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Natasha Mitchell MVB DVOphthal MRCVS Understanding eye medications and discharging the ophthalmic patient Abstract: There are a wide range of ophthalmic medications used in dogs and cats, and there can be confusion about what each product is used for. It is important to stock a range of medications so that the most appropriate one is available when needed. Most ophthalmic preparations are human medications, and therefore a prescription can be supplied if a medication is needed promptly. The following is a discussion of ophthalmic medication available in Ireland along with their uses. Tips are given for discharging the ophthalmic patient after a procedure such as surgery. Topical antibiotics Broadly speaking, topical antibiotics are given for surface eye disease (for example infection of the eyelids, conjunctiva or cornea) whereas systemic antibiotics are given for intraocular or more serious infections (for example uveitis or a deep corneal ulcer). Antibiotics are over-used in veterinary medicine in general, and they should only be given when an infection is suspected or would result in harm. Gentamycin 0.3% eye and ear drops Mainly Gram negative activity Amdipharm Limited Pseudomonas - Melting ulcers? Chloramphenicol 0.5% eye drops Broad spectrum, good corneal penetration Martindale Pharmaceuticals Ltd Good when epithelium intact or deep ulcer Chloramphenicol eye ointment 1% As above Martindale Pharmaceuticals Ltd Avoid ointment with deep ulcers Exocin 0.3% eye drops Broad spectrum but more Gram negative than positive – melting corneal ulcers Allergan Fucithalmic Licensed for cats, dogs and rabbits Dechra Mainly Gram positive, carbomer base Opticlox Licensed for cows, horses (food) and sheep Norbrook Gram positive Topical anti-inflammatories Topical anti-inflammatories can either be steroids or non-steroidal anti-inflammatory agents (NSAIDs). Steroids are contraindicated if there is a corneal ulcer (in other words, if there is fluorescein uptake). NSAIDs are preferred if the patient is diabetic because a small amount of the drug will be absorbed systemically, particularly if the eye is inflamed or immediately following surgery. Steroids can interfere with diabetic control with insulin by altering glucose levels. Systemic steroids or NSAIDs are given for more serious conditions such as uveitis. Topical steroids: Maxidex 0.1% eye drops Superficial ocular inflammation Alcon Anterior uveitis Maxidex 0.1% eye ointment As above Alcon Longer contact time, less frequent application Betnesol eye, ear and nasal drops Superficial ocular inflammation RPH Pharmaceuticals AB Betnesol 0.1% eye ointment As above RPH Pharmaceuticals AB Longer contact time, less frequent application Pred forte 1% eye drop suspension Pannus Allergan Uveitis FML liquifilm 0.1% Superficial ocular inflammation Allergan FML forte liquifilm Increased strength Allergan Anterior uveitis / pannus Combination steroid / antibiotic drops Maxitrol eye drops, Alcon Dexamethasone, Neomycin, Polymyxin B Inflammation plus infection Maxitrol eye ointment, Alcon Dexamethasone, Neomycin, Polymyxin B Betnesol-N eye eye, ear and nasal drops RPH Pharmaceuticals AB Betnesol-N eye ointment UCB Pharma Limited FML / Neo liquifilm 1/5 mg/ml Allergan NSAIDs Acular When topical steroid undesirable e.g. diabetes Ketorolac, Allergan Don’t use with deep or melting ulcer Glaucoma medication Glaucoma is the result of a raised intraocular pressure. It is very painful and leads to irreversible blindness. Blindness can occur very rapidly, and it is important that the owners know that they must religiously apply the medication as directed by the vet. Ideally the pressure-lowering response to the medication should be monitored by tonometry. Trusopt (dorzolamide) Carbonic anhydrase inhibitor MSD and others Reduced production of aqueous humour qid Azopt (brinzolamide) Carbonic anhydrase inhibitor Alcon Reduced production of aqueous humour tid Xalatan 0.005% (latanoprost) Prostaglandin analogue, increased drainage of aqueous, contraindicated if uveitis Pharmacia Ireland Limited and others Travatan 0.004% (travoprost) Alcon Prostaglandin analogue, increased drainage of aqueous, contraindicated if uveitis Timoptal Β-blocker Side effects miosis, local irritation, MSD or Wockhardt UK Ltd bradycardia Cosopt (dorzolamide plus timolol) Not commonly used in small animals Several, including MSD Immunosuppressants Certain immune-mediated ocular conditions respond very well to topical immunosuppression treatment. Examples include dry eye (keratoconjunctivitis sicca), pannus and eosinophilic (or proliferative) keratitis in cats. These drugs are powerful and the owner must not get them on their own skin. At the start they could wear gloves when applying it to ensure they don’t get any on themselves. However, with a little practice, it is usually simple for them to apply. They could wash their hands if not wearing gloves. Optimmune is a long-term medication, and it is common for an animal to need to continue with treatment with life. Sometimes the vet will reduce the dose but may have to increase it again. It is normally started twice daily. The tube is inflated with air so they owner might think that they have been sold a faulty tube, but this is normal. They should be told not to role up the tube (like some people do with tooth-paste) as they go along, as this can crack the tube and result in product loss. Before applying Optimmune, any ocular discharge that is present should be gently cleansed from the eye. If this is not done, the drug is not