Spherical half-year lenses are a type of contact lens that is designed to correct vision problems caused by spherical refractive errors, such as nearsightedness (myopia) or farsightedness (hyperopia). These lenses are called "half-year" lenses because they are typically replaced every six months.
The main difference between spherical half-year lenses and other types of contact lenses is their design. These lenses have a uniform curvature across their entire surface, which helps to correct the spherical refractive error. They are available in both soft and rigid gas permeable (RGP) materials, allowing individuals to choose the option that suits their preferences and needs.
Soft spherical half-year lenses are made from a flexible, water-containing material that provides comfort and ease of wear. They conform to the shape of the eye, making them comfortable to wear for extended periods. Soft lenses also tend to be more resistant to debris and protein buildup, making them easier to maintain.
Rigid gas permeable spherical half-year lenses, on the other hand, are made from a rigid material that allows oxygen to pass through to the cornea. This promotes better eye health and reduces the risk of complications associated with long-term contact lens wear. RGP lenses also provide sharper vision and are more durable compared to soft lenses.
It is important to note that spherical half-year lenses are not suitable for individuals with astigmatism, as they do not correct for this specific refractive error. For individuals with astigmatism, toric lenses are recommended.
To learn more about spherical half-year lenses, you can visit the following link: Spherical Half-Year Lenses.