So as we look forward to a winter season ahead (more tame than last?), I thought I would talk a bit about what dogs see when they look ahead. We commonly get the “are dogs color blind?” question and occasionally deal with visual acuity issues, so a little education on the subject seemed timely.

VISION IN THE DOG

When we talk about vision in any animal, the first thought that needs to come to mind is “what does this animal do?”. In fact, just about every adaption within a species is there to facillitate it to do its job. I took a course at UC Davis when I was an undergrad called The Functional Anatomy of Vertebrate Structure. Within that course, we examined primarily the bone structure of different animals to see how it helped them fly, dig, swing or swim, for example. Adaptations such as hollow bones in birds to decrease their weight to help them fly or large flat bones to increase the surface area of the feet of turtles for pushing water were some of the many differences that we investigated. The same goes for the eye. Some animals hunt in the dark, others have to adapt to both a water and air environment, some must be able to focus accurately and quickly as they move through a complex environment. And yet the basic anatomy of the eye is same. A dog’s vision is different than ours because dogs are built to perform different tasks from a different perspective for a different reason. A fascinating book by a fellow named Walls called the Vertebrate Eye and its Adaptive Radiation gives his view on the subject of anatomical adaptations from an ocular standpoint. Let’s look at some of these variations that make the dog’s vision different than ours.

Perspective is a good place to start. We perceive our world from on average 5-6 feet above the ground. Some small dogs may be inches above ground and others are up to waist-high level for some big dogs. Think of your children walking through a crowded event with their noses in the backs of the adults also in line. Many dogs will be in a similar line of sight when the grass is high and they are running through a field. Or how about the Shih Tzu or Sheepdog with the long haircut covering their eyes? Not only are they operating from a low vantage point, they have a curtain of thick hair to peer through. The following three pictures are taken from the exact same location just different heights off the ground to give you an idea of what your dog may be seeing. Take into consideration this does not reflect total field of view, focus or color, just the forward perspective!

Small dog perspective

Medium-sized dog perspective

Average human view

Field of view and a feature called binocular overlap become important. The more forward your eyes are placed on your skull equates to better stereo vision and depth perception but you see a smaller amount of space around you. Predators commonly have more forwardly placed eyes so they can focus accurately on their prey when attacking. Prey, on the other hand, often have eyes placed more on the sides of their head, like a rabbit for example, so that they can see the predator sneaking up behind them. Their only defense is often to run early before the strike if they can detect the stalking prey. Dogs have forward placed eyes that give them a visual field in front of them that is approximately 240 degrees wide with 60 degrees of binocular overlap. Humans, for comparison, have a smaller visual field of 200 degrees but 140 degrees of binocular overlap since our eyes are more forwardly placed.

Visual acuity and color vision are features that are commonly assessed in people and thus our curiosity leads us to question if they are similar in our pets. It is difficult to determine these values in non-verbal patients, but there are many tests to evaluate how well an eye focuses and processes light. Simply put, the ability of the lens to focus light on the retina and the retina’s sensitivity to this stimulus create acuity.

Different species have various ranges of accomodation, meaning whether they can focus on something in the distance as well as focus on something close by without aid. The lens can change shape via muscles and their attachments to the lens which allows it to focus. Some species may even move the lens backwards or forwards to acheive the same goal. Think of a nice camera where we twist the lens to focus the image in the viewfinder. We are changing the distance from the lens to the film until the image is sharp. Our lens does the same thing as we try to read a book. We may be able to relate to the need for reading glasses as we age which relates to stiffening of our lens and its inability now to change shape enough to focus clearly on the film, our retina. Different species can change the shape of their lens to different degrees base on their environment and needs. In addition, the resting shape of the lens varies from completely round (fish) to more oval (humans) or even bell-shaped (some owls) depending on the environment in which they live. Dogs have a more oval lens like us but less ability to change its shape and thus have a smaller range of accomodation.

The retina plays a role in image quality as well with the number, type and density of the rods and cones accounting for its function. This is a very complex area that is difficult to summarize, but dogs have a rod-rich retina which makes them better for seeing in low light and for movement. The cones are better for color vision and acuity. We have a cone-rich retina with a macula, an area with a high density of cones that is the “sweet spot” of our vision. Dogs don’t have a macula but rather a strip of retinal tissue that is more cone dense than the surrounding region but not as dense as a macula. In addition, dogs have a tapetum which is a reflective layer that helps amplify light which is another mechanism in addition to the rods to help them see when the lights are dim. Color vision is not too helpful for them for hunting and finding a mate, like in birds for example, so they are a little red-green color blind but still see a yellow-blue spectrum. I guess if dogs were more brightly colored and ate pretty flowers for dinner, their retinas may have evolved to differentiate those colors as well. But a brown dog looking for a brown meal or mate doesn’t really need good color vision to survive and thus genetics have moved them another direction. All things considered, dogs are best corrected at 20/80 meaning what we see clearly at 80 feet, they need it to be 20 feet away from them to be in clear focus. Glasses won’t improve this since the limitation is at the level of the retina, not the lens.

