Hard lenses are also known as Rigid Gas Permeable (RGP). Soft contact lenses are not successful in patients with high astigmatism. Hard contact lenses only cover part of the cornea surface and are rigid, not flexible. Perhaps the reason that people are less likely to use hard contact lenses is that they get used to hard contact lenses after longer periods of time.
On the other hand, these lenses can be used for a longer period of time, they are less likely to get dust and attract and breed bacteria and can be cleaned easier compared to soft lenses. Ophthalmologists usually recommend hard lenses to those who are looking for higher quality vision.
The most important problem with hard lenses is that you have to wear them regularly until you get used to it, but for soft lenses, even if you don't wear your soft lenses for a week, they'll still be comfortable when you put them on a week later.
Since about 1981, Oxygen transmission contact lenses have entered the market, which even provide the necessary oxygen for the cornea during the night (roughly six times higher than previous ones). The lens oxygen permeability is indicated with the abbreviation of DK which is a certain number for each lens and should be greater than 120 DK for wearing overnight (although they are not recommended because of the risk of eye infection).
Some RGP lenses that are most commonly used in infants and children after cataract surgery and corneal astigmatism, which may develop after an eye injury or eye surgery, and are prescribed for overnight wearing, can be used up to 30 days . Orthokeratology lenses are a type of hard lenses which are only used overnight during sleeping. Today they are rarely used t due to a higher risk of infections and corneal scratches and ulcers, and are not recommended.
Advantages of Hard Lenses:
First, because hard lenses are made from a firm plastic material, they retain their shape when you blink, which tends to provide sharper vision than pliable soft lenses. Second, hard lenses also are extremely durable. Although you can break them (for instance, if you step on them), you can't tear them easily, like soft lenses, and the protein and fat of tears will not be attached to them.
In fact hard lenses are the best choice for some people for whom soft contacts don't produce the desired visual acuity and they want to have sharper vision, or for people with astigmatism which their astigmatism can not corrected by soft contact lenses. Hard lenses also are suitable for the treatment of corneal keratoconus and presbyopia correction. Recent studies have shown that in children with myopia (nearsightedness) wearing hard lenses can slow down the progression of myopia.
Make sure to purchase your contact lenses from a trusted ophthalmic center and Take advantage of the experts’ advice of the optical shop on choosing the right contact lenses. Never purchase your contact lenses from an optical shop of another medical center or office different from where your ophthalmologist examined your eyes and prescribed contact lenses for you, because the examiner is responsible for your examination and should be answerable to you.
How to Deal with Hard Contact Lenses:
• It is better to do this over a clean flat surface so that you can easily find your lens if you drop it.
• Try to use a concave magnifying mirror to insert and remove your contact lenses.
• First, rinse your hands thoroughly with soap.
• Dry your hands carefully with a lint free towel.
• If you want to put the lens in your right eye, first bend the head slightly. Open your eyes completely. With your left hand, hold the upper eyelashes of the right eye upward, and place the lens on the right hand index finger, and pull your lower eyelid down with your middle finger of your right hand and slowly move your index finger toward your eye, while focusing on your finger steadily, place the lens on the cornea.
• The lens should be placed in the center of the cornea. If the lens does not settle onto your eye properly, you should move it toward the center of your cornea with your finger or the edges of your eye lid.
• Look at the mirror; see where the lens is located. Look at the opposite side of its location, and then move the lens with the edges of your eyelid toward the center of your cornea. If you are not able to do this, remove the lens and put it in your eye again.
How to Take Out Hard Contact Lenses:
First, wash your hands and then dry them thoroughly. Make sure that the lens settles properly onto the center of your cornea and then remove it with one of the two following methods:
1- Open your eyes as wide as possible so that your upper eyelid is placed on the white of your eye. Place one of your fingers at the outer corner of the eye and gently pull it to the corner at the same time slowly. Once you blink, the lens will fall out into your other hand.
2- In this method, you use your middle fingers of your both hands to hold your eyelids open. The fingers should be as close as possible to the edges of the eyelashes and then push your eyelids toward the center of your eye so that the edge of your lower eyelid goes under the lens and causes it to fall out.
Wearing Schedule for Hard Contact Lenses:
On your first week of contact lens use, wear your contact lenses for 2 hours per day, and then each week increase your wearing time gradually 1 hour per day up to the seventh week when you can wear your contact lenses for 8 hours per day comfortably.
Care Instructions for Hard Contact Lenses:
• Remove your contact lenses before sleeping, and after rinsing them with tape water and cleaning them with serum or 9% Sodium Chloride solution, leave them in a sterile soaking solution until morning. When rinsing your contact lenses with tap water, it is best to put a plastic basket below the tap so that if you happen to drop them, they will fall in the basket and not be lost. In the morning rinse them again with tap water before putting them in your eyes.
• For more information bout how to use a cleaning or soaking solution or the best brands of these solution, ask the eye care professionals in the lens clinic who are responsible for providing patients with more information.
• Always remove your lenses from your eyes before going to bed, taking a shower or doing aerobic exercises.
• Finally, if you can not do this yourself, be sure to be referred to the lens clinic of Noor Eye Hospital.