The cornea is the clear, protective outer layer of the eye. Along with the sclera (white of the eye), the cornea serves as a barrier against dirt, germs, and other particles that can harm the eye’s delicate components.
The cornea also plays a key role in vision. As light enters the eye, it is refracted, or bent, by the outside shape of the cornea. The curvature of this outer layer helps determine how well your eye can focus on objects close up and far away. If the cornea becomes damaged through disease, infection, or injury, the resulting scars or discoloration can interfere with vision by blocking or distorting light as it enters the eye.
Specific eye conditions, diseases, and disorders that can affect your vision include:
Swelling or decompensation of the cornea
Cornea thins and bugles into a cone shape, causing blurred vision
Causes of keratoconus include:
- Eye trauma - from rubbing your eyes or long-term use of hard contacts)
- Eye diseases- such as retinitis pigmentosa, retinopathy of prematurity, and vernal keratoconjunctivitis
- Other diseases, like Down syndrome, osteogenesis imperfecta, Addison’s disease, Leber’s congenital amaurosis, and Ehlers-Danlos Syndrome
Corneal dystrophy are generally genetic conditions and it comprises a number of dystrophies including Fuchs' dystrophy and stromal dystrophies.
Fuchs' endothelial corneal dystrophy
The gradual deterioration of endothelial cells (inner layer of the cornea) for no apparent reason. As these cells thin over time, the cornea is less capable of removing water form the stroma, causing it to swell and distort vision. Haze and small blisters on the corneal surface may also appear.
As a slowly progressing disease, signs of Fuch’s dystrophy begin to appear in people 30 to 40 years old; however, the disease doesn’t normally affect vision until about 20 years later. It is more common in women than men.
This is a viral infection of the eye that may reoccur. The main cause of ocular herpes is the herpes simplex virus I (HSV I). This is the same virus that causes cold sores, but ocular herpes can also result from the sexually transmitted herpes simplex II virus (HSV II) that causes genital herpes. Ocular herpes produces sores on the surface of the cornea; over time, the inflammation can spread deeper into the cornea and eye.
Herpes zoster (shingles)
Shingles is a recurrence of the chicken pox virus in people who have already had the disease. After initial infection, this virus usually remains inactive within the nerves of the body. It can later travel down these nerves, infecting specific parts of the body, like the eye.
Recurrent corneal erosion results when the epithelial cells don't adhere to the layer below
Or keratoconjunctivitis sicca, is an ocular disease caused by by either decreased tear production or increased tear film evaporation
Systemic autoimmune inflammatory
Ocular cicatricial pemphigoid, Sogrens, rheumatoid arthritis
Non-cancerous growth of the conjunctiva that lays over the sclera (white part of eye). Once it grows over the cornea, it can cause irritation, redness and astigmatism, which can blur your vision.
Symptoms of Corneal Disease
The cornea has the ability to quickly repair itself after most injuries or diseases. However, more serious situations may result in a much more prolonged healing process. If this is the case, the following symptoms should serve as an immediate indicator of a deeper medical issue:
- Eye pain
- Blurred/blurry vision
- Tearing Redness
- Extreme sensitivity to light
- Corneal scarring
If you feel you may be experiencing any of these symptoms, schedule an appointment with The Eye MD to discuss treatment options.