Different Types of Contact Lenses
Contact lenses have become a more fashionable way of treating poor vision; they are fast overtaking the traditional eye glasses and come in many different forms.
Contact lenses can be worn and disposed of daily, weekly or monthly and there is a vast range to choose from. Contact lenses are now being worn purely for cosmetic reasons by way of clear lenses that alter the colour of the eye and even change the eye drastically. Costume or special effect lenses are available in a huge range of different styles giving you the chance to have anything from glow in the dark eyes to cat’s eyes. For the majority of us though contact lenses are a necessity so what is the difference in contact lens types?
Spherical and Aspherical contact lenses
These are the most common type used and will correct most problems in eyesight. There are two common problems occurring with eyesight, these are nearsightedness and farsightedness. Myopia is the clinical term for nearsightedness and people suffering from this eye problem will find that things that are further away may appear blurred. Hyperopic is when the person is farsighted and is the opposite; things that are closer to them will appear blurred. The corrective power of the spherical lens is the same over the entire lens, this allows the eye to focus better and blurred vision is reduced. The Aspheric lens is a specialised lens for people with very slight or the beginning of Astigmatism, this type of lens is also used for people in the very early stages of Presbyopia which is when the person has trouble focusing on closer objects such as when reading. This is a natural occurrence of general wear and tear on the eye due to aging.
Toric contact lenses
Some people suffer from what is called Astigmatism; this is when an irregular shaped cornea causes vision problems. People suffering from this can also be farsighted or nearsighted as well, things may appear to be slightly skewed from top to bottom when suffering from Astigmatism. The toric lens has more than one power fitted into them at different angles to correct this problem and will have an anchoring mechanism built in to stop the lens from moving around once placed in the eye.
Bifocal contact lenses
Bifocal contact lenses will also have different powers built into them but are different from toric lenses in that the powers are not angled. Some lenses may have two obvious prescriptions built into them, if needed then the top half of the lens can be fitted for nearsightedness or farsightedness and the bottom may have corrections for Presbyopia which will help when reading. Sometimes the definition line of the two different powers will be gradually blended into each other which will eliminate the hard line if this causes problems. Another option for people suffering eye problems due to aging is called mono vision, this means that one eye may be treated for corrections needed when reading and the other corrected for farsightedness. The eye will then learn to differentiate between different tasks eventually. |