The cornea is the ‘central clear window of the eye;’ a transparent outer layer covering the front part of the eye. It helps shield the rest of the eye from germs, dust and other harmful matter. The cornea shares this protective task with the eyelid, eye socket, tears and the sclera. Together with the tear film, it is the major structure to focus light and vision, accounting for approximately two-thirds of the eyes’ focusing power. As such, any small alterations to the cornea can dramatically affect vision.
Corneal infections can be caused by
- Bacteria – numerous causes but risk factors include contact lens wear, injuries and use of topical steroid medication at the time of onset. Treatment includes very frequent (ie. every hour) medications to sterilise the eye surface. Sometimes, multiple antibiotics are required to ensure the organism is being adequately treated. Anti-scarring (topical steroid) medications may cautiously be used to limit scarring that can result from deep inflammation and infections as well as adjacent inflammation that may result.
- Viruses – the two most common are:
- Fungal keratitis
- Parasites – ie Acanthomoeba keratitis
Autoimmune causes of corneal inflammation or keratitis are possible, and may be related to immune disorders in the rest of the body, for example rheumatoid arthritis.
- Sensitivity to light
- Reduced or blurred vision
- Ocular discharge
- White spot in the eye or cornea
Treatment is individualized in all cases so it is difficult to generalize.
- Treating the underlying infection – if present or excluding one if suspected. This can include eye swabs and samples sent to patholoty and treatment for suspected causes commences immediately whilst awaiting results
- Preventing complications – scarring of the cornea can cause irreversible vision loss so treatment with anti-scarring medications (aka topical steroids) may be needed once the infection is adequately controlled
- Lubrications – a moist eye is faster to heal, so lubricants are often used for comfort and to assist healing
After the infection or acute ulcer is treated, restorative laser or surgery may be needed to obtain the best vision possible.
- Corneal infections may cause rapid vision loss
- Symptoms include pain, blurred vision and discharge
- Contact lens wear is a major risk factor for all corneal infections, and the contact lens may be sent as a sample to investigate the cause so should be kept if suspected
- Treatment includes antibiotics to the likely organisms and tests sent to investigate for all causes, along with anti-inflammatory and lubricating medications
- Restorative and rehabilitative treatment may be needed after the eye has settled