Nearsightedness (myopia) is a common refractive error where distant objects appear blurry while near objects remain clear. This occurs because the eye focuses light in front of the retina rather than directly on it, often because the eyeball has grown too long. Contact lenses are a highly effective solution for correcting myopia, providing clear, comfortable vision without eyeglasses. They work by precisely altering the path of light entering the eye, ensuring the focal point lands correctly on the retina.
How Contact Lenses Correct Nearsightedness
The optical correction for nearsightedness involves placing a diverging lens in front of the eye to reduce its overall focusing power. A contact lens designed for myopia is a concave lens, meaning it is thinner in the center and thicker at the edges. When light rays pass through this concave shape, they are spread slightly outward, or diverged. This divergence moves the focal point backward, from its incorrect position in front of the retina to precisely onto the retinal surface.
The power of this correctional lens is measured in diopters (D) and is always indicated by a minus sign (-) on a prescription. For example, a prescription of -3.00 D signifies a lens with three diopters of negative, or diverging, power needed to achieve clear distance vision. The lens rests directly on the eye’s tear film, becoming an integrated part of the eye’s optical system. Because of this direct placement, the corrective lens power needed in a contact lens prescription is often slightly different than for a pair of glasses.
Different Types of Contacts for Myopia
The majority of nearsighted individuals wear soft contact lenses, which are made from flexible plastics like hydrogel or silicone hydrogel. Silicone hydrogel lenses are particularly popular because they allow a high amount of oxygen to pass through to the cornea, promoting better eye health and comfort. Soft lenses are available in various wear schedules, including daily disposables, which are discarded after a single use, or planned replacement lenses, such as bi-weekly or monthly options. Daily disposables offer maximum convenience and hygiene, as they eliminate the need for cleaning solutions and reduce the risk of deposit buildup.
Rigid Gas Permeable (RGP) lenses are another option, made from a firmer plastic material that retains its shape. While RGP lenses may require a short adjustment period for comfort, they often provide sharper vision than soft lenses and are highly durable. RGP lenses allow oxygen to pass through them, making them a healthy option for corneal oxygenation. They are especially useful for individuals with a high degree of astigmatism or other corneal irregularities. Specialty lenses, such as multifocal designs, can also be used for myopia control in children or for correcting presbyopia in adults who are nearsighted.
The Essential Steps to Getting Fitted
Obtaining contact lenses requires a comprehensive process that begins with a specialized eye examination, which is distinct from a standard glasses prescription check. The eye care professional performs a comprehensive eye exam to determine the current state of your vision and overall eye health, checking for conditions like dry eye or allergies that might affect lens wear. Precise measurements of the eye are then taken using instruments like a keratometer or corneal topographer to map the curvature of the cornea. This measurement, called the base curve, ensures the lens sits correctly on the eye, preventing it from being too tight or too loose.
Based on these measurements and your lifestyle, the doctor selects a trial lens to evaluate the fit and visual performance. During this diagnostic fitting, the doctor observes how the lens moves on the eye when you blink and ensures it covers the cornea appropriately. You are given this trial pair to wear for a specified period to assess comfort and clarity in real-world conditions. This allows you to communicate any discomfort or vision issues to the doctor so that adjustments can be made to the lens material, power, or fit.
For first-time wearers, a training session is provided, covering the proper techniques for safely inserting and removing the lenses. You will also receive instructions on the correct cleaning and disinfection procedures for your specific lens type to maintain eye health and prevent infections. A follow-up appointment is typically scheduled a week or two later, where the doctor re-examines the fit, checks your eye health, and finalizes the contact lens prescription before you purchase a full supply.