Complications due to contact lens use are presented in roughly 5% of users on an annual basis. Most serious complications are caused by poor hygiene resulting in a build up of antigen/protein deposits or bacterial stagnation of the tear film or inner lens surface. In order to function correctly the surface of the eye must have a continual supply of oxygen. More modern material such as silicon hydrogels have an O2 permeability 5 or 6 times that of older materials. Use of lenses for extended periods of time without rest or beyond manufacturers recommendations is not advisable. The eyelid is no more permeable to oxygen than the lens and so not wearing your lenses only when you are asleep will almost certainly result in some degree of oxygen deprivation.
Complications may affect one of several different regions of the eye.
The cornea and conjunctiva are prone to the greatest diversity of syndromes associated with contact lens use. Simply speaking these can be broken down into infection, physical injury and physiological reaction.
The inner surface of a poorly maintained lens is a breeding ground for bacteria, fungi (fusarium) and protozoa (Acanthamoeba), when combined with a compromised innate immunity due to drying of the eye or hypoxia the chance of infection is increased. Infections beyond the common bacterial or viral conjunctivitis include keratitis which if affecting the deep tissue layers can result in blindness if scarring occurs near the visual access.
Other disorders resulting from excessive wear include dermatitis, giant papillary conjunctivitis, corneal abrasion, corneal erosion, corneal ulceration and kertoconus (a degenerative disorder of the cornea resulting in a gradual shift toward a conical shape with major adverse affects to the visual field including streaking, ghosting and hypersensitivity to light.
Also worthy of individual mention is corneal neovascularization where new blood vessels are formed radiating toward the centre of the eye and arising in the limbal vascular plexus. If these blood vessels cross the area of the cornea over the pupil or otherwise intersect the visual detection area loss of colour perception or other problems occur.
Disclaimer: The author is not a medical doctor, optician, ophthalmologist or any other medical professional, this article has been compiled using a variety of internet reference sources and while every effort has been made to ensure accuracy this cannot be guaranteed. No preference for product or brand is inferred or intended and the contents of this article are not to be used in whole or in part to inform a decision regarding any aspect of contact lens use.