I could go on and on about species differences in vision but I think you get the idea. Our sensual world is different than a dog’s but we both do fine with our limitations and our specializations. Wouldn’t it be cool to experience their world for a day? I wonder what we would see, hear and smell then?

Sassie and Dr. Stuhr

It has been a decade since I became the sole owner of the Animal Eye Clinic in Wilton and it stuns me to think of all that has happened over that time. When Dr. David Covitz gave me the keys and I promptly found the basement in the old clinic had flooded the next morning, it hit me right between the eyes that this was now my baby to care for and shape into the practice I wanted it to be. Ten years later, I can gladly say that the journey so far has been a pleasure and that I am happy and proud of what my business here represents to those who use our service.

From the get go, our mission has been to create a warm and friendly atmosphere where our professionalism and expertise creates an atmosphere where you as the client and your pet feel comfortable and reassured that you are in good hands. Our new location (since January 2010) is perfect as we renovated a beautiful house on a hillside property right on Route 7 to accomodate our needs as an out-patient facility. It is bright and cheery, clean with spacious exam rooms to allow examination of all your pets, big and small. My experience is that without the stress, odor and tension of a multispeciality hospital or general practice, most pets here are very comfortable and allow examinations more readily than in those other environments. We hope you will share that feeling.

But the variable that makes us shine is the personality of the staff that supports my philosophy of excellent care in a nurturing environment. My office manager, LisaMarie, technicians Chris and Christina, and receptionists Suzanne and Katie define our excellence by taking care of each individual with great pride and compassion. We take the approach that if we give you the time to learn, make educated decisions and trust the people that are handling your pets, you will be able to make a better and more confident decision than when given the facts alone in a more hectic and less friendly environment. I hire staff based on their skills in handling these situations and insure that we are a cohesive group when it comes to your pet’s care. As a single doctor practice, I rely on my staff to make many phone calls to doctors and clients to pass along information promptly. I trust my staff implicitly in this facet and they have rewarded me with their loyalty of many years devotion to this business. I could not operate without them!

I approach each client in a personal fashion, presenting the the information in the best way I feel gives you the facts in a clear and concise manner. If you need your hand held, we’ll hold it. If you are busy and need to cut to the chase, I do. And if we can’t fit you in but we can schedule a drop off and you accept a phone call with the information later, that can work for us too. We won’t skip the details to lessen the time, just have to make the time to get the information to you from me or my staff. And if we don’t have time to do the best job we can, unfortunately we might have to talk with your veterinarian on the phone and/or potentially recommend you go elsewhere to those with a different philosophy.

The Animal Eye Clinic continues to evolve over time, both in our services and our expertise. I continue to attend meetings and purchase equipment to keep our skills current. The American College of Veterinary Ophthalmologists (www.ACVO.org) is our core governing body that organizes these meetings and other continuing education seminars. It plans the annual Service Dog Month and has developed a list serve that the diplomates of the college can share to ask questions of each other about difficult cases. I continue to educate as well, speaking to local veterinary associations like in Hudson Valley this month and Fairfield County next month. All in all, we hope that if you use our service, you and your pet will be comfortable, confident and happy with the experience here in Wilton.

Left me wax poetic a bit about these issues as it relates to ophthalmology. First, there are very few medications that are veterinary only. Many of the drugs we use are used in the human population for similar or different disease states. However, different species have different responses and tolerances to the same drug. In the realm of side effects, it is the FDAs job to report all the concerns that may have been noted during the research and development stage of a given drug. If you read the package insert of just about any drug, you would probably not use it! Certainly, safety is important, but one must recall that warnings are placed to show the exceptions as well as the common. And human responses to topical eye medications may not develop in our pets as the life span of our pets may not be long enough to accumulate drug to then result in an unwanted reaction. The point here it, don’t read the drug inserts too critically or at all as the concerns stated may not apply to your dog or cat! Certainly educate yourself but ask questions before stopping a drug because the insert says the drug causes glaucoma and we are using it in your dog that has it!

Drug availabilty and purchase, especially with online pharmacies, has become a big issue in medicine. Many people are trying to access drug to save money by going through these services. A point to note is that what you are getting may not necessarily be the drug in the concentration, sterility and stability that you may get from a known pharmacy or your veterinarian. There are stories out there of people buying drug online only to get pills in almost identical packages that are only placebo and not the real drug. We have had clients that have purchased compounded medications from companies outside the US only to find increased irritation with application or a loss of control that we attribute to the quality of the drug given. I am sure there are some legit services out there but the point is that it is difficult to tell. Is it worth saving a few bucks or delaying treatment when you can access the drug in a trusted form and start immediately? Ease of access, prompt treatment and a drug that is known and supported by your doctor may be worth the additional fee it costs for us to carry it on our shelves.

