OVERVIEW OF THE EYE Flashcards
The ciliary body lies directly ______ to the iris and it extends from ______ anteriorly to the _______ (as part of the uveal layer) or ________ (from an internal view by the vitreous) posteriorly.
.
This layer of the eyeball lies directly internal to the choroid:
Retinal pigment epithelium
The limbus of the eyeball is at the junction of the _______ with the _________
Cornea and sclera
This dimension is the largest dimension of the eyeball:
- anterior-posterior diameter:
- horizontal diameter:
- vertical diameter:
Anterior-posterior diameter: 24mm
Horizontal: 23.5 / Vertical: 23 (flatter vertical dimension)
This iris is the _____ boundary of the anterior chamber while the ______ is the peripheral boundary of the anterior chamber.
Posterior (along with the anterior surface of the lens behind the pupil)
The trabecular meshwork and anterior surface of ciliary body is the peripheral…
The posterior boundary of the posterior chamber is the ________
Anterior surface of the vitreous (anterior hyaloid membrane)
This region of the eyeball lies 1/2 way between the anterior and posterior poles of the eyeball:
Equator of the eye lies midway between anterior and posterior pole (each half around 12mm)
The optic nerve is formed by the ______ of _____ cells.
Axons of ganglion cells of the retina
These three ocular structures form the uveal layer of the eyeball:
______ & _______
Iris, ciliary body, choroid
Two major characteristics of the uveal layer are:
_______ & _______
Vascular and highly pigmented (contains melanocytes)
Iris and CB also have pigment granules in epithelium
A retinal detachment occurs between these 2 layers of the retina:
9 layers of the neurosensory retina and the RPE cells
The medial boundary of the posterior chamber is the ________
Pars plicata of the ciliary body and equatorial zone of the lens
The posterior boundary of the anterior chamber is formed by: ___________
Iris and anterior surface of the lens (behind pupil)
The ______ (inner or outer?) layers of the retina lie adjacent to the vitreous.
Inner
The retina extends from the _______ anteriorly to the _______ posteriorly.
The retina extends from the ciliary body (anteriorly) to the optic nerve (posteriorly) and lies directly adjacent to the choroid
Just anterior to the optic nerve, this layer of the eyeball lies directly internal to the sclera:
____________
Choroid
What is the optic disc? __________
The anterior surface of the optic nerve that is visible during direct ophthalmoscopy
Looking at the optic disc is just like you are standing in the vitreous looking at the optic nerve (eraser of a pencil)
The approximate anterior-posterior dimension of the eye is: _______ mm.
24 mm
Externally on the eye, what is the approximate location of the posterior edge of the ciliary body inside the eye?
Externally on the eye, where does the ciliary body terminate anteriorly inside the eye?
Posteriorly in the eye, the zonules originate from the _____. Be specific.
The point of insertion of the rectus muscles into the sclera approximates the location of the posterior edge of the ciliary body inside the eye.
Anterior border of ciliary body is at the edge of the iris
They extend from pars plana of the ciliary body (near the ora serrata) to the lens capsule
(CO) 1. describe/state the approximate dimensions of the eyeball (vertical, horizontal & anterior-posterior)
see previous question
(CO) 2. define the following terms and locate them on a figure of the eyeball: limbus, anterior pole, posterior pole, optic axis, visual axis, equator of the eyeball, optic disc, optic nerve, lamina cribrosa, zonules, lens, vitreous, hyaloid membrane of the vitreous, fovea, ora serrata, anterior chamber, posterior chamber, cornea, sclera, iris, ciliary body, choroid, retina, bulbar conjunctiva, fornix, palpebral conjunctiva
Limbus: juncture where the cornea & sclera are continuous with each other
Anterior pole: center of curvature of the cornea
Posterior pole: center of the posterior curvature of the eyeball
Optic axis: line connecting anterior and posterior pole
Visual axis: line passing from cornea to the fovea
Equator: line midway between the anterior pole & posterior pole of the eye
Optic disc: see previous question
Optic nerve: formed by the axons of cells in the retina called the ganglion cells; exits back of eyeball slightly nasal to posterior pole (in contrast, the FOVEA is temporal to posterior pole)
Lamina cribosa: the part of the sclera the ganglion cell axons pass through to exit the eyeball (full of holes to allow ganglion cell axons to exit)
Zonules: Thin connective tissue strands that extend from pars plana of the ciliary body
(near the ora serrata) to the lens capsule (made of glycoprotein arranged as microfibrils; NOT typical elastic fibers)
Lens: Biconvex disk located posterior to the
iris & anterior to the vitreous (enclosed in capsule); its main job is to focus light on retina
Vitreous: Transparent gel that fills the space between the lens and retina. It has the consistency of the “white” of a raw egg. It is also a reservoir of metabolites for retina/lens.
Hyaloid membrane of vitreous: The vitreous is enclosed by the “hyaloid membrane” (which is a condensation of collagen fibrils at the outer edge of the vitreous).
