Entropion is a condition where the eyelids roll inwards, causing the eyelashes and facial hair to contact the surface of the eye. This results in tearing, pain and possible ulceration of the cornea. This is seen in many different breeds in dogs and cats, and can be due to a whole raft of different conformational problems.
- Causes of Entropion
There are various causes of entropion. Entropion may be primary (due to an underlying anatomic problem as seen in breeds such as Rottweilers, Mastiffs, Retrievers, Cocker Spaniels, Bulldogs, Sharpeis and Persian cats), or secondary to something painful in the eye, causing persistent squinting, or due to age where the fat and muscle stores behind the eye become lessened, and the eyelids begin to roll inwards.
- Surgical Intervention
Entropion usually needs surgical intervention. There are various types of surgical procedure which may be used in entropion repair. Each case is slightly different. The important thing to remember is that some cases may require more than one surgical procedure, especially breeds which have a lot of facial folds, or in breeds where the entropion is severe. These surgeries are best performed under an operating microscope, as the eyelids have important roles in distributing the tear film and protecting the eye. If there is any malalignment of the eyelid margin, functional disturbances can occur. The success rates for surgery are very high. As eye specialists we are trying to correct something that is anatomically abnormal. Our goal is an eye which is not irritating, and to achieve the most cosmetic result possible within this goal.
- Eyelid Masses and Tumours
The eyelids contain many different cell types, including skin, glands, blood vessels and mucosa. Therefore, abnormal growth of any of these tissue types can occur and form a mass or tumour. These masses can distort the shape and function of the eyelid, and not allow it to perform its vital roles in maintaining ocular surface health. Or worse, these masses may be directly contacting and irritating the eye. For these reasons, it is best to have eyelid masses removed. Thankfully, the vast majority of eyelid masses and tumours are benign in both dogs and cats. However, we always will send these masses to the laboratory to evaluate this to ensure additional treatments are not required.
- Surgical Intervention
The type of surgical excision and eyelid reconstruction that is performed is dependant on many factors, including the size of the mass, the predicted biological behaviour of the mass, the location of the mass, and the normal eyelid conformation of the animal. These repairs can range drastically in complexity. As the eyelids have a crucial role in maintaining ocular health, any malalignment of the eyelids can drastically alter their function. Therefore, these procedures are best performed by a specialist ophthalmologist, who operates beneath an operating microscope to ensure the best surgical outcomes possible. The success rate of these procedures are ultimately very high.
This is a congenital defect that is rare in dogs, and uncommon in cats where a portion of the eyelid margin has never successfully developed. This can cause many issues, as blinking is poor and adjacent hairs frequently will rub on to the eye. These eyes are often chronically sore, inflamed and may become blind.
- What causes Eyelid Agenesis?
This is believed to occur due to maternal nutritional stress in utero, late in gestation.
- Treatment for Eyelid Agenesis
Historically, treatment for this condition has involved large facial reconstructions to allow for skin to be pulled from other locations of the face to create extra skin at the eyelid margin. However, the eyelid is a very unique anatomical tissue, as it is the border of skin and a mucous membrane (aka a mucocutaneous junction). To replicate this skin, our very own Dr. Cameron Whittaker pioneered a technique approximately 15 years ago where skin from the corner of the mouth could be rotated to the eyelid margin (called a “lip to lid transposition”). This is a technically challenging surgery, and is no small feat. More recently however, our Dr. Kelly Caruso has been revolutionising the surgical options for this disease, using a skin filler (similar to what humans use for lip fillers in cosmetic surgery) to help stretch the eyelid skin, and force the body to generate more tissue there. This can be performed often without sedation or a general anaesthetic. This can be performed 2-4 times (depending on need of the animal), before a small procedure is performed to take a region of the mouth tissue, and place it on the new eyelid tissue bed. This is a vastly less stressful, less painful and less complicated procedure than that available anywhere else.
- Typically, these animals after receiving surgical reparation have a vastly enhanced eyelid function and quality of life.
Abnormal Eyelid Hairs (Distichiae)
Abnormal eyelid hairs are a common cause of chronic irritation and pain in the eyes. These abnormal hairs are called distichiae or ectopic ciliae (depending on their location). Like entropion, they can cause pain, irritation, squinting, and tearing. Some breeds seem to be more predisposed than other breeds. These include Bull Mastiffs, Cocker Spaniels, Poodles, Shih Tzus, Lhasa Apsos, Shetland Sheepdogs and Staffordshire Bull Terriers.
Treatment involves surgery of some type to remove the hairs. Occasionally plucking the hairs is sufficient to remove the problem permanently. More than likely however they grow back. Therefore permanent removal by surgery is usually the best thing to do. Surgical removal of these hairs is done usually under an operating microscope, using nitrous oxide to freeze the hair follicles in the case of distichiae, while surgical removal is used for ectopic cilia. For distichiae, we can only freeze those hairs which we can see. New hairs may appear at other sites, and we may need to repeat the procedure in up to 15% of cases.
- Success of Surgery
The success of surgery is high, but repeat surgery sometimes needs to be performed. It is usually the hairs which had not emerged on the first surgery that 4-6 weeks later cause the problems necessitating a second freeze.
Complications of surgery can involve loss of pigmentation in the eyelid margins so the eyelids become pink (usually temporarily) or grow white hair (which may be permanent). Eyelid swelling after surgery is common but not usually painful. In most cases, the swelling disappears after a few days.
- Home Care
Hot compressing after surgery helps to reduce the swelling and to clean discharges which may accumulate. Your pet may also be sent home with tablets to help with pain relief if needed.
“Cherry eye” describes a prolapse of the lacrimal gland of the third eyelid. This gland is responsible for producing approximately 33% of the aqueous portion of tears in dogs, and so has an important role and should under no circumstances be removed. This gland can proptose to form a “cherry” that becomes inflamed and bright red. What causes this is suspected to be due to a weakness of anatomical anchoring of the gland to its normal location. There is a strong breed bias in these cases observed, with breeds such as the American Cocker Spaniel, Beagles and English Bulldogs particularly predisposed. Often, animals are under 2 years old and this condition can effect either one eye, or more commonly both eyes.
- Treatment of Cherry Eye
“Cherry eye” is best treated with a surgical replacement. No two cherry eyes are the same, and the anatomical factors contributing to the proptosis of the gland differs from patient to patient, and so the exact surgical reparation also varies patient to patient. Essentially though, the underlying principles remain the same. This surgery will aim to replace the gland to its normal location, and lessen any anatomical features of the third eyelid that predispose the gland to prolapsing. Often, this surgery is very successful. However, occasionally the gland will re-prolapse and a further repair is required.