Hard contact lenses have become less popular over time, particularly following the introduction of soft contact lenses into the market. The main reason being the difficult adjustment required for hard contact lenses vs. soft lenses. This adjustment is not only longer but might even be felt in continuous use of lenses, since every time the lens is used, the eyelid must adjust to the brief encounter with the hard lens. Over time, the lid becomes rigid and the lens is no longer felt.
In principle, regular contact lenses affix to the cornea of the eye. When this is not possible or when problem occur for the user, for example, when the corneal structure is not standard, or has a complex geometry, due to keratoconus or any other eye disease. In these situations, contact lenses that are placed on the cornea create acute dry eye, or are not properly positioned, resulting in severe discomfort. One solution to this situation is use of special contact lenses: scleral contact lenses.
In recent years, the process for purchasing contact lenses has become easier and more accessible. Contact lenses can be purchased at any pharm chain, and even online. Sound good? Apparently only to 50% of contact lens wearers.
Setting aside momentarily the general risks of purchasing contact lenses off the shelf, we will focus our discussion on only those people who cannot purchase contact lenses off the shelf: those who need cylinder contact lenses. This covers 50% of contact lens wearers.
Even in this modern era, an age of science and information, there are still no answers to all questions. One of the questions that remain unanswered is the disease keratoconus – an eye disease in which the cornea becomes increasingly thinner, resulting in a cone-shaped instead of a cap-shaped cornea. The result: significant decline in vision that might even deteriorate to blindness.
Numerous theories were raised with regards to the cause of the keratoconus. Certain studies indicate congenital causes, i.e. genetics that gives rise to the disease Other studies indicate acquired causes such as eye inflammation and chronic allergies in the eye, increased rubbing of the eyes, etc.
Dry Eye Disease is extremely common, particularly among contact lens wearers. The international Dry Eye Work Shop reported that approximately 50% of contact lens wearers reported symptoms related to dry eye – 12 times more than people with normal vision and 5 times more than eyeglass wearers.
Why? The main causes of dry eye are related to the tear secretion mechanism. Use of contact lenses might result in increased evaporation of tears, impair the tear secretion mechanism and cause unbalanced dispersal of tears on the eye. The result: increased dryness for contact lens wearers.