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Bacterial infections of the conjunctiva and peripheral cornea: course code: C-14743 O/AS/SP/IP.

Changing legal background use and supply of anti-infectives

Special access provisions, within the broad context of the Medicines Act, have been progressively updated over the years to define optometric access to anti-infective drugs. These updates, or statutory instruments, do not define the nature or severity of the eye disease that might be treated, but there are some relevant Clinical Management Guidelines (CMGs) from the College of Optometrists, principally those for 'Conjunctivitis (bacterial)' and 'Keratitis (marginal)'.

UK optometrists were allowed to use and supply eye drops containing chloramphenicol from the late 1980s onwards. Reclassification of chloramphenicol multi-dose eye drops, and then the ophthalmic ointment, to P medicines occurred in 2005 and 2007, respectively, along with further laws that allowed optometrists to sell and supply any P medicine, providing it was in the course of their professional activity, ie, the so-called emergency stipulation for P Medicines access and use was removed. These products (eg, diamidine anti-infectives and P medicine chloramphenicol) are marketed with guidelines for their use, and for chloramphenicol these differ slightly from those for the PoM products. The Statutory Instruments in 2005 also removed optometrist access to framycetin, with fusidic acid eye drops substituted. Both chloramphenicol and fusidic acid products can be used, supplied and sold by optometrists. Stocks can be obtained by wholesale trading, or the optometrist may also access these products for a named patient and via a pharmacist, by a written (signed) order.

Mechanisms of action of drugs

Antibacterial drugs can slow down or stop further replication of bacteria (bacteriostatic) or can kill bacteria (bactericidal). There is also a notable selectivity of drug action according to the bacterial type, usually broadly classified on the basis of being gram-positive or gram-negative, with sub-categories according to whether they grow best in culture under oxygen-rich (aerobic) or oxygen-deficient (anaerobic) conditions. The vast majority of suspected bacterial infections of the conjunctiva and peripheral cornea are managed without culture tests for identity of type or actual sensitivity to specific drugs, but rather a 'shotgun' therapy undertaken, ie, to expose the ocular surface with an excess of antibacterial drugs and see if it responds (see later). The various antibacterial drugs have different mechanisms of action targeted at the permeability of the inner cytoplasmic (cell) membrane of bacteria and/or their intermediate metabolism, at the protein synthesis mechanisms of bacteria, at the mechanisms by which the outer cell wall is assembled or at the DNA replication mechanisms of the bacteria. (1,2) Some of these drugs are available to non-therapeutically qualified optometrists, some to AS level optometrists and also to IP optometrists. If a suspected bacterial infection of the external eye fails to respond to the initial shotgun therapy, the bacteria may be resistant to the 'entry level' drugs and so referral to a therapeutically trained optometrist (or an ophthalmologist) can provide access to different types of drugs to which the bacteria may be sensitive.

Overview of bacterial infections of the external eye and their presentation

One type of blepharitis can be infectious, where poor eyelid hygiene most commonly leads to colonisation of the eyelashes with the same bacteria found on the skin, eg, Staphylococcus epidermidis and S. aureus. These are not visible in a clinical setting (although can be seen with an electron microscope; see OT September 17 2010) but can lead to the development of acute-onset focal infections that are visible clinically. These are most commonly of the eyelash follicles (sometimes with the glands of Moll and Zeis) and give rise to a stye or external hordeolum (see OT September 17 2010).

An infectious blepharitis, if not managed properly, can easily lead to development of blepharoconjunctivitis whereby the bacteria infect the mucous membranes of the conjunctiva as well as the eyelid margins, and can also be associated with a marginal keratitis (see next article in this series). As part of the innate immune response (see OT October 15 2010), the conjunctiva not only reacts with development of redness (Figure 1) but also a discomfort usually described as a burning (rather than an itching) sensation. (3,4)

The conjunctiva is normally covered with the tear film which provides defense against infective organisms, especially bacteria. (5) Antibacterial substances such as lysozyme are notably active in dissolving the outer cell walls of staphylococcus sp., so should limit bacterial levels to a minimum or low level. Logically, a bacterial blepharoconjunctivitis or conjunctivitis will develop as and when the levels of bacteria exceed the protective functions of the tear film and the capacity of the tear film drainage to remove bacteria from the ocular surface. (5) If a patient already has suboptimal tear properties (eg, because of chronic dry eye disease, allergic conjunctivitis or acne rosacea), they are at higher risk for developing bacterial blepharoconjunctivitis or conjunctivitis.

