Corneal Refractive Therapy (CRT) Contact Lenses
What is myopia?
Myopia, or nearsightedness, is an eye condition in which children or adults have difficulty seeing clearly at far distances but are relatively clear at near distances. The farthest distance the patient can see clearly is determined by the degree of myopia. The higher the myopia, the closer the patient has to place objects to be in focus. Myopia is usually associated with lengthening of the eyeball from front to back, causing images of distant objects not to focus on the retina and resulting in blurred vision. Aside from the impact that blurred distance vision may have on a patient’s lifestyle and activities, longer eyeballs have important consequences on ocular health. They have increased risk of retinal detachment, glaucoma, retinal degeneration, and blindness. Therefore, preventing the further lengthening of the eyeball is important in reducing a patient’s lifelong risk of eye disease. In some patients, the degree of myopia may increase significantly year by year, sometimes at an alarming rate. We call this progressive or pathologic myopia. The exact cause of myopia is unknown but genetics plays a key role. Patients can inherit the tendency or risk to develop myopia from their parents, but evidence shows that environment may then push the patient to actually develop it. Studies suggest that extensive close-up work, such as reading, computer work, smartphone use, and handheld video game playing, can increase the chance of developing or worsening myopia. Generally in children, eyes continue to grow until the age of 20, and I find at least with my patients that the highest rates of progression of myopia is during this growth phase.
The incidence of myopia is increasing in the U.S. and worldwide and some have even called it an epidemic. Population studies show that as a nation becomes more and more literate, the incidence of myopia becomes higher. Indeed, much of our technologies today place devices close to our eyes and we are spending more time with them day by day.
What is Corneal Refractive Therapy (CRT) Contact Lenses?
Corneal Refractive Therapy (CRT), or Orthokeratology, or Ortho-K, uses hard contact lenses to reshape the curvature of the cornea, the front surface of the eye. The lenses flatten the cornea so that the light rays can focus further back in the eye, which are long in myopic patients. They therefore reduce myopia and make distance vision clearer. The patient wears the contact lenses during sleep for 7 to 8 hours each night and they gradually reshape the cornea over a period of 7 to 14 days. When fully treated, the patient does not need to wear glasses or contact lenses during the day. However, if the contact lens wear is discontinued, the effects will fully reverse and the original myopia will return. Therefore, the patient should consistently wear the contact lenses every night unless advised differently by the doctor. CRT is FDA-approved for adults and children of all ages and is a nonsurgical, reversible method for correcting myopia. Although approved or all age groups, we usually limit CRT fittings to ages 7 and up. We find that patients who enjoy sports or swimming or who do not like to wear glasses benefit the most from being freed from glasses or daytime contact lenses.
CRT contact lenses have an added benefit of slowing down the growth of the eye. Studies have shown that progression of myopia is slower in CRT contact lens wear than without. This slower rate not only means that vision can be more stable long-term, but the risks associated with high myopia, such as retinal detachment, glaucoma, retinal degeneration, and blindness, is less over the patient’s lifetime.
If CRT contact lenses seem to be the right option for you or you would like to receive more information, our managers Stevie or Winnie will be happy to speak with you.