Conjunctiva, Eyelids, and Tear Film: Effects of Contact Lens Wear

What is the conjunctiva?

A highly vascular mucous membrane lining the inner eyelids and sclera.

What are the vascular supplies of the conjunctiva?

Ophthalmic artery, anterior ciliary arteries, and lacrimal artery.

What are the effects of contact lens wear on the conjunctiva?

Hyperemia, chemosis (swelling), and inflammation.

What causes hyperemia and injection in the conjunctiva?

Dilation and engorgement of blood vessels due to hypoxia, desiccation, tightly fitting lenses, mechanical rubbing, or immunological response.

What is chemosis?

Swelling of the conjunctiva, often due to inflammation from soiled or poorly fitting lenses.

What is inflammation of the palpebral conjunctiva caused by?

An immune or mechanical response to antigens on the lens surface or poor lens design.

What are papillae in the context of conjunctival inflammation?

Tiny bumps on the superior palpebral conjunctiva caused by lens rubbing and irritation.

What are the primary functions of the eyelids?

1. Rewet the corneal and conjunctival surfaces with tear film. 2. Flush away debris. 3. Protect the eyes from injury.

What is papillary hypertrophy?

Enlargement or swelling of papillae on the palpebral conjunctiva due to contact lens wear.

How does contact lens wear affect blink rate?

It can lead to less frequent and less complete blinking, causing desiccation of the cornea and conjunctiva.

What is lid sensitivity in relation to rigid contact lens wear?

Eyelids can become desensitized to the lens edge, which may lead to undetected inflammation or mechanical insult.

What is ptosis in the context of contact lens wear?

Drooping of the eyelids due to decreased sensitivity and pulling during lens removal.

What are the three layers of the tear film?

1. Lipid 2. Aqueous 3. Mucin.

What is the function of the lipid layer in the tear film?

It slows the evaporation rate of the aqueous portion and prevents spillage over the eyelids.

What is the primary component of the aqueous layer of the tear film?

Water, electrolytes, and proteins.

What does the mucin layer of the tear film do?

It adheres to the corneal surface and creates a hydrophilic surface for the aqueous layer.

What are the optical functions of the tear film?

It creates a smooth anterior refracting surface for clear vision.

How does the tear film protect against microbes?

It contains immunoglobulins, lysozyme, and lactoferrin.

What metabolic functions does the tear film serve?

It supplies glucose and oxygen to the cornea and carries away shed epithelial cells and carbon dioxide.

What changes occur in tear film structure with rigid contact lenses?

The lipid layer may beecome thin or absent, the aqueous layer is thin and dries rapidly, and the mucoid layer may appear absent.

How does hydrogel lens wear affect tear film structure?

The lipid layer is thin and varies in thickness, the aqueous layer is present, and the mucoid layer is thicker but loosely attached.

What is the overall effect of contact lenses on tear film stability?

They decrease tear film stability, leading to a dryer lens surface and potential symptoms.

What considerations should be made regarding contact lens wear?

Effects on the ocular surface, CL material and design, follow-up schedule, wear time, and management plans.