Contact Lenses

 

Contact Lenses

 

 
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Background

There are over 140 million contact lens wearers worldwide, with an estimated 3.5 million living in Canada and more than 1 million in Ontario. Surveys performed in the late 1990s showed that approximately 50% of contact lens wearers suffered from symptoms of dryness and discomfort, which are the most frequent cited reasons for the 20-25% of patients who eventually discontinue lens wear despite preferring or requiring lenses for vision correction.

There was some hope that the introduction of silicone hydrogels could eliminate some proportion of dryness or discomfort related dropouts with their vastly increased oxygen permeability, but this has not been the case. 'Dryness’ associated with lens wear is a deceptively complicated concept. While there is an intuitive connection with wettability, and the ability of a lens to maintain a healthy tear film, there are many other mechanisms through which a contact lens can become too uncomfortable to wear – all of which are typically described by the umbrella term ‘dryness’. This problem is in fact so complex that there is no agreement within the literature regarding causes or solutions.

It seems certain, however, that novel, smart materials will play a role in solving the issue. With more comfortable lenses that have a lower incidence of complications, other therapeutic applications can be considered. Using contact lenses to deliver drugs to the eye over a longer period of time will alleviate the need for the instillation of multiple drops as well as lowering the dose necessary to achieve efficacy.  

An example of where this might be useful is in the treatment of myopia, a disease which is increasing at an alarming rate and affects as many as 1 billion patients worldwide.  This disease has been linked in part to the time spent by children on screens. Atropine has been shown to be effective at decreasing the rate of myopia progression but is extremely toxic and must be instilled on a regular and frequent basis for efficacy.  By pairing the drug with a contact lens, both an improvement in visual acuity and delivery of the drug may be possible. 

 

Methodology 

Various technologies have been developed through the 20/20 Network that have the potential to address the issues outlined above. However, to transition these platform technologies into specific products that can be transferred to the clinic and/or commercial partners, additional preclinical testing is required. Specifically, we will: 

  1. Prepare novel conventional hydrogel and silicone hydrogel materials with incorporated wetting agents or the ability to take up wetting agents.
  2. Examine properties of modified materials in vitro
  3. Examine properties of modified materials on the eye