Keratitis is often easy to recognize based on fluorescein staining of the ocular surface.
Early diagnosis improves treatment results significantly.
Patients with keratitis should be referred to an ophthalmologist.
If the infection is caused by the herpes simplex virus, treatment can be started by a GP.
Allergic keratitis
Allergic eye infections and atopic keratoconjunctivitis, in particular, may also involve keratitis; see article on Allergic conjunctivitis Conjunctivitis.
Untreated, prolonged atopic keratoconjunctivitis may cause permanent corneal opacity and decline in vision.
Symptoms and findings
Often severe itching, which may lead to intensive rubbing of the eyes
Red eyes, watery discharge, photophobia and foreign body sensation
Often significant signs on lid skin: thickening, swelling, periocular dermatitis and erythema
Under blue light, fluorescein staining shows inflammatory alteration of the corneal surface.
Treatment
Allergic keratitis requires examination and treatment by an ophthalmologist.
Frequent use of moisturizing drops may alleviate the symptoms.
Intensified topical antiallergic medication and, if necessary, short-term use of glucocorticoid drops, both prescribed by an ophthalmologist
Referral for specialized care
Allergic keratitis requires referral to an ophthalmologist within 1-3 days to confirm the differential diagnosis.
Bacterial keratitis
Aetiology
The most common causative agents of bacterial keratitis are staphylococci.
Bacterial keratitis associated with ocular injury is often caused by streptococci.
The possibility of a Pseudomonas infection should be considered in patients using contact lenses.
Patients confined to bed for a long time may have infections caused by enterococci, Proteus or Serratia species, Escherichia coli or Klebsiella.
Symptoms and findings
Tearing and redness of the eye
Foreign body sensation, pain, photophobia
Reduced visual acuity
Differential diagnosis by an ophthalmologist based on a corneal bacterial sample will improve the appropriateness of antimicrobial medication.
Treatment
Topical antimicrobial medication: 1 fluoroquinolone eye drop (e.g. levofloxacin or ofloxacin) once an hour when awake
Medication can be started by a GP.
If Pseudomonas is suspected, microbial samples should be taken before starting the medication.
Referral for specialized care
Patients should be referred to an ophthalmologist within 24 hours, contact lens users with suspected Pseudomonas infection as emergency cases.
Acanthamoeba keratitis
Acanthamoeba keratitis may lead to a serious infection in the whole eye area and to permanent corneal opacity. Early diagnosis will improve the prognosis significantly.
The possibility of Acanthamoeba keratitis should be kept in mind particularly if the patient uses contact lenses.
The infection may be caused by contaminated water.
Symptoms and findings
Severe pain in the eye area
Reduced visual acuity
Photophobia
Often severe conjunctival redness
Fluorescein staining may show an inflammatory focus and a superficial tissue defect in the central cornea. The inflammatory focus may be visible to the naked eye.
Treatment
Chlorhexidine combined with either propamidine or polyhexamethylene biguanide (PHMB), as prescribed by an ophthalmologist
Referral for specialized care
Emergency referral to an ophthalmologist
Herpes simplex keratitis
Symptoms and findings
Bloodshot conjunctiva
Photophobia, lacrimation
Dendritic corneal epithelial defects seen after fluorescein staining are a typical finding.
Initially: 3% aciclovir ointment 5 times daily for 7 days; for severe symptoms, additionally oral aciclovir (200-400 mg 5 times daily) or valaciclovir (500 mg twice daily)
Referral for specialized care
Referral for further treatment by an ophthalmologist within 1-3 days
Herpes zoster ophthalmicus (HZO)
More than 20% of all people will have herpes zoster at some point, and about 15% of these will have an eye infection associated with herpes zoster at some point.
In most cases, the eye infection is due to reactivation of the varicella zoster virus (VZV).
Rare in children
Involvement of the cornea may lead to permanently reduced visual acuity.
Herpes zoster in the eye area always requires treatment by an ophthalmologist.
