Contact lenses represent a good instrument to correct refractive errors, especially the most commons (myopia, hyperopia, astigmatism and presbyopia). There are many indications and some contraindications related to the use of contact lenses. The three criteria you need to follow in order to have a proper application are:
Vision criteria: the contact lens needs to guarantee a good vision performance and the best vision acuity the subject could achieve.
Physiologic criteria: contact lens needs to respect the right corneal conjunctive metabolism, without damaging the eye system balance.
Comfort criteria: the contact lens needs to be comforting, without that annoying sensation of a foreign body in your eye.
ADVANTAGES AND DISADVANTAGES OF THE CONTACT LENSES USE
The optic correction with contact lenses requires attention and punctuality. It is important to have a proper maintenance and a good personal hygiene (especially your hands hygiene), in order to avoid microbial or chemical contaminations of lenses or eyes. The use of contact lenses also requires frequent eye exams, at least each six months, in order to check the state of the contact lenses and the condition of the anterior segment of the eye.
Contact lenses represent a valid alternative to glasses, especially for optical reasons. Contact lenses, indeed, do improve the vision performance in case of a high ametropia, anisometropia (an important difference between the two eyes diopter) and in case of irregular corneal astigmatism (given by keratoconus, corneal scarring or surgeries). Sometimes contact lenses are used for therapeutic purposes, to facilitate the recovery of ocular pathologies or to reduce their symptoms, or even to improve vision functions in case of amblyopia or nystagmus. Contact lenses are also used during the night, in order to restore the clear vision and not to need optic correction during the day (orthokeratology).
CONTACT LENSES TYPOLOGIES
There are many contact lenses categories. They are generally classified looking at the material (rigid, soft or hybrid) or the frequency of substitution (single-use, with scheduled replacement, conventional). Rigid contact lenses are made of gas-permeable materials and used for specific applications of advanced contactology (keratoconus, post-surgery or orthokeratolgy). Soft contact lenses can be made of hydrogel materials, hydrogel-silicon or biopolymers.
Contact lenses can be daily replaced, with frequent scheduled replace (weekly, bimonthly or monthly) or with extended replace (biannual or annual).
Contact Lenses Maintenance
The single use contact lenses, with daily replace, must be eliminated after the use. Others typologies of contact lenses require a proper maintenance, in order to avoid infections and complicacies. Two main steps compose maintenance procedure: cleaning and disinfection. To clean contact lenses is necessary a cleaner with surface-active substances, which can remove lipid deposits, detritus and microbial biofilm. Its action must be completed by a mechanical scrubbing, a rinsing with salty solution and a following use (every week) of enzymes for proteins removal. Disinfection of contact lenses is made up with preserved chemical solutions or antioxidant systems. Today the most common solutions for contact lenses maintenance are the multipurpose solutions, so called because they can provide at the same time:
Cleaning, Disinfection, Rinsing, Lubrication, Conservation
RULES FOR AN APPROPRIATE MAINTENANCE OF CONTACT LENSES