Eyelid agenesis is a congenital disorder in which the eyelid doesn’t form properly during development within the womb. The cause of the condition is unknown, but it is speculated to be either genetic, viral or environmental.
While rare, agenesis is the most common congenital eyelid disorder found in cats. It may be partial (coloboma) or complete and usually affects both eyes (bilateral). One kitten or several within a litter may be born with the condition and there is a higher incidence in Burmese and Persian cats.
The function of the eyelid is to protect the eye from drying out, debris and trauma. The lower portion of the eyelid has the eyelashes, which point away from the face. Because cats with agenesis don’t have an eyelid margin, the remaining fur around the eye can rub against the delicate cornea (trichiasis). The eyes are exposed to debris from the environment, tears will not be able to spread across the eyeball, which leads to dryness, pain, discomfort, and trauma.
The lateral (side) portion of the eyelid is most commonly affected, although the entire eyelid can be missing. The extent of the deformity can range from barely perceivable to a complete lack of upper eyelid.
Due to constant exposure common symptoms that commonly occur in cats with agenesis include:
- Rubbing the eyes
- Reduced ability to blink
- Red bloodshot eyes
- Epiphora (overflow of tears)
- Blood vessels in the cornea
- Eye discharge
- Ocular discomfort
- Conjunctivitis (inflammation of the conjunctiva)
- Keratitis (inflammation of the cornea)
- Sensitivity to light
- Corneal ulcers
The veterinarian will perform a complete physical examination of the cat (or kitten) and obtain a medical history from you. Most veterinarians can diagnose agenesis based on appearance. However, they will need to carry out a thorough ophthalmologic (eye) exam.
Corneal ulcers are common in cats with agenesis; large ulcers are visible to the naked eye; however, the veterinarian may use a fluorescein stain, which is a harmless orange dye placed in the eye to look for corneal ulcers.
The goal of treatment is to address conjunctival and corneal damage and prevent further trauma to the eyes. Mild cases may be managed conservatively with artificial tears to lubricate and protect the corneal surfaces and antibiotics to treat corneal ulcers.
Cryoepilation to freeze and destroy the hair follicles which prevent the regrowth of hairs along the eyelid margins. Multiple procedures may be necessary to ensure all hair follicles are destroyed.
In some cases, surgical reconstruction (Roberts–Bistner procedure) for cats with chronic conjunctival irritation and corneal involvement. The procedure involves removing a portion of skin from the lip or lower lid and creating a new functional upper eyelid to provide comfort and protection to the eye. This specialist surgery requires the expertise of a veterinary opthalmologist.
In some cases, if medical management is unsuccessful it may be necessary to enucleate (remove) the eye.
The prognosis for cats with eyelid agenesis is good.
Do not breed with cats who have produced kittens with this condition.