Compounded drugs are commonly used in veterinary medicine since these same products for use in animals may not be easily accessed in a human form, is not utilized in human medicine or has been replaced by a newer and potentially more costly medication. Different that you and I that may have insurance or a copay to cover a pricey drug, we as veterinarians and you as owners must balance the cost of care with our drug choices. Compounding pharmacies have strict guidelines as to how to create these formulations or change a pill to a liquid, for example, of a drug that may be more easily delivered to your pet. We have a great relationship with a compounding pharmacy in the Carolinas who has been doing this for a long time. There are other reputable companines and we are hopeful that they practice the same diligence to get drug to you in a safe and accurate formulation. These drugs often require shipping to you directly which creates a lag in treatment but is usually necessary as there may not be an alternative on the shelf that can be purchased.

We all understand that the cost of health care is going up all over. I honestly understand the pricing of medicine as good as I understand the price of an airline ticket. The guy sitting next to you may have paid half of what you did for the same flight because he got it on a different day from a different vendor. The same is true for drugs and we hope to guide you in the right direction with good choices that are cost-effective that can be given at manageable frequencies to solve the problem!

As the Spring season begins, a new set of ocular symptoms appear to arise along with the emergence of the bulbs. One would not necessarily think of disease as cyclical, but we all see different ailments at different times of the year. Or maybe just more of some at different times since most diseases are not restricted by time. But before we go there, a different seasonal reminder first.

The 4th Annual Nation Service Dog Eye Exam Month

For the fourth consecutive year, Merial and the American College of Veterinary Ophthalmologists have combined to provide free eye exams for any dog officially performing a service function. Whether you are the Dalmation on the fire engine, a Guiding Eye dog or drug sniffing for Homeland Security, you are entitled to a free ocular exam by a participating ACVO diplomate during the month of May. We have participated each and every year and are happy to examine your friend once you have registered through the appropriate website provided. We have made space available on Thursday afternoons throughout the month of May for this purpose. If you and your dog fulfill the criteria, go to ACVO website (www.ACVO.org) for the link to the official registration site and then call our office to set up your free exam! Additional details are provided on the website and at the Helpful Resources tab on this website. Hope to see you soon!

Conjunctivitis

Seasonal conjunctivitis is very common around this time of year and in the fall. Most of these allergies are probably related to aerosol bourne antigens related to all the blooming plants and grasses. However, many things can create allergic responses. Most dermatologists won’t commit to an allergy diagnosis before 2 years of age in a dog, however, some reactions are seen. In addition, small lymph node-like structures called follicles will become elevated and irritated as a non-specific response to low-grade, chronic irritation. We see this response in our allergic dogs, those running through the fields like the hunting breeds, secondary to diseases like dry eye, and also in youngsters as a presumed maturation issue. All of these entities present with a history of discharge as well as redness.

If discharge is grey-white, it is usually mucus indicating irritation and inflammation. Clear tear may be present of the only type of discharge in this situation as well. If it is yellow green, this suggests bacterial infection. Brown discharge is not specific for any condition and is usually related to a pigment called porphyrin that is in the tears. This is responsible for the tear staining you may see in the corner of white-haired dogs that are tearing. Treatment therefore depends on whether the problem is inflammatory, infectious or irritative in nature. Also, local problems such as ear and teeth infections can contribute to discharge and, once treated, may resolve or diminish the discharge. The upshot….an examination is warranted to help with diagosis and drug selection.

Traumatic corneal injuries

With the weather changing, our dogs are relieving their cabin fever by racing outside and sticking their faces in bushes in search of balls, squirrels and other interesting things. This indiscriminate placement of the eye in imminent danger leads to numerous traumatic injuries that may warrant our service. Corneal lacerations, foreign bodies, simple erosions and deep melting ulcers seem to spike in the spring due to this increase in activity.

Foreign Bodies

Foreign bodies can be anything that sticks to the cornea and can be a small plant seed hull to a thorn in the eye. The depth of penetration is what dictates what can be done and the prognosis after recovery. I have numerous pictures that can be unsavory of the many things that get stuck or poked into the eye. To keep things “G rated”, a small plant object is shown. This type may be flushed out or removed with a topical anesthetic. Others that may penetrate into the eye may cause the eye to leak once removed and are removed under a general anesthetic. If leakage is noted, closure or grafting could then be safely performed.

Superficial corneal foreign body

Corneal lacerations

Corneal lacerations are seen most commonly in puppy versus cat altercations, however, any sharp object or tree limb can do it. These lesions are typically linear. Depending on the angle of entry, they may be straight and even or have a flap of tissue. Again, depending on the depth and angle, these may resolve with just medical treatment like a simple scratch wound or necessitate suturing if deep and/or long. If penetration into the eye has occurred, the prognosis depends on whether the intraocular structures have been involved and if bacteria have become transfered into the eye.

