Ординатура / Офтальмология / Английские материалы / The Ophthalmic Study Guide for Nurses and Health Professionals_Field_2009

The ophthalmic study guide

SELF TEST answers on page 203

1.What four transparent areas within the eyeball are responsible for refracting light within the eye?

2.Focusing the eyes requires three processes. What are they?

3.Emmetropia is another name for what?

4.What are the medical terms for long sight and short sight, respectively?

5.Sometimes the corneal curvature is slightly irregular. What is this called?

6.What is the medical term for double vision?

7.Is a mydriatic refraction an objective or subjective refraction?

8.What is the name given to a simple plus or minus lens?

9.What is a cylinder (cyl.) used to correct?

10.What word beginning with ‘p’ might be something that is used in spectacles to correct a

mild squint?

11. What is a ‘reading addition’ used for?

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Chapter 4

Basic pharmacology

Julie Tillotson and Dorothy Field

Drugs for the management of ophthalmic conditions are available in the form of eye-drops, ointment and oral preparations. Eye-drops and ointment are both absorbed into the systemic circulation and should therefore be given the same respect and consideration as any other drug. For this reason it is important that nurses new to ophthalmology should have a good working knowledge of all the drugs commonly used, as well as their effects, their side effects, contraindications and possible interactions with other drugs.

Most hospital Trusts have access to an online version of the British National Formulary through the hospital’s intranet and pharmacy department sites. Alternatively you can go to the British National Formulary Online and register for personal access. The Electronic Medicines Compendium is another useful website for accessing drug information, which gives a summary of product characteristics (SPC) and the patient information leaflet (PIL) for each drug.

Eye-drops – the potential dangers of systemic absorption

In 1994 a report by Urtti et al. reminded medical professionals that eye-drops might be absorbed systemically and in sufficient amounts to cause potentially hazardous effects. Cautions continue to be issued, particularly regarding the use of eye-drops in babies and children

See the Neonatal Formulary 5 website.

The problem arises because many drugs (like phenylephrine) are absorbed directly into the bloodstream via the blood vessels of the conjunctiva and the mucosa of the nasolacrimal duct. Consider the example of glyceryl trinitrate medications, which are absorbed systemically via the mouth. Drugs that are given orally are often coated in order to delay absorption, and are extensively metabolised by the digestive tract and liver. Phenylephrine in the eye-drop formulation is particularly hazardous in very young babies and children and some older people because it is absorbed via the conjunctival blood vessels without prior mediation by the liver.

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The ophthalmic study guide

Allergies

Always remember to document all your patient’s allergies because some eye ointments (e.g. chloramphenicol) have a lanolin (wool fat) base. Some people are quite allergic to this substance.

The British National Formulary does not state the carrier base for ophthalmic ointments, so you need to look in the patient information leaflets to be sure if it contains lanolin or not.

Do advise parents that eye-drops should not be used for more than 4 weeks after first opening because of the risk of inadvertent contamination of the contents. Most eye-drops, except minims, contain preservatives to inhibit the growth of micro-organisms within the bottle. Some eye lubricants are now available preservative-free in bottles with 3-month disposal dates. The preservatives used are generally either benzalkonium chloride or thiomersal, but unfortunately some patients develop allergies to them, particularly in patients with very dry eyes who have been using a lot of eye-drops over a long period of time. Preservatives are absorbed by soft contact lenses. The soft lenses may, as a result, become toxic to the eye after a period of time. Therefore contact-lens wearers should be advised to wear spectacles for the duration of their eye-drop treatment. People wearing ‘bandage contact lenses’ should be issued with preservative-free eye-drops.

Minim is a word used to describe a tiny container of preservative-free eye-drops intended for a single use. If, for example, a soft contact lens wearer required these drops for use at home, the hospital pharmacy would commonly issue one minim per day; therefore these drops must be stored carefully between uses in the refrigerator, and discarded at the end of the day.

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Basic pharmacology

SELF-LEARNING

The following ‘self-learning’ section involves you in researching your own answers to the questions posed. Use the British National Formulary online at work to get your basic information, and make some brief but relevant notes for yourself on the following questions. You can ask colleagues to help you with some of the more difficult ones, but do try to answer them all, even if it takes some time. When you have finished the work for this chapter, make it a habit to thoroughly check into each ‘new’ ophthalmic preparation you encounter professionally. As you mature in ophthalmic nursing practice, you might also check to see if your hospital library has a copy of Bartlett and Jaanus (2007).

To do …

You may prefer to use your folder as well as, or instead of, this workbook for this section. Phenylephrine eye-drops

●What strengths is phenylephrine available in? Why?

●Is phenylephrine a mydriatic or a cycloplegic drug and what is the difference? How does it work, and on which iris muscle?

● What do you need to think about if asked to use phenylephrine in a child? Check your answers with a pharmacist, an ophthalmologist and an ophthalmic nurse to get a grip on this important issue.

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● What are the cautions required regarding the use of phenylephrine in adults?

● On discharge, what advice would you give to adult patients about the side effects they may experience?

Cyclopentolate eye-drops

●Does cyclopentolate have another name?

●What strength is cyclopentolate available in, and why?

●Is it a mydriatic or a cycloplegic and what is the difference?

●How does it work, and on which iris muscle?

●Can it be used for babies and children?

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Basic pharmacology

●Are there any potential drug interactions?

●Does cyclopentolate have any side effects?

●What advice would you give to patients on the side effects?

Pilocarpine eye-drops

●What strengths is pilocarpine available in?

●What does a miotic drug do?

●How does it work, and on which iris muscle?

●Can it be used for babies and children?

●Are there any potential drug interactions?

●Does pilocarpine have any side effects?

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The ophthalmic study guide

● What is pilocarpine used for these days?

Latanoprost eye-drops

● Does latanoprost have another name?

What eye problem is latanoprost used to treat?

●What group of drugs does latanoprost belong to?

●How does it reduce the intraocular pressure? Relate this knowledge to what you have learned about aqueous drainage in Chapter 2.

●Are there any potential drug interactions?

●Does latanoprost have any side effects?

●What advice would you give to a patient about the side effects?

Acetazolamide injection and tablets

● What is acetazolamide used for in ophthalmology?

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Basic pharmacology

●What is the other name for this drug?

●Which area of the eye does it act on?

●Does it have any side effects?

●How would you advise a patient on the side effects?

●Are there any potential drug interactions?

●What is the normal oral dose?

●What is the normal intravenous dose?

●What is the maximum dose of acetazolamide that can be given in 24 hours?

●Why is it unsuitable for long-term use?

●If used in the longer term, what must be monitored?

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The ophthalmic study guide

Iodipine eye-drops

●What is iodipine used for in ophthalmology?

●What is its other name?

●Which area of the eye does it act on?

●Are there any cautions regarding driving?

●How would you advise a patient on these?

●Are there any potential drug interactions?

Oxybuprocaine eye-drops

●Does oxybuprocaine have another name?

●What is oxybuprocaine used for?

●How long does it act for?

●How would you advise a patient whose eye has been instilled with oxybuprocaine?

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Basic pharmacology

Tetracaine eye-drops

●Does tetracaine have another name?

●What is it used for?

●How long does it act for?

●How would you advise a patient when tetracaine has been used in their eye?

Timolol eye-drops

●Are timolol drops sometimes known by another name?

●What eye problem is timolol used to treat?

●What group of drugs does timolol belong to?

●How does it reduce the intraocular pressure?

●Are there any potential drug interactions?

●Does timolol have any side effects and how important is the person’s health history?

●Why are people on timolol eye-drops advised to compress their tear ducts following administration?

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