What Is Keratoconjunctivitis?

Keratoconjunctivitis is a condition that causes inflammation of the cornea and the conjunctiva membranes of the eye. Infections and allergies are the major causes of keratoconjunctivitis; however, some cases can be due to autoimmune conditions. Depending on the underlying cause, it can often be treated with eye drops and mostly has a good prognosis.

Overview

Keratoconjunctivitis is an inflammatory process that involves the conjunctiva and the cornea of the eye.¹ Each eye's pupils are protected by a clear, transparent membrane called the cornea, while the conjunctiva protects the sclera, the white component of the eye. Conjunctivitis and keratitis are terms used to describe inflammation of the conjunctiva and cornea, respectively. Both can become inflamed, causing keratoconjunctivitis. Up to 6 million Americans may present to a healthcare professional each year with conjunctivitis or keratoconjunctivitis symptoms. Up to 40% of patients who arrive with conjunctivitis or keratoconjunctivitis have underlying allergies, which make up the majority of cases. Depending on the underlying cause, treatment is typically conservative and in general, the prognosis is good.

Types of keratoconjunctivitis

Epidemic keratoconjunctivitis (EKC)

EKC (also called viral keratoconjunctivitis or adenoviral keratoconjunctivitis) is a viral eye infection caused by a human adenovirus. EKC is highly contagious and spreads easily in crowded areas. Although there is no treatment, symptoms typically resolve themselves after persisting for a few weeks. 

Vernal keratoconjunctivitis (VKC)

VKC is a chronic allergic form of keratoconjunctivitis. It is a severe infection, and the cause is still unclear. It can result in small and round bumps underneath the eyelid that affect the upper eyelid more than the lower. VKC is characterized by recurrent episodes of itching, redness, sensitivity to light, and watering.²

Superior limbic keratoconjunctivitis (SLK)

SLK is a rare chronic inflammation that affects parts of the conjunctiva. The cause of SLK is unknown. This condition is mostly seen in individuals between 25 and 60 years of age, with an average age of 50 and is more common in women. Symptoms may include eye irritation, burning, dryness, foreign body sensation and sensitivity to light.³

Keratoconjunctivitis sicca

Keratoconjunctivitis sicca (also known as dry eye syndrome) is inflammation of the cornea and conjunctiva due to abnormalities in the tear film on the eye. It can be caused by either an imbalance in the tear composition, a lack of tears, or too quickly evaporating tears.

Phlyctenular keratoconjunctivitis

Phlyctenular keratoconjunctivitis is an eye inflammation that causes nodules to grow on the cornea or conjunctiva. It happens because of a hypersensitive response to a microbial antigen. Staphylococcus aureus infections are currently the most common cause of phlyctenular keratoconjunctivitis in the United States. It occurs mostly in children from 6 months to 16 years old and can present with irritation in the eye, pain, and sensitivity to light.⁴

Atopic keratoconjunctivitis (AKC)

AKC is an allergic form of keratoconjunctivitis and occurs due to a genetic condition called atopy that makes a person more likely to develop allergies. It is more common in men than women, and the lower eyelid is affected more than the upper eyelid.  AKC can develop major consequences that are sight-threatening if untreated.⁵

Herpetic keratoconjunctivitis

Herpes simplex virus (HSV) infection can spread to the cornea, resulting in herpetic keratoconjunctivitis. Herpes keratitis continues to be the most prevalent infectious cause of corneal ulceration and blindness in the world. If the infection is superficial (involving only the superficial layer of the cornea), it will usually heal without scarring.⁶

Neurotrophic keratoconjunctivitis

Neurotrophic keratoconjunctivitis is a rare degenerative condition that is caused by nerve damage. It can cause loss of sensation in the cornea, leaving the cornea susceptible to injury. Early management is essential because this illness is progressing.

Causes of keratoconjunctivitis

Some causes of keratoconjunctivitis are contagious, while others are non-infectious. The type of keratoconjunctivitis depends on the cause. These may include:

• Allergens- Dust, pollen, or animal dander
• Viruses - Adenovirus, herpes simplex virus
• Bacteria- Staphylococcus aureus is a common infectious agent.
• Air pollutants or climate change
• Genetic conditions
• Autoimmune disorders such as Sjögren's syndrome 

The majority of cases of keratoconjunctivitis are caused by allergies. Among infectious causes, viruses are the most common type of infection that occurs across all age groups, while bacterial infections are more common in children. 