Corneal erosions

The cornea can get scratched in numerous ways but what makes the difference in healing is whether infection is present. A garden variety corneal ulceration will heal from side-to-side in a few days in the presence of prophylactic topical antibiotic, an Elizabethan collar and dilating agents if needed for discomfort. If the corneal becomes inoculated with bacteria, some nasty types will produce enzymes that digest the cornea. Depending on the severity of the bug, a hole can develop in 1-2 days that can rupture the cornea. Others may digest the tissue more slowly and the ulcer will appear more sloping than cookie-cutter in appearance. Aggressive medical and surgical therapy is required in these cases with surgery typically suggested if the depth is greater than 50% in an active ulcer. Marked discomfort and yellow-green discharge are usually noted in these cases. We may talk about surgical treatment and the postoperative appearance later, but here is an example of a typical “melting” corneal ulcer.

Deep ulcer with inflammation

All for now….see you soon, and don’t forget to get your Service Dog examined!

Ok, enough already! I get it, we live here for a reason, get to enjoy all the seasons and the diversity they bring to our lives. I like to ski, go sledding with my kids, build the occasional snowman. I have lived in more temporate and more severe climates so I have a nice barometer on weather variation and I do love the activities that each season allows. But I think we all agree….enough of the white stuff already! We have got nowhere to put it!

In all seriousness, we are trying our best, like most businesses, to keep ourselves open and available through all the inclement weather while trying to keep you, your pets and ourselves safe on the roads coming and going to the clinic. We have bulldozed as much snow as we can to keep the parking lot safe only to have the recent ice put a nice layer over the top of what remains. So be careful as we sand and salt and take your time if you are coming in to see us. Everyone has been very patient being seen earlier or later than their scheduled appointment times as scheduling itself is a challenge. We will try our best to be here and ready for you!

A number of different ocular diseases will present with a “white spot on the eye” with or without associated redness, irritation or discharge. Since there is some much white on the ground, let’s talk about what can be white on your pet’s eye.

Corneal Dystrophy

A corneal dystrophy by definition is a deposit of lipid on or in the cornea that is usually bilateral (both eyes), symmetrical, non-inflammatory, unassociated with systemic disease and genetic in basis. We see this on a regular basis and is the most common diagnosis associated with the “white spot on the eye” complaint. There are a number of different breeds that develop this abnormality that have some science to support that it is genetic in basis and I am sure there are others where we presume this is the case by the appearance. Common breeds noted in this practice include the Cavalier King Charles Spaniel, Golden Retriever, Husky, Cocker Spaniel and many others. If we rule out any other reason for cholesterol deposition on the cornea, we default to this diagnosis based on appearance and history. Typically, dystrophic areas may get bigger or more dense, can occasionally fade, and usually create no observable vision compromise to the dog. All in all, this is not a serious issue for your dog. A typical appearance would be like this:

Cornea dystrophy in a 3 year old German Shepherd

Corneal Degeneration

Lipid and mineral can be deposited into the cornea as a response to local irritation, old aging change, post-inflammatory change, secondary to elevation of blood fats and other entities that change the metabolism of the corneal tissue. This may occur in either or both eyes and may or may not have a vascular response associated with the deposition. These are classified as degenerations and may warrant intervention to stablize the region and prevent ulceration or extensive vascularization. Old age degeneration is not uncommon, especially in dogs with exposed eyeballs where protection is not optimal. Mineral binders may help smooth the area as the irregular surface can cause discomfort. In a severe form, sometimes the mineral is sloughed off and a deep hole in the cornea is created that necessitates surgery to prevent the eye from rupturing.

Corneal degeneration: note the blood vessels to the mineral

Eosinophilic keratitis

This is an odd but interesting disease of the cat. The eosinophil is a type of white blood cell that we see elevated in diseases where allergy or parasites are the primary concern. Cats have a series of diseases, primarily in the skin, where the eosinophil accumulates and creates lesions. In the eye, we can see something similar where the conjunctiva or cornea, the surface tissues of the eye, become inflamed and accumulate white plaques usually associated with vessels. The surface is usually not ulcerated so discomfort is not a feature. Herpes, the most common cause of surface disease in the cat, may be concurrent or it may be its own entity. This disease is usually responsive to antiinflammatory medication and is typically controlled, not cured. The white does go away!

Eosinophilic plaques and vessels

Cataracts

Cataracts are opacities of the lens that can be very small and difficult to observe or involve the entire lens and make the pupil appear white. When the lenses are extensively involved, vision compromise may be a feature if both eyes are affected. The color of the iris will be visible around the cataract and the central region is opaque and white. I have a posting concerning all the details of cataracts and cataract surgery on this site if you think your dog has this problem or are being referred for cataract evaluation. Here is a picture of a dog with signficant cataracts.