[FIGURE 1 OMITTED]

As bacteria numbers increase, the innate immune reaction produces pronounced vasodilatation that allows for emigration of white blood cells from fenestrated capillaries into the loosely compacted conjunctival parenchyma and eventually onto the conjunctival surface. The net result is a mixture of rapidly proliferating bacteria, white blood cells and some mucous from goblet cells, a mixture referred to as mucopurulent discharge. A bacterial conjunctivitis is generally diagnosed on the basis of signs and symptoms at first presentation, and likely to include early morning 'glued' eyes that result from the mucopurulent discharge that accumulates in the fornices and seeps out between the closed eyelids (Figure 2). (6,9) Substantial generalised eyelid oedema should not be present and the superior palpebral fold (sulcus) should be evident. If not, referral to ophthalmology should be considered for systemic antibiotic treatments. (10)

Such discharge can be expected to be associated with a generalised redness of the bulbar and palpebral conjunctiva (which may sometimes be remarkable). The condition is more likely to be bilateral, but can be asymmetrical in its initial presentation. At the earliest development of symptoms, the quantity of discharge may only be very slight, but can develop substantially over just 24 hours. Cultures from human eyes diagnosed with presumed bacterial conjunctivitis have revealed that different bacteria can be present (Figure 3).

A positive culture of viable bacteria from the eyelid margin or the lower fornix is not uncommon, even though the actual number of bacteria (in colony forming units--CFUs) can be very small (especially in a nominally 'clean' eye where eyelid hygiene is good). Therefore, as illustrated in Figure 3, the commonest isolate was S. epidermidis (STAPHE), followed closely by S. aureus (STAPHA). (11-13) Ocular isolates of S. epidermidis are usually considered non-pathogenic as they are part of the 'normal' flora of the eyelid margin, while S. aureus should be considered a pathogen especially if showing resistance to the cell wall synthesis-inhibiting antibiotic methicillin (MRSA). Other bacteria such as Haemophilus influenzae and Streptococcus pneumoniae are not uncommon causes of an infected throat that can accompany a bacterial conjunctivitis, thus the moderately high incidence of positive cultures (designated as HAEMOPH and STREP in Figure 3) for bacterial conjunctivitis, especially in children.

For the most part, even when quite substantial discharge is present, the ocular surface will likely only stain diffusely with fluorescein, indicating intact barriers. A more serious infection of the external eye can develop, even due to so-called non-pathogenic organisms, because of the presence of even the smallest focal lesion on the surface. If the initial number of bacteria ('bacterial load') or other pathogens was high (including on a soiled contact lens), then even non-virulent strains are more likely to establish themselves on a compromised ocular surface and so result in a serious infection. Low numbers of a particularly virulent bacterial strain (or other microorganism) can overwhelm even the highest levels of defenses and barriers, especially that of the cornea and an infection (keratitis) develops. A notable pathogen, such as Pseudomonas aeruginosa, would be expected to invade even healthy tissue and make a lesion, but such pathogens are much less common when a bacterial conjunctivitis is diagnosed (see Figure 3; PSEUDOM). (11,14) However, with certain risk factors (eg, contact lens wear), a check should be made with slit lamp biomicroscopy for any sign of surface lesions or ulcers (Figure 4).

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

Even a suspected peripheral ulcer of this type should be considered for antibacterial drug treatment, even if just for prophylaxis (see later). In rare cases, a true infected ulcer can develop in the corneal periphery and pseudomonas should always be considered in a contact lens wearing patient presenting with an acute-onset red eye (CLARE), and the patient usually referred to ophthalmology.

