Types of contact lenses Today, the use of glasses and refractive surgery to solve vision problems is very common. But people who for any reason cannot wear glasses and perform refractive surgery, go for contact lenses. A contact lens is a type of thin and transparent lens that is placed on the surface of the cornea (the clear part in front of the eye). These lenses are used to correct vision problems such as myopia, farsightedness, astigmatism and keratoconus. Some contact lenses have a beauty aspect and are used to change eye color. In the past, contact lenses were designed from handmade glass that covered the entire surface of the eye and it was not possible for people to use them for a long time. But with the advancement of technology, various types of contact lenses were designed and manufactured. Improper use of contact lenses can cause corneal infection and, if not treated in time, may cause vision loss. Therefore, the correct choice and correct use of contact lenses can minimize the risk of their complications. For this reason, contact lenses must be prescribed and used by an ophthalmologist. Which type of contact lens is right for you depends on your vision needs, corneal condition, dry eyes, type of refractive error, and lifestyle. In this article, we will examine the types of contact lenses and their proper use and which of the contact lenses is suitable for your eyes. Soft contact lens Soft contact lenses, which are the most common contact lenses, are very thin and flexible, and since they absorb more water, they deliver more oxygen to the cornea. Soft contact lenses may be unscored and used as a dressing for corneal wounds and **refractive surgery** or they may be scored and used in place of glasses. Soft contact lenses are commonly used to treat nearsightedness, farsightedness, and mild astigmatism. Soft contact lenses, due to their high flexibility, are easily placed on the surface of the eye and do not cause discomfort and are a suitable option for everyday use. However, soft contact lenses are less durable and must be replaced periodically and disinfected regularly to prevent eye infections. Also, long-term use of soft contact lenses can cause dry eyes. Rigid gas permeable contact lens Hard contact lenses, also known as gas permeable (RGP) lenses, are made of a durable plastic material that allows oxygen to pass through to the cornea. Due to their hard structure, these lenses provide better vision than soft lenses. They are usually prescribed for people who have severe keratoconus or astigmatism. Hard contact lenses are more durable and less damaged due to their structure and resistance. Due to their hard structure, using these types of contact lenses may cause discomfort at first and it may take a few weeks for the eyes to get used to them. **Read more: Eye LASIK is better or intraocular lens?** Scleral contact lens Scleral lenses are a type of contact lenses that cover the cornea due to their large diameter. These lenses are placed on the sclera (white part of the eye) without putting pressure on the cornea, and for this reason, they are also called scleral lenses. Scleral lenses, unlike other contact lenses that are placed on the cornea, create a gap between the cornea and the lens. These lenses are filled with isotonic fluid before being placed on the eye. Due to the lack of direct contact of these lenses with the cornea, the patient feels less uncomfortable. The space between the cornea and the back surface of the scleral lens, which is filled with isotonic fluid, acts as a reservoir of artificial tears and helps moisten the eye. For this reason, scleral lenses are a good option for people with severe dry eyes. Also, scleral or scleral lenses are suitable for patients with keratoconus, especially in severe cases, and should be prescribed by an ophthalmologist or optometrist. Scleral lenses last longer than soft lenses. They are less damaged, but they must be regularly disinfected to prevent the accumulation of sediments. Scleral lenses are more expensive than other types of contact lenses. Also, some people need more time to get used to these lenses. ### Conclusion Today, the use of contact lenses is one of the most common methods for correcting refractive errors. Choosing the most suitable contact lens should be done by an ophthalmologist according to eye conditions, vision needs, and people's lifestyle. Consulting with an ophthalmologist and observing the principles of care and use of contact lenses has a great impact on the health of the eyes and the quality of vision.