Dense resorbing cataract in a dog

Lipid flare

Animals will commonly get inflammation inside the eye called uveitis. Uveitis is a symptom of many problems from simple trauma to cancer. Infectious diseases like the tick-bourne entities in the Northeast or fungal disease in the Midwest can manifest themselves as uveitis with a red eye and protein and/or cellular debris suspended within the fluid that bathes the front of the eye. If your pet has uveitis for any reason and also has high levels of triglycerides or cholesterol in their blood stream, these fats can leak into the eye while it is inflamed. When that occurs, presto, you have a white eye that can look pretty scary. This is not too common, but we will see it usually on an emergency basis since it happens rapidly. Often the referral is for cataracts but compare this photo with the last one. You cannot see the brown iris clearly because the fluid in front of it is opaque, not the lens behind it.

Lipid flare in a dog with high blood cholesterol

There are certainly other lesions that can present as white in and around the eye. As I look out the window and see the snow piling up, I figure I have plenty of white to go around for a few more months. I even had to dig out Otto, our official greeter, so he wouldn’t get rolled by the plows! Good thing his eyes still look good….well, maybe!

Otto at the entrance to the AEC!

I had to post this picture of Ozzy Posey and his family with his festive Elizabethan collar! Fortunately his corneal erosion has finally healed. The bad news is he won’t be needing the collar any more! Merry Christmas, Ozzy!!!

The AEC reception area

Welcome to the Holiday edition of the Animal Eye Clinic in Wilton, Connecticut!

To date I have posted medical information and photographs of some disease states that may be of interest. But today, as Thanksgiving has quickly passed us by and the Christmas holiday bears down on us, I decided to wax poetic about something I feel strongly about: Customer Service.

I am one of those folks who really enjoys this time of year. One of the reasons is that many people seem to embrace the Christmas spirit and actually start treating people nicely, are thinking of giving rather than receiving, and are looking on the bright side of life. Whether you are religious or not, the positive vibe given off at this time of year can be infectious if you are open to receiving it.

Alas, many are brought down by the demands of the season. Gift giving, party attendance, travelling to the in-laws are some of the many responsibilities that can become a hassle rather than a pleasure during this busy time of year. Getting trampled on Black Friday just does not seem to be a good way to start the season off right to me!

But seeing the joy of children while writing their letters to Santa can bring me back to a time of innocence in a hurry. Meeting that person that smiles at you while hustling down a crowded street can prompt the smile back when, during other times of year, you may be facing straight ahead to avoid eye contact. Stopping to gaze at a decorated tree or house in your neighborhood when otherwise you would be racing home for dinner is special this time of year. Or taking the time to give someone directions that is obviously lost while looking for that perfect gift in the mall may otherwise not be considered at any other time. It makes me smile to see people treat others nicely, be approachable or themselves approach someone inspired by the season.

But why should this attitude be more apparent or present in December and not April? Why not have the Christmas spirit all year long? Why is this simple act of taking care of each other so difficult to find? Why do clerks in stores or receptionists in offices sometimes talk to you like you just insulted their mother? I mean, really, why do so many businesses continue to treat their customers like you need them more than they need you?

In a way, my business philosophy tries to reflect this lost art of customer service. Isn’t taking care of people what customer service is all about? And shouldn’t that be the easiest task in you and your employee’s day? It is just not that hard to be friendly!

This doesn’t have to be a big act of kindness, but rather the day-to-day friendliness and interaction between client, patient, staff and doctor that sets a tone in a practice. Or elsewhere between shopper and clerk, homeowner and contractor, patron and waiter. Isn’t everyone more pleased if someone treats them nicely, with respect and courtesy rather than with a gruff response? I don’t care how good your retail items, counter tops or beef satays are, if you don’t give me the time of day, I doubt I will use your service.

Here at the Animal Eye Clinic, I have chosen to remain a small business for exactly these reasons. I feel I can provide my excellence in veterinary ophthalmology in a warm, friendly, and personal setting better than in any other venue. It’s like Cheers here where we know your name and you will see familiar faces every visit. Our new waiting area is quite pleasant and you would be surprised how well many dogs and cats behave here when they may not at your primary veterinarian’s practice. They sense the calm, are not surrounded by sick animals and are comforted in a clinic that feels like a home. We think you will feel the same. Sure, we sacrifice the benefits of having other specialists right down the hall as you might experience at a multispecialty or emergency practice. Yes, I am not open 24/7 as I prioritize my family when not at work, and maybe I will be a little behind if an emergency comes in that needs attention while you are waiting. But most clients will tell you that once I am present, you will get my 100% attention, a thorough description so you can understand your pet’s problem, and a staff that will follow you from beginning to end of the process. And if you don’t get a smile, a hello, goodbye or thank you somewhere along the line, I would be surprised.

We may be only one of few veterinary ophthalmologists in the area, but we won’t act like it. It is our pleasure and priviledge to be be here for you, and we try to prove it every day. It doesn’t have to be Christmas season just once a year.

Happy Holidays from the Animal Eye Clinic! Treat someone nicely today and see how good it feels!

