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Keep the atropine within arm’s reach...

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01 January 2013, at 12:00am

JAYNE LAYCOCK reports on the ‘pick of the month’ CPD webinar presented by Pip Boydell, BVetMed, CertVOphthal, MRCVS, of Animal Medical Centre Referral Services in Manchester

DEALING with an ocular emergency in the middle of the night is stressful enough without the added pressure of the patient belonging to your mother-in-law.

Personally, I can’t imagine a worse case scenario, but this is exactly what Pip Boydell, co-founder and senior clinician (neurology and ophthalmology) at Animal Medical Centre Referral Services in Manchester, asked us to assume whilst presenting a number of ophthalmology cases at a recent webinar, entitled Case studies in ophthalmology, organised by The Webinar Vet.

The interactive nature of this session allowed the participating audience, whether in the UK or further afield, to give their opinion on diagnostics and treatment for the various cases he presented.

Cat with corneal perforation

So what would you do with your mother-in-law’s cat presenting in the middle of the night with an obvious corneal perforation?

The majority of attendees responded by suggesting prioritising pain relief and, whilst Mr Boydell agreed this was one important consideration, he was also keen to stretch our line of thought and make us consider the process most likely to make this cat blind: “uveitis”.

He explained that uveitis would need to be treated as a priority, and administering one drop of atropine to this cat’s eye would not only help to alleviate its uveitis but would also relieve pain by relaxing the iris muscle spasm.

Atropine is a drug we should never be without under these circumstances but it can cause, in some cases, quite alarming hypersalivation, and owners should always be made aware of this potential side-effect to prevent any undue concern. 

The use of systemic steroids was also discussed as they play an important role in treating uveitis and should be used as a priority. The use of additional pain relief in the form of opiates was advocated by the speaker, but the use of NSAIDs was not deemed appropriate in this particular case due to the concurrent use of steroids.

Now what would you do? Would you take the cat straight to theatre? According to Mr Boydell, unless there is fluid actively leaking from the anterior chamber or the globe is collapsed, there is usually no need to consider immediate surgery. 

 A successful outcome is more likely to be achieved when a full complement of normal working day staff are present and, in this particular case, a conjunctival flap was performed and the mother-in-law’s cat made a full recovery.

JRT with the blue eye

The next case involved a JRT which presented with a “blue eye”. Initially, mother-in- law described the eye as sore but over time she felt the eye became increasingly comfortable again.

The participating audience made a swift diagnosis of anterior lens luxation based on the pictures presented. So now what? Do we operate to remove the lens straight away even though it is 2am in the morning?

Mr Boydell believes the days of consistently performing lens removal on these cases are over, and although some will still need surgery, the majority can be managed with medical treatment only. By the lens falling anterior to the pupil, the drainage of the aqueous fluid can be obstructed to cause pupillary block glaucoma.

The main aim of treatment in these cases is to prevent this glaucoma from developing and once again atropine plays an important role. By dilating the pupil, the lens is given the opportunity to fall back into position.

Mr Boydell suggested that in some of these cases the lens will just fall into its correct position with no further treatment but in some situations a mannitol infusion may be necessary to reduce the volume of the vitreous body within the eye and encourage movement of the lens. 

Once the lens has fallen back into its correct position, the pupil needs to be constricted using a prostaglandin such as Travoprost. Mr Boydell was keen to stress that although he has been advocating medical treatment for these cases, they will still need very close monitoring over several hours to ensure glaucoma does not develop.

Puppy with a scratched eye

Mr Boydell advised to always encourage patients with ocular problems to be seen, no matter how minor they may seem. Compared to cats, dogs tend to be a lot less tolerant of uveitis and examples were cited demonstrating that, if seen promptly, serious consequences could be avoided.

A puppy that appears, according to the owner, to make a full recovery 24 hours after some form of ocular trauma (often a scratch from the resident cat), is a typical example. If veterinary attention isn’t sought early on in these cases, it is possible that uveitis could be missed and without treatment this puppy may present several days later with a sight- threatening glaucoma. This is a case where a simple drop of atropine given at an appropriate time would have prevented potentially catastrophic consequences.

Cat with a melting ulcer

Nobody wants to see a melting ulcer in a cat, let alone in the middle of the night with a distressed mother-in-law. So what would you do?

Members of the audience were now well-versed with using atropine to treat pain and potentially sight- threatening uveitis and to use opiates for further pain relief.

Topical antibiotics were suggested as an additional treatment and Mr Boydell asked for justification of their use especially when discussions centred on the class of antibiotic to be used.

As the ulcer was melting, pseudomonas was likely to be involved and a simple scrape should be taken so cytology could be performed. If, after cytology, pseudomonas is suspected, the use of either topical gentamycin or enrofloxacin could be justified.

The use of a contact lens was suggested as part of the treatment plan but Mr Boydell was concerned that infection could be retained in situ. If the protective effects of a contact lens were needed, then Mr Boydell suggested using Hyalan drops, a component of joint fluid which has a viscous consistency needed to help protect the eye.

A third eyelid flap was also suggested but again Mr Boydell was concerned that if a third eyelid flap were performed we would be unable to see what was going on and there might be inappropriate forces applied to the weakened cornea that could precipitate perforation.

The administration of plasma topically was discussed and Mr Boydell was positive about its use but his preference is to use acetylcysteine for its superior anti-collagenase properties. In the first 2-3 hours he would administer acetylcysteine drops every 5-10 minutes in an attempt to remove collagenases causing the corneal damage.

There was some debate as to whether steroids were an appropriate drug of choice under these circumstances. Mr Boydell pointed out that he would rarely use topical steroids in an ulcerated eye but would almost always use systemic steroids if a uveitis was present.

In this particular case, he eventually went on to perform a keratectomy followed by a large conjunctival graft.

Mr Boydell discussed a number of other cases including a cat with a proptosed eye and a dog with a somewhat surprising diagnosis. To find out more you will need to log into The Webinar Vet website and I highly recommend taking an hour of your time to listen to all the cases.

There does, however, appear to be one key message running through a significant portion of this webinar. If you do happen to encounter your mother-in-law in the middle of the night with an ocular emergency, in a significant number of cases atropine should never be more than an arm’s reach away.