Infections of the eye
The eye and its adnexae can be subject to infection at different sites, summarised below.
|Site||Infection||Possible associated risks|
|Orbit||Orbital cellulitis||Local and distant spread|
|Lacrimal system||Dacryocystitis||Recurrence, nasolacrimal duct obstruction|
|Eyelid: margin||Blepharitis||If prolonged, secondary changes to conjunctiva and cornea|
|Eyelid: glands||Hordeolum||Recurrence and spread to develop preseptal cellulitis|
|Conjunctiva||Conjunctivitis||Usually trivial; if prolonged, cicatrisation and poor tear film|
|Cornea||Keratitis||Scarring, opacification; when severe: ulceration, perforation|
|Intraocular||Endophthalmitis||Retinal damage, severe sight impairment|
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 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).
General management principles
- 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. Common sense should prevail and it is reasonable for those who are likely to transmit the virus (eg, very young children, individuals with general learning disabilities 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 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 separate Eye Drugs - Prescribing and Administering article which may be useful when considering prescribing antimicrobial eye preparations.
Referral to a specialist unit
This should be done in the following situations:
- Moderate-to-severe pain.
- Red eye in a patient with suspected herpes infection.
- Conjunctivitis not apparently responding to repeated topical antibiotics.
- Surgery within the previous six weeks.
- Contact lens wearers and other patients at risk of more serious infection.
- Newborn babies (less than 28 days old).
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.
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 have been advised to apply the chloramphenicol two-hourly (excluding sleep time) over 48 hours and then four-hourly thereafter for a further three days. They will have been told to seek medical advice should the symptoms worsen during that period of time or persist beyond it.
Since this initiative has started, research has shown that GP prescribing of ocular chloramphenicol has decreased but this has been more than counteracted by the increase in chloramphenicol issued from over the counter (resulting in an overall increase of 47.8% between 2005 and 2007). This has prompted concerns from the GP community about increases in inappropriate use (with associated increased resistance) and conflicting public health messages regarding the need to decrease antibiotic use generally.
- Use - drug of choice for superficial 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.
- Administration - drops: two-hourly until symptoms abate; then gradually reduce - continue for 48 hours after cessation of symptoms. Ointment: three to four times a day. In more severe infections, drops during the day and ointment once at night. As with all ocular infections, avoid contact lens wear during the period of 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.
- 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.
- Administration - one drop twice a day: useful in the very young and the very old. Continue until 48 hours after the resolution of symptoms.
- Ocular side-effects - transient blurring of vision, theoretical risk of sensitivity.
- Systemic side-effects - none reported.
- 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.
- 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). Treatment should not exceed ten days.
- 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).
- 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.
- Administration - one to two drops up to six times a day. Contact lenses should be removed during the period of treatment.
- 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.
Ophthalmic conditions requiring systemic antibiotic treatment are more rare and need specialised supervision. Listed below are some of the more common examples.
- 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. Flucloxacillin, 500 mg, six-hourly for seven days and metronidazole, 400 mg, eight-hourly for seven days (or if penicillin-sensitive, erythromycin, 500 mg, six-hourly for seven days).
- 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. Requires hospital admission: treatment depends slightly on local protocols but high-dose intravenous (IV) flucloxacillin/cefuroxime and metronidazole are typical regimes. IV vancomycin may be used in penicillin-allergic patients.
- 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 but an example would be co-amoxiclav (625 mg, eight-hourly for a week) with topical chloramphenicol (six-hourly for a week). If penicillin-sensitive, erythromycin, 500 mg, six-hourly for 10-14 days).
- Chlamydial infection - oral azithromycin (1 g, stat) or doxycycline (100 mg, 12-hourly for seven days). Treat sexual partners too and evaluate for evidence of other sexually transmitted diseases. If pregnant: erythromycin 500 mg, 12-hourly for two weeks.
- Neisserial infection - ceftriaxone (1 g intramuscularly (IM), single dose). Treat sexual partners too and evaluate for evidence of other sexually transmitted infections.
- 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.
- 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.
- Examples - aciclovir, ganciclovir.
- Use - acute herpetic keratitis, cytomegalovirus (CMV) retinitis (ganciclovir).
- Action - inhibit viral DNA polymerases.
- Caution - pregnancy.
- Administration - five times a day for at least three days following healing (aciclovir) and three times a day for a week after healing (ganciclovir).
- 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.
- Fungal eye infections are rare and tend to present as fungal keratitis. More unusually, orbital mycosis can occur, usually as a result of direct spread from the paranasal sinuses.
- Risk factors include: trauma - especially agricultural injuries in warm, humid conditions, topical steroid use and pre-existing chronic corneal surface disease. Age and debility can also increase the risk of fungal infections. Very occasionally, a fungal endophthalmitis can develop as a result of blood-borne spread from a distant location.
- Follows a more indolent course than bacterial keratitis.
- Diagnosis and treatment are carried out in specialist units.
- Antifungal eye preparations are not generally readily 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 0.15% or 0.3%. There are a number of other antifungals also available but they remain within the remit of the specialist.
- Systemic antifungals may be used in deeper infections: azoles are the favoured group (eg, miconazole, fluconazole and itraconazole).
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 vancomycin, amikacin, ceftazidine, amphotericin and ganciclovir.
Further reading and references
The Eye: Basic Sciences in Practice
Conjunctivitis - infective; NICE CKS, August 2015 (UK access only)
Guidance on infection control in schools and other childcare settings; Public Health England (September 2017)
Davis H, Mant D, Scott C, et al; Relative impact of clinical evidence and over-the-counter prescribing on topical antibiotic use for acute infective conjunctivitis. Br J Gen Pract. 2009 Dec59(569):897-900. doi: 10.3399/bjgp09X473132.
Summary of Product Characteristics (SPC) - Minims Chloramphenicol®; Bausch & Lomb UK Limited, electronic Medicines Compendium, May 2016
Summary of Product Characteristics (SPC) - Exocin®; Allergan Ltd, electronic Medicines Compendium, April 2016
Summary of Product Characteristics (SPC) - Genticin Eye/Ear Drops®; Amdipharm Mercury Company Limited, electronic Medicines Compendium, February 2015
The Wills Eye Manual
Oxford Handbook of Ophthalmology
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