We see a lot of patients of all species that present with a complaint of cataracts in either or both eyes. I decided to post our owner information sheet that we give out if cataracts are present and cataract surgery is a consideration. A few basic points that I thought I would stress. 1) Nuclear sclerosis is an old aging change of the lens where the lenses appear grey but are not truly opaque and are often misconstrued for cataract. This is an increase in density of the lens that we see commonly in older patients. 2) Cataracts are not just an old aging change! We see many young dogs that present with cataract that are genetic in basis and occur at an early age (3-6 years). 3) Cataracts can present rapidly and may be associated with an inflammatory response or conversely, intraocular inflammation can cause cataract formation. 4) Age does not preclude anesthesia and successful cataract removal! It is an elective surgery, however, I have plenty of old dogs that were behaving like older dogs because of vision deficits that “are acting like puppies again” after having the cataracts removed. Hopefully the following information will help if you or your veterinarian see cataracts in your dog and are referred for possible cataract surgery.

Definition:

Cataracts are opacities in the lens of the eye. Although some people mistakenly think the cloudiness is on the surface (a “film on the eye”), it is actually a physical change within the lens which is deep inside your pets eyeball. A cataract may be very small and insignificant or can involve the entire lens and cause vision loss.

Insignificant incipient cataract

Why did your dog get cataracts?

Many cataracts are inherited and are found in breeds such as the Cocker Spaniel, Bichon Frise, Poodle, Siberian Husky, Miniature Schnauzer, Golden Retriever, Labrador Retriever and a number of terrier breeds. Other causes of cataracts include those secondary to Progressive Retinal Atrophy (PRA), diabetes mellitus, trauma, inflammation, geriatric change or puppy milk replacers. Many cataracts will worsen to the point of blindness but certain types, especially in the Retrievers, can remain small for the entire life of the pet. Cataracts are not limited to old dogs, especially the genetic based ones that can develop at an early age.

Lens-induced Uveitis:

A local inflammatory reaction inside the eye due to the development or progression of a cataract (lens-induced uveitis) can occur and is not uncommon. This can occur immediately upon the development of a cataract if this process is rapid (Bichon Frise commonly do this) or due to slow release of the liquefied lens proteins outside the lens capsule. This reaction can result in many complications such as retinal detachment, glaucoma, intraocular hemorrhage and scar formation.

Topical medications to control or prevent this inflammation are commonly utilized if inflammation is apparent or for prophylaxis of this inflammation if progression is suspected. These medications have no effect on cataract development but are used only to control or prevent this inflammatory reaction while you decide if surgical intervention is appropriate for your pet. This must be controlled prior to scheduling surgery if present. Unfortunately, some eyes become so inflamed that adhesions form, the cornea becomes compromised or other changes occur that can preclude successful surgery. Our goal at that point is to try and keep the eye comfortable.

Iris adhesion to lens from inflammation

How are cataracts treated?

Small cataracts do not warrant any intervention. We typically document the size and location and follow for progression if that possibility is suspected. Many cataracts are very small and are in a location that does not create worry and thus routine follow-up may be limited to your annual visits with your primary care veterinarian.

Treatment of significant cataracts is surgical removal of the lens with implantation of a man-made lens to return visual acuity back to normal. This is an elective procedure that is performed if you think improvement in vision will improve your pet’s quality of life. The procedure may be performed in one or both eyes depending on the specifics of each pet.

Prior to performing surgery, your pet may need to have special tests performed to evaluate the health of the retina (the “film in the camera”). An electroretinogram is like an EKG for the eye and evaluates retinal function. An ultrasound is utilized to detect any retinal detachment. These two tests are not painful, are usually performed without sedation and have virtually no risk associated with them. The tests take approximately 40 minutes to perform and we get the results immediately. If your pet does not pass these tests, removal of the cataracts may not be indicated and surgery would not be performed. These tests are not done on the day of surgery in this practice in case they fail. If the tests are successful, then surgery can be scheduled if your veterinarian confirms that anesthetic risk is low. Routine blood tests in addition to a physical exam will be advised for your veterinarian to assess this risk.

Normal ERG in a dog with cataracts

Cataract on the left, normal clear lens on the right

The surgery is performed under general anesthesia. The anesthetics are state-of-the-art medications that are used in human hospitals. Blood pressure, pulse rate, oxygen level, blood and respiration are monitored by a technician throughout the surgery. We make every effort to avoid complications but as with general anesthesia in any species, risks including death do exist.

Routine cataract surgery is performed using high-frequency ultrasound power to break the lens up into small pieces which are concurrently vacuumed out of the eye. This process is called phacoemulsification. This is performed through a small 3mm incision and is performed in over 95% of our patients. Phacoemulsification is the same technique performed for human cataract removal. Many people believe that cataract removal is done with a laser but that is not true for the primary cataract. After removal of the cataract, a new man-made lens is implanted to bring their visual acuity back to normal. We currently use foldable acrylic lenses that can be implanted through the same small incision. Although lens replacement is routine, it is sometimes inappropriate or impossible to implant a lens due to tears in the lens capsule or a breakdown of lens ligments which does not allow support of the new lens. Vision without a lens (aphakic vision) can be surprisingly good in dogs. Their view is now unobstructed by the cataract but out of focus due to the loss of the lens.

