Antimicrobial Eye Preparations

The eye and its adnexae can be subject to infection at different sites, summarised below.

Most superficial infections are trivial and can be adequately managed in the community but in certain predisposed individuals infection can be severe, prolonged and potentially sight threatening. Such patients include: contact lens wearers, immunocompromised patients and those 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).²

• 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 slit lamp and any other examination tools too. Advise patients to avoid touching their eyes, shaking hands with others and sharing towels.³ For those with adenoviral conjunctivitis, the Health Protection Agency does not advise exclusion from work or school⁴ but common sense should prevail and it is reasonable for those who are likely to transmit the virus (e.g. very young children, learning disabled individuals in day centres, ophthalmologists!) to stay at home until 48 hours after remission of symptoms.
• 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 is very limited data regarding the safety of eye preparations in the fetus and baby. If there is no spontaneous resolution after 5 days when managed conservatively, treatment needs to be considered.
• Before initiating treatment, consider swabbing if aetiology suspect (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 Chlamydia.
• Allow adequate time for treatment to work (5 days in bacterial conjunctivitis) before considering change in antimicrobial 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 patient to withhold from contact lens wear during period of infection.

You may find our record on Prescribing for and Administration of Drugs to the Eye useful when considering prescribing antimicrobial eye preparations.

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®:⁵

• 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 some improvement after 48 hours.

Chloramphenicol³

• Use - drug of choice for superficial eye infections.
• Action - inhibitor of protein synthesis. Effective against a wide range of organisms including Gram-negative and Gram-positive bacteria.
• Contraindications - pregnant or breast-feeding women - especially during the third trimester pregnancy (theoretical risk of grey baby syndrome). In people who have experienced myelosuppression during previous exposure to chloramphenicol. Also contraindicated in people who have a blood dyscrasia, who have a family history of blood dyscrasias or who are concurrently on myelotoxic drugs.
• Caution - avoid prolonged treatment.
• Administration - drops: 2 hourly until symptoms abate then gradually reduce - continue for 48 hours after cessation of symptoms. Ointment: 3 to 4 times a day. In more severe infections, drops during day and ointment once at night.
• 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 not well founded.
• Additional information - minims® (single dose vials for patients with preservative sensitivity) available. Continue using antibiotics for 48 hours after resolution of symptoms. However, if these do not resolve or worsen over 5 days, consider referral. If the patient is already on eye drops, try and use chloramphenicol drops rather than ointment.

Fusidic acid³

• Use - superficial eye infections
• Action - bacteriostatic activity against Gram-positive bacteria, especially S.aureus
• Contraindications - none reported
• Caution - none reported but usual caution with pregnancy and breast-feeding
• Administration - one drop twice a day - useful in the very young and very old. Continue until 48hours after the resolution of symptoms.
• Ocular side-effects - transient blurring of vision, theoretical risk of sensitivity
• Systemic side-effects - none reported

Fluoroquinolones⁷

• Example - ofloxacin
• 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.
• Action - wide spectrum of activity, notably effective against Pseudomonas aeruginosa. Little effect on anaerobes.
• Contraindications - little is known of its effects in pregnancy and breast feeding.
• Caution - previous history of convulsions, epilepsy, liver or kidney failure.
• Administration - frequent: can be up to every 15 minutes. Infections needing such intensive treatment should be monitored in a specialist unit. Otherwise, as for chloramphenicol (above).
• Ocular side-effects - burning, stinging, photosensitivity, lid crusting, very frequent use can lead to precipitations on cornea.
• Systemic side-effects - (rare in topical use): gastrointestinal disturbance, taste disturbance, neurological disturbance.

Aminoglycosides⁸

• 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 Pseudomonas aeruginosa) as well as staphylococci.
• Contraindications - 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.
• Administration - 1 to 2 drops up to 6 times a day (can be more frequent if required. Contact lenses should be removed during the period of treatment.
• Ocular side-effects - hypersensitivity reaction, blurred vision.
• Systemic side-effects - (rare in topical use): ototoxicity, vestibulotoxicity, nephrotoxicity, exacerbation of symptoms of myasthenia gravis.

