Ocular anatomy Exam #1

Posterior pole - define and label

- center of the posterior curvature of the eyeball - the optic nerve exit the back of the eyeball slightly nasal to the posterior pole of the eyeball.

Anterior pole - define and label

- found in the center of curvature of the cornea.

Optic axis - define and label

- is the line connecting the two poles. NOT = to the visual axis which passes through the fovea.

Retina - define and label

- some of the the 9 sensory layers of the retina contain cell bodies (ganglion cell bodies) other do not have cell bodies and they have dendrites and axons which is where synapses occur

Ciliary body - define and label

-The anterior posterior extent of the CB (from the iris to the anterior edge of the retina aka the ora serrata) is the ciliary body width.

Equator of the eyeball - define and label

-lies midways between the anterior pole and the posterior pole of the eye. - located 12 mm posterior to the anterior pole ??: the region of the eyeball lies 1/2 way between the anterior and posterior poles of the eyeball: the equator

Lens - define and label

= biconvex disk located posterior to the iris and anterior to the vitreous = enclosed in a capsule = focuses light on the retina. - the iris is a sheet like circular diaphragm just anterior to the lens. - zonules attach to the lens capsule - vitreous body is a transparent gel that fills the space between the lens and the retina - lens is part of the anterior segment of the eye; NOTE the posterior segment is defined as the portion of the eyeball posterior to the lens. VS anterior segment is defined as the portion of the eyeball between the cornea and the posterior surface of the lens ??: the medial boundary of the posterior chamber is the equatorial zone of the lens OR the pars plicata of the CB

Hyaloid membrane of the vitreous - define and label

= encloses the vitreous, vitreous is not uniform, condensation of collagen fibrils at the outer edge of the vitreous - posterior chamber of the eyeball's posterior boundary is the anterior surface of the vitreous AKA the anterior hyaloid membrane

Ora serrata - define and label

= anterior termination of the retina. Serrata refers to the scalloped appearance of the edge. Anteriorly the retina becomes thinner and thinner until the retina ends and the CB begins. —> RETINA IS THICKEST IN THE BACK NEAR THE OPTIC NERVE THEN GET THINNER UNTIL CB BEGINS Retina —> ora serrata —> pars plana —> par plicata Zonules extend from the pars plana of the CB (near the ora serrata)

Optic disc - define and label

= antreior surface of the optic nerve that is visible during the direct ophthalmoscopy (or with 90D/78D lens) - looking at the optic disc is just like you are standing in the vitreous and looking at the optic nerve. ??: What is the optics disc? Anterior surface of the optic nerve.

Vitreous - define and label

= eyeball is filled with clear/transparent gelatinous material called vitreous =maintains the shape of the eye and retina in position =Reservoir for metabolites =Shock absorber - Internal to the retina -anterior surface of the vitreous is the posterior boundary of the posterior chamber - part of the posterior segment portion of the eyeball - "Fills the eye" - the 9 inner sensory layers of the retina lie close to the vitreous - has a consistency of the white of an egg - lens is anterior to the vitreous =enclosed by the hyaloid membrane. —> VITREOUS IS NOT UNIFORM = the vitreous functions to transmit light and hold the retina in its proper position - if you are standing in the vitreous this means you have an internal/clinical view: Ie. Internal view point the ciliary body extends from the iris to the anterior edge of the retina called the ora serrata. = CB appears directly anterior to the retina not the choroid because the CB lies anterior to the choroid if looking at the uveal layer. (RECALL uveal layer is iris CB then choroid) Vitreous —> retina —> choroid —> sclera Vitreous —> neural sensory layers -> RPE -> choroid —> Sclera ??: the inner layers of the retina lie adjacent to the vitreous

Optic nerve - define and label

= formed by the axons of cells in the retina called the ganglion cells. = exits the back of the eye ball slightly nasal to the posterior pole - optic disc is the anterior surface of the optic nerve - part of the posterior segment of the eyeball - the choroid extends from the CB anteriorly to the optic nerve posteriorly - the retina extends from the CB anteriorly to the optic nerve posteriorly and lies directly adjacent to the choroid [internal to choroid] ??: the optic nerve is formed by the axons of the ganglion cells. ??: the retina extends from the ciliary body [pars plana] anteriorly to the optic nerve posteriorly.

Iris - define and label

= part of the middle layer, uveal, of the eye along with the CB and the choroid. =sheet like circular diaphragm anterior to the lens. =When the iris is viewed from the front of the eye it is a complete ring with a central hole called the pupil. = with an anterior view the iris is seen through the cornea. = contraction of the sphincter or dilator papillae muscle of the iris regulates the size of the pupil and therefore the amount of light coming into the eye through the pupil.

Cornea - define and label

= the anterior pole is found at the center of curvature of the cornea. = the outer layer of the eye is comprised of the cornea and sclera. = the cornea is a clear FIBROUS layer forming the anterior 1/6 of the eyeball. = cornea and sclera are continuous with each other but come together at the "juncture" called the limbus. = With an anterior view, the iris is seen through the cornea. = the anterior boundary of the anterior chamber is the posterior surface of the cornea. = anterior segment is the portion of the eyeball between the cornea and the posterior surface of the lens.