In the majority of cases, non-bacterial causes of an infectious conjunctivitis are essentially identified as a result of failure to respond to an initial treatment with antibacterial drugs. Notable exceptions to this, which should be considered as part of the diagnosis, are infections of the eyelid margin and eyelashes associated with mites or lice (see OT September 17 2010) or viral infections (ie, EKC or especially Herpes simplex); neither would be expected to produce a mucopurulent discharge. These cases should be referred to an IP optometrist or ophthalmologist.

Treatment options

The treatment options really depend on the bacteria type, antibacterial drug mechanisms and level of training. A non-specific 'treatment' for recurrent mild bacterial infections of the external eye is to reduce the bacterial load by improving lid hygiene (see OT September 17 2010). This should always be considered for recurrent mild infections, since such 'lid scrubs' can hopefully reduce the number of viable bacteria without exerting any specific bactericidal or bacteriostatic effect. They should also be considered to control the condition after a course of anti-infective drug therapy. These lid scrubs are non-medicinal products that can be supplied by all optometrists (see OT September 17 2010).

[FIGURE 3 OMITTED]

The next level of drugs is represented by the diamidines, namely propamidine and dibromopropamidine. These are also available to all optometrists and are chemical agents (ie, anti-infectives not antibiotics) best described as general-purpose bacteriostatic agents. They were introduced in the 1940s and have several effects including blocking a cell membrane-sited 'permease' transport system for uptake of purine nucleotides; (1,2,15) the bacteria are therefore unable to synthesise adequate quantities of precursors for DNA, RNA or even protein synthesis, and so fail to thrive. Other secondary effects on this intermediate metabolism also likely achieve the bacteriostatic effect.

It is largely unknown as to what type of resistance can develop to these drugs and/or whether resistance is a problem with their ophthalmic use. The sulphonamides or 'sulfa' drugs (eg, sulphacetamide sodium) inhibit folic acid-linked intermediate metabolism of bacteria and these drugs had substantial use from the late 1940s, showing efficacy against common gram-positive bacterial eye infections. These drugs were available to optometrists in an 'emergency', but commercial products were discontinued in the late 1980s when it became recognised that their efficacy was declining, most likely due to resistance.

The mainstay of treatment of bacterial infections of the conjunctiva (and probably many cases of peripheral cornea conditions) is with the antibiotic chloramphenicol. This is a protein synthesis inhibitor and with its broad spectrum of activity can be expected to affect the protein synthesis of many types of bacteria, a notable exception being some pseudomonas strains. (16-18) It was originally made available to all optometrists as PoMs (eg, PoM Chloromycetin eye drops and ointments, generic PoM Chloramphenicol eye drops and ointments, and the PoM Minims Chloramphenicol; British National Formulary, 2010). There is no obvious evidence that its overall efficacy has declined over the many years it has been used for external eye infections, with resistance routinely found to only be at a low level (c. 10%).

An inappropriate chronic use and overuse of chloramphenicol eye drops or ointments prompted a considerable degree of professional concern in the 1980s over its routine selection as a short-term, all-purpose topical ocular antibacterial for conjunctivitis. (19)

However, the evidence provided to support a case for stopping this routine use was clearly not substantial enough for the products to be withdrawn in the UK. Indeed, quite the opposite has happened as chloramphenicol-containing eye products were reclassified as P Medicines (eg, Golden Eye Antibiotic drops and ointments, Brochlor eye drops and ointments, as well as several generic products from major pharmacies such as Boots Infected Eyes eye drops), with any UK optometrist being able to sell and supply these under the proviso that their use should be undertaken with a little more care and organisation (see later).

Fusidic acid is another antibiotic directed at protein synthesis of bacteria, available in a special viscous eye drop/ gel. Its site of action is different to chloramphenicol and it has a narrow spectrum only. (20) Notwithstanding, providing it is not used when the possible pathogens causing the conjunctivitis are those associated with bacterial infections of the throat (ie, streptococcus and haemophilus sp.), it should have an equivalent efficacy to chloramphenicol eye drops or ointment and work on 90% of patients. From 2005, an ophthalmic fusidic acid preparation, as PoM Fucithalmic, became available to all optometrists.

