Benefits of Silicone Hydrogel Contact Lenses

The introduction of Silicone Hydrogel contact lenses onto the market, 1999, was an excellent solution for patients requiring higher levels of oxygen permeability than standard Hydrogel lenses could provide. Silicone Hydrogel contact lenses solved the corneal hypoxia problem by delivering increased amounts of oxygen to the eye. Many people spend long hours in front of computer screens, which, in standard Hydrogel lenses, can result in rapid dehydration of the lens' surfaces leading to discomfort and red eye. Dryness, often exacerbated by climatic and altitude conditions, is the most quoted reason for reduced lens wear or even discontinuation of contact lens wear altogether.

 

When first introduced to the market, SiH lenses were better than non-Silicone Hydrogels in terms of reducing drying effects. However, these first SiH lenses had comfort issues related to stiffness of material (modulus), difficulties in surface wetting and a propensity to encourage deposits. A second generation of SiH lenses, with much lower moduli, were developed to address the issue of comfort. However, patients with more complex prescriptions still could not benefit from the increase in ocular health that SiH can bring.

 

'The Full Collection' from UltraVision

UltraVision is now able to produce a lathe-cut SiH contact lens, made with Definitive™ by Contamac Ltd, which has the benefit of increased oxygen transmission, combined with the best attributes of hydrogels.

 

Properties	Attributes
Naturally hydrophilic SiH	Excellent wetting
Lathe cut	Wide range of powers
75% water content	Higher comfort level
DK 60	Increased oxygen transmission
Modulus 0.27	Faster settling time
High water retention	Longer wear times

 

HydroWave, is a 3-monthly SiH lens, is available in a very wide range of prescriptions, including Spherical, Toric, Multifocal Spherical and Multifocal Toric designs. UltraVision's SiH contact lenses are extremely comfortable, and require no plasma treatment to increase wettability thereby reducing deposition. All these attributes make a powerful addition to a contact lens fitter's range of contact lenses.

 

Definitive™ SiH is a unique material, in that it has high water content and high water retention, which has the benefit of not drying out throughout the day, therefore does not need to absorb tears to maintain hydration, thus providing increased comfort levels.

 

 

Indications

Red Eyes

Eyes that look red at the end of the day are one of the most common complaints from contact lens wearers and RGP wear often leads to 3 and 9 o'clock drying with resultant redness at the limbal areas. UltraVision's SiH lenses are excellent at reducing this problem, due to the high oxygen transmission and high water retention.

 

Dry Eyes

Definitive™ is excellent at reducing dry eye problems for many reasons:

•   Increased oxygen supply improves ocular health generally.

•   High water retentiveness leaves more of the tear film on the eye rather than being taken up by the lens.

•   Lid irritation at the end of the day is very much reduced because of the high comfort levels.

•   The improvement in wearing time is most marked in certain adverse conditions such as; air conditioning, travelling on planes and at altitude.

 

Ocular Health

Due to its high oxygen permeability, SiH has consistently proven to be excellent for long term ocular health.

 

Complex Fittings - RGPs Vs. SiH

It is now possible to fit most irregular or distorted corneas with UltraVision's SiH contact lenses, which provide excellent comfort, and in many cases surpass RGP lenses regarding ocular health. Acuity levels rival those of RGP wear, thanks to UltraVision's patented wavefront technology optics.

 

•   Keratoconus

With RGP lenses Keratoconus patients are often forced to ration their "good vision time" during the day as they cannot tolerate RGP lenses for all their working hours. SiH KeraSoft®3 lenses enable the patient to wear lenses for much longer periods of time.

 

•  New Surgical Technologies

However well an RGP lens is fitted it will cause the corneal shape to fluctuate when wear is discontinued, which makes treatment with new technologies such as corneal cross linking, intacs and phakic implants more of a problem. UltraVision's contact lenses made from SiH do not compromise the corneal health and shape, and therefore a successful outcome is much more likely if surgery is required. KeraSoft®3 can also be used after these surgical procedures to give useful vision while the refraction is settling down.

 

KeraSoft®2 Vs. KeraSoft®3

If you have patients who are happy with KeraSoft®2 lenses - Why upgrade?

The new KeraSoft®3 is made from 74% water content SiH material, which has 4 times the oxygen transmission of the KeraSoft®2 material. The different modulus means that the lens can be flatter than KeraSoft®2, producing a good lens movement that encourages tear exchange beneath the lens. This ensures a greatly improved oxygen transmission to the sensitive keratoconic cornea.

 

Many patients, who could not achieve all day wear in KeraSoft®2, find they can get 14 to 16 hours wear in the new KeraSoft®3 lens, due to the SiH material. This is particularly so in areas of the world with extremes of temperature or altitude.