going to work as effectively. The ointment may be applied to the cornea or to the conjunctiva at the back of the eyelids. A small amount is sufficient, about the length of a rice grain. If I find owners needing more than one tube a month, I usually demonstrate how to apply it to ensure they are not applying too much. Applying an excessive quantity does not improve the eye condition, and therefore it is wasteful. If the owners complain that they squeeze out too much ointment and cannot retract it, I suggest that they store the Optimmune in the fridge. This makes it more difficult to squeeze the tube, and therefore there is more control over what comes out of the nozzle. However in normal circumstances, it is not necessary to store Optimmune in the fridge. The benefits of Optimmune are not immediately apparent. Treatment needs to continue for 4-6 weeks before it achieves maximal effect. If it is being used to treat keratoconjunctivitis sicca, there is no need for the owner to withhold treatment on the morning of a follow-up appointment, as it doesn’t have an immediate effect on the Schirmer tear test result. Optimmune 0.02% Suppresses T-cells; KCS, pannus, Merck Animal Health episcleritis Proliferative eosinophilic keratitis in cats Protopic 0.03% ointment Off-label use, full effects not known, CARE! Astellas Pharma Europe BV KCS when Optimmune not effective Artificial tears There are several types of artificial tears available. Recently, some have been marketed in Ireland for animals. They are usually multi-dose solutions which contain preservatives, but single use vials without preservatives are useful if the pet seems irritated by the medication. Artifical tears may be drops, gel or ointment. Ointment lasts the longest length of time but tends to blur vision, and for this reason is usually used only at bed-time. Gels are very popular, especially carbomer gel. Common trade names in this country include Vidisic and Gel Tears. Drops are uncommonly used as the effect is so short-lived, although drops containing hyaluronic acid do last longer than regular aqueous tear preparations. Carbomer 980 Vidisic / Gel Tears Gel, good contact time, still qid Acetyl cysteine (Ilube) Mucolytic. KCS with much mucous Melting ulcers but stop once melt improves Hylo-Tear 0.1% sodium hyaluronate Single use or multi-use vial URSA Pharm Viscoelastic gel with mucomimetic properties Hylo-Forte 0.2% sodium hyaluronate URSA Pharm Lacrilube Longer contact time but blurs vision At bed-time for KCS Mydriatics Mydriatics are drugs that dilate the pupil. They are used in two situations clinically. During the ocular examination, the short-acting drug tropicamide is applied. This takes 20 minutes to work and lasts on average 6 hours. By dilating the pupil, the vet can examine the lens and fundus much more thoroughly. The second situation is when there is miosis (a constricted pupil) due to uveitis. This may be due to immune-mediated disease or secondary to a corneal ulcer, among many other possible causes. By dilating the pupil, several potentially harmful events are avoided. It stops the edge of the pupil sticking to the lens (called a posterior synechia). If that happens, there might be permanent opacity of the lens capsule as pigment is left behind. The peripheral edge of the iris can also swell and stick to the cornea, and this or posterior synechia can interrupt the normal circulation of aqueous humour within the eye, and that causes glaucoma which leads to irreversible blindness. Another good effect of mydriatics is that they paralyse intraocular muscles which spasm when they are inflamed, and thus they improve the over-all comfort of the eye. Tropicamine is excellent for short-term dilation and is very useful in cats which can resent atropine. Atropine is useful because it lasts much longer and therefore can be applied less frequently. However it dries the ocular surface in some circumstances, and so shouldn’t be used in animals with dry eye. It can raise the intraocular pressure and so is avoided in glaucoma patients. After application, some of the medication runs down the tear duct and into the mouth. It has a bitter taste and some dogs (and many cats) will start to salivate profusely and seem quite irritated for 1-3 minutes. It is important to warn owners about this so that they don’t think that their pet is having a seizure. Tropicamide 0.5% or 1% Single use vial (discard after 24 hours) Minims vials, Chauvin Pharmaceuticals Ltd Short-acting, for diagnosis or treatment Atropine 1% Single use vial (discard after 24 hours) Minims vials, Chauvin Pharmaceuticals Ltd Long-acting, for treatment only Topical anaesthetic agents Topical anesthetic drugs numb the cornea by acting on the sensory nerve endings of the Trigeminal Nerve (Cranial Nerve V). They are available only as Minims vials. Proxymetacaine (also called proparacaine in the USA) is a useful preparation as it is potent and works quickly (within 30 seconds). It sometimes makes the conjunctiva a little red but otherwise it is well tolerated. It must be stored in the fridge. Tetracaine (also called amethocaine in the USA) is also potent and works in 30 seconds, and it doesn’t need to be stored in the fridge. However in general it causes more ocular irritation and occasionally a mild allergic reaction which chemosis. They are used to facilitate diagnostic tests such as tonometry and distinguishing spastic from anatomical entropion. They are also used to facilitate examination of a painful eye. They are epitheliotoxic and therefore will inhibit healing of a corneal ulcer. For this