incomplete eyelid closure
What breeds are affected?
Incomplete eyelid closure during sleep is a common problem among breeds such as Shih Tzus, Lhasa Apsos, Pekingese and Pugs.
What causes it?
These animals have a prominent eye that resides in a shallow orbit. The result is during relaxed eyelid closure (sleep), the eyelids do not completely close over the cornea.
What are the symptoms?
Owners often will notice the slight opening between the eyelids, the dog that sleeps on its back or wakes easily if you come into the room. When affected, young animals can compensate by increasing tear production at night. Eventually, the ability of these dogs to compensate for the anatomic defect is compromised and the central area of the cornea will dry. When the central area of the cornea dries, it is predisposed to corneal ulceration. Initially, the ulcers are small and respond to conventional ulcer therapy. As the condition persists the ulcers become more severe and result in corneal scarring. If the scarring becomes severe, blindness may result.
How is it diagnosed?
A good ophthalmic examination will generally reveal linear scars across the cornea. If ulcers have occurred, they will generally be located in the center of the cornea. Owners can make the diagnosis most easily by observing the dog during sleep for the slight separation between the upper and lower eyelids.
How is it treated?
The best way to correct the defect is to make the anatomy more like what nature would select for. Nature selects for a ‘Coyote’ style of head with more almond-shaped eyes. Dogs with incomplete eyelid closure can be surgically corrected by performing a lateral or medial canthoplasty. In these surgeries, a small portion of the eyelid margin is removed and muscle from the upper eyelid is transposed to the bottom eyelid and muscle from the bottom eyelid is transposed to the upper eyelid. The surgery creates a more almond-shaped eyelid and improves the efficiency of the eyelid closure. In short, it allows the dog to protect the cornea during relaxed closure.
Alternatively, or in the interim between diagnosis and when surgery can be performed, topical tears and ointments can be applied before bedtime. These medications will help protect the cornea but do nothing to correct the defect.
What aftercare is required?
Other than protecting the surgery site from the patient there is little aftercare following surgery. Often an Elizabethan collar will be used to keep the patient from traumatizing the surgery site. Unless there are other eye related conditions requiring treatment, no medications are prescribed following surgical correction.