[FIGURE 4 OMITTED]

AS-trained optometrists can also access two other antibacterial drugs, namely bacitracin and polymyxin B. Bacitracin was introduced in the 1950s as a narrow spectrum antibiotic that interferes with the synthesis of the cell wall, especially in gram-positive bacteria, (21) while polymyxin B non-specifically increases the permeability of the membrane of common gram-negative and gram-positive organisms. (16) Both drugs generally exert concentration-dependent bacteriostatic then bactericidal effects at higher levels, and are routinely used in combination. Such an option is available in the form of PoM Polyfax eye ointment. Another drug option for AS-trained optometrists was listed in the 2005 legislation changes. This was trimethoprim, which inhibits folic acid-linked intermediate metabolism, (22) but commercial products were discontinued in the UK at about the same time.

IP optometrists have access to any ophthalmic antibacterial drugs for use as part of their professional practice with the general caveat that they should only be used when there is an appropriate level of professional experience and competence. So, for example, a substantial mucopurulent conjunctivitis developing in a newborn infant is designated in the current CMGs as a condition requiring urgent referral to an ophthalmologist. Options to an IP optometrist include the aminoglycoside antibiotics with gentamicin, like framycetin once available to UK optometrists, being considered to be able to block protein synthesis in a broad spectrum of gram-positive and gram-negative bacteria (providing resistance to the antibiotics has not developed). (13,14,18) While commercially available (eg, PoM Genticin eye drops) and on some NHS regional formularies, its recommended use however, is unlikely to include routine cases of bacterial conjunctivitis. The same applies to another protein synthesis inhibitor, chlortetracycline, a tetracycline antibiotic widely used in the 1950s and 1960s. (23) Ophthalmic commercial products are no longer available but may be prepared and made available by specialist NHS pharmacies for use on special cases.

Another aminoglycoside is neomycin, available in combination with bacitracin and another cell membrane-active antibiotic gramicidin (PoM Neosporin) that might be used as a broad-spectrum antibiotic approach for managing corneal abrasions (see next part of this series). The last antibacterial drug option generally available to IP optometrists is that of the fluoroquinolone drugs, eg, ofloxacin and levofloxacin. These are also broad spectrum but inhibit bacterial DNA replication rather than protein synthesis, (24) and are generally bacteriostatic. However, at the present time, while these drugs (eg, as PoM Exocin and PoM Oftaquix) can be expected to be effective, neither is advocated for routine use for commonly presenting bacterial conjunctivitis. They should be reserved for use for more stubborn or severe infections not responsive or susceptible to chloramphenicol or the aminoglycosides. Even chloramphenicol eye drops may still be used for a marginal, non-ulcerating keratitis, as a prophylaxis. Another option, ciprofloxacin (PoM Ciloxan eye drops and ointment), would be considered suitable as an initial monotherapy for suspected infectious ulcers of the peripheral (or central) cornea, with or without cultures being taken.

[FIGURE 5 OMITTED]

Pharmacokinetics of topical antibacterial drugs

Products containing anti-infective drugs can be presented to the human eye in three ways, namely as an ophthalmic solution (eye drops), eye ointments or special very viscous solutions. For eye drops containing dibromopropamidine, no pharmacokinetic data appear to have been published. However, the time-dependent changes in the concentration of this drug in the tear film, after presentation to the conjunctival surface as a 0.1% solution, would be expected to be similar to that reported for chloramphenicol (Figure 5); (1,25) these eye drops were specified to also contain some hypromellose polymer, an inclusion that would increase the retention time.

In relative terms, immediately after instillation, the drug concentration in the tears will be 100%, but this will decline rapidly as the volume of the eye drops is rapidly washed away through the puncta and down the nasolacrimal duct. The relative concentration can be expected to be only half the initial value within about five minutes if the eye drops contained hypromellose, and within only one or two minutes without hypropmellose. (1) Regardless, within 30 minutes of instillation of such eye drops, only a small fraction (ie, less than 0.1% concentration) would expected to be present, a level that is likely to be below that required to exert a useful bacteriostatic effect. If the same drug were presented to the eye as a small ribbon (0.5cm to 1cm long, extruded into the lower fornix), then a remarkably different time-related profile of drug concentration is expected, extending to some five hours (Figure 6). (25) The practical consequences of this clinical pharmacokinetics will be discussed later.

