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HomemifeatureA Different Set of Eyes: Veterinary Ophthalmology

A Different Set of Eyes: Veterinary Ophthalmology

In humans and animals alike, the eye is a fascinating and complex organ that requires our care and attention. From the nature of disease, diagnosis and management through to the equipment used, the parallels, as well as differences, between human and animal ophthalmology provide medical professionals in the field with great potential to learn and share knowledge.

mivision spoke to Dr Negar Hamzianpour, a Royal College of Veterinary Surgeons (RCVS) Advanced Practitioner in Veterinary Ophthalmology and European College of Veterinary Ophthalmologists (ECVO) Board-eligible Clinician, about the animal eye. Her vast experience provides a valuable insight into the little-known nuances of vet ophthalmology.

Dr Negar Hamzianpour

Australia is home to over 29 million pets – that’s more than the estimated population. Three in five (61%) Australian households have a pet and, with lockdowns leading to a pet ownership boom, this statistic has likely soared since being extrapolated from 2019 data. Interestingly, pet ownership rates are higher in Australia than in any other country in the world.

And that’s only taking into consideration the domestic animal population.

Not only are there more pets in Australia than ever before, the nature of pet ownership has shifted drastically in the last 20 years. Pet owners want, and expect, more for their animals who are considered an important part of the family. It is due to this that the demand for general veterinary care has skyrocketed and with it the evolution of specialist fields such as veterinary ophthalmology.

THE PATH TO SPECIALISING

To put it into perspective, Dr Negar Hamzianpour is one of fewer than 30 veterinary ophthalmologists in Australia. Her path to specialising in ophthalmology began in the United Kingdom with six years in vet school, and another four in general practice, followed by a year-long general rotating internship where her desire to specialise developed. This led her to an ophthalmology internship and a three-year ECVO residency in veterinary ophthalmology, before moving to Sydney in April 2021.

“In general practice your role is hugely varied. One minute you’ll be doing a C-section and the next minute a limb amputation. It requires a wide breadth of knowledge. It was during this time that I realised my need for a deeper understanding and confidence in one subject, and so my urge to specialise developed.

“Chronic medicine and end-of life care of patients was an area of general practice I personally struggled with. It wasn’t uncommon to euthanise a pet daily, or on a really bad day five to six pets. As vets, we’re so used to euthanasia, it’s such an acceptable and common thing,” said Dr Hamzianpour.

According to research by Monash University, the suicide rate among vets is twice as high as it is for other health disciplines – and four times higher than the general population.2 Dr Hamzianpour attributes this not only to the pressures in the profession but the acceptance and day-to- day dealings with euthanasia in order to relieve the suffering in their patients. What attracted Dr Hamzianpour to ophthalmology was the ability to drastically improve the vision of her patients and see positive changes almost instantly, as well as rarely having to deal with end-of-life care.

“Giving animals vision is amazing. Few things will ever compare to the reward of seeing a worried diabetic dog, blinded by cataracts and bumping into walls, waking up following surgery wagging their tail, looking at you and running up to their owner.’’

Dr Hamzianpour currently works at the Eye Clinic for Animals, which undertakes a range of work – from seeing paid clientele in their Artarmon clinic on Sydney’s lower North Shore, to paid and pro-bono work at the RSPCA in Yagoona, South-west Sydney, and working with wildlife at a range of rehabilitation centres and zoos around the country, including Taronga Zoo.

The clinic sees 150 animals a week and operates on around five to eight per day.

“We are booked out for weeks in advance – there’s a huge demand and only a small number of formally trained and fully qualified ophthalmologists.’’

WORKING SIDE BY SIDE

An approach known as One Health has become particularly poignant given the recent COVID outbreak. This is the concept that animal and human health are interdependent and stresses the importance of collaboration between veterinarians and physicians to help solve global health problems.3

Dr Hamzianpour applies this concept to ophthalmology. “Communication between human and veterinary ophthalmologists enables unique knowledge and insights to be shared that can benefit both parties, and ultimately patient outcomes.”

In fact, during Dr Hamzianpour’s training in the United Kingdom, she spent a lot of time with human ophthalmologists – working alongside them, learning from them, and presenting at conferences with them.

“There are human ophthalmologists who come in and spend time with us. These ophthalmologists are helping because they are interested, which is fantastic. The more that our ophthalmology residents from the veterinary side and the medical world communicate, the more we have conversations between groups, the more people learn, and the more ideas come from it.

