Fingers, bugs and contact lenses.
Dear OT, eye hospitals continue to report a significant cause of red-eye presentation associated with contact lens wear.
This begs the questions: Why is this? What are we doing wrong? And is there anything we can do about it? It is not only bad for the individual concerned but also bad for the contact lens industry and for overstretched hospital eye departments.
Numerous studies show storage case biofilm contamination is likely to be a significant cause of complications and that daily disposable lenses pose a significantly lower risk of serious visual loss than re-usable lenses. Worryingly it also may well be that the disinfecting solutions we rely upon are not as effective as we think particularly against some strains of Pseudomonas which Acanthamoebae feed upon.
Logically, one would anyway expect a lower risk of complications with daily disposable (DD) rather than reusable lenses (REL) as there is no maintenance requirement, no storage case contamination possibility and no potential chemical or preservative sensitivity issue.
Professor Simon Kilvington's presentation at last year's British Contact Lens Association (BCLA) conference, Bacteria biofilms provide protection from disinfection by multipurpose contact lens care solution, showed yet again how nasty storage cases can be. Even ones that look clean may not be, as disclosing agents reveal biofilms invisible to the naked eye.
If lack of compliance can be minimised through eye care practitioners making a much greater effort to repeat both verbal and written instruction at first fitting and annual reviews, from the above there is a strong case to be made that as a professional duty of care practitioners should always fit daily lenses in preference to reusable lenses, if the prescription permits, largely because one of the risks, the storage case, has been removed.
However, one possible cause of complications even with DD lenses that may have been overlooked is back surface contamination, either from fingers or eyelashes. Professor Kilvington's presentation showed little difference in microbial growth on agar plate hand imprints before and after careful hand washing, demonstrating how hand washing has remarkably little effect upon the microbial bio-burden. However, many manufacturers and eye care practitioners continue to advise patients to remove lenses from the blister pack by placing the finger into the back of the lens thereby trapping the transferred microbial bio-burden between the lens and cornea, and the smallest epithelial compromise may well explain many of the clinical cases seen at eye departments.
We therefore promote a 'tap-and-tip' method for accessing lenses whereby the lens is loosened by tapping the blister pack before tipping and pouring the lens into the palm of the hand thereby avoiding any possibility of back surface finger contamination. I declare no proprietary interest, but the Menicon flat pack lenses are designed to address this problem, so the Japanese seem to agree.
Mike Killpartrick, optometrist, Ellis and Killpartrick, Bath and Cheltenham
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|Article Type:||Letter to the editor|
|Date:||Apr 18, 2015|
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