Keratitis

Keratitis is a severe and potentially sight-threatening condition that arises due to inflammation of the cornea – the clear front surface of the eye (1,2). This is often due to infection by a variety of micro-organisms and is more likely to occur in eye surface disease and contact lens wearers (1-3). Subsequent scarring can cause permanent vision loss and so all forms of keratitis need prompt diagnosis and treatment by an optometrist to save sight and improve comfort (2,3).

There many different types of keratitis: the main categories are infective keratitis and non-infective (sterile) keratitis.

Infective keratitis

Infection of the cornea by a micro-organism such as bacteria, a virus (including herpes simplex and herpes zoster viruses), fungi or protozoan can be potentially blinding and very painful (1-3). If you think you may have infective keratitis you must see your optometrist as soon as possible, as certain bacteria can perforate the cornea within 24 hours unless treated.

Patients will often present with pain, redness, light-sensitivity and sometimes discharge. The most common corneal infections are bacterial and viral. These present with characteristic appearances which help your optometrist to make the correct diagnosis. Infective keratitis requires frequent use of the appropriate topical anti-microbial medication and close monitoring as the condition improves (4). In some cases of viral keratitis, the area affected may be debrided at diagnosis to decrease the quantity of virus at the infection site (5). The optometrists at Innovative Eye Care are therapeutically qualified and trained to diagnose and treat these types of infections.

CAPTION: A typical appearance of a herpes virus corneal infection in one of our patients when stained with fluorescein.

Contact lens wear increases your risk of microbial infection (1-3). This risk is much higher if you sleep in your lenses, wear them longer than recommended or do not follow your optometrist's recommendation for cleaning and hygiene. Rigid lenses such as RGPs and ortho-K have been shown to pose a lower risk of microbial infection than soft contact lenses. Visit our pages on contact lens cleaning and hygiene here.

Pre-existing ocular surface disease also increases the risk of microbial infection (1-3). Blepharitis and dry eyes as well as many other causes of chronic irritation of the eyes predispose to infective keratitis.

Non-infective keratitis

Often called 'marginal keratitis' or a sterile ulcer, this is when the eye shows similar signs to an infective keratitis but there is no active infection in the corneal tissue. The condition often occurs due to a reaction in the body's immune system to bacterial particles or toxins from the eyelid margins or dirty contact lenses (6). These areas of keratitis are often located at the edge of the cornea, are smaller and cause less discomfort than an infective keratitis. Treatment is still necessary and is targeted at preventing any opportunistic infection, calming the inflammation in the eye (often with topical steroid drops) and removing the cause of the inflammation. This may include lid hygiene or modification of contact lens cleaning habits.

CAPTION: A non-infective keratitis near the edge of the cornea. This cleared with anti-inflammatory drops and lid hygiene.

Traumatic keratitis (or corneal abrasion)

The cornea is forty times more sensitive than skin. It follows that if the cornea is scratched or damaged then the symptoms may be very similar to other types of keratitis. These incidents will heal with time but often require prophylactic antibiotics to stop infection and ointments to soothe the surface of the eye and assist healing.

CAPTION: A child's fingernail caused this 3mm corneal abrasion. It healed with appropriate lubrication and pain relief.

  1. Ng ALK, To KKW, Choi CCL, Yuen LH, Yim SM, Chan KSK, Lai JSM, Wong IYH, Arnalich-Montiel F. Predisposing Factors, Microbial Characteristics, and Clinical Outcome of Microbial Keratitis in a Tertiary Centre in Hong Kong: A 10-Year Experience. J Ophthalmology, 2015, Vol.2015, 9 pages

  2. Otri AM, Fares U, Al‐Aqaba MA, Miri A, Faraj LA, Said DG, Maharajan S, Dua HS. Profile of sight‐threatening infectious keratitis: a prospective study. Acta Ophthalmologica, Nov 2013, Vol.91(7), pp.643-651

  3. Green M, Apel A, Stapleton F. Risk factors and causative organisms in microbial keratitis. Cornea 2008;27:22-7.

  4. Watson S, Cabrera-Aguas M, Khoo P. Common eye infections. Aust Prescr 2018;41:67–721 Jun 2018

  5. Wilhelmus KR. Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis. Cochrane Database Syst Rev. 2015 Jan 9;1

  6. Sharma S. Keratitis. Biosci Rep. 2001 Aug;21(4):419-44.