Ocular adnexa and the lacrimal system

What is the function of our eyelids?

• Protection for the globe

• •Acts as a shutter, closing during sleep

• Move tears towards lacrimal drainage system

• Spread tear film over anterior eye surface

• Contains structures that produce tear film

what structures make up the eyelid

1. superior palpebal sulcus

2. tarsal

3. orbital

what are structures at the medial canthus

1. plica semilunaris

2. caruncle

what are the types of glands in eye

1. Lacrimal Gland

   • Function: Produces tears for lubrication and protection.

   • Location: Above the outer corner of the eye.

2. Meibomian Glands

   • Function: Secretes oils to prevent tear evaporation.

   • Location: Inside the eyelids.

3. Goblet Cells

   • Function: Produces mucus to help tears stick to the eye.

   • Location: Conjunctiva (clear membrane on the eye).

4. Conjunctival Glands

   • Function: Produces extra tears for moisture.

   • Location: Conjunctiva.

5. Ciliary Glands

   • Function: Secretes fluid to keep lashes clean.

   • Location: Base of eyelashes.

6. Sweat Glands

   • Function: Keeps the skin around the eyes cool and moist.

   • Location: Eyelids.

what are meibomian glands

1. large sebaceous glands

2. release meibum into tear film

what are zeis glands and glands of moll

• found in eyelash follicle

• contain antimicrobial properties

what are the types of palerbral glands

• Meibomian glands: These are located within the tarsal plates of the eyelids. They produce an oily substance that helps keep the eyes lubricated by preventing the tear film from evaporating too quickly. These oils are secreted onto the surface of the eye through small openings along the edge of the eyelids.

• Zeis glands: These are sebaceous glands found near the eyelashes. They secrete an oily substance that helps lubricate the eyelashes and the eyelid skin.

• Moll glands: These are sweat glands located in the eyelid margin. They contribute to lubricating the eyelids.

what are palpebraal glands

glands found in the eyelids.

what are the functions of the tear film

• Refractive interface

• Lubricates the ocular surface and eyelids

• Smooths corneal abnormalities

• Provides oxygen to the cornea

• Antibacterial function

• Flushes debris and foreign bodies

what produces and drains tears

lacrimal system

what are the layers of the tear film

1. lipid layer

2. aqueous layer

3. mucus layer

what makes up the mucous layer of the tear film

1. glycocalyx

2. mucoproteins

what makes up the aqueous tear film layer

1. proteins

2. water

3. electrolytes

what components make up the liquid tear film layer

meibum

1. non polar lipids - wax esters and cholesterol

2. phospholipids

where does lacrimal secretion occur from

• Main lacrimal gland

• Accessory glands (Krause and Wolfring)

• Conjunctival goblet cells

• Meibomian glands

where does Nasolacrimal drainage occur from

• Punctum

• Canaliculus

• Lacrimal sac

• Nasolacrimal duct

• Valve of Hasner

what are main features of the main lacrimal gland

1. sits in a fossa in the frontal lobe

2. divided into two portions: orbital , palpebral

what is nasolacrimal drainage system

refers to the pathway through which tears are drained from the eyes into the nasal cavity. This system helps keep the eyes moist and clear of debris

What is the process of nasolacrimal drainage

• Tear Production: Tears are produced by the lacrimal glands, located above the outer corners of each eye.

• Tear Distribution: When you blink, tears spread across the eye's surface, helping to lubricate and clean it.

• Drainage: After they serve their purpose, tears are drained through small openings called puncta, located in the corners of the upper and lower eyelids.

• Canaliculi: The tears pass from the puncta into small channels called canaliculi.

• Lacrimal Sac: The canaliculi lead to the lacrimal sac, which is located at the inner corner of the eye.

• Nasolacrimal Duct: From the lacrimal sac, tears travel down the nasolacrimal duct into the nasal cavity, which is why your nose can get runny when you cry.

what is used to test nasolacrimal drainage

fluorescein dye

what is the aveage thickness of the conjunctiva

33 microns

what is the conjunctiva

thin clear layer on top of the sclera

what are the functions of the eyeball

1. smooth movement of the eyeball

2. lines the inner eyeball

3. joins eyeball to eyelid

4. secretes mucous for the tear film

what are the three parts of the conjunctiva

1. Palpebral conjunctiva : Part lining the eyelids, Starts at fornices and ends at eyelid margins.

2. Bulbar conjunctiva : Covers sclera , Starts at limbus and ends at fornices.

3. Conjunctival fornix : The transition region between bulbar and palpebral conjunctiva.

what is the structure of the conjunctiva

1. loose connective tissue

2. epithelial cells

3. goblet cells secrete mucous and located on fornix

what is the conjunctivas blood supply like

1. highly vascularised

2. smaller vessels in the conjunctiva

3. larger vessels in underlying episclera

what are related condition that elevates mass of conjunctival tissue

pinguecula and pterygium

what causes pinguecula and pterygium

uv radiation exposure and long term eye irriation

what are symptoms of pinguecula

1. yellowing of conjunctiva

2. breakdown of collagen in the eye

3. formation of abnormal elastic tissue

what happens in pterygium

head invades the cornea