“That’s where amazing science happens, that’s when we come up with out-of-the-box ideas that we may not have thought about before because we’re talking to someone with a completely different perspective,” said Dr Hamzianpour. Pre-COVID, the lines of communication that existed between the two worlds were strong, and developing further, however due to pandemic-induced restrictions, such communication has been stunted. “Eye Clinic for Animals is the type of practice that would usually welcome any ophthalmologist to come spend the day with us, but COVID’s made that much more difficult. It would be nice, going forward, for that relationship to exist again,” said Dr Hamzianpour.

One example of where human ophthalmologists work alongside Dr Hamzianpour and her team of veterinary ophthalmologists is with retinal surgery.

“We do retinal reattachment surgery and every fortnight a human ophthalmologist (Associate Professor Alex Hunyor) comes in to spend the day with us, providing valuable insights on his experiences. Everything we know about retinal reattachment is extrapolated from humans.”

Interestingly, the Eye Clinic for Animals is the only place in Australia, and one of a handful of centres around the world, that does retinal re-attachment surgery on animals.

EVERYONE’S BEST FRIEND

With 40% of Australian households having at least one pet dog,1 it’s not surprising that they are Dr Hamzianpour’s most common paid clientele.

Dogs present with a range of complications such as corneal issues – dry eye, keratitis, endothelial degeneration; eyelid issues – entropion, ocular exposure, ectopic cilia, distichiasis; cataracts and lens luxations; and retinal detachment.

Dr Hamzianpour says some of the most common problems in dogs are mostly related to conformational issues that arise due to inbreeding and inherited conditions. The ‘designer dog’ trend, which has seen increased popularity in short-nose breeds such as Bulldogs, French Bulldogs and Pugs, has resulted in many issues requiring surgical correction.

“What humans have done is shorten their snout lengths and that, in effect, has shortened their orbits, so their eyes don’t sit properly in their heads and they have huge exposure issues as well as issues with their eyes proptosing – coming out of the socket,” said Dr Hamzianpour.

“Ocular issues also arise because their eyes are too exposed or the hair from the facial folds is rubbing on their eyes. Wrinkly breeds, like Bulldogs, essentially have too much skin. Therefore, a lot of the surgery we do is akin to facelift surgery to correct eyelid conformational issues.”

Cataracts 

“Cataract surgery is really commonplace in veterinary specialty practice, it’s our bread and butter. Cataracts can be multifactorial, including inherited and traumatic cataracts, however, by far the most common cause of cataracts in our canine patients is diabetes. With pet obesity on the rise, it is not surprising that we are seeing more of these cases,” Dr Hamzianpour explains.

“In humans with diabetes, diabetic retinopathy is one of the biggest concerns. Dogs don’t live long enough to experience the impact of retinopathy, however, they do suffer from cataract formation. We know that 80% of diabetic dogs will develop cataracts within 15 months following initial diagnosis, and without surgery these dogs will be blind, or worse still, have painful complications including lens-induced uveitis and glaucoma.”

When it comes to animal eyes, Dr Hamzianpour says the formation of cataracts and cataract surgery is very similar to what it is in humans, however canine eyes, in particular, are far more prone to inflammation.

Additionally, dogs frequently present with very advanced cataracts because, unlike humans who will notice the early stages of cataract development with slight changes in vision, cataracts in dogs only become apparent when their owner notices changes in their behaviour, which typically involves the dogs bumping into things or losing track of their favourite ball.

“The cataracts you operate on in humans in first world countries are very mild in comparison to dogs. Canine cataract surgery is performed on mature to hypermature cataracts, often with lens instability or capsule rupture from intumescence. The dogs are usually completely blind, it’s not a small spot of cataract.

“So often, the human ophthalmologists who come and spend time with us are amazed. They’re like ‘Oh wow! This is the kind of cataracts that you’re operating on in Africa’.

“There are a lot of factors that add to the complexity. Human cataract surgery, for example, is done under local anaesthetic – you go in, you have your cataract surgery, you go home the very same day. In animals we have to completely anaesthetise them. A difficult cataract surgery for us will probably take an hour whereas in humans it can take less than 20 minutes.”

