NAVLE Special Senses

Canine Eyelid Disorders Study Guide

March 28, 2026 25 min read 146 views
Eyelid disorders are among the most common ophthalmic conditions encountered in canine practice. The eyelids serve critical functions including globe protection, tear film distribution, and secretion of the lipid layer of the precorneal tear film...
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Overview and Clinical Importance

Eyelid disorders are among the most common ophthalmic conditions encountered in canine practice. The eyelids serve critical functions including globe protection, tear film distribution, and secretion of the lipid layer of the precorneal tear film via the meibomian glands. Disorders of the eyelids can lead to significant ocular discomfort, corneal damage, and vision impairment if left untreated. This study guide covers conformational eyelid abnormalities (entropion, ectropion), eyelash disorders (distichiasis, ectopic cilia, trichiasis), and eyelid tumors, which together represent a significant category of NAVLE questions.

Layer Description and Key Structures
1. Outer Skin Layer Thin, pliable skin continuous with facial skin. Contains cilia (eyelashes) on upper lid only in dogs. Glands of Moll (modified sweat glands) and Zeis (sebaceous glands) associated with cilia follicles.
2. Muscle Layer Orbicularis oculi muscle (CN VII - facial nerve) enables eyelid closure. Levator palpebrae superioris (CN III - oculomotor nerve) opens upper eyelid.
3. Tarsal Plate/Stroma Fibrous connective tissue layer providing structural support. Contains meibomian (tarsal) glands (20-40 per eyelid) that produce the lipid layer of tear film. Less rigid in dogs compared to cats and humans.
4. Palpebral Conjunctiva Innermost mucous membrane lining the inner eyelid surface. Contains goblet cells producing mucin layer of tear film. Continuous with bulbar conjunctiva at fornix.

Eyelid Anatomy

Understanding eyelid anatomy is essential for diagnosing and treating eyelid disorders. The canine eyelid consists of four histologic layers from external to internal:

High-YieldDogs have cilia (eyelashes) only on the UPPER eyelid, not the lower. Cats have NO true cilia. The meibomian glands are the most common site of origin for eyelid tumors in dogs.
Type Description
Developmental/Inherited Most common form. Related to globe size, eyelid muscle tone, and palpebral fissure length. Typically diagnosed in young, rapidly growing dogs under 1 year of age.
Spastic (Secondary) Caused by ocular pain (e.g., corneal ulcer, uveitis) leading to blepharospasm, globe retraction, and secondary eyelid inversion. Resolves with treatment of underlying cause. ALWAYS apply topical anesthetic before assessing for surgical correction.
Cicatricial Results from scarring and fibrosis following trauma, burns, or previous surgery. Contraction of scar tissue pulls eyelid margin inward.
Senile (Acquired) Occurs in older dogs due to loss of periocular skin elasticity, facial droop. Common in English Cocker Spaniels. Often associated with upper eyelid entropion and trichiasis.

Conformational Eyelid Disorders

Entropion

Entropion is the inversion (rolling inward) of all or part of the eyelid margin, causing the haired skin and/or cilia to contact the cornea and conjunctiva. It is the most common inherited eyelid defect in dogs.

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