The concentration of chloramphenicol in eye ointments is usually 0.5% w/v rather than the 1% w/v in eye drops. While there is still a relatively fast initial wash out as the ointment is likely squeezed out over the eyelid margins, around half of the initial drug is still measurable in the tear film after 30 minutes and coating of the eyelid margins likely serves as a reservoir to feed small quantities of the drug back into the tear film over an extended period of time. (26) There is thus a slow secondary decline in drug concentrations over perhaps some three hours. If the eye was irritated, and there was not much soothing effect from the application of the lubricating ointment, then reflex tearing would be expected to enhance the rate of washout, eg, half washout may be as short as 20 minutes and secondary washout complete within two hours. Notwithstanding, the ointment application provides an extended time period of antibiotic drug coverage of the ocular surface. Similar effects would be expected for dibromopropamidine or polymyxin B and bacitracin eye ointments.

The use of a special viscous eye drop, with the viscosity provided by a carbomer 'gel' formulation similar to that used for various ocular lubricants in dry eye (see OT August 13 2010), substantially extends the time period of antibiotic drug coverage from that achievable with inclusion of hypromellose polymer into eye drops; the drug retention time can extend out to 12 hours (Figure 7). As the profile shows, the use of such carbomer-based eye drops can be expected to provide similar initial time-dependent delivery over the first one-two hours to that of an eye ointment, and an even further prolonged secondary drug delivery. Such effects can be attributed both to the viscous 'gel' coating the eyelid margins (so serving as a reservoir of drug) and to the carbomer actually adhering to the cornea and conjunctival surface.

[FIGURE 6 OMITTED]

Clinical use of anti-infective drugs for bacterial infections

There are four inter-related aspects to clinical use of antibacterial drugs for the external eye. These are: (a) evaluation and diagnosis (especially of the severity of the presenting condition), (b) selection of the most appropriate product to treat the condition, (c) selection of the most appropriate schedule of use of the particular product chosen (including how long it should be used for), and (d) consideration of the follow-up required. Prophylactic use of antibiotics (including for corneal abrasions) will be considered in the next article of this series.

For management of mild or suspected cases of bacterial conjunctivitis or blepharoconjunctivitis, diamidine treatment is appropriate as an initial measure. The two drug options available in the UK are propamidine, in the form of P Brolene and P Golden Eye eye drops, and dibromopropamidine, in the form of P Brolene eye ointment and P Golden Eye ointment. The original Golden Eye ointments contained yellow mercurial oxide, but the active ingredient was changed to a dibromopropamidine, which is also used in topical skin antibacterial preparations (also available as P Medicines). Use of propamidine eye drops on a QDS basis would be appropriate, with the patient needing to be told that if the condition does not respond promptly, then further attention should be sought. This may simply be to then try antibiotic eye drops (eg, chloramphenicol), either supplied by the optometrist or via a pharmacist; either provider should take time to instruct the patient that the use needs to be intensive. With the expected pharmacokinetics for chloramphenicol eye drops, current recommendations for the use of these P medicines is for the drops to be instilled every two hours during waking hours for the initial 48 hours. This will mean that there are only short periods when the surface is not exposed to a suitable level of antibiotic. After 48 hours, dosing can then be reduced and overnight coverage with the companion ointment products (eg, P Brochlor eye ointment, P Golden Eye Antibiotic eye ointment) added at some stage as appropriate (even during the first 48 hours if necessary). For older children (above the age of two years) and elderly people, management of many cases of bacterial conjunctivitis might be more effective with the use of the ointments QDS from the outset, since a much better coverage would be expected.

The P Medicines are not indicated for use in infants.