Signs and symptoms of keratoconjunctivitis

The symptoms vary depending on the cause and can range from mild to severe. Some signs and symptoms associated with keratoconjunctivitis may include:

• Dryness and itching
• Photophobia (increased or abnormal light sensitivity)
• Eye pain, including a burning sensation
• Eye redness
• Blurred vision
• Watery discharge

Diagnosis

Procedures that may be used to diagnose keratoconjunctivitis  include:

• A comprehensive eye examination is performed with slit lamp equipment. A dye called Fluorescein is applied to the eye in the form of an eyedrop or a paper strip that is softly applied to the inside of the lower eyelid. Using a cobalt blue filter, your doctor can analyse the existence and pattern of corneal abrasions or abnormalities using a slit-lamp microscope or ophthalmoscope. The eye examination includes assessment of best-corrected visual acuity, pupillary reactions, extraocular motility, visual fields, and intraocular pressure.
• An external examination includes determining the presence of preauricular lymph nodes or oedema. The eyelids are examined for rash, discharge, and hyperpigmentation.
• Cell culture and immunoassay testing are used to identify the infectious agent in the discharge from the eyes. In cases of suspected epidemic keratoconjunctivitis, rapid-sequence adenoviral testing can be performed.
• Lacrimal function tests are used to determine how well the eyes create tears.
• A tear osmolarity test analyses the water and particle content of tears. An elevated tear film osmolarity can be seen in keratoconjunctivitis sicca, as there will be less water in the eyes.
• The Schirmer test measures the number of tears produced when keratoconjunctivitis sicca is suspected. Strips of blotting paper are placed under the lower eyelid. The eye care professional counts the number of tears that have saturated the strip after five minutes.
• Corneal sensory testing is a possibility when a herpetic viral infection is suspected. These examinations assess corneal sensitivity, as herpes infections reduce corneal sensitivity. 

Management and treatment for keratoconjunctivitis

Management largely depends on the underlying cause and type of keratoconjunctivitis. The treatment is usually focused on relieving symptoms. Artificial tears, gels and ointments are the first line of treatment- these treatments aim to lubricate the ocular surface. Warm compresses and lid scrubs can also be used to improve natural oil production. 

Infectious causes of Keratoconjunctivitis can be extremely contagious and can spread through direct contact with contaminated objects. The most important steps in preventing transmission are regular hand washing and cleansing of household objects.

Allergic causes can be treated with topical antihistamines and topical mast cell stabilisers. A combination of antihistamines and mast cell stabilisers can control symptoms in moderate cases, with and are available, such as olopatadine, azelastine, and ketotifen. It is advised to use additional cool compresses and lid scrubs to try to remove any potential allergens. Other treatment options include topical nonsteroidal anti-inflammatory drugs (NSAIDs) or topical corticosteroids. The most efficient use of topical corticosteroids often involves a high initial dose followed by a rapid tapering approach.

Keratoconjunctivitis sicca is initially treated with artificial tears, warm compresses, and lid scrubs. There is a procedure that involves inserting punctal plugs to stop tear leakage from the eyes. The punctum is a small hole in the inner corner of the eye, and plugging it helps keep tears in the eyes, preventing them from drying up. Due to its distinct anti-inflammatory effects, oral doxycycline has been demonstrated to be beneficial in low dosages.    

FAQs

How can I prevent keratoconjunctivitis?

• Avoid known allergies:
  • Regular cleaning of pet dander, particularly on carpeted flooring
  • Installation of air-filtering equipment
  • Switch to hypo-allergenic bedding materials
• Contact lens care:
  • Before handling the contacts, properly wash, rinse, and dry your hands
  • Follow the lens maintenance guidelines supplied by your eye specialist
  • Use only sterile items designed exclusively for contact lens maintenance
  • Every three to six months, swap out your contact lens case
• Limiting the spread of viral infections:
  • Frequent hand washing can help stop virus outbreaks
  • If you have a cold sore or a herpes blister, avoid touching your eyes, your eyelids, and the skin around your eyes unless you've thoroughly washed your hands.
  • Cleaning and sanitization of household items
• Use eye drops solely according to recommendations by an eye doctor.

How common is keratoconjunctivitis?

According to some estimates, 6 million Americans may present to a healthcare professional each year with conjunctivitis or keratoconjunctivitis symptoms. Up to 40% of individuals who arrive with conjunctivitis or keratoconjunctivitis have the majority of their cases due to allergic causes.⁷

Who is at risk of keratoconjunctivitis?

Factors that may increase the risk of keratoconjunctivitis include:

• Wearing contact lenses can increase the risk of developing infectious and non-infectious keratoconjunctivitis.
• You run a higher chance of getting keratoconjunctivitis if your immunity is compromised by illness or drugs.
• You can be more prone to getting keratoconjunctivitis if one of your corneas has already been injured in the past.

What can I expect if I have keratoconjunctivitis?

Some forms of keratoconjunctivitis are chronic diseases that require regular treatment. Infectious causes may have faster recovery with medication. Allergic causes of keratoconjunctivitis can cause eye damage if left untreated.

When should I see a doctor?

If you have had an extended period of redness, irritation, itchiness, or pain in the eyes, consult your healthcare professional. Other possible signs include swelling of the eyelids and sensitivity to light.

Summary

Keratoconjunctivitis is the medical term for inflammation of the cornea and conjunctiva. There are multiple types of keratoconjunctivitis, defined by their causes. The most common causes are allergies, bacterial infection, and viral infection. Some types are linked to autoimmune or congenital diseases.  A comprehensive eye exam is used to make the diagnosis. Epidemic keratoconjunctivitis is a self-limiting condition that typically resolves in two to three weeks. Some types are chronic and require regular treatment. The overall prognosis for keratoconjunctivitis is often good, with no long-term damage to the eye with appropriate medical intervention.