Cataract surgery in the dog is a highly successful procedure that many owners have chosen for their four-legged friends to regain or improve vision. Cataracts in general and a brief discussion of the preoperative workup and surgery is presented in a prior post that you can peruse if interested titled Cataracts in the Dog. (You can find this older post if you scroll to the bottom of this page and click on Older Entries.) Removal of an opaque, cataractous lens is an elective procedure that is chosen if we feel we can improve our dog’s quality of life by returning his or her vision. This surgery is rewarding for dog, owner and doctor as it can truly bring the “puppy” back in many dogs whose lifestyle had changed with a loss of sight. Nothing beats watching the joy on our client’s faces as their dog ambles back into their arms and makes eye contact after surgery!

The technical aspects of this surgery have evolved over the years with the goal to improve the ultimate success of the procedure. These improvements involve everything from patient selection and timing, pre- and post-operative medical management, surgical technique, quality and type of lens implants, instrumentation and last but not least the science of the cataract surgery machine itself. Veterinary medicine often trails human medicine when it comes to technical advances primarily due to the financial limitations of the very expensive equipment used for diagnosis and treament of many diseases. Here at the AEC, were are proud to introduce an upgrade to the most recent technology for cataract extraction in the dog in the form of a new cataract surgery machine, the Alcon Infiniti, and this post will focus on this machine.

Our new Alcon Infiniti Vision System

Cataract removal is primarily achieved by what is called phacoemulsification. In general, a small, beveled needle is introduced into the eye through a 3mm incision. While concurrently irrigating with fluid and aspirating it out, the needle will vibrate with ultrasound power to break the cataract into small pieces that are ultimately sucked out through the tip. Very cool! As you can imagine, there are numerous factors that are involved to make this work. How fast do you introduce the fluid? How much suction do you need to suck the fluid and lens pieces out while keeping the eye inflated? How much ultrasound power do you safely use to break up the lens without disrupting the other structures? How do you create a handpiece to deliver this energy inside the eye? How do you minimize the heat and inflammation that is generated in the process? Lot’s of smart people have worked on these and many other issues to help create different machines to maximize success while miniimizing risk.

The main feature that makes the Infiniti and its Ozil handpiece better is the development of torsional or elliptical phaco. Standard phaco, used for the last 30-40 years, is in a longitudinal mode. The action of the needle is in an in-and-out motion that “jackhammers” the lens material into small pieces. The torsional movement this system features adds a side-to-side motion that shears the cataract as well. This combination creates two benefits. It reduces the heat that is created during the process which can affect inflammation and incision quality and it keeps the pieces stuck to the tip to allow faster breakdown and removal.

Other advances with the pump system help add a smoother delivery and removal of the fluid while protecting against “surge” of the fluid that disrupts the evenness of the procedure. I could go into this and other parameters in more detail here but the take home point for us and your pet is that the procedure becomes faster, easier and less traumatic with this new technology. The biggest difference between a human and a dog getting cataract surgery is that dogs generate more inflammation than people with similar ocular trauma. And inflammation after surgery is the linchpin of complication. Thus, if we can decrease our inflammation by utilizing the above upgrades we should see better success. Our pets are thus benefiting from these advances and possibly to a greater degree than people in respect to inflammation. We are excited to have this new machine in our clinic and maybe your dog will see the reason why!

We had last started a discussion about lid disease. We see lots of patients here with a variety of lid maladies that affect its position, function and appearance. Some are genetic in origin, many are acquired problems, and most are succesfully treated. My last post talked about congenital lid changes. Let’s dip into some of the common acquired issues we see in the dog and cat.

ENTROPION

Entropion is rolling in of the lids and this presentation comes in two flavors, primary or spastic. With primary entropion, the lid isn’t built quite right with the lid rolling into the eye causing local irritation from hairs rubbing on the corneal or conjunctival surface. This is typically a surgical disease. Many breeds of dog are predisposed to this such as the hunting or large breed dogs. In cats, I see this most often in older cats for the big males with deepset eyes and large jowls. Sometimes this may be a “normally abnormal” finding such as in the Saint Bernard or Newfoundland where the lids are loose and rolling in a little but the dog shows minimal evidence of irritation. In these dogs, a minor mucoid discharge or surface redness from exposure is not uncommon and surgery is often not warranted. In other dogs, squinting and rubbing is obvious and the development of corneal ulceration is not uncommon. These will warrant surgical intervention.