Lamina cribrosa - define and label

= the part of the SCLERA the ganglion cell axons pass through to exit the eyeball. = this region of the sclera is full of "holes" and the ganglion cells axons exit the eyeball through these "holes"

Zonules - define and label

= thin connective tissue strands that extend from the pars plana of the CB (near the ora serrata) to the lens capsule = composed of glycoprotein arranged as microfibrils - zonules pass through the posterior chamber and attach to the lens capsule - zonules originate from the pars plana of the CB - zonules are part of the anterior segment (along with the lens) ??: posteriorly in the eye, the zonules originate from where? The CB (pars plana).

Fovea - define and label

= visual axis passes through the fovea =specialized region of the retina where a person has the highest visual acuity - Needs to be intact and healthy for 20/20 vision. = it lies in the TEMPORAL RETINA. - formed by the peripheral displacement of the inner retinal layers leaving only the outer layers of the retina (including the- photoreceptors) in the foveal region... THIS ARRANGEMENT ALLOWS FOR INCOMING LIGHT TO HAVE A GREATER, MORE DIRECT ACCESS TO THE PHOTORECEPTORS THAN ELSEWHERE. = because of the change in contour (as the inner retinal layers are displaced and it is only the outer layers that causes this "dip") it gives off a fovea light reflex.

SIDE NOTE: anatomically VS clinically anterior to posterior

Anatomically: iris, pars plicata, pars plana, choroid (uveal tract, 2nd layer) Clinically: pars plana —> retina. Internal of eye Vitreous Retina Choroid Sclera External of eye

Anterior chamber - define and label

Anterior and posterior chambers are interconnected by the pupil. They both contain aqueous humor The anterior chamber is a small space lying behind the cornea and its boundaries are: 1. Anterior = posterior surface of the cornea 2. Posterior = iris and anterior surface of the lens [where the pupil is] 3. Medial = NONE, no medial because it covers the entire front surface. 4. Peripheral/lateral = trabecular meshwork and anterior surface of the ciliary body. ??: the iris is the posterior boundary of the anterior chamber while the trabecular meshwork and the anterior surface of the ciliary body (pars plicata) is the peripheral boundary of the anterior chamber. ?? The posterior boundaries of the anterior chamber is formed by: Anterior surface of the lens and the iris

Describe/ state the approximate dimensions of the eyeball (vertical, horizontal and anterior-posterior)

Anterior-posterior = 24 mm Horiztonal = 23.5 mm Vertical = 23.0 mm NOTE: the eyeball is FLATTER in the vertical dimension compared to the horizontal and AP dimensions

State the position of the ciliary body on the exterior of the eye as shown in the lectures notes —> this is to make sure you are aware of how anterior the retina extends in the eyeball.

Ciliary body runs parallel to the limbus. Internal view/clinical view = ciliary body extends from the iris to the anterior edge of the retina called the ora serrata BUT here asking what the exterior of the eye position is and that is at the limbus (where iris ends and CB starts)

Posterior chamber - define and label

Interconnected with the anterior chamber by the pupil 1. Anterior: posterior surface of the iris 2. Posterior: anterior surface of the vitreous ( aka the anterior hyaloid membrane) 3. Medial: equatorial zone of the lens OR the pars plicata of the ciliary body . 4. Peripheral/lateral : equatorial zone of the lens OR the pars plicata of the ciliary body . - zonules pass through this space to get from the pars PLANA to the lens capsule. THINK OF AN INNERTUBE. Part of the anterior segment (along with the anterior chamber too) ??: the posterior boundary of the posterior chamber is the anterior surface of the vitreous (anterior hyaloid membrane) ??: the medial boundary of the posterior chamber is the : equatorial zone of the lens OR the pars plicata of the CB

Limbus - define and label

Junction where the cornea and sclera are continuous with each other EXTERNALLY bulbar conjunctiva begins at the limbus ??: The limbus of the eyeball is at the junction of the cornea with the sclera.

Visual axis - define and label

Passes through the fovea.

RETINA: describe where a retinal detachment occurs (separation occurs between which layers of the retina?)

Retinal detachment occurs and the RPE cells remain attached to the choroid while the 9 sensory layers of the retina separate from the RPE cells (the 10th outermost layer of the retina) There are 10 layers total. The outer pigmented layer is the single layer of cells that lies adjacent to the choroid (internal to the choroid) and is called the retinal pigmented epithelium or RPE while the 9 sensory layers of the retina lie close to the vitreous The 5 outermost layers of the retina (4 sensory and 1 RPE) gets nutrients from the choroid.

Describe the three layers of the eye ball: general characteristics of the 3 layers or their parts

Sclera = opaque Cornea = clear Uveal tract = highly vascular and pigmented

Sclera - define and label

Sclera is the opaque FIBROUS layer composed of collagen that cover the posterior 5/6 of the eyeball. Externally the anterior part of the sclera is covered by a transparent layer called the bulbar conjunctiva that begins at the limbus and cover the eyeball for a variable distance. At the fornix the bulbar conjunctiva reflects onto the posterior surface of the eyelid as the palpebral conjunctiva The ciliary body when viewed from the front of the eye is a completed ring that runs around the inside of the eyeball just deep to the sclera. The point of insertion of the rectus muscles in to the sclera approximates the location of the posterior edge of the CB inside the eye. ??: The limbus of the eyeball is at junction of the cornea with the sclera. ??: just anterior to the optic nerve, this layer of the eyeball lies directly internal to the sclera: Choroid.