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One of a veterinary technician’s jobs is to obtain a thorough history and help describe a pet’s problem to the veterinarian. When I first started working for a veterinary ophthalmologist, I was surprised to learn that in many instances, I barely knew how to describe what I was looking at. Sure, I knew what a cornea, pupil, and retina were, but I soon discovered that describing abnormal eye anatomy to an ophthalmology specialist was a different ballgame. Not only was I not familiar with specific ocular terminology, but I had to learn how to use a handheld microscope while trying to focus on the eye of a head-bobbing critter. Of course, a veterinary ophthalmologist sees anything but normal eyes, and I was soon going cross-eyed myself looking through a slit lamp at pigmented corneas, descemetocele fluorescein stains, and floating uveal cysts. Eventually, I learned enough of the ophthalmology lingo to at least be able to describe to the ophthalmologist where the abnormality was located in the eye (hey! It’s not as simple as it sounds!).

This may come as a surprise to you, but pets cannot read an eyechart. They cannot tell us whether “1 or 2” is more in focus for them. Combine this with the fact that many veterinarians learn very little about ophthalmology in veterinary school and that specific eye abnormalities can be hard to visualize without special microscope lamps, head sets, and lenses, and you see why eyeballs can be a mystery to even those in the veterinary field. This is where a vet tech’s history taking and preliminary examination skills can be of great use, especially if you are referring to or working for an ophthalmology specialist. In this post, I have listed some examples of important questions to ask while taking a history of a potential ophthalmology patient.


Has there been a change in the appearance of the eye(s)?

  • Is the eye continually squinted shut or does the animal squint periodically? Does squinting seem to be due to a specific trigger like being outside, a change in seasons, or a period of stress for the animal?
  • Is there increased ocular discharge? “Increased” is the key word here. Try to differentiate between abnormal discharge and the normal tearing that some breeds are prone to. The type of discharge can be important as well. Is it thick and green or white, or is it clear and watery?
  • Is there cloudiness in one or both eye(s)? Does the cloudiness come and go or does it stay consistently cloudy? Is the surface (cornea) of the eye cloudy? Or is the cloudiness within the eye? Is the cloudiness in front of or behind the pupil? Now I know you are probably thinking that these last few questions are very specific. Indeed they are, and most of the time owners will not be able to distinguish where exactly the cloudiness is. However, it is important for vet techs to know that saying “the eye is cloudy”, especially when speaking to an ophthalmology specialist, could point to a variety of different ocular problems, and that narrowing down the location of the cloudiness can significantly help the veterinarian later on in the exam. Also, some owners are very observant (especially if their pets are established ophthalmology patients with long term eye issues), and this knowledge can be especially helpful if the owner is trying to describe the problem to you over the phone.
  • Is there redness? Again, location of the redness is helpful. Is the redness located on the whites of the eyes or the conjunctiva? Is it located on the cornea or within the eye? Does the redness come and go, or has the eye stayed consistently red?
  • Is there a change in the size of either or both eyes? If there appears to be a change in size, or bulging of the eye(s), is it accompanied with cloudiness or vision loss? Does the size of the eye fluctuate? Or has it enlarged and stayed the same? Keep in mind, that sometimes what looks like a change in the size of the eye can be somewhat of an optical illusion. Patients that have had one eye removed can sometimes look like their remaining eye is bigger than normal. Sometimes fixed and dilated pupils can make the eye look “bigger”, especially if it occurs in one eye and not the other. And of course there are the beloved brachycephalic breeds who have normal bulging eyes by design. However, true bulging eyes (called buphthalmia) do occur and are associated with blindness  and painful glaucoma.

Jessica Animal-eyes-fig

When did the problem start?

  • Has the patient had this problem since it was a puppy/kitten? Or did it develop later in life?
  • Is it a recurring problem? Does it manifest during certain seasons or in certain environments? Does it manifest in times of stress?

Are there any systemic signs?

  • Polyuria(PU)/Polydipsia(PD): Is the patient constantly drinking water like it can’t get enough (polydipsia) and then urinating either more frequently (pollakiuria) or in greater volume (polyuria)? Some systemic diseases, such as Diabetes Mellitus, can cause ocular changes. There is even a retinal disease that presents with Cushing’s symptoms even though the patient has normal bloodwork (I bestow major street cred to anyone who can list this disease in the comments section below). Ruling out this ocular disease is important since treating for Cushing’s in this case is contraindicated and may make the patient Addisonian.
  • Is the patient’s activity level normal? Is there any lethargy? Normal appetite? Some ocular problems manifest in the face of infectious diseases or cancer that can first present with generalized lethargy or decreased appetite. Also keep in mind that glaucoma (increased intraocular pressure) does not generally appear as “eye pain”. In other words, with glaucoma, an animal usually does not squint, rub, or act like the eyes specifically are bothering them. Humans suffering from from glaucoma describe it instead as a headache or migraine type pain. This type of generalized headache pain can be hard for owners to notice in their pets especially for very stoic animals and especially in cats. Nevertheless, the owner may notice that their pet may not be as active or want to eat normally if they have significant pain from glaucoma. This can also be an especially important piece of information if the hospital does not have access to a tonometer which measures the intraocular pressure within the eye.

Are there vision deficits?

  • Was vision loss sudden and complete? Answers to this question can help rule out certain retinal diseases or lens abnormalities.
  • Or did the patient’s vision gradually deteriorate over time? Patients that all of a sudden lose complete vision will be a lot more obvious to owners than patients who lose vision over a long period of time. Dogs and especially cats can adapt quite well to vision loss especially if it is a gradual process. Some owners may not even realize that their pet is blind, especially if only 1 one eye is affected. Follow up questions for vision deficits include:
  • Are they bumping into things in the house? Do they bump into things on one particular side? Again, dogs and cats adapt quite well to vision loss and can quickly memorize the layout of a consistent environment. Therefore, asking if the patient has trouble navigating new or changed environments can be helpful.
  • Does the patient seem to have better vision in dim light or in well lit conditions? Some of the most common retinal disease start with dim light vision deficits and then progress to complete vision loss.

What medications is the patient taking?

  • As for any patient, get a complete medication history from the owner. Be aware that overdoses of certain drugs such as Ivermectin have been linked to acute blindness in dogs, so ask the owner if their pet has had exposure to these medications and at what dose, if known.
  • If the patient is already receiving ophthalmic medications, when did the patient received its last dose? Many topical medications for dry eye and glaucoma are only effective for a certain length of time and are supposed to be given multiple times a day. These conditions require regular monitoring of tear production or intraocular pressure, and when retesting these values, it helps the ophthalmologist or primary veterinarian interpret the values if they know when the last dose of the medication was given.



Photo credit for animal eyechart: http://batpigandme.com/2012/09/26/animal-eye-charts-by-local-paper-studio/