Entropion of the lower lid.

Spastic entropion is a dynamic rolling in of the lid secondary to ulceration, lid swelling or some overt pain. Dog’s and cats can retract their eyeball into the socket as a pain or protective response. When this occurs, the lids may have the tendency to roll in and aggravate the pain. The globe retracts farther, the lid rolls in more, they start to rub, the lid swells, rolls in more….you get the idea! If the pain response is removed or blunted, with topical anesthetic for instance, the lid may return to a normal position as the spastic component relaxes. In this patient, we need to palliate the entropion while the irritation is resolved and hopefully the lid will remain in a normal place at the conclusion. I see this a lot with Bulldogs that have skin allergies where their face swells, for example.

Some cases are a variation on this catergorization as a primary component is worsened by a spastic component. A good example would be the Shar Pei puppy with entropion that is not developed enough to determine if the lids will remain rolled in as they grow. This case may be treated like a spastic entropion initially and then need surgery later once the dog matures. Or the allergic dog with entropion that has made the eye look worse than it is due to inflammation or self trauma. One needs to resolve this features before surgery as overcorrection can ensue.

ENTROPION REPAIR

Repair of primary entropion entails removing skin to evert, shorter or loosen the lid margin. There are many techniques to accomplish this goal. Which technique is employed depends on the features that contribute to the abnormality. The “basic” repair involves removing skin in an ellptical shape away from the lid marging with a width that approximates the amount of roll. The wound is then closed to pull the lid margin away from the cornea. Over correction or under correction are the biggest risks.

Lower lid entropion in a large dog. Note discharge and hair on cornea.

Using my thumb to roll out lid and expose lid margin.

Temporary tacking is the term used to palliate a spastic entropion. Suture or staples can be used to gather the skin and evert the lid without actually removing the skin. Once the irritation is resolved, these are removed to assess the true lid position without the active spastic component. Some may need primary repair after this procedure where others with complete spastic entropion will be fine unless another episode of pain occurs. This procedure is also used in young puppies, like the Shar Pei, to allow them time to “grow into” their lids before determining if primary repair is needed.

Stapling lower lid for a spastic entropion.

LID TUMORS

Lid tumor development is very common in our patients. Fortunately, 95% of lid tumors are benign. They typically arise from the meibomian glands or the lid skin itself. Ease of removal is proportional to size. If a tumor is less than 1/3 of the total lid length, simple excision can be performed. If it is greater than this, cryosurgery or removal with lid reconstruction may be needed. Many tumors remain small and don’t enlarge significantly over time. Thus, if a mass is noted and it is irritating or obviously enlarging then it will be much easier to remove if it is small. If it is stable then waiting and watching or removing if another anesthetic event is needed would be prudent advice. Many general practitiioners are comfortable removing smaller masses. Larger ones should be addressed by a specialist who may have different options and approaches to maintain good lid function.

Small upper lid tumor.

Large lid tumor that warrants surgery.

BLEPHARITIS

Inflammation or infection of the lid is called blepharitis. The lid is just fancy skin with a function to protect the eye and thus reacts like skin anywhere to allergy, trauma, immune-disease, etc., by becoming red and swollen. Organisms, primarily bacteria, can be the source or result of these issues. Similar to skin, oral medications are often used for a number of weeks to try and reverse the problem. Unlike skin, topical medications are typically not used due to ocular irritation to the products in the lotions or salves. Topical eye drops don’t necessarily penetrate well into the lid and may be ineffective. This photo shows a lid with bacterial blepharitis that responded well to oral antibiotics and antiinflammatories. The dreaded Elizabethan collar is oftern needed in these cases as self trauma is usually evident as noted by the concurrent hair loss.

Blepharitis with moderate swelling and hairloss.

These are just a few of the many problems that can be seen in the lids of our patients. If you notice these changes, give us or your veterinarian a call as most times early intervention is best!

