The cornea is the clear outer layer at the front of the eye. The cornea is shaped like a dome and helps your eye to focus light so you can see clearly. Light enters the eye through an opening called the pupil and then the iris (colored part of the eye) controls how much light the pupil lets in. Next the light passes through the lens (clear inner part of the eye) that works with the cornea to focus light.
There are several common conditions that affect the cornea:
Small abrasions (scratches) on the cornea usually heal on their own. Deeper scratches or other injuries can cause corneal scarring and vision problems.
Allergies to pollen can irritate the eyes and cause allergic conjunctivitis (pink eye). This can make your eyes red, itchy, and watery.
Keratitis is inflammation (redness and swelling) of the cornea. Infections related to contact lenses (link to Optometry page) are the most common cause of keratitis.
Dry eye happens when your eyes don’t make enough tears to stay wet. This can be uncomfortable and may cause vision problems
Corneal dystrophies cause cloudy vision when material builds up on the cornea. These diseases usually run in families.
There are also a number of less common diseases that can affect the cornea — including ocular herpes, Stevens-Johnson Syndrome, iridocorneal endothelial syndrome, and pterygium.
Contact lenses are thin lenses that sit on top of the cornea (the clear outer layer of the eye). They correct refractive errors to make your vision clearer — just like eyeglasses. If you use them the right way, they can be a safe and effective alternative to eyeglasses. If you have a refractive error, like being nearsighted or farsighted, your eye doctor can prescribe contact lenses to help you see clearly.
Types of Contact Lenses
When you’re choosing contact lenses, there are 3 main things to know: whether they’re soft or hard, how long you can wear them, and how often you need to replace them.
Soft or hard
Daily wear or extended wear
Single use or reusable
Specialty Contact Lenses
Specialty contact lenses can be helpful for patients with certain eye conditions which prevent glasses and soft contact lenses from providing adequate vision or comfort. Some of these conditions include keratoconus, pellucid marginal degeneration, pathological myopia (nearsightedness), severe dry eye, graft-versus-host disease, irregular corneas after surgery, corneal transplants, or corneal scarring.
At the Shiley Eye Institute, we have two specially trained optometrists, Andrew Vo, OD and Carol Yu, OD, that provide customized contact lens fitting for a wide variety of different contact lenses. They utilize advanced technology and the latest in contact lens designs to customize the lens according to each patient.
Types of Specialty Contact Lenses
Corneal Rigid Gas Permeable (GP) Lenses
Corneal GP lenses are small diameter lenses made of a rigid gas permeable polymer that rests on the cornea. This material creates a smooth surface for our patients with irregular corneas, a high prescription, or high astigmatism.
Hybrid lenses have a central GP portion surrounded by a soft skirt. They offer the same visual benefits as a corneal GP, but the soft skirt can be helpful for patients with difficulty in adapting to the sensation of having a hard contact lens on the eye.
Scleral lenses are highly customizable larger diameter GP lenses. These create a layer of fluid between the eye and the lens. This results in both sharp vision and comfort, especially in patients with irregular corneas or debilitating dry eye disease.
Prosthetic Soft Lenses
Prosthetic soft lenses are contact lenses with the ability to influence and change perceived colors. These lenses can be fit for cosmesis to hide a damaged or scarred eye. They can also be utilized for decreasing light sensitivity or altering color perception.
These are specialty lenses that are worn at night by the patient and allow them to see clearly without correction during the day. They can be used for prescription correction or slowing of myopic progression.
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