BASICS
- A variety of conditions lead to abnormal function of the upper and lower eyelids, predisposing the globe to secondary diseases such as conjunctivitis and keratitis
- Major categories of eyelid disease include congenital, inflammatory, neoplastic, and traumatic. Manifestation of each type of disease depends on age, environment, duration and progression of problem, and prior treatment
- Regardless of the etiology, all eyelid diseases disrupt normal eyelid function—to provide the lipid part of the tear film, to distribute the tear film across the cornea, to protect the globe
- SCC and sarcoids have separate topics devoted to each of them and are not discussed here
These are variable according to the disease process.
- Eyelid disease may be acute or chronic. The owner may not notice a change in the eyelids until the disease is advanced. Trauma, however, is usually acutely recognized
- Blepharospasm
- Epiphora
- Conjunctivitis
- Acute (ulcers, edema) or chronic (vascularization, fibrosis, pigmentation) keratitis
- Rubbing
- Blepharedema
- Periocular discharge ranging from frank blood to purulent or serosanguineous
- Asymmetry of eyelids can be due to raised firm or soft masses, erosive blepharitis, or overt trauma
- Lack of palpebral reflex may stem from a neurogenic disorder or trauma
- Entropion is an inward rolling of the eyelid margin. It can be a primary problem in foals or secondary to dehydration or emaciation. Prior eyelid damage that leaves scarring may lead to a cicatricial entropion. Acquired or blepharospastic entropion is a secondary condition due to chronic irritation and pain, causing spasms of the orbicularis oculi muscle
- Some foals have eyelid abnormalities identified at birth. Microphthalmos causes a related macropalpebral fissure and secondary entropion requiring intervention. Dermoids (choristomas), aggregates of skin tissue aberrantly located within adnexal tissue, conjunctiva, and cornea, have been reported in the eyelids of foals. Eyelid colobomas are areas of eyelid agenesis leading to exposure keratitis. Faulty induction of the surface ectoderm by defective or absent neuroectoderm results in these congenital anomalies
- Blepharitis, or inflammation of the eyelids, has multiple causes, including viral, fungal, parasitic, allergic, and immune mediated. Traumatic blepharitis can develop into eyelid abscesses and may be associated with orbital fractures, penetrating and lacerating trauma, subpalpebral lavage system irritation, and bony sequestra
- Trichophyton or Microsporum spp. are known to cause blepharitis, as are Histoplasma farciminosum and Cryptococcus mirandi
- Equine viral papillomas cause focal eyelid inflammation in immature horses
- Demodex infestation may lead to lid alopecia, meibomianitis, and papulopustular blepharitis
- Thelazia lacrimalis is a spirurid nematode and a commensal parasite of the equine conjunctival fornices and nasolacrimal ducts. This parasite can cause diffuse blepharitis
- Habronemiasis, a common cause of granulomatous blepharitis, occurs mainly in the summer months when house and stable flies serve as vectors. Dying microfilariae in the eyelids, conjunctiva, lacrimal caruncle, medial canthus, and nictitans incite an immune-mediated hypersensitivity
- Fly-bite blepharitis, Dermatophilus, and staphylococcal folliculitis cause blepharitis, especially in young foals
- Juvenile Arabian leukoderma, or “pinky” syndrome, is a cutaneous depigmentation condition affecting 6–24-month-old Arabians. This disease may present with cycles of depigmentation and repigmentation
- Allergic blepharitis, eosinophilic granuloma with collagen degeneration, pemphigus foliaceous, bullous pemphigoid, solar blepharitis of nonpigmented skin, and St. John's wort photosensitization of the lids are also reported
- Topical chemical toxicities can cause a caustic blepharitis
- Eyelid lacerations are common in the horse. Upper eyelid damage is more significant because the upper lid provides the greater degree of coverage of the cornea. Medial canthal lid trauma can involve the nasolacrimal system
- Tumors of the eyelids other than SCC and sarcoids include but are not limited to melanoma, mast cell tumor, and lymphoma
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS