Antimicrobial eye preparations

Infections of the eye

The eye and its adnexae can be subject to infection at different sites, summarised below. See also the links in the 'Infection' column for further information.

Most superficial infections are benign and can be adequately managed in the community. However, in certain predisposed individuals, infection can be severe, prolonged and potentially sight-threatening. Such patients include the following:

• Contact lens wearers.

• Immunocompromised patients.

• Patients in whom the natural defences of the eye have been breached (via disease process or trauma, including surgery).

These infections need to be treated in a specialist unit. Organisms involved may be commensals, such as a number of bacteria and fungi, or exogenous (bacteria, viruses, fungi and intracellular parasites) .

General management principles²

• When assessing and subsequently treating eye infections, handwashing before and after touching the eye is paramount to avoid contamination of the fellow eye or of the carer's/physician's eye. If suspecting adenoviral infection, clean the slit lamp and any other examination tools too. Advise patients to avoid touching their eyes, shaking hands with others and sharing towels. For those with adenoviral conjunctivitis, exclusion from work or school is not recommended unless the individual is feeling generally run down.³

• Consider whether antimicrobial treatment is needed at all: for example, mild blepharitis may respond to careful lid hygiene measures and many infections are self-limiting. This is particularly important to bear in mind in pregnant and breast-feeding women, as there are very limited data regarding the safety of eye preparations in the fetus and baby. If there is no spontaneous resolution of the blepharitis after five days when managed conservatively, treatment can be considered.

• Before initiating treatment, consider swabbing if infective aetiology is suspected (such as recent foreign travel, possibility of sexually transmitted disease). Swabs are also appropriate in non-resolving infections. They should include bacterial cultures, viral swabs and swabs for chlamydial infection.

• Allow adequate time for the treatment to work (five to seven days in bacterial conjunctivitis) before considering any change in antimicrobial preparation, or referral.

• Have a low referral threshold in the presence of pain (as opposed to discomfort, itching, tearing, etc).

• Avoid prescription of preparations combining antibiotics with corticosteroids: patients requiring steroids should be assessed and monitored in a specialist unit.

• Advise the patient to withhold from wearing contact lenses during the period of infection.

See the separate Eye Drugs - Prescribing and Administering article which may be useful when considering prescribing antimicrobial eye preparations.

Over-the-counter antimicrobials

There are a number of over-the-counter eye preparations and pharmacists work within the guidelines of the Royal Pharmaceutical Society of Great Britain when dispensing these drops. Common examples include Brolene® and Golden Eye®:

• The drop forms contain propamidine isethionate and the ointment forms contain dibromopropamidine isethionate as their active agents.

• They have antibacterial, trypanocidal and fungicidal activity.

• They are licensed for local, superficial infections.

• Application is four times a day for the drops and twice a day for the ointment.

• Patients are advised to seek medical advice if there is no stabilisation or any improvement after 48 hours.

Chloramphenicol drops²

Since 2005, chloramphenicol eyedrops have been available over-the-counter. Pharmacists have well-defined referral criteria regarding when to suggest seeking medical advice . In this context, chloramphenicol is used for the treatment of acute bacterial conjunctivitis in individuals aged 2 years and over where there is no pain, visual deterioration or contact lens use. The patient will be told to seek medical advice should the symptoms worsen or persist.

Topical antibiotics⁴

Chloramphenicol^{2 5}

• Use - drug of choice for superficial bacterial eye infections.

• Action - inhibitor of protein synthesis. It is mainly bacteriostatic in action but exerts a bactericidal effect against some strains of Gram-positive cocci and against Haemophilus influenzae and Neisseria gonorrhoeae. It is effective against a wide range of organisms including Gram-negative and Gram-positive bacteria.

• Contra-indications - pregnant or breast-feeding women, especially during the third trimester of pregnancy (theoretical risk of grey baby syndrome). In people who have experienced myelosuppression during previous exposure to chloramphenicol. Also contra-indicated in people who have a blood dyscrasia, who have a family history of blood dyscrasias or who are concurrently on myelotoxic drugs. Avoid in cases of previous hypersensitivity (rare).

• Caution - avoid prolonged treatment.

• Ocular side-effects - transient blurring of vision with ointment; occasionally: transient stinging.

• Systemic side-effects - previous concerns regarding systemic toxicity and risk of aplastic anaemia are not well founded.

• Additional information - Minims® (single-dose vials for patients with preservative sensitivity): available but are half the strength (0.5%). Continue using antibiotics for 48 hours after resolution of symptoms. However, if these do not resolve, or if they worsen, over five days, consider referral. If the patient is already on eye drops, try to use chloramphenicol drops rather than ointment.

Fusidic acid²

• Use - superficial eye infections.

• Action - bacteriostatic activity against Gram-positive bacteria, especially Staphylococcus aureus.

• Contra-indications - none reported.

• Caution - none reported but usual caution with pregnancy and breast-feeding.

• Ocular side-effects - transient blurring of vision, theoretical risk of sensitivity.

• Systemic side-effects - none reported.

Fluoroquinolones⁶

• Example - ciprofloxacin, ofloxacin, levofloxacin.

• Use - although this can be used in a range of external ocular infections, in practice it tends to be reserved for more serious situations such as contact lens-related keratitis. Ciprofloxacin eye drops are licensed for the treatment of corneal ulcers.

• Action - wide spectrum of activity, notably effective against Pseudomonas aeruginosa. Little effect on anaerobes.

• Contra-indications - little is known of its effects in pregnancy and breast-feeding. Levofloxacin is not recommended for children less than 1 year old.

• Caution - previous history of convulsions, epilepsy, liver or kidney failure.