And then there is the myriad of behavioural complexities associated with dealing with non-human patients. Essentially, Dr Hamzianpour likens managing an animal patient to paediatrics. It can, at times, be a challenge to calm an excited dog who is jumping up and down, sneezing into your face and getting distracted, making it very difficult to conduct an ophthalmic exam or administer eye drops. That said, she is often surprised by how well behaved and patient the animals are.

Ascertaining the finer details can be even more difficult – you’re relying on a human to give you the symptoms and describe how the patient is behaving and their level of discomfort, based on observation alone.

Anatomical Variation – The Tapetum

Ever wondered why, if you shine a light in the dark, you’ll see the reflection of an animal’s eyes shining back at you? In the same vein, you may have noticed that this doesn’t happen with humans.

This is because of a unique layer of tissue, present in the eye of many vertebrates, called the tapetum. This enhances scotopic vision by reflecting light back through the retina, increasing the light available to the photoreceptors and thus giving these species superior night vision.

“The human retina is just red, but in most other animals there is a beautiful green or a blue shiny surface that many human ophthalmologists would never have seen,” says Dr Hamzianpour.

“The tapetum can make diseases look more obvious. With degeneration or retinal atrophy in humans it’s harder to spot, whereas in an animal, it’s much more obvious because you’ve got this bright surface looking back at you.”

TREATMENT

One of Dr Hamzianpour’s recent patients is Honey, the nine-year-old beagle of mivision’s Digital Manager Kirsten Black, and much-loved visitor to the mivision office. Overnight, Honey’s inner eyelid became extremely inflamed, prompting a visit to the emergency vet. After seeing three different general practice vets, and being incorrectly diagnosed with conjunctivitis, Honey was recommended to see Dr Hamzianpour who Kirsten said knew straight away what was wrong. Honey was suffering from immunemediated dry eye in addition to a corneal ulcer, the latter being somewhat similar to a recurrent corneal erosion in humans.

Honey before, and after.

Dr Hamzianpour performed a grid keratotomy and placed a Bausch + Lomb contact lens in until it healed. Honey required topical ophthalmic treatment three times a day including chloramphenicol, Hylo-forte and tacrolimus ointment.

“Two to three weeks after visiting Dr Negar, Honey was back to normal again,” said Kirsten. “She said it would be a lifelong treatment for the dry eye and we had to be her tears.”

“For many conditions, medications are the same between humans and animals,” said Dr Hamzianpour. “Dry eye is a good example of where lubricants are very similar across species. A lot of the drugs that we prescribe are human drugs, they can be picked up from the local chemist.”

However, while similarities do exist, there are also huge differences. Topical steroids, for example, are a risk factor for glaucoma in humans, but this isn’t the case in dogs.

“I’ve had clients be very concerned about topical steroids causing glaucoma in their pet dogs, but that just doesn’t happen in dogs. On the other side of things, animal ophthalmologists would recognise topical non-steroidals, like Yellox or Acular, as posing a risk for glaucoma whereas, in humans, they would never worry about that.”

In terms of glaucoma, a lot of the treatment strategies are different to humans. This is because humans present more commonly with open-angle glaucoma, as opposed to mostly dealing with closed-angle glaucoma in animals.

DIFFERENT PATIENTS, SAME EQUIPMENT

Dr Hamzianpour believes there remains a low awareness of the existence of the vet ophthalmology profession among the broader medical profession. This is evidenced by the surprise and interest professionals from other medical fields express when they discover certain similarities, and indeed differences, that present with animal ophthalmology.

Binocular indirect ophthalmoscopy in a dog.

It’s also evidenced by the shock reaction when they walk into a veterinary ophthalmologist’s clinic. With slit lamps, ophthalmoscopes, ultrasound, ultrasound biomicroscopy, optical coherence tomography, electroretinogram, pachymetry and more, it resembles a very well equipped human ophthalmic clinic.

“I’m not sure how many people realise that the equipment that we have is parallel to human equipment,” said Dr Hamzianpour.

“The only difference is that it’s all portable. So, for example, with our slit lamp, we can’t get a dog to put their chin on the chin-rest so we just have a hand-held one. Everything’s hand-held so that we can move with the patient. Similarly, the operating theatre at the Eye Clinic for Animals is fully equipped with operating microscopes, phaco and vitrectomy machines, intraocular lenses and all of the usual disposables.”

