Exposure keratopathy syndrome (exophthalmos, lagophthalmos, and/or macroblepharon)

What is ... ?: 

 With this syndrome, there is chronic irritation of the surface of the eye (the cornea) because of  increased evaporation of tears and increased corneal exposure. This is a result of a combination of anatomic features including exophthalmos (protrusion of the eyeball), lagophthalmos (inability to close the eyelids completely) andmacroblepharon (an exceptionally large eyelid opening, often associated with lower lidentropion). The result is inadequate blinking, and therefore reduced protection for the eye. Affected dogs experience chronic discomfort and are prone to ulceration of the cornea.

It is important to note that these anatomic features are normal for certain breeds, as a result of selection by breeders and demand by the public for a particular facial conformation with very prominent eyes, heavy facial folds and/or droopy eyelids. For example, the breed standard for pugs calls for a round head "with very large, bold and prominent eyes."
To avoid problems such as exposure keratopathy syndrome, breeders and dog owners are encouraged to choose dogs with less exaggerated facial features.

How is ... inherited?: 

The syndrome is associated with a combination of anatomic features that are influenced by several genes affecting skull and facial conformation.

What does ... mean to your dog & you?: 

 Signs of chronic corneal irritation include reddening of the eye, increased tears, and discomfort (pawing or rubbing the eye).  Affected dogs are prone to eye injuries from environmental insults (dust, twigs, et cetera). Corneal ulcers may develop due to increased corneal exposure.

Over time, pigmentation of the cornea may occur in response to chronic irritation. This may eventually interfere with your dog's vision.

How is ... diagnosed?: 

 The eyeballs are prominent and the eyes may be reddened from chronic irritation. If corneal ulceration has developed, the eye will be painful and your dog may paw or rub it. With lagophthalmos, you may notice that your dog's eyes do not close completely when s/he is asleep.

Your veterinarian may do a fluoroscein dye test to check for corneal ulceration. 

How is ... treated?: 

 Tear substitutes provide only temporary relief. Surgical correction to reduce the size of the eyelid opening (permanent partial tarsorrhaphy) is usually effective in protecting the cornea over the long term. Where other associated eyelid defects such as entropion are present, several surgeries may be required.

Corneal ulceration, if present, must also be treated.

Breeding advice: 

 Exposure keratopathy syndrome is one of the eye conditions that is a result of selection by breeders and a demand by the public for such features as excessively prominent eyes and heavy facial folds. A responsible breeding programme will choose animals for breeding with a more normal head conformation, so as to select away from these exaggerated facial features and the problems associated with them.

Any dog that has required surgical correction to treat this condition should not be used for breeding, and may not be exhibited in the show ring.


 Slatter, D. 1993. Textbook of Small Animal Surgery. p. 856-889. W.B. Saunders Co. ,Toronto.

What breeds are affected by ... ?