• Ocular side-effects - burning, stinging, photosensitivity, lid crusting/oedema, hyperaemia and lacrimation (ciprofloxacin). Very frequent use can lead to precipitations on the cornea.

• Systemic side-effects - (rare in topical use): rhinitis (levofloxacin), gastrointestinal disturbance, taste disturbance, neurological disturbance, nausea and headaches (ofloxacin).

Aminoglycosides⁷

• Example - gentamicin.

• Use - bacterial conjunctivitis. They are also used as prophylaxis against infection following trauma to the eye.

• Action - bacteriostatic and bactericidal (inhibition of protein synthesis), active against Gram-negative aerobic bacilli (including P. aeruginosa) as well as S. aureus.

• Contra-indications - none noted for topical use other than sensitivity to the drop.

• Caution - extremes of age, auditory problems, renal disease, myasthenia gravis patients. Long-term treatment should be avoided.

• Ocular side-effects - hypersensitivity reaction, blurred vision (do not drive).

• Systemic side-effects - (rare in topical use): ototoxicity, vestibulotoxicity, nephrotoxicity, exacerbation of symptoms of myasthenia gravis.

Other topical antibiotics

• Polymyxin B sulfate - broad spectrum of activity covering both Gram-positive and Gram-negative bacteria. Used in superficial eye infections and applied to sutured, cleaned lid lacerations. Administration as per chloramphenicol drops and ointment. Usual precautions in pregnant and breast-feeding patients.

• Propamidine isetionate - specifically used in the treatment of acanthamoebic keratitis: this is a rare but extremely serious infection that is only managed within the specialist setting.

Systemic antibiotics⁴

Ophthalmic conditions requiring systemic antibiotic treatment are more rare and need specialised supervision. Listed below are some of the more common examples.

Cellulitis

• Preseptal cellulitis - mostly caused by S. aureus but H. influenzae is also a culprit. Periorbital swelling and erythema, may be a history of sinusitis and there is no restriction/pain on moving the eyes.

• Orbital cellulitis - pathogens include: Streptococcus pneumoniae, Streptococcus pyogenes, S. aureus, and H. influenzae. Periorbital swelling is rapid and associated with severe malaise, fever, pain and difficulty with ocular movements.¹ Requires hospital admission: treatment depends on local protocols.

See also the article Orbital and Preseptal Cellulitis for further information.

Dacryocystitis¹

• Pathogens - most often: staphylococci, streptococci and diphtheroids.

• Management - antibiotic treatment initially but incision and drainage may be required where there is formation of a lacrimal abscess. Chronic dacrocystitis warrants a dacrocystorhinostomy (DCR).

• Antibiotics used - this varies according to local protocol.

See also the article on Dacryocystitis and Canaliculitis for further information.

Adult conjunctivitis

• Chlamydial infection - oral azithromycin or doxycycline. Treat sexual partners too and evaluate for evidence of other sexually transmitted infections. If pregnant: erythromycin.

• Neisserial infection - ceftriaxone. Treat sexual partners too and evaluate for evidence of other sexually transmitted infections.

See also the article on Infective Conjunctivitis for further information.

Ophthalmia neonatorum

• Pathogens - N. gonorrhoeae, Chlamydia trachomatis, other bacteria (eg, staphylococci, streptococci, Gram-negative species), herpes simplex virus.

• Management - refer to a specialist centre; this is a notifiable disease; treat the mother.

• Antibiotics used - depending on the pathogen: ceftriaxone (N. gonorrhoeae), erythromycin (C. trachomatis), aciclovir (herpes simplex virus). All cases will be swabbed and antimicrobials will be modified accordingly.

See also the article on Ophthalmia Neonatorum for further information.

Endophthalmitis

• Pathogens - most commonly: Staphylococcus epidermidis but also encountered: S. aureus and streptococcal species other than pneumococcus.

• Management - a sample of vitreous is obtained in theatre and intravitreal antibiotics are instilled (see 'Intravitreal antimicrobials', below). The mainstay of subsequent treatment is topical antibiotic therapy (along with topical steroids) but, in some circumstances (eg, trauma), IV antibiotics may be used.

• Antibiotics used - intravitreal: vancomycin, topical: vancomycin or tobramycin, systemic: levofloxacin.

See also the article on Endophthalmitis for further information.

Antivirals

See also the article on Herpes Simplex Eye Infections.

• Examples - aciclovir, ganciclovir.

• Use - acute herpetic keratitis, cytomegalovirus (CMV) retinitis (ganciclovir).

• Action - inhibit viral DNA polymerases.

• Caution - pregnancy.

• Ocular side-effects - local irritation, red eye and stinging; ganciclovir: visual disturbances, superficial punctate keratitis.

• Systemic side-effects - very rarely, hypersensitivity reactions (including angio-oedema) can occur.

• Additional information - local treatment does not protect against infection of the other eye or against systemic involvement. Can be taken in conjunction with oral antiviral agents and, where there is severe skin involvement, systemic antibiotics may be added to the treatment regime . Occasionally, long-term topical aciclovir treatment is undertaken as a prophylactic measure.

Antifungals⁴

Fungal infections of the cornea (eg, fungal keratitis) are rare but can occur particularly in agricultural areas and tropical climates. Antifungal preparations for the eye are not generally available. However treatments can be available in specialist centres.

Intravitreal antimicrobials⁸

Occasionally, infection may be located at the posterior pole of the eye such that topical antibiotics will not reach the infection site at optimum concentrations or infection may be so widespread (eg, endophthalmitis) that topical antibiotics are simply not enough. In these cases, antimicrobials can be injected directly into the vitreous. This is performed under sterile conditions and usually in theatre. Often, a sample of vitreous is taken at the same time to send to microbiology. Antimicrobials used in this way include amphotericin and voriconazole.