What is Cornea ?
The cornea is the clear tissue at the front and center of the eye. Its transparency permits light to pass into the eye, through the pupil, lens, and onto the retina at the back of the eye. The three major corneal layers are the outer layer of the cornea or epithelial layer, the middle layer termed the stroma, and finally a single layer of cells called the endothelium.
The curvature of the cornea plays an important role in focusing (refracting or bending) light. The normal cornea is smooth, clear, and tough. It helps protect the eye from infection and foreign material.
With its ability for quick repair, the cornea usually heals after most injury or disease. However, when there is deep injury to the cornea, the healing process may be prolonged, possibly resulting in a variety of symptoms, including pain, tearing, redness, blurred vision, light sensitivity, and scarring.
Herpes Zoster (shingles)
Shingles is a recurrence of the chicken pox virus in people who have already had the disease. This virus usually remains inactive within the nerves of the body after a case of chicken box. It can later travel down these nerves, infecting specific parts of the body, like the eye. Herpes zoster can cause blisters or lesions on the cornea, fever, and pain from nerve fibers. Corneal lesions usually heal by themselves, but antiviral treatment may reduce the inflammation. Shingles can occur in anyone exposed to the chicken pox virus, but there is an increased risk in older adults and people with a weakened immune system.
Herpes zoster is treated with anti-viral, pain and anti-inflammatory medications. Eye drops and ointments may be prescribed to treat ocular problems.
This is an inflammation of the cornea that sometimes occurs with infection after bacteria or fungi enter the cornea. These microorganisms can enter the eye after deep injury, causing infection, inflammation, and ulceration of the cornea. Though uncommon, this type of infection can also arise after injury from wearing contact lenses. Symptoms of keratitis include severe pain, reduced visual clarity and corneal discharge.
Treatment usually includes antibiotic or antifungal eye drops.
Keratoconus is a progressive disease in which the cornea thins and changes shape. The curvature of the cornea is affected, creating either mild or severe distortion, called astigmatism, and usually nearsightedness. Keratoconus may also cause swelling and scarring of the cornea and vision loss. Causes of keratoconus include genetics, trauma and disease.
In early stages the conditions is correctible with glasses or soft contact lenses. As the disease progresses, rigid gas permeable contact lenses may be needed to help shape the cornea for clear vision. In some cases, a corneal transplantation may also be necessary. During this procedure, the damaged cornea is replaced with a donated cornea. This operation is successful in about 9 out of 10 people with advanced keratoconus. Even after a transplant, you most likely will need glasses or contact lenses to see clearly.
Ocular Herpes (herpes of the eye)
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. There is no cure for ocular herpes, but it can often be controlled with the use of antiviral drugs.