Anatomy of the eyeball 1

Question 1

the protective layer of the eyeball (tenant’s capsule):

Answer 1

thin membrane that envelops the eyeball from theoptic nerveto thecorneal limbus, separating it from the orbital fat and forming a socket in which it moves.

Question 2

the episclera

Answer 2

outermost layer of the sclera composed of loose, fibrous, elastic tissue and attaches toTenon’s capsule.
A vascular plexus is found between thebulbar conjunctivaand the sclera consisting of two layers of vessels, the superficial episcleral vessels and the deep episcleral vessels

Question 3

cornea VS sclera:

Answer 3

• cornea:
  Higher convexity
  Completely avascular
  Receives nourishment from the lacrimal gland (outside) and aqueous humor (inside)
  Highly sensitive (CN V1)
• sclera:
  Relatively avascular
  Provides insertion to the muscles
  Less sensitive
  Arrangement of collagens allows needing for less hydration

Question 4

cornea VS sclera VS limbus:

Answer 4

slide 10

Question 5

scleral icterus:

Answer 5

(yellow eyes). This condition — also called icteric sclera — is a yellowing of the white of the eye. It is associated with hepatitis and other liver diseases.

Question 6

scleritis:

Answer 6

inflammation of both the episclera and the underlying sclera itself. Up to 50 percent of cases of scleritis involve an underlying systemic disease, such as rheumatoid arthritis.
Generally, the onset of scleritis is gradual, and most patients develop severe, piercingeye painover several days. This pain tends to worsen with eye movements. In most cases, the inflammation begins in one area and spreads until the entire sclera is involved.

Question 7

uveal tract:

Answer 7

• Iris: The colored part of the eye (e.g., brown, blue) that controls the size of the pupil, regulating how much light enters the eye.
• Ciliary Body: Located behind the iris, the ciliary body produces aqueous humor (the fluid in the front part of the eye) and contains the ciliary muscle, which helps the eye focus by changing the shape of the lens.
• Choroid: The layer of blood vessels and connective tissue between the retina and sclera. The choroid supplies oxygen and nutrients to the outer layers of the retina, essential for visual function. continues anteriorly with ciliary body

Question 8

role of iris: function (sympathetic vs parasympathetic system):

Answer 8

• function: sphincter muscle within iris adjusts pupillary size in response to light + autonomic system
• parasympathetic system = light exposure: miosis (narrows pupils) + sphincter pupillae muscle
• sympathetic system = darkness: mydriasis (widens pupils) + dilator pupillae muscle

Question 9

function of aqueous fluid:

Answer 9

• Deliveryofoxygen & nutrientsandremoval of waste products, inflammatory products, and other cellular debris from the posterior cornea and crystalline lens
• Provision of a low refractive indextransparent mediumbetween the lens and cornea
• Maintenance ofintraocular pressure (IOP)for optimal shape and alignment of ocular structure

Question 10

aqueous fluid formation:

Answer 10

slide 19

Question 11

solute present compared to aqueous concentration relative to plasma:

Answer 11

• sodium = =
• proteins = vrm peu peu
• ascorbate = vrm bcp bcp

Question 12

passage of aqueous fluid:

Answer 12

Aqueous fluid is formed by the ciliary body and secreted into the posterior chamber.
The fluid traverses the pupil to enter the anterior chamber and exits the eye through one of the two drainage pathways:
Thetrabecular meshwork route
Theuveoscleralroute

Question 13

IOP + which one = produced in the back and which one in the front + how they are regulated in and out of the body:

Answer 13

• The chamber at the back of the eye is filled with vitreous humor (a thick, gel-like material).
• A liquid called aqueous humor fills the area at the front (the space between the cornea and iris).
• Aqueous humor is thinner and waterier than vitreous humor.
• The body regulates IOP automatically. As eyes create new aqueous humor, an equal amount of older aqueous humor leaves the eye.
• Old aqueous humor runs out through the drainage angle.
  (- IOP is measured with a test called tonometry. Tonometry measures the pressure inside the eye by flattening the cornea. The more force that’s needed to flatten the cornea, the higher is the eye pressure)

Question 14

aqueous exit pathways:

Answer 14

1. The trabecular meshwork route:
   Aqueous traverses the TM, across the inner wall of Schlemm’s canal (SC) into SC. From there, it passes into collector channels, aqueous veins, and episcleral veins. It accounts for most aqueous drainage (50–75 %); this may increase with age. This pathway is pressure sensitive; outflow increases with greater IOP.
2. The aqueous freely passes from the anterior chamber angle into the connective tissue spaces within the ciliary muscle via the iris root and anterior face of the ciliary body.
   - (Uveoscleral flow is Intra ocular pressure independent (IOP). It is consistently less than IOP and is constant. This is why uveoscleral flow keeps on draining despite IOP fluctuations, PCQ: Inflammation causes the TM to become clogged by inflammatory cells and debris reducing trabecular outflow; however, locally produced prostaglandins enhance uveoscleral drainage of the aqueous preventing dangerously high IOP)

Question 15

refractive media of the eye:

Answer 15

These are the parts of the eye that help focus light so we can see clearly. They include:
The Cornea - The transparent front layer of the eye that refracts (bends) light.
The Aqueous Humor - A clear fluid in the anterior (front) segment of the eye that maintains pressure and provides nutrients.
The Lens - The transparent structure that focuses light onto the retina.
The Vitreous Humor - A gel-like substance filling the back of the eye, maintaining its shape.

Question 16

flow path of aqueous humour: (from prod to IOP (regulation en passant par venous drainage):

Answer 16

• Posterior Chamber (Post chamb) - Aqueous humor is produced here by the ciliary body.
  Anterior Chamber (Ant chamb) - The fluid flows from the posterior chamber through the pupil into this chamber.
  Iridocorneal Angle - This is the angle formed where the iris meets the cornea. It is also known as the anterior chamber angle and is crucial for draining aqueous humor.
  Scleral Venous Sinuses - These are channels (often called Schlemm’s canal) where the aqueous humour drains from the anterior chamber and into the blood circulation.
• Limbic Plexus - A network of small veins around the limbus (the junction between the cornea and sclera).
  Vorticose & Anterior Ciliary Veins - These veins help drain the aqueous humor from the eye, leading it into the general venous circulation.
• IOP represents the pressure inside the eye, which is maintained by the balance between the production and drainage of aqueous humor. Elevated IOP can lead to conditions like glaucoma, which can damage the optic nerve and impair vision.