When a patient presents with an obvious bacterial conjunctivitis (eg, Figure 2), then cleansing needs to be the first step. Any signs of discharge, no matter how slight or substantial, should be removed by cleansing. A simple approach, especially applicable to children or old people, is to use cotton wool repeatedly wetted with warm water and wiping the eyelid margin and periocular skin from inner to outer aspects. Dried discharge ('crusting') may take several wipes to soften. The water should be clean, and some may get into the eye. Additional cleaning of the conjunctiva and fornices is better done with a sterile eyewash product, with patients being advised that the discharge can be contagious (so ocular, facial and hand hygiene is important to stop spreading and/or transmission). After cleansing, the P medicines containing chloramphenicol can be used as just indicated above, with it being important that the patient understands that treatment should be continued for a couple of days after a cure is apparently achieved. With the availability of numerous P medicines containing chloramphenicol, the PoM products have all but become redundant for routine optometric practice, although are likely still prescribed by GPs for patients presenting with a bacterial conjunctivitis.

An alternative to chloramphenicol, for patients presenting with an obvious bacterial conjunctivitis, is to use the fusidic acid product; (4,6,8,12,26) this can be used in infants. The pharmacokinetics of this product is such that intensive use is not required. This may be especially useful if, for example, the patient is unable to readily comply with a two-hour dosing with eye drops or even QDS use of ointments. This may be because the patient is a younger child, when a parent or caregiver needs to instill the drops, but care should be taken not use PoM Fucithalmic to treat bacterial conjunctivitis associated with a bacterial throat infection (see earlier). Similar considerations apply to elderly people, when, for example, manual dexterity problems may limit their ability to regularly apply eye drops or ointments. A standard dosing with PoM Fucithalmic is twice daily (BDS), with the usual duration of the treatment being for at least five days. However, if the condition is considered moderate or even severe, then the initial treatment can be QDS (ie, every four hours or so) for the first day.

[FIGURE 7 OMITTED]

Optometrists may sell and supply PoM Fucithalmic, but it is likely easier to access it via a written order. If a written order is being used, then details should be on the supply and labeling instructions to the pharmacist, eg, "supply 1 tube Fucithalmic for morning and evening use, both eyes, for five days". The written order should also include details of the patient's name, address and age, and be on stationary that clearly indicates the optometrist's registered practice.

Fusidic acid viscous eye drops may also be useful in cases of infectious blepharitis. (27-29) This might be considered as an 'unlabelled use', but is a useful alternative to chronic use of chloramphenicol eye ointments. Whilst the viscous eye drops are instilled into the lower fornix, providing there is adequate retention, then the antibiotic would be expected to seep out and coat the marginal zone of the eyelids and even get around the bases of the eyelashes.

The necessity of using the eye drops or ointments as indicated, needs to be stressed to the patient (or their parent/ guardian for paediatric cases), and that treatment should continue for two days after a 'cure' has been achieved. This recommendation applies even if the course of treatment was just five days. For a milder infection, a sufficient improvement may have occurred in just three days such that the patient considers that they no longer need to bother with using their eye drops.

Follow-up should be as appropriate, depending on the severity of the condition and the expected compliance of the patient. As a guideline, as the optometrist is directly or indirectly initiating the supply, the patient should be advised to return if the condition gets worse, and this is best indicated on the patient records.

This advice can be facilitated by providing the patient with a business card (or similar) with practice telephone number. A patient will, in all likelihood, be prompted to seek further attention if the condition does not resolve in a few days, and so there is no formal requirement for a specific follow-up visit (eg, at 48 hours or after five days of treatment), providing the patient has been given instructions as to when and where to seek further attention. This follows the same sort of procedures used in UK accident and emergency departments. (30,31) Notwithstanding, there is no reason why an optometrist cannot choose to see a patient for a specified follow-up visit (eg, at 48 hours) if they feel that it is appropriate.

Summary

Despite a rather muddled rationale behind changes in the laws pertaining to access to anti-infectives and antibiotics, current UK optometrists do have the means to therapeutically manage many types of common ocular bacterial infections from the outset, and should only need to refer if they are uncertain about the diagnosis or a condition gets worse despite the initiation of treatment.