reason, they must never be dispensed to an owner to apply as treatment at home. Proxymetacaine 1% Single use vial (discard after 24 hours) Minims vials, Chauvin Pharmaceuticals Ltd Store in fridge Tetracaine 1% Single use vial (discard after 24 hours) Minims vials, Chauvin Pharmaceuticals Ltd Keep at room temperature Discharging the ophthalmic patient Receiving clear instructions on discharge is a vital component of good post-op recovery and a good surgical result. If there are complicated instructions, it would be very useful to supply them in written form as well as going over them verbally. The vet should have already explained to the owner what was wrong with the eye and the surgical procedure. They will probably be discharged wearing a buster collar, and it is important that the owner understands the importance of leaving this on for the recommended period of time. If the dew claws were bandaged, this should be pointed out (there may also be a bandage on the site where the catheter was placed) and routine advice given about not getting them wet, watching for toe swelling and when to remove them (usually 2-3 days). Medications should be individually and clearly labeled. The owner always asks when they should give the first dose, and this of course depends on what peri-operative injections were given. Owners can find it difficult to apply eye medications and to understand why they are required. It is the role of the veterinary nurse to help explain to the owner the importance of applying the medication as directed by the vets, and to demonstrate to them how they might apply it easily and effectively. The following are a list of instructions that can be explained to or printed out for the owner. HOW DO I APPLY EYE MEDICATIONS? It is important to store eye medications correctly. All need to be stored below 25ºC. Some need to be kept in the fridge (including Chloramphenicol, Xalatan until opened and Serum). The majority need to be discarded 28 days after opening, but some expire sooner. Eye medications may be drops, gels or ointments. Where a combination of these formulations has been dispensed, first apply the drops, then the gel, then the ointment. Gently invert the dropper bottle a couple of times to make the suspension uniform. The animals head should be slightly elevated. This is achieved by placing one hand under the chin. The other hand holds the dropper bottle, and this hand may rest against the animals forehead in order to steady it, and to feel if the animal is going to make a sudden movement. The drop or ointment should be applied to the centre of the cornea (the clear window of the eye). If the drop misses the eye, another attempt can be made straight away. Care should be taken that the nozzle does not come into contact with the cornea. This is to prevent trauma to the eye but also in order to keep the nozzle clean. One drop is all that is required. A strip the size of a rice grain is all that is required when applying ointment. The animal should be allowed to blink, and where possible the head should remain slightly elevated for a few seconds. Where multiple medications are dispensed, allow at least five minutes between each application. It is useful to distract the animal immediately after applying eye medication to stop them from rubbing at the eye. Feeding a meal or a treat, or taking them for a walk may provide a good distraction. Some animals will have a buster (Elizabethan) collar which prevents them from traumatizing the eye. A standard 5ml bottle of eye drops contains approximately 100 drops. By regularly applying eye drops, you get a chance to check the appearence of the eye. If any changes concerns you, please contact your veterinary clinic immediately. When drops are to be given several times a day, it is important that the owner is aware that these need to as spread out as possible – for example, twice daily application means every twelve hours, and four times daily means every 6 hours etc. Do point out that the left eye refers to the animal’s left eye (therefore the right eye as the owner looks at them) as this can often confuse owners and lead to medication being applied to the wrong eye. The owners are encouraged to cleanse the eye and eyelids if there is ocular discharge. They could use previously boiled water soaked into cotton wool and squeezed out. This should be done before applying topical medications. Routine advice is given regarding eating, drinking and toileting on return home after the anaesthetic. A harness is a good idea as it prevents any pressure on the neck. Some harness designs don’t have to be fitted over the head, and these are preferable for dogs that have to wear a buster collar. The owner should be given a time frame for when to expect an improvement. They should be given instructions for when to call – for example if the eye is sore and squinting, or if vision is suddenly lost. Depending on the surgery carried out, of course a small amount of redness or swelling is expected. They should be encouraged to phone if they are in doubt, and a post-op appointment should be made. Many stitches used in ocular surgery are dissolvable and therefore don’t need to be removed, but wound healing still needs to be checked. Further reading: Veterinary Ophthalmology - a manual for nurses and technicians. Sally Turner. 2005. Elsevier. ISBN 0750688416 Chapter 2: Ocular pharmacology and therapeutics BSAVA Manual of Small Animal Ophthalmology. Simon Peterson-Jones and Sheila Crispin 2002. BSAVA. ISBN 0 905214 54 4 Chapter 2: Ophthalmic surgery and anaesthesia Chapter 3: Ophthalmic drugs