A Bassett with a bothersome eye

Posted on August 29, 2011 by davidwilliams

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This rather depressed looking twelve year old dog is presented with a red irritated eye. What is your likely diagnosis?

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Well given that its a Bassett with a red painful(ish) eye my mind immediately springs to a diagnosis of glaucoma. But have another look at the redness – tiny vessels diffusely hyperaemic.

In dogs at least, an acutely glaucomatous eye should have engorged episcleral vessels with white sclera between them more like this:

And sure enough while the Bassett with the very red eye immediately above has an intraocular pressure of 45mmHg, the one we started off with only has a pressure of 8mmHg, and it isn’t blind! That makes it more likley to have a uveitis, with the only problem being that it has a dilated pupil while a uveitic eye should have a constricted one. Clearly it hasn’t read the books! We’ve put it on topical steroid drops and will watch and wait to see what happens.

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An owl with unequal pupils

Posted on August 25, 2011 by davidwilliams

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This barn owl has unequal pupils – anisocoria if you want a bit of ancient Greek thrown in for good measure! But how are we to know if its the eye with the small miotic pupil which is abnormal or the one with the large mydriatic pupil?

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Well truth be told bird eyes are a bit different from mammalian ones – their irises consist of striated not smooth muscle and their optic nerves decussate (cross over) completely at the optic chiasm. But those differences don’t change this simple test in cases of anisocoria. What happens when the animal is in the dark?

Sorry the photo is a bit blurred – the camera has difficulty focussing in the dark! But you can see that the anisocoria is less in the dark than it is in the light. So the left pupil which is miotic in the light dilates in the dark showing that this iris and its associated nerve supply is working correctly. It is the right eye where the pupil is not constricting in the light. This may be a defect of iris atrophy in this old bird or an oculomotor nerve defect. As the iris looks normal I’m leaing towards a neurological explanation. You might expect a lateral strabismus in an oculomotor neuropathy, but the owl eye is so tightly packed into the orbit that such a change in globe position will not happen.

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Is there an eye at all?!

Posted on August 22, 2011 by davidwilliams

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This poor little cat came in to us via the RSPCA with no home and apparently no eye either! What has happened here and how would you proceed diagnostically and therapeutically?

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This cat has a severe orbital cellulitis. An ultrasound scan shows the eye to be structurally normal but surrounded by echogenic inflammatory tissue.

The abscess was drained with an incision through the cheek as the mouth could not be opened. Ampicillin and metranidazole antibiotics were given per os to cover both aerobic and anaerobic bacteria  and a non-steroidal anti-inflammatory was also prescribed. A day later the cat is on the road to recovery and while the eye cannot yet see much, at least it can be seen! If anyone wants to give him a home, e-mail me straight away!

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An ophthalmic e-bay purchase!

Posted on August 20, 2011 by davidwilliams

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I love buying stuff on e-bay (try http://www.youtube.com/watch?v=YKtlK7sn0JQ !) but today’s find is perhaps my favourite to date – what it is?

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This is an ophthalmoscope by Andrew Stanford Morton at the turn of the 19th to 20th centuries. In its obituary to him in 1927, the British Journal of Ophthalmology stated:

Well of course current ophthalmoscopes are a darn site easier to use, but a quick look inside the mechanism of this machine of over one hundred years ago shows its intricacy with thirty lenses rotated to give the desired dioptre setting.

This figure is from Casey Albert Wood’s wonderful monograph ‘The Fundus Oculi of Birds as viewd through the ophthalmoscope’ and below is a line drawing from the same volume of Morton’s ophthalmoscope being used to view a bird’s eye.

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A dog with a black blob!

Posted on August 18, 2011 by davidwilliams

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If the last case was a cat with white blobs on its cornea, here is a labrador with a black blob on or in its eye! Again its a case of pattern recognition – so what is the diagnosis and what needs to be done? By the way the owner is worried its a melanoma – can you reassure her or does it need a referral?

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The perfect circular profile of this structure strongly suggests it is an iris cyst – a closer view shows it is somewhat translucent demonstrating it not to be a neoplastic mass. Well truth to tell we should call this a uveal cyst as it arises not from the iris but from the ciliary body. In this black labrador nothing needs to be done but in some other breeds such as the Golden Retriever multiple cysts can be associated with uveitis or glaucoma – or both! If it is likely to be causing a problem the cyst can be removed by flushing it from the eye with a flush of fluid and a small incision in the cornea, or maybe even by lasering it. The intraocular pressure was 13mmHg (15mmHg in the other eye) showing that no such heroics are needed!

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A cat with white blobs on its eye!

Posted on August 15, 2011 by davidwilliams

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Much of ophthalmology is simple pattern recognition. If you’ve seen a cat with these striking white lesions on its cornea before you’ll immediately know what the diagnosis is, and if you haven’t you’ll know after looking at this one! What is the diagnosis?

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There really isn’t anything this could be apart from eosinophilic keratoconjunctivitis, but if one wanted to be sure, a corneal scrape should show eosiphils like this one, although some cases have a more varied inflammatory cell population. The trouble is not so much diagnosis as treatment. Topical steroid may be effective but often oral megoestrol acetate is the best treatment regime, even given the possible side effects of this drug.

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Tawny Owl with apparent cataracts

Posted on June 12, 2011 by richardfrank

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This young tawny owl is able to see but seems to have bilateral cataracts. What would you do to help it?


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In fact these apparently cloudy lenses are completely clear, as examination with distant direct ophthalmoscopy, seen here,demonstrates. Quite why this occurs, as it does in many young owls, is not clear, but the bird needs no treatment, surgical or otherwise.
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Rabbit with odd eye appearance

Posted on May 14, 2011 by richardfrank

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Our first case in this new blog was a guinea pig, so now we’ll move on to a rabbit….this animal doesn’t seem to be in any discomfort but its owner is worried about the appearance of the eye. Are you? What tests might you do to determine what is happening here and what possible differentials might you consider?

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There is a rather florid vascular keratitis here isn’t there – or maybe they are engorged vessels in the iris? In fact the lack of a defined pupil suggests they are in the cornea, but in the eye is a yellowish mass. This is likely to be inflammation and measuring the intraocular pressure showed a hypotony (reduced pressure) signalling intraocular inflammation. It could be a Staphylococcal abscess or Encephalitozoan cuniculi-associated lens-induced uveitis. This latter parasite enters the lens during development, then exits when the rabbit is growing as a young adult and causes a uveitis as it bursts through the lens capsule. This animal was E cuniculi positive on serology so we made that as our tentative diagnosis. Treatment with topical predisolone acetate and fenbendazole by mouth, while not curative, reduced the severity oif the ocular lesions.
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Lack of Effects on Lymphocyte Function of Topical Cyclosporine

Posted on May 7, 2011 by richardfrank

Some years ago research suggested that topical cyclosporine, as used for canine dry eye, resulted in reduced lymphocyte function. Yet the drug has been used for years without immunosuppressive effects. Here we repeated the original work and showed that there is no systemic absorption of topical cyclosporine and hence no generalised immunomodulatory effect…

View the pdf of the paper below:

2010 Lack of effects on lymphocyte function from chronic topical ocular cyclosporine medication: a prospective study


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Congenital ocular abnormalities in farm animals

Posted on May 7, 2011 by richardfrank

Here we review not all congenital abnormalities in farm animals but rather concentrate on a smaller number of conditions in which research on their aetiopathology has been undertaken over the past decade – from cylopia in lambs to anophthalmos in calves…

View the pdf:

file0267.pdf


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