Phacoemulsification of the cataract

Cataract surgery is elective and requires a significant time commitment on your part. Eyedrops must be administered before and after surgery. These drops may be as high as 4 times a day for the first week but taper quickly over the next 2 weeks barring complication. The patient must wear a protective plastic collar for 2-3 weeks after surgery to prevent self-trauma. Postoperative checkups are usually performed the next day, one week after surgery, two weeks later and one month after that. At the time of the third postop exam, the protective collar is usually removed. Long term checkups are made about 4 months after surgery and then two times annually thereafter. Some dogs may need a drop a day continually as maintenance but many do not if inflammation and pressure are normalized. Expect to be medicating for at least 4-6 months after surgery. The success rate is over 90% but as with any surgery, there are risks.

Implanted intraocular lens after cataract surgery

What are the complications of cataract surgery?

There are five major complications of cataract removal: 1) Intraocular inflammation will occur due to the surgical trauma and thus most of the medications before, during and after surgery are geared towards controlling this reaction. Inflammation is the linchpin of most complications and is evaluated at every recheck. 2) Glaucoma is increased pressure inside the eye and can occur at any point after surgery. Mild to moderate elevations in pressure can be treated, but if the pressure goes up and stays up, irreversible vision loss can occur. This is the worst complication because it creates a painful blind eye that may require removal if uncontrolled. The general risk is 4%. 3) Retinal detachment is a painless blinding condition that carries a 2% complication rate. This can occur if a tear in the retina is created and the retina is pulled off or if inflammation pushes it off. Reattachment surgery is not common but is currently being performed by only a handful of specialists in the US. 4) Cataract regrowth can occur in 2 forms. Lens material may form globules that can contribute to inflammation. This is most common in young animals. The capsule that is left behind and houses the man-made lens commonly has or develops cataract as well. This regrowth is seen in basically all dogs but may not contribute greatly to vision impairment. Rarely is any surgical treatment required for either of these two entities. 5) Intraocular infection is a rare complication but is disastrous if it occurs and usually leads to loss of the eye.

I hope this information is helpful as you investigate cataracts and cataract surgery in the dog. A nice video clip is in the Helpful Resources section that has some images of the procedure, client testimonials and other tidbits that may be of value. As always, feel free to call the clinic and set up an appointment if you would like your friend evaluated.

Limbal Melanoma

The junction between the clear cornea and the white sclera is called the limbus and is a circular line that separates them. Melanoma can arise from here and is also considered benign. Growth, however, can occur and is more common in young animals than in old where it may remain static. If progression is suspected and your dog, less commonly cat, is affected, you have 3 basic choices. First is to remove the affected tissue and then graft in a donor piece of sclera to replace the wall of the eye that was resected. This is the most aggressive approach and carries the benefit of the surgeon being able to hold the tumor in their hand once removed and hopefully confirm complete excision. The negative is the invasiveness of the procedure and the inflammatory reaction that must be controlled both inside and outside the eye after surgery. The second and third is ablation of the tissue using cold (cryosurgery) or heat (laser). The mass is typically debulked or shaved off and the remaining pigmented tissue is destroyed by placement of the probe over the mass and treating the area. Although you are leaving tumor behind, this treatment is very successful, less invasive and reasonably well tolerated. The negative is that you are relying on your adjunct therapy to resolve the tumor rather than knowing you have completely removed it with resection. The area retains some pigment which has to be monitored for progression but usually remains a charcoal gray color. Both laser and cryo incur an inflammatory reaction to the eye which must be managed. Cryosurgery is my typical treatment of choice. The last option, especially in older dogs, is to measure, wait and watch as clinically they may not progress or progress quickly in which case there is little risk to leaving them there.

Limbal melanom in the dog

Limbal melanoma, post-op cryosurgery

Corneal Sequestrum

One of my favorite diseases in the cat is called a corneal sequestrum where the collagen of the cornea becomes discolored and turns a dark brown or black. It usually starts with a minor, poorly defined, tea-staining of the clear cornea, usually in the central region, and then progressively organizes and becomes more dense with well defined borders. In its beginning stages, it is not uncommon to see this associated with a corneal ulceration. What causes this pigmentation? Well, three basic entities are related to sequestrum formation. The first is breed which implies a genetic predisposition. We will see these develop more commonly in the Persion, Himalayan and Burmese cat although any cat can get one. Second is due to any low-grade, chronic irritation. The most common of these would be entropion, or rolling in of the lids. As the hair around the lid is directed onto the surface of the cornea, it is not uncommon to see ulceration and subsequent sequestrum formation that lines up with the offending hairs. The last is our friend the herpes virus, the most common cause of surface disease in the cat, which creates ulcerative disease of the cornea with deposition of pigment in the ulcer bed.

