Ophthalmic Anatomy: Eyelids & Lacrimal System

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Questions and Answers

What are the layers of the upper eyelid's lamellae?

The layers are skin, orbicularis, tarsus, and palpebral conjunctiva.

Why is the skin of the eyelid unique compared to other body parts?

It is among the body's thinnest skin, allowing for quick blinking movements.

What is the superior palpebral crease and its location in Caucasians?

It is a dividing point between preseptal and pretarsal skin, located approximately 10 mm above the lid margin in Caucasian women and 8-9 mm in men.

Where is the inferior palpebral crease located in relation to the lower lid margin?

It courses from about 5 mm below the lower lid margin medially to about 7 mm laterally. Signup and view all the answers

Describe the occurrence and direction of the nasojugal crease.

It is located below the medial aspect of the inferior palpebral crease and extends infralaterally at a 45-degree angle. Signup and view all the answers

What is the most common cause of ectropion?

Involutional (age-related) changes. Signup and view all the answers

What is a primary treatment for paralytic ectropion?

Lubrication and taping of the eyelid, followed by ectropion repair. Signup and view all the answers

What is entropion and how does it usually present?

Entropion is the inversion of the eyelid margin, typically seen as lower eyelid entropion from involutional causes. Signup and view all the answers

List two causes of blepharoptosis (ptosis).

Myogenic causes such as myasthenia gravis and aponeurotic causes due to involution. Signup and view all the answers

What is a notable risk associated with blepharoptosis?

There is a risk of amblyopia due to poor visual development. Signup and view all the answers

What is the primary function of the orbicularis oculi muscle?

The primary function is forced eyelid closure. Signup and view all the answers

What separates the orbit from the eyelid and prevents the spread of infection?

The orbital septum acts as a barrier between the orbit and the eyelid. Signup and view all the answers

Where does the orbital septum of the upper eyelid originate?

It originates from the periosteum of the orbital rim, known as the arcus marginalis. Signup and view all the answers

What are the two portions of the levator palpebrae superioris muscle?

The two portions are muscular (40 mm) and aponeurosis (14-20 mm). Signup and view all the answers

What is the role of the preseptal and pretarsal regions of the eyelids?

They facilitate involuntary eyelid movement like blinking and sleep. Signup and view all the answers

What nerve supplies the orbicularis oculi muscle?

The orbicularis oculi muscle is supplied by the facial nerve. Signup and view all the answers

How does the orbital septum insert into the eyelid?

It inserts into the levator aponeurosis superiorly and lower eyelid retractors inferiorly. Signup and view all the answers

What muscles are responsible for eyelid retraction in the upper and lower lids?

The upper eyelid is retracted by the levator palpebrae superioris muscle, and the lower eyelid by the inferior tarsal muscle. Signup and view all the answers

What forms the eyelid crease on the anterior surface of the superior tarsal plate?

An aponeurosis. Signup and view all the answers

What is the nerve supply to the superior tarsal muscle?

Sympathetic nerve supply. Signup and view all the answers

What are meibomian glands, and how long are they?

Meibomian glands are glands in the eyelid that secrete oil, and they are 29 mm long. Signup and view all the answers

What is trichiasis?

Trichiasis is a misdirection of normally positioned eyelashes. Signup and view all the answers

What characterizes an internal hordeolum?

It is an acute staphylococcal infection of the meibomian gland. Signup and view all the answers

List a common treatment for a chronic chalazion.

Incision and curettage. Signup and view all the answers

What is ectropion, and what is one of its potential consequences?

Ectropion is the eversion of the eyelid margin, which may cause keratinization of the conjunctiva. Signup and view all the answers

What type of eyelid pathology involves aberrant cilia emerging through meibomian orifices?

Distichiasis. Signup and view all the answers

What does MRD stand for and what is the value associated with it?

MRD stands for marginal reflex distance, with a value of 4mm. Signup and view all the answers

List the four components of Blepharophimosis Syndrome.

