Superficial eye infections such as blepharitis and conjunctivitis are generally treated adequately with antimicrobial agents applied topically. More serious infections may require subconjunctival injections. 

Although it is always recommended that a swab be taken for culture and sensitivity, so that specific therapy may be instituted later if the infection does not respond to the drug used empirically (initially), this is not always practical for superficial infections.  However, if an eye infection is at all serious and extends beyond the conjunctiva, specimen collection for culture and sensitivity tests is essential before commencing therapy.

Blepharitis

This is often seen as a chronic inflammatory process involving the eyelid margins and is usually due to Staphylococcus aureus.  

Treatment: Lid hygiene is important.   It involves cleaning the lid with diluted baby shampoo (one or two drops of baby shampoo in a bottle cap full of warm water), using a cotton-tip applicator or washcloth, two to three times daily PLUS topical antistaphylococcal antibiotics e.g. topical bacitracin + neomycin solution (4 - 6 times a day for 1 - 2 weeks).  Then reduce frequency to once daily before bedtime and continue for 4 - 8 weeks.   Alternatives include fusidic acid drops 1 - 2 drops 4 - 6 times daily for 1 - 2 weeks.

Hordeola

o             External hordeolum (Stye):

          Staphylococcus aureus is the predominant microbial pathogen.  These lesions usually come to a head and rupture spontaneously within a matter of days.  Application of warm compresses 4 - 6 times per day usually suffices for treatment of this condition.  Resolution can be hastened if the pointing lesion is pricked with a sterile needle.

          Topical antibiotic therapy is unnecessary unless there are multiple styes, when topical fusidic acid or bacitracin PLUS neosporin or framycetin may be warranted.

o             Internal hordeolum: (acute meibomianitis):

          Staphylococcus aureus is the major microbial pathogen.  Treatment require warm compresses PLUS an oral antistaphylococcal agent e.g. cloxacillin or flucloxacillin.  If the condition does not respond to this regimen, incision and drainage are indicated and the patient should be referred to an ophthalmologist.

Conjunctivitis

Both infectious (viral, bacterial, chlamydial) and noninfectious (allergy, foreign body) should be considered. Watery discharge may be associated with upper respiratory infection or adenovirus.  Hallmarks of viral conjunctivitis are a follicular reaction and preauricular lymphadenopathy.

Purulent or mucopurulent discharge suggests a bacterial or chlamydial cause.

o             Viral conjunctivitis (“pink-eye”):  Treatment is supportive.  The use of topical corticosteroid therapy is controversial.  Children are generally kept out of school for up to 2 weeks after the onset of the infection.

o             Bacterial conjunctivitis:  Acute bacterial conjunctivitis in the adult is most often due to staphylo-cocci and/or streptococci.  Haemophilus influenzae is more common in children. Topical antibiotics usually suffice. Topical chloramphenicol may rarely cause idiosyncratic bone marrow suppression.  Alternative agents include gentamicin or tobramycin eye drops (for adults) and ointment (for children), or fusidic acid eyedrops.

o             Conjunctivitis in the newborn (ophthalmia neonatorum): due to Chlamydia trachomatis or Neisseria gonorrhoeae.  Note:  The best form of prophylaxis is 2.5% aqueous povidone-iodine solution. 

*          Chlamydia trachomatis: Erythromycin syrup (40 - 50 mg/kg/ day) in 4 divided doses for 14 days.  Investigate and treat parents for genital infection.

*          Neisseria gonorrhoeae: Ceftriaxone 25 - 50 mg/kg IM as a single dose.  Investigate and treat parents for genital infection.

o             Chlamydial disease in the adult: Oral tetracycline (500 mg 8 hourly) or doxycycline (100 mg 12 hourly) or erythromycin (500 mg 6 hourly) for 7 days, or azithromycin 1 g PO as a single dose.

o             Gonococcal conjunctivitis in adults: Ceftriaxone 1 g IM as a single dose.

Lacrimal system infections

o             Canaliculitis:  This is usually caused by Actinomyces, and rarely by Propionibacterium spp., Nocardia or Bacteroides.  Treatment consists of mechanical expression of the exudative or granular material from the canaliculi, combined with probing and irrigation of the nasolacrimal system with a penicillin G (100000 U/ml) eyedrop solution.  Patients should be referred to an ophthalmologist for definitive treatment.

o             Dacrocystitis (infection of the nasolacrimal sac):  Usually due to streptococci (including Streptococcus pneumoniae) or Staphylococcus aureus but culture should guide definitive therapy. 

          Acute infections:  Treat with oral amoxycillin-clavulanate or cefuroxime.

          Chronic infections:  Irrigate the outflow tract with an antibiotic solution such as penicillin G (100000 U/ml) as a temporary measure.  Definitive surgical decompression ultimately rests with the ophthalmologist.

Keratitis (Infection of the cornea)

Causes include bacteria, fungi, Herpes simplex virus or rarely, acanthamoeba. Keratitis is a sight-threatening ocular emergency and requires prompt recognition and immediate referral to an ophthalmologist.

o                  Herpes simplex keratitis:

*       Epithelial disease: Topical antiviral agents e.g. acyclovir ointment applied to eye five times a day, continued for at least 3 days after healing.

*        Stromal disease: Complex - combination of antiviral therapy and topical corticosteroids.

o             Bacterial keratitis:

          Usually due to Pseudomonas aeruginosa, Streptococcus pneumoniae and rarely Staphylococcus aureus.  Cefazolin eye drops (100 mg/ml; parenteral cefazolin mixed with tears naturale) and either gentamicin or tobramycin eye drops (3 mg/ml) or ciprofloxacin instilled every 15 - 60 minutes around the clock for the first 24 - 72 hours, with a slow reduction in dosing over a period of several weeks.

o             Fungal keratitis:

          Usually due to Fusarium, Aspergillus or Candida.  Treat empirically with natamycin (5%) eyedrops; administer every 30 - 60 minutes around the clock for the first 24 - 72 hours.  Alternative agents include amphotericin B in a concentration of 0.15% (to be made up by a pharmacist) or miconazole.