Treatment of corneal sequestra involves managing the primary problem (lid surgery if entropion, antivirals if herpetic, for example) and concurrently watching to see if the pigment dissipates or organizes. If an ulcerative problem is active and resolves, sometimes the tea color will dissipate as the ulcer heals. Sometimes the sequestrum will organize, develop sharp borders and the body will try to extrude or “kick it out” like a foreign body. This may take months but if the cat is comfortable, carries anesthetic risk for removal or has other issues to contend with, time may be on your side. If viral or genetic in basis, the ulcer may be difficult to heal, the eye remains painful and then this becomes a surgical problem.

Surgery involves shaving off the pigmented region of the cornea (keratectomy) and, depending on the depth of the pigment into the corneal tissue, subsequent grafting. Grafting of the cornea is performed if we have a structural weakness due to thinning of the cornea as a result of tissue removal that is greater than 50% of the true thickness. It may also potentially decrease the chance of recurrence which is not uncommon in this disease. The method of grafting depends on the size and depth of lesion and includes conjunctival grafts and corneoscleral transpositions. These methods are highly successful and result in a relatively clear cornea at the conclusion in the cat as we try to return to a comfortable and visual state.

Corneal sequestrum in a cat

Corneal sequestrum, post-op keratectomy

Pigmentary Keratopathy/Keratitis

Chronic, low-grade irritation comes in many flavors in the dog. Usually, a combination of exposure issues, hair abnormalities, dry eyes and genetic predisposition can result in slow and steady deposition of pigment in the clear cornea. Thererfore, breeds like the Pug, Pekinese and Shih Tzu are frequent fliers to our clinic because of this constellation of problems. Surface disease may resolve but the pigmentary change may continue. Treatment involves resolution of the primary problem (lid surgery? hair removal? tear replacement?) then monitoring for progression of the pigmentary component. If advancement is obvious, then medications to try to dissolve the pigment or slow its advancement are utilized. These drugs, primary tear stimulants, are the only true medications we have in our armamentarium to halt pigmentation and their response is unpredictable and often limited. Surgical removal of the pigment is only a temporary treatment since the pigment returns quickly. Thus, procedures to minimize the exposure component and improve protection of the cornea or tear distribution may be used together to try and halt vision loss in these cases.

Pigmentary keratopathy

Dense pigmentary keratopathy

As you can see, pigment in the eye comes in many forms so keep a look out and call if you notice anything that resembles these changes. Early diagnosis and intervention, as in most cases, may increase the possibility of a good outcome. Talk to you later!

Iris Cysts

Cysts inside the eye are a common and benign problem we see in dogs and, less commonly, cats on a regular basis. The ciliary body, which produces the fluid which bathes the front part of the eye, is lined by pigmented cells. In some instances, this tissue will bud off in the process of making fluid which causes a pigmented, fluid filled structure to peek out from behind the iris. As the processs continues, this cyst may release from behind the iris and float in the anterior chamber. As one may intuit, these cysts are typically round, see-through and mobile unless they become wedged between the clear cornea and the lens. This is a very common finding in the Goldern Retriever and Boston Terrier but can be seen in any breed. They are benign and warrant no treatment.

Iris Melanoma in the Dog

A melanoma in the iris or ciliary body of the dog is another common problem observed inside the eye. Although benign, meaning it will not spread outside of its location, it can be bad news for the eye as slow growth is expected. The presence of the mass can cause inflammation, cataract formation, retinal detachment and glaucoma. Usually, resection or laser destruction of the mass is not practical or successful unless quite small or easily approached. Therefore, removal of the eye to try and prevent it from becoming painful as well as confirming the benign nature of the mass by pathological evaluation is often advised. Eye removal sounds horrible but honestly dogs and cats do wonderfully with this surgery if warranted.

Iris melanoma

Iris Melanoma in the cat

Different than dogs, melanoma in the cat eye is determined as diffuse meaning it is not localized to a single location. The iris can become spotted with pigmentation change and does not form a visible lump like it does in the dog. Although considered malignant, meaning it can spread to distant locations, the progression to this state can take years. To confuse the matter, cats can get benign freckles on the iris that look identical and are probably an early version of the same process before the cells transform into cancer cells. In more advanced cases, the iris in the region of the pigmentation may take on a velvety look and pigmented cells may be seen floating in the fluid in front of the iris. Because of the slow development, we now take digital photos of the iris and follow for change. If these changes become concerning, eye removal may be advised if a systemic workup for metastasis is negative. Occasionally, irises that have progressed in pigmentation that are removed still receive a histopathological diagnosis of melanosis which is taken as a good sign that we may have gotten it out before it transformed to a malignancy. Below are two pictures of irises, one with melanoma and one with melanosis…..difficult to tell which is which, isn’t it?

I will talk about other diseases with a pigment component in the cornea in my next post….don’t forget to sunblock!

Iris melanoma

Iris melanosis