Lecture 1/12 Flashcards
2 main veins involved in the eye
- superior ophthalmic vein
- inferior ophthalmic vein
which is the larger of the 2 orbital veins?
superior ophthalmic vein
route of the superior ophthalmic vein
starts with an anastomosis on face, then flows posteriorly out of orbit through superior orbital fissure, then enters into cavernous sinus
contributors to the superior ophthalmic vein
- anterior and posterior ethmoidal
- lacrimal
- muscular branches (SR, SO, levator, MR)
- vortex veins
- central retinal vein (CRV)
- anterior ciliary veins
what do the vortex veins drain?
the choroid
where is the central retinal vein found and what is the variation in the SOV?
found on the lateral site and exits through optic nerve head
-it may or may not join the SOV to the cavernous sinus
drainage of the anterior ciliary veins
drain the ciliary body
-receive branches and blood from the conjunctiva and the episcleral venous plexus
route of the inferior ophthalmic vein
begins with anastomosis on face near the inferior margin of the orbit, then passes posteriorly on the floor of the orbit and goes to the cavernous sinus
inferior ophthalmic vein receives from:
- muscular branches (IR, IO, LR)
- vortex veins (lateral, medial)
what is the unique small branch from the inferior ophthalmic vein?
small branch that goes down from inferior orbital fissure to pterygoid plexus
direction of flow posteriorly from SOV
SOV -> cavernous sinus -> jugular foramen -> internal jugular
direction of flow posteriorly from IOV
IOV -> cavernous sinus -> jugular foramen -> internal jugular
direction of flow inferiorly from IOV
IOV -> pterygoid plexus -> external jugular
what is the shape of the lens?
biconvex
which is flatter: the anterior or posterior surface of the lens?
the anterior surface is flatter
radius of curvature of the anterior surface of the lens
10 mm
radius of curvature of the posterior surface of the lens
6 mm
what is the area of the largest diameter of the lens called?
the lenticular equator
along the edge
what is the lenticular axis
the theoretical line from anterior pole to posterior pole through the lens
what is the lens diameter of an unaccommodated lens viewing distant object
9-10 mm
unaccommodated lens thickness is:
4-5 mm
describe the placement of the lens in the eye
suspended posterior to the iris from the circular ciliary body and in the center of it
what is the space between the lens and the ciliary body called?
circumlental space (0.5 mm)
2 spaces of the lens
- between lens and ciliary body
- behind the lens and vitreous
describe the attachment at the capillary space of Berger
firm attachment in a circle around this potential space
-diameter is 8-9 mm
(on the posterior side of the lens)
how is the lens attached to the ciliary body?
at zonules
composition of the lens
66% water
33% protein (water soluble and water insoluble)
list the 3 parts of the lens
- capsule
- anterior epithelium
- lens substance
where is the thinnest part of the lens capsule?
at the posterior pole
the anterior pole is about 4x as thick
where are the thickest parts of the lens?
circular zones (one anterior, one posterior)
what is the diameter difference between the circular zone on the anterior and posterior sides of the lens?
anterior: 3 mm in diameter
posterior: 4 mm in diameter
what are the two lens capsule zones on a cross section?
- outer zonular
- inner cuticular
what is the origin of the lens capsule?
formed during embryonic development (not added to in life after birth)
outer zonular section of the lens capsule is where:
zonules attach, made of dense fibers
describe the inner cuticular zone of the lens capsule:
(capsule proper)
about 30-40 lamellae
describe lens elasticity and age changes
capsule has low amounts of lens tissue (it is mostly collagen) the lens assumes spherical shape on its own but as a person ages, the lens loses elasticity and is less likely to assume that spherical shape
what is unique about the cell types in anterior epithelium of the lens?
describe as cuboidal epithelium, but not cuboidal throughout the whole length (cuboidal at the pole)
what is the “lenticular shagreen”
the dimpled appearance of the anterior surface of the lens (obvious with slit lamp)
what are the 3 regions of the anterior epithelium?
- central zone
- intermediate zone
- equatorial zone
describe the central zone of the lens anterior epithelium
- cells look flattened
- low metabolic activity
describe the intermediate zone of the lens anterior epithelium
- cells are square (cuboidal)
- metabolism picking up
describe the equatorial zone of the lens anterior epithelium
- cells elongate