References

See www.optometry.co.uk and search 'references'

Module questions

Course code: C-14743 O/AS/SP/IP

1. Which of the following is a characteristic sign associated with onset of blepharoconjunctivitis?

(a) Dry eye sensation

(b) A burning discomfort

(c) Marked mucopurulent discharge

(d) Redness of the lid margins and bulbar conjunctiva

2. Which of the following bacteria would be the MOST likely cause of a severe conjunctivitis with marginal keratitis?

(a) Staphylococcus epidermidis

(b) Staphylococcus aureus (methicillin sensitive)

(c) Haemophilus influenzae

(d) Pseudomonas aeruginosa

13. A mucopurulent discharge is:

(a) A special mucous secretion from the glands of Moll and Zeis

(b) Derived from the glands of Krause in the lower fornix

(c) A mixture of bacteria, mucous and white blood cells

(d) Secreted from the lacrimal gland following infection

4. Which of the following is a major component of the action of dibromopropamidine?

(a) Dissolving the cell wall of gram-positive bacteria

(b) Increasing the permeability of bacterial cell membranes

(c) Blocking a cell membrane purine transport system

(d) Specifically inhibiting DNA synthesis of bacteria

5. Current products of Golden Eye ointment contain which active ingredient?

(a) propamidine

(b) dibromopropamidine

(c) yellow mercuric oxide

(d) chloramphenicol

6. Eyelid hygiene products should be effective in milder cases of bacterial conjunctivitis because they:

(a) Have a selective action on gram-positive bacteria

(b) Should exert a general non-specific bactericidal effect

(c) Should be able to remove all bacteria from the lid margins

(d) Contain specific antibacterial / anti-infective chemicals

7. Which of the following drugs can exert effects on protein synthesis of bacteria?

(a) dibromopropamidine

(b) framycetin

(c) chloramphenicol

(d) All of the above

8. What is the expected time period for half of an antibiotic eye drop to be washed from the ocular surface?

(a) About 5 minutes or less

(b) 20 to 30 minutes

(c) One hour

(d) About 3 hours

9. Which of the following statements about a carbomer-based ophthalmic formulation of fusidic acid antibiotic drug is TRUE?

(a) It is only suitable for patients with dry eyes

(b) It can be used in infants

(c) It ensures rapid wash out of antibiotic from the eye

(d) It provides broad-spectrum coverage against many bacteria

10. Which of the following statements about Pharmacy (P) Medicine eye drops that contain chloramphenicol is TRUE?

(a) They are not recommended for children under 2 years of age

(b) They are generally not recommended for use in children

(c) They should only be used in children after a culture test

(d) They should be used cautiously in the elderly because resistance develops easily

11. Which of the following products can be provided to a patient via a written (signed) order?

(a) chloramphenicol eye ointment

(b) fusidic acid viscous eye drops

(c) Minims Chloramphenicol

(d) All of the above

12. Which of the following drugs works to block DNA synthesis and assembly in bacteria?

(a) fusidic acid

(b) gramicidin

(c) ofloxacin

(d) gentamicin

PLEASE NOTE There is only one correct answer. All CET is now FREE. Enter online. Please complete online by midnight on December 15 2010--You will be unable to submit exams after this date--answers to the module will be published on www.optometry.co.uk

[ILLUSTRATION OMITTED]

Professor Michael J. Doughty, PhD

This article discusses the aetiology and demographics of acute and sub-acute infections of the conjunctiva and peripheral cornea as caused by bacteria, including those associated with contact lens wear. The rather complex legislation relevant to access and use of topical ocular anti-infectives and antibiotics, extending to additional supply (AS) and independent prescriber (IP) levels, will be reviewed. Specific consideration of product ingredients and their expected pharmacokinetics will be covered, leading to an outline of the indicated uses by optometrists including follow-up guidelines.

Professor Doughty has been teaching ocular pharmacology, as well as many aspects of ocular physiology and eye disease, for over 25 years and authored books on the subject. He has held the post of research professor at Glasgow-Caledonian University, Department of Vision Sciences, since 1995.
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Title Annotation:MANAGEMENT OPTIONS FOR UK OPTOMETRISTS PART 5
Publication:Optometry Today
Article Type:Report
Geographic Code:4EUUK
Date:Nov 12, 2010
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Previous Article:Magnification explained: Part 1.
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