Eyelid anatomy

There really is not much to the eyelid. Skin is on the outer surface with a relatively normal makeup of hairs, feathers, or scales and glands. Not all animals have eyelashes, though, and most domestic animals don’t have lashes on the lower lid. A hairless region at the lid margin maintains a smooth surface for contact with the clear cornea and help with tear distribution. In addition, tiny meibomian glands produce an oily substance that helps keep the tears from evaporating. This material exits onto the corneal surface from small pores at the lid margin. The muscle that closes the lids is called the orbicularis oculi and surrounds the eyelid margin as one might expect. Contraction closes the lid and relaxation opens the lid with a little help by another muscle called the levator palpebrae superioris that lifts the upper lid. The inner aspect of the lid is lined by conjunctiva which, in this location by the lid, have special goblet cells that secrete another component of the tear film that allow the tear to “stick” to the cornea called mucin. Admixed throughout these structures is connective tissue.

Mammalian lid cross section.

Many species have a third eyelid which also helps dispense and distribute tear. In mammals, it is usually located in the inner, lower aspect of the eye and comes up passively whereas in birds it is located in the upper inner quadrant and can be actively moved. In our dogs and cats, the gland of the third eyelid is an accessory gland that produces 35% of the watery tear and is located at the base of a “T” shaped cartilage that gives the membrane some rigidity. I could go off on bird third eyelids but will save that for another posting as that is one very cool structure!

It just ain’t built right!

Congenital diseases in our patients that are associated with the lids are relatively uncommon. The two most prevalent are lid agenesis, most commonly seen in the cat, and dermoids.

Lid agenesis is a prominent lack of lid tissue development that affects the lid margin. Instead of having that nice hairless zone with the meibomian glands and their related pores, there is a stark transition from conjunctiva to the haired skin. This creates a local region of irritation and lack of protection for the adjacent cornea. Cats may present for discharge and squinting from the skin hair that is now directly rubbing on their cornea while some seem relatively content. With lid closure, a noticeable gap is present which predisposes the adjacent cornea to scarring, vessels or ulceration. This can involve one or both eyelids.

Lid agenesis of 2/3 of the upper lid in a cat.

Treatment of these lesions are aimed towards decreasing or stopping the local irritation from offending hairs and/or improving the coverage of the exposed cornea. Reconstruction of the lid using grafting techniques to slide tissue into the gap are well described with variable success. Although these are geared to “filling the gap” from the lost tissue, hair irritation may still be present and need to be managed depending on which direction the hairs on the grafted tissue are directed. Another method of treatment, which I use more commonly, is to address the offending hairs by using cryosurgery to make the region bald and leaving the gap alone. Cats do amazingly well with this approach as the exposed area rarely ulcerates and extensive changes associated with pigmentation, vessels and scarring into the more normal cornea is uncommon. The procedure is tolerated well, does not require suturing and is usually only needed once although repeat surgery is always a concern with either approach.

A dermoid is simply a piece of skin in an abnormal location. In the eye, this usually will result in a distortion of the lid in the region or a patch of haired tissue on the conjunctiva or cornea itself. The hairs are typically irritating so a degree of mucus discharge is not uncommon. Resection of the skin from the abnormal location is curative and regrowth does not occur unless a hair follicle is left behind. This gives a new meaning to the term “hairy eyeball”!

Dermoid on the cornea of young Shih Tzu.

Eversion or scrolling of the cartilage in the third eyelid is another congenital entity that we may see. The third eyelid, or nictitating membrane if you want to impress your friends, should conform to the cornea as it floats over the surface to distribute the tear. The cartilage is what maintains this shape. Some dogs have a predilection for this cartilage to bend usually away from the corneal surface which gives it a scrolled appearance and affects its optimal function. Surgeries have been described to correct this condition by resecting, reversing or stretching the bended section to try and create a more normal lid/corneal relationship. We are currently publishing a technique using heat to remodel the cartilage that shows a lot of promise and is less invasive than other techniques. Here are before and after images of a dog treated in this fashion.

Everted cartilage of the third eyelid

Postoperative appearance of scrolled cartillage after remodelling

This is just a sampling of some of the changes we can see on the lid. Remember, congenital does not necessarily mean genetic! Events can happen during the pregnancy that change how tissues develop rather than having a genetic predetermination that a certain disease or anatomical change will develop. We will talk about some genetic and acquired conditions of the lid next time!