The components are blepharophimosis, ptosis, epicanthus inversus, and telecanthus. Signup and view all the answers

What are the complications associated with Lagophthalmos?

The complications include conjunctival and corneal issues. Signup and view all the answers

What is the primary treatment for Floppy Eyelid Syndrome?

The primary treatment is to first manage obstructive sleep apnea and then consider surgical repair. Signup and view all the answers

Identify the two main parts of the lacrimal gland.

The two parts are the orbital part and the palpebral part. Signup and view all the answers

What type of cells in the conjunctiva are responsible for mucin secretion?

Goblet cells in the conjunctiva are responsible for mucin secretion. Signup and view all the answers

What defines Floppy Eyelid Syndrome (FES) and its association with another condition?

FES is characterized by loose eyelids that easily evert and is strongly associated with obstructive sleep apnea. Signup and view all the answers

What is the meaning of tarsorrhaphy in the context of Lagophthalmos treatment?

Tarsorrhaphy refers to the surgical procedure to partially or fully sew the eyelids together to protect the cornea. Signup and view all the answers

Study Notes

Eyelids

Eyelid anatomy includes distinct layers: skin, orbicularis, tarsus, and palpebral conjunctiva.
Eyelid skin is the thinnest in the body, facilitating quick blinking for eye protection.
Superior palpebral crease is located 10 mm above the lid margin in Caucasian women and 8-9 mm in men, marking a skin adhesion boundary.
Lower eyelid features include three creases: inferior palpebral, nasojugal, and malar creases, contributing to eyelid shape and function.
Protractors of the eyelid are orbicularis oculi, responsible for eyelid movement.
The orbital septum acts as a barrier preventing infection spread between the orbit and eyelids; originates from the periosteum of orbital rims.
Upper lid retractor is the levator palpebrae superioris muscle; lower lid uses capsulopalpebral fascia.
Tarsus is a dense connective tissue plate in each eyelid, containing meibomian glands, crucial for tear film stability.

Common Eyelid Pathologies

Eyelash Disorders:
- Trichiasis: misdirected eyelashes; Distichiasis: aberrant cilia emerging through meibomian orifices.
Hordeolum (Stye):
- Internal: acute infection of meibomian gland; presents as a tender nodule.
- External: severe abscess of a lash follicle; treated with hot compresses and topical antibiotics.
Chalazion:
- Inflammatory reaction to meibomian gland secretions; related to conditions like blepharitis and seborrheic dermatitis.
Ectropion:
- Outward turning of eyelid leading to keratinization; primarily age-related or due to CN VII paralysis.
Entropion:
- Inward turning of eyelid; occurs congenitally or from scarring.
Blepharoptosis (Ptosis):
- Drooping of upper eyelid; causes include congenital factors and neurogenic issues.
- Symptoms include absent upper lid crease and poor levator function; treatment varies based on onset age and causes.
Blepharophimosis Syndrome:
- Characterized by horizontal shortening of the palpebral fissure and associated conditions; treated with frontalis suspension.
Lagophthalmos:
- Incomplete eyelid closure due to various causes, with significant complications for ocular surface health.
Floppy Eyelid Syndrome:
- Characterized by loose eyelids and associated with obstructive sleep apnea; treatment begins with addressing underlying conditions.

Lacrimal System

The lacrimal system comprises a secretory system (main and accessory lacrimal glands) and an excretory system.
Main lacrimal gland divided into orbital and palpebral parts, responsible for aqueous secretion.
Accessory glands (Krause and Wolfering) also contribute to lacrimal fluid production.
Goblet cells in the conjunctiva secrete mucin, essential for tear film stability.

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Description

This quiz explores various aspects of the eyelids and lacrimal system, including their anatomy and common pathologies. Understand the structure of the eyelids, such as the lamellae and skin components, while gaining insight into eyelid malposition and lid pathology. Perfect for medical students and professionals in ophthalmology.