THROUGH THE EYES OF HUMAN OPHTHALMOLOGISTS

Simon N Madge, a specialist cataract, refractive and eyelid surgeon in the world of human ophthalmology, spent a lot of time working alongside Dr Hamzianpour in a clinical setting, during her time in the United Kingdom. He was particularly fascinated by the very common genetic problems that certain breeds suffer from, as well as the impressive ability of the vet to manage both anaesthesia and the surgery.

“Rather naively for an ophthalmologist, I hadn’t realised or considered that animals would get the same diseases as humans – a real eye opener for me – and that many of the techniques we use to examine patients are the same for animals, e.g. indirect ophthalmoscopy,” said Dr Madge.

Associate Professor Alex Hunyor, a retinal specialist with expertise in vitreoretinal surgery and macular disease, shares a similar perspective.

“The whole cross-species anatomy/ pathology comparison is totally amazing to human eyeball mechanics like me. It really blows me away how much breadth and depth of knowledge vet ophthalmologists have across so many species – sure, there are plenty of commonalities, but the differences are so fascinating.”

The fundus in various animals. Images courtesy of John Mould BA BVSc DVOphthal ILTM MRCVS, RCVS Specialist in Veterinary Ophthalmology,
Eye Veterinary Clinic, Herefordshire, England.

Assoc/Prof Hunyor works at the Eye Clinic for Animals in Sydney fortnightly. His main experience is with vitreoretinal surgery, but he has also witnessed cataract surgery and a limited amount of corneal and eyelid surgery.

“As far as vitreoretinal surgery goes, the surgical technique can be much the same as in humans with a few minor modifications. Routine use of silicone oil tamponade is required as other options, such as gas, are not feasible the way they are in humans.

“I think most human ophthalmologists would be amazed at the skill of vet ophthalmologists in cataract (and other) surgery, and the fact that intraocular lenses (IOLs) are routinely implanted in dogs and cats, and customised IOLs are available for other species,” he said.

In the five years working alongside vet ophthalmologists, Assoc/Prof Hunyor has been struck by the number of species operated on – from dogs, cats, birds and rabbits, through to koalas, kangaroos and, most recently, a Tasmanian Devil joey.

When it comes to dogs, which are almost exclusively the animals undergoing retinal reattachment surgery, the anatomical and pathological variations span far and wide, providing interesting comparisons with human ophthalmology.

“The cornea, iris, lens and vitreous are fairly comparable overall, however corneal curvature is quite different and therefore, far higher IOL powers are required in dogs. For example, the standard power is 41 dioptres in dogs.”

When it comes to the retina, he notes there are major variations in vascularisation compared with humans and between animal species. There are also similarities and differences with retinal tears and detachments, with giant retinal tears being far more common in dogs.

Despite the complexities, similarities and differences, Dr Madge and Assoc/ Prof Hunyor both commented on how surprisingly cooperative animal patients, particularly small domestics, are to ocular examination – no doubt a testament to the abilities of the vet ophthalmologist caring for them.

A REWARDING PROFESSION

Having found her calling with veterinary ophthalmology, Dr Hamzianpour says the ability to give animals vision is ‘second to none’.

“There is nothing like a dog coming in and bumping into stuff, going in for surgery and waking up able to see again. The ability to massively impact a patient’s quality of life from one surgery, and so quickly, is amazing,” she said.

“The other rewarding thing is that we deal with so many species – anything can walk through our door – so we always have to be thinking.

“If we see a turtle, for example, there’s probably not a lot of information or literature published on turtle eyes – you just have to take the concepts that you know from a familiar species and translate them to other species.”

Veterinary ophthalmology is a continual learning process, rich with rewards for the patients, their owners and the professionals caring for them.

References 

  1. Animal Medicines Australia, Pets in Australia: A national survey of pets and people, 2019 nano.net.au/ userfolders$/office_toma/Downloads/sub122%20-%20 Attachment%201.pdf 
  2. Monash University, Monash University report identifies occupations with greater risk of suicide, 19 October 2020, www.monash.edu/medicine/news/latest/2020-articles/ monash-university-report-identifies-occupations-withgreater- risk-of-suicide 
  3. J. Zinsstag, E. Schelling, D. Waltner-Toews, M. Tanner, From “one medicine” to “one health” and systemic approaches to health and well-being. Preventive Veterinary Medicine, Volume 101, Issues 3–4

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