance to sustain comfort.
References
- Guillon M, Maissa C. Use of Silicone Hydrogel Material for Daily Wear. Contact Lens & Anterior Eye, 2007, 30: 5-10.
- Morgan P, et al. International contact lens prescribing in 2007. Contact Lens Spectrum, 2008 Jan: 36-41.
- Eurolens Research 2008.
- Opinion Market Research & Consulting 2006.
- Jones D, Woods C, Jones L, Morgan P. The Use of Silicone Hydrogel Contact Lenses by Canadian Optometrists 2000 to 2006. Silicone Hydrogel Lens Website. 2007 March.
- CIBA Vision data on file 2007.
? Dr Tim Giles is global director, professional education, CIBA Vision