Basically, there are two different types of contact lenses: hard (rigid gas permeable) and soft (flexible) contact lenses. Only an ophthalmologist or optician can determine which type is suitable for you. An eye examination first provides information about whether the eyes are healthy and therefore suitable for contact lenses.
The optimal lens is determined on the basis of your individual needs and the results of the examination and measurements. Factors such as visual acuity, refractive error, corneal surface, and tear film play a decisive role. You can find out here how the two types of lenses differ in detail.
Hard Contact Lenses Are Good for the Eyes
Hard contact lenses have a high long-term tolerance. With every blink fresh tear-film gets pumped under the hard contact lens which makes the oxygen supply for the cornea better and more reliable compared to soft lenses. For example, if you wear a hard contact lens with a material that is particularly permeable to oxygen the supply does not change to your eyes whether you are outside or in a room with an AC running.
When you wear soft contacts in comparison to hard lenses the material changes the oxygen permeability in relation to the water content. That means the dryer your eyes get the less oxygen reaches your cornea with soft contacts.
If you want to wear your lenses every day, wearing hard lenses is the healthiest alternative. The great advantage of hard lenses is that they float on the tear film and are constantly flushed by tear fluid. Hard contact lenses also do not need your tear-film to stay in shape. Soft contact lenses on the other hand will sponge some of your tear film to stay in shape. This makes them less of a good choice when you have dry eyes.
When dry eyes come into play which is very common the break-up time for the tear film of the wearer of the contact lenses is oftentimes below 10 seconds. In such a case discomfort and visual impairment will hinder the wearer to wear the soft contacts for the whole day. In such a case hard contacts work better as the break-up time of the tear film will be less impaired by hard lenses in comparison to soft ones.
Unlike soft lenses, hard lenses require much less fluid to stay in shape. So your eyes are optimally supplied with oxygen throughout the day and do not dry out.
Hard Lenses Are Also Suitable for Complicated Refractive Errors
With the help of hard lenses, even complicated or irregular refractive errors, such as severe astigmatism or ocular diseases like keratoconus, can be corrected. This is because hard contact lenses bridge a gap between the irregular cornea and the back surface of the lens. When the gap gets filled up with tear film the irregularities are corrected.
In comparison, a soft contact lens is extremely thin. The soft foil-like material adapts to the irregular shapes of the cornea. With the altered shape of the soft lens, irregularities can not be corrected.
Hard Lens Acclimatization Period
Unfortunately, hard lenses are often clearly perceived when blinking in the initial period and are perceived as a foreign body. Since rigid lenses do not automatically adjust to the curvature of the cornea, the fitting is more complicated than with soft lenses. However, if your lens has been properly fitted, you will get used to it after some time and will hardly feel it! But if you want contact lenses with a high spontaneous tolerance, soft lenses are the better alternative.
Foreign body sensations are gone with soft contact lenses after a few minutes while the acclimatization period with hard contacts may last a couple of weeks. With very sensitive eyes soft lenses are oftentimes the easier way to start.
Why Do Most People Choose Soft Contact Lenses?
Although soft contacts have drawbacks when it comes to long-term tolerance compared to hard contacts most people choose them because they can not endure the foreign body sensation in the first weeks. The high spontaneous tolerance makes soft contacts solve visual problems oftentimes the day you visit the optician.
In contrast, hard contact lenses need an acclimatization phase in which the time of wear gets increased day by day by an hour or two. Eventually, you will end up wearing them the whole day. But this process can take up a week or two depending on your tolerance of the foreign body sensation.
Soft Lenses Come In a Wide Variety of Materials
Whether daily lenses, weekly lenses, monthly lenses, annual lenses – soft lenses are available in a wide variety. There are soft contact lenses that are extremely thin and have coatings on them for better lubrication. Especially if you only want to wear contact lenses occasionally, e.g. for parties or sports, soft daily lenses are a good alternative.
You can simply dispose of daily disposable lenses in the evening and replace them with a fresh, new pair the next time you wear them. If you want to know more about how to dispose of contacts the right way I wrote you an article here.
Soft Lenses Are the Better Choice for Sports
Soft lenses are the better choice for sports activities because they have a larger diameter than hard lenses. With the larger diameter, the soft contacts sit firmly on the eye and produce less foreign body sensation even during stronger movements. Hard lenses, on the other hand, only float on the tear film and can fall out and get lost during jerky movements.
There are also hard lenses available with bigger diameters and they practically produce no foreign body sensation. They are called scleral lenses but in most cases, scleral lenses are fitted in more complex cases as the fitting and the lenses can get pricier compared to the more conventional lenses listed above. If you want to learn more about the difference between sclerals and conventional hard lenses this here is the article for you.