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HomemieyecareContact Lens Deposition

Contact Lens Deposition

Deposits are a well known contact lens complication, however contact lens patients may not be aware of the significance of lens deposits in contributing to lens discomfort or intolerance, eye redness, reduced vision and overall reduced success with contact lens wear. As contact lens practitioners, it is necessary to understand the nature of deposits in order to be able to treat and manage contact lens deposits efficiently.

Proteins, lipids and mucins function in the tear film to combat microbial action on the ocular surface, to prevent evaporation of the tear film and to maintain overall health of the ocular surface.

The major lacrimal proteins include secretory IgA, lysozyme, lactoferrin and lipocalin. These proteins play important bacteriostatic and antibacterial roles, defending the ocular surface from microbial contamination. Mucins which are comprised of glycoproteins and glycosaminoglycans, produced by the conjunctival goblet cells and the corneal epithelial cells, also provide protection against microbial invasion.1

The lipid layer covers the tear film and is secreted by the meibomian glands. This complex layer comprises wax esters, sterol esters, fatty acids and fatty alcohols.2 The primary roles of the lipid layer are to prevent the overspill of tears and to retard tear film evaporation.3

Alteration to the contact lens surface by contact lens deposits causes decreased lens wettability, which can lead to symptoms of discomfort, increased inflammatory responses and ultimately, discontinuation of contact lens wear.

Tear Film Disruption

Upon insertion of a contact lens into the eye, the structure of the tear film is disrupted. Moreover, deposits originating from the tear film immediately start to form on the lens and these deposits increase and vary over time.4 Deposits can also originate from external sources, such as the patient’s finger or lens cases5 and cosmetics. Alteration to the contact lens surface by contact lens deposits causes decreased lens wettability, which can lead to symptoms of discomfort, increased inflammatory responses and ultimately, discontinuation of contact lens wear.6 As proteins (specifically lysozyme) denature and build up on the contact lens surface, it creates a challenge to the ocular immune system. This challenge produces an antibody response7 which may result in side effects such as ocular irritation, redness, and itching. Denaturation of proteins can lead to increased risk of contact lens induced papillary conjunctivitis and contact lens induced superior limbic keratoconjunctivitis.8

The type and degree of contact lens deposits are influenced by several factors, including:

  • the contact lens material
  • water content
  • surface charge
  • interaction of lens material with lens solution components
  • contact lens replacement schedule
  • care regime
  • contact lens age

Silicone hydrogel lenses deposit significantly lower amounts of protein than traditional hydrogel lenses, however, an increase in lipid deposits has been reported with use of these lenses.9 In addition, the degree of lysozyme denaturation varies between contact lens materials.10 Lens water content and ionicity play a major role in protein deposition,11 especially FDA group IV lenses, which accumulate higher amounts of lysozyme than lenses from other FDA lens groups.2 Lenses possessing hydrophobic surfaces or containing vinyl pyrrolidone have exhibited a tendency to deposit lipids.12,13 The tendency to develop contact lens deposits is also dependant upon individual tear film characteristics since tear film composition varies between individuals.

Lens Surface Deposits

In addition, it is important to treat and manage any lid conditions of patients. For example, patients with Meibomian Gland Dysfunction have exhibited increased lipid deposition.14 Recently, differing contact lens and solution combinations have elicited varying amounts and types of deposition.13

As mentioned above, the presence of deposits on the lens surface can lead to symptoms of discomfort, dryness and potentially, contact lens discontinuation. A comfortable contact lens is one of the key factors in continuation of lens wear and likewise, discomfort and dryness with contact lenses is the leading cause of contact lens discontinuation.6

Due to the great variety of contact lenses and solutions available on the market, practitioners have a wide variety of options in the management of lens deposition. Selection of the appropriate contact lens, solution and wear modality can be a complex process. The efficacy of contact lens solutions in removing deposits is dependent upon the lens material and the individual’s tear film composition.15 A better understanding of the interactions between contact lenses and solutions may reduce the levels of complications.

Clinicians should be prepared to modulate lens/solution regimens in striving for successful management of contact lens deposits for each patient. Further, continuous patient education is vital to ensure safe contact lens wear. During contact lens appointments and aftercare, ongoing patient education is crucial to help the patient manage contact lens deposits successfully. Ongoing aftercare presents an opportunity to demonstrate and reinforce optimal contact lens care such as routine “rubbing” of the lens during cleaning, regular contact lens and case replacement, and the use of the recommended care solution.5 Use of a “rub” step in contact lens cleaning regimen has demonstrated a clinically significant decrease in the level of deposits16 and without education in this area many patients may not recognise the importance of this step.

Other demonstrated effective strategies in reducing and controlling lens deposition include increasing the replacement frequency of contact lenses (fortnightly instead of monthly)), the use of daily disposable contact lenses,17 and use of appropriate contact lens and solution combinations.13

Minimising deposits will not only decrease the risks of ocular complications, but will also lead to satisfied contact lens patients.

Kay Shih B. Optom is a clinical optometrist at the Institute for Eye Research. She reports on the importance of clinician and patient education in reducing deposits on contact lenses.

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18. Gellatly KW, Brennan NA, Efron N. Visual decrement with deposit accumulation of HEMA contact lenses. Am J Optom Physiol Opt. 1988 Dec;65(12):937-41.