Fovea: The fovea is the specialized region of the retina where a person has the highest visual acuity, formed by peripheral displacement of inner retinal layers
leaving the outer layers of the retina (including the photoreceptors) in the foveal region.
Ora serrata: anterior termination of the retina; as the retina approaches anterior eyeball, it gets thinner and thinner until it meets the CB. This junction is called ora serrata.
Anterior chamber: small space lying behind the cornea
anterior boundary = posterior surface of cornea
peripheral boundary = TM and anterior surface of CB
posterior = iris and anterior lens behind pupil
Posterior chamber: a slit-like space lying behind the iris
anterior boundary = posterior iris surface
lateral/medial = pars plicata of CB; equatorial zone of lens
posterior = anterior surface of vitreous (anterior hyaloid membrane)
Cornea: cornea is a clear fibrous layer forming the anterior 1/6 of the eyeball (major refractive structure)
Sclera: sclera is an opaque white fibrous layer composed of collagen that covers the
posterior 5/6 of eyeball
Iris: Sheet-like circular diaphragm anterior to the lens
Ciliary body: structure containing smooth muscle, divided into 2 parts
(1) pars plicata - anterior, folded region (the folds are called “ciliary processes”) (2) pars plana - posterior, flat region
Choroid: It is the part of the uveal tract that lies posterior to the ciliary body, extends from CB anteriorly to optic nerve posteriorly. Contains blood vessels + capillary bed supplying outer retinal layers
Retina:Innermost layer of the eyeball; a thin (0.1mm - 0.5mm), transparent, photosensitive layer of neural tissue extending from CB (anterior) to optic nerve (posterior) composed of 10 layers (know in detail)
Bulbar conjunctiva: anterior part of the sclera is covered by a transparent layer called the bulbar conjunctiva. The bulbar conjunctiva begins at the limbus & covers the eyeball for a variable distance (least = nasal; most = temporal)
Fornix: at the fornix the bulbar conjunctiva is reflected onto the posterior surface of the eyelid as the palpebral conjunctiva
(CO) 3. correctly label all the various parts of the eyeball on a diagram or eyeball model. Be specific where needed.
see previous question
(CO) 4. describe the three layers of the eyeball including:
• the names of the three layers
• general characteristics of the 3 layers or their parts (i.e. sclera opaque; cornea clear;
uveal tract highly vascular and highly pigmented, etc.)
• name the structures that form each layer
• state the 2 parts of the ciliary body and how to distinguish them
• describe the relationships of the structures in each of the three layers of the eye both within a layer and between layers as discussed in the lecture (i.e. anterior vs.posterior and internal vs. external)
OUTER LAYER = cornea + sclera
MIDDLE UVEAL LAYER (surrounds retina/vitreous and looks like a grape) = iris, CB, choroid
INNERMOST LAYER = retina (adjacent to choroid)
2 parts of Ciliary Body = (1) pars plicata - anterior, folded region (the folds are called “ciliary processes”) (2) pars plana - posterior, flat region
(CO) 5. state the position of the ciliary body on the exterior of the eye as shown in the lecture
notes. (Why? To make you aware of how anterior the retina extends in the eyeball).
see previous question
(CO) 6. state how far anteriorly and posteriorly the ciliary body extends (i.e. as far forward as this
structure: ________________ and as far posteriorly as this structure:______________ and how the posterior border is different depending if looking from the vitreous vs. looking within the uveal layer.
CB anterior border = end of iris and posterior border = where EOMs end and insert into sclera
Differences: The internal view of the retina is as if you are in the vitreous looking at it. Then the ciliary body (CB) appears directly anterior to the retina not the choroid. The ciliary body lies anterior to the choroid if looking at the uveal layer.
(CO) 7. for the retina:
• describe how many layers there are to the retina and the name of its outermost layer
• describe where a retinal detachment occurs (the separation occurs between which
layers of the retina?)
• describe which layers of the retina are present at the fovea (inner or outer layers?)
• how far anteriorly and posteriorly the retina extends (i.e. as far forward as this structure:
________________ and as far posteriorly as this structure:______________
- 10 layers; outermost = RPE
- Retinal detachment is between 9 neurosensory layers and RPE
- Layers of the outer retina are present at the fovea (from OPL outward; Henle’s Layer = OPL @ fovea)
- anterior = edge of CB (ora serrata) and as posterior as choroid in the back of the eye/surrounding optic nerve
(CO) 8. describe & name the boundaries of the anterior chamber of the eye
see previous question
(CO) 9. describe & name the boundaries of the posterior chamber of the eye
see previous question
(CO) 10. describe the bulbar conjunctiva including:
• its location on the eye
• where it approximately begins
see previous question
(CO) 11. describe/state what forms the optic nerve
see previous question
(CO) 12. describe what the optic disc is compared to the optic nerve
see previous question
(CO) 13. describe which parts of the eye are circular or form an annulus = ring. For example, the iris
is an annulus. (Why do this? So you have a sense of the three dimensional shape of some of these structures).
.
