Hard contact lenses were the first to be developed and were fabricated from polymethylmethacrylate. The very low oxygen permeability of these lenses limited their use to daytime wear and frequently caused corneal edema. Rigid, gas-permeable lenses, allowing greater oxygen permeability, have replaced the original hard design and material and provide improved comfort and longer wearing times. Gas-permeable contact lenses accounted for about 10% of all contact lens fits. Rigid lenses require longer initial adaptation and may dislodge more frequently than soft contact lenses. However, rigid, gas-permeable lenses can provide superior vision, especially in patients with high amounts of astigmatism or irregular corneal shape. They are relatively easy to clean and can last for several years if cared for properly. Long-term tolerance is good, and the risk of corneal ulcerations, corneal neovascularization, and infection is low. Compared with soft lenses, rigid, gas-permeable lenses require relatively greater practitioner experience, skill, and knowledge to design and fit properly.

Nearly 90% of contact lens fittings are with soft lenses. The primary clinical advantage of soft contact lenses is the good initial comfort and tolerance. They can be worn for long periods, do not dislodge easily, and can be disposable. The disadvantages include less effective correction of high astigmatism; fragility, which can result in tearing or ripping; absorption of pollutants including lotions and soaps, which can irritate the eyes; and higher rates of ulcerative keratitis and neovascularization.

Disposables represent an attempt to further enhance convenience and long-term comfort. Disposable lenses are available for replacement after a single use, weekly, bimonthly, monthly, or quarterly. The rate of single-use contact lens fittings has been increasing, representing 25% to 30% of all soft contact lens fits worldwide. Daily-wear soft contact lenses are removed for sleep and are cleaned and disinfected before insertion the following day. Extended-wear soft wear lenses were developed with the goal of allowing the patient to sleep with the lenses in for one or more nights.

First-generation extended-wear lenses were associated with an increased risk of ulcerative keratitis due to hypoxia-induced corneal microcysts, stromal edema, endothelial polymegethism, and neovascularization. Improved design and materials led to a new generation of soft lenses made of silicone hydrogel. These lenses were approved for 7-day continuous wear in 1999, followed by 30-day continuous wear in 2001. Contact lenses approved for extended wear can provide more than four times more oxygen permeability when compared with lenses made of traditional materials. Silicone hydrogel lenses can lower the risk of developing severe keratitis during extended wear five times compared to traditional hydrogel materials. With the benefits of higher oxygen permeability, these lenses are also frequently used for daily wear. Silicone hydrogel lenses constituted 51% of all soft contact lens fits in 2010, and their market share is growing. A rigid, gas-permeable extended-wear lens was approved in 2002 for 30-day continuous wear.

Orthokeratology is a nonsurgical process using custom-designed rigid, gas-permeable contact lenses to reshape the cornea. It is U.S. Food and Drug Administration (FDA) approved to correct up to -6 diopters of myopia and -1.75 diopters of astigmatism. The contact lenses are normally worn only at night. By reshaping the cornea, they can eliminate or reduce the need for glasses or contacts during daytime hours. Orthokeratology is not permanent and is reversible. Once the desired corneal shape is achieved, a nighttime retainer
contact lens is worn to maintain the results. Advantages include less visual disruption from perspiration, dust, wind, weather, and temperature. Avoiding glasses and contact lenses during waking hours can be appealing to many patients including athletes or people with occupations hindered by the use of glasses or contacts such as firemen or police officers. Orthokeratology is being studied as a possible treatment to slow the progression of myopia. Disadvantages include higher initial cost of fitting, frequent visits during the initial fitting process, several months may be needed to achieve desired visual results, higher dropout rate as some patients find the process cumbersome or the lenses uncomfortable, and risk of microbial keratitis. Long-term effects of corneal reshaping on endothelial function are not currently known.