Symptoms and findings
Initially headache, fever and nausea; in addition, there may be scalp pain
There are often either clusters of blisters or single such clusters on one side of the body
The upper eyelid on the affected side may be quite swollen, erythematous and sore.
Hutchinson's sign (vesicles on the tip of the nose); a high risk of corneal disease, too
Inflammatory changes (discoid or punctate, for instance) may be seen after fluorescein staining on the cornea.
Workup
The virus can be shown by antigen or PCR test. Viral culture may be considered.
Treatment
Treatment should be started within 72 hours from the beginning of the infection. Symptom-based treatment started by a GP sufficiently early will improve the prognosis.
Referral to an ophthalmologist within 24 hours; emergency referral if reduced visual acuity is detected
Adenoviral keratitis
No specific treatment exists so far.
Treatment should concentrate on alleviating symptoms and preventing secondary diseases.
In most cases, the acute stage of epidemic keratoconjunctivitis lasts 2-3 weeks but it may last up to 6 weeks.
The disease is highly contagious and spreads by contact.
Symptoms and findings
Red eye, watery discharge
Foreign body sensation, pain, photophobia
Reduced visual acuity
Workup
The typical clinical picture is sufficient for diagnosis; no laboratory tests are necessarily needed.
To investigate epidemics, laboratory diagnosis of conjunctival samples is recommended.
Immunofluorescence test of the adenovirus antigen (results can be obtained urgently)
Viral culture (results can be obtained in three weeks)
Nucleic acid detection (more expensive but useful for investigating epidemics)
A rapid test is also available, with results obtainable during the consultation
Treatment
For mild forms of disease, artificial tears
Eyelid swelling can be alleviated by using cold compresses.
If needed, topical antimicrobials (such as chloramphenicol drops or ointment) should be administered if there is purulent discharge.
It is important to inform patients about the course and duration of the disease and to remind them of good hygiene.
Due to the risk of transmission, unnecessary follow-up visits should be avoided.
Referral for specialized care
During epidemics, treatment can be started and follow-up arranged by a GP.
In the case of more severe disease or unclear diagnosis, the patient should be referred to an ophthalmologist.
The ophthalmologist
often prescribes topical antimicrobial medication to prevent secondary bacterial infections
releases pseudomembranes and adhesions in ulcerated conjunctiva mechanically every 1-2 days
will not usually prescribe glucocorticoid drops at the acute stage because they increase the number of viruses and slow down healing at the acute stage.
If the symptoms are abundant and the infection is serious, short-term use of mild glucocorticoid drops, monitored by an ophthalmologist, must be considered to alleviate the inflammation and to control severe symptoms.
Fungal keratitis
A prolonged eye infection not reacting to ordinary antimicrobial treatment may be caused by fungi, particularly if there is eye trauma involved.
Fungal keratitis is a usually slowly progressive inflammation beneath the superficial epithelial layer, which may lead to permanently reduced visual acuity if diagnosis is delayed.
It is most commonly seen after injury where fungal spores get underneath the epithelium (scratching by a twig, organic material getting into the eye or the like).
It is caused by Aspergillus, Fusarium or Candida species.
Symptoms and findings
Foreign body sensation in the eye
Gradually worsening eye pain
Elevated corneal lesion, possibly with feathery margins and satellite foci outside the larger inflamed area
Corneal ulcer
Eye infection responding poorly to antimicrobials
Workup
Ophthalmological workup
Fungal sample from the cornea with a special fungal swab
Bacterial culture to detect any simultaneous bacterial infection
Treatment
As treatment may have adverse effects, it should be based on a microbiological sample.
Antifungal medication (natamycin or amphotericin B) administered to the ocular surface, monitored by an ophthalmologist and combined with oral antifungal medication (such as itraconazole)
Referral for specialized care
Referral for ophthalmological workup in 1-7 days
If an inflammatory focus can be seen on the cornea after fluorescein staining or with the naked eye and a fungal infection is suspected, within 1-3 days