Soft contact lenses made out of modern hydrogels have become overwhelmingly the most popular type of contact lens in recent years for a variety of reasons. These lenses have been made possible by advances in materials technology, and have been steadily improved through considerable research and development efforts over the years.
It is specifically the soft structure and use of materials with a high water content that define soft contact lenses. First-generation hydrogels were introduced to the general market in 1999, signalling the start of the modern era in advanced soft contact lenses.
However, second and third-generation hydrogels are in common use today, and these mean contact lenses with up to 46% water in their structure and a high oxygen flow. In 2012, a new type of technology was launched on the market in the form of a new water gradient silicone hydrogel where the water content of the lens changes from the core to the surface.
Soft contact lenses have many advantages, but they also have a few downsides, which is why rigid contact lenses (or rigid gas-permeable lenses) are also still manufactured and widely available. The choice of whether to wear soft or hard contact lenses frequently depends on lifestyle factors as much as on the actual medical or vision correction needs of the eye, which can often be addressed with either type of lens.
Advantages of soft contact lenses
Soft contact lenses, as their name implies, are very comfortable for most people who wear them thanks to the fact that they have no rigid edges, their texture is soft, and they mould themselves naturally to the eye surface, matching its individual contour. These contact lenses are used for a variety of purposes, including correcting nearsightedness, farsightedness, astigmatism, and nowadays also presbyopia.
Given their soft nature, people are usually able to adapt very quickly to wearing soft contact lenses, allowing the wearer to gain their benefits immediately and without discomfort. Since these lenses remain securely in the eye after being inserted, they are good for people of all ages with active lifestyles, and are great for activities such as jogging, cycling and other outdoor pursuits.
Furthermore, soft contact lenses are less likely to slip off-center while being worn, which lessens the chance of blurred vision while wearing them. Soft contact lenses come in several different types and are often classified depending on their replacement schedule, including daily wear (which are taken out and washed every night); extended wear, which can be worn for a week or even up to thirty days; and disposable lenses, which are thrown out after use.
Since the eye adapts very quickly to soft contact lenses, they are well suited to people who do not wear contact lenses all the time. They can be worn sporadically, when vision correction is actually necessary, without running into the adaptation problems that rigid lenses often cause.
Disadvantages of soft contact lenses
Soft contact lenses have some downsides compared to their rigid counterparts, however. One of the largest benefits of rigid gas-permeable lenses is that they typically transmit a higher level of oxygen to the eye surface, which is vital for eye health. However, technological developments in soft contact lenses means that they increasingly allow high levels of oxygen to reach the eyes, especially the new generation of silicone hydrogels.
Soft contact lenses provide somewhat less crisp vision than rigid lenses and to some wearers, they may even appear slightly blurry. The reason for this is that rigid lenses are made from firmer materials so do not change shape so easily, for example when a person blinks. There are also some types of vision problems that simply cannot be corrected using soft contact lenses.