Other topical antibiotics

• Polymyxin B Sulphate - 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 acanthamoeba keratitis: this is a rare but extremely serious infection that is only managed within the specialist setting.

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

Cellulitis

• Preseptal cellulitis - mostly caused by S.aureus but H. influenzae also a culprit. Periorbital swelling and erythema, may be history of sinusitis, no restriction / pain on moving eyes. Amoxicillin (500 mg, 8 hourly for 10 days) or if penicillin sensitive, erythromycin (500 mg, 6 hourly for 10 days).
• Orbital cellulitis¹ - pathogens include: S. pneumoniae, S.aureus, S.pyogenes, and H. influenzae. Periorbital swelling is rapid and associated with severe malaise, fever, pain and difficulty with ocular movements. Requires hospital admission: treatment will consist of i.m. ceftazidine and oral metronidazole. IV vancomycin may be used in penicillin allergic patients.

Dacrocystitis¹

• Pathogens - most often: staphylococci, streptococci and diptheroids.
• Management - antibiotic treatment initially but incision and drainage may be required where there is formation of a lacrimal abscess. Chronic dacrocystitis warrants a DCR (dacrocystorhinostomy).
• Antibiotics used - flucloxacillin (500 mg, 6 hourly for 10-14 days) or if penicillin sensitive, erythromycin (500 mg, 6 hourly for 10-14 days).

Adult conjunctivitis

• Chlamydial infection - tetracycline (500 mg, 6-8 hourly for 7days) or doxycycline (100 mg, 12 hourly for 7 days). Treat sexual partners too and evaluate for evidence of other sexually transmitted diseases.
• Neisseria infection - ceftriaxone (1gm i.m., single dose). Treat sexual partners too and evaluate for evidence of other sexually transmitted diseases.

Ophthalmia neonatorum

• Pathogens - Neisseria gonorrhoeae, Chlamydia trachomatis, other bacteria (e.g. staphylococci, streptococci, Gram-negative species), herpes simplex virus.
• Management - refer to specialist centre, notifiable disease, treat mother.
• Antibiotics used - depending on pathogen: ceftriaxone (N. gonorrhoeae), erythromycin (C. trachomatis), aciclovir (herpes). All cases will be swabbed and antimicrobials will be modified accordingly.

Endophthalmitis

• Pathogens - most commonly: S.epidermidis but also encountered: S. aureus and streptococcal species other than pneumococcus.
• Management - vita sample of vitreous is obtained in theatre and intravitreal antibiotics are instilled. The mainstay of treatment is topical antibiotic therapy (along with topical steroids) but in some circumstances (e.g. trauma), i.v. antibiotics may be used.
• Antibiotics used - intravitreal: vancomycin, topical: vancomycin or tobramycin, systemic: levofloxacin.

• Examples - aciclovir, ganciclovir
• Use - acute herpetic keratitis, CMV retinitis (ganciclovir)
• Action - inhibit viral DNA polymerases¹⁰
• Caution - pregnancy
• Administration - 5 times a day for 7 days beyond cessation of symptoms
• Ocular side-effects - local irritation and stinging; ganciclovir: visual disturbances, superficial punctate keratitis
• Systemic side-effects - none noted in topical treatment
• 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.⁹ Occasionally, long term topical aciclovir treatment is undertaken as a prophylactic measure.

• Fungal eye infection is rare and tends to present as fungal keratitis.
• Risk factors include: trauma - especially agricultural injuries in warm, humid conditions, topical steroid use and pre-existing chronic corneal surface disease.⁹
• Follows a more indolent course than bacterial keratitis.
• Diagnosis and treatment is carried out in specialist units.
• Antifungal eye preparations are not generally available in the UK but treatments can be made up in specialist centres following discussion with the local health authority (or equivalent in Scotland and Northern Ireland).
• Typical antifungals include econazole 1% and amphotericin B 0.15% or 0.3%.
• Systemic antifungals may be used in deeper infections: azoles are the favoured group (e.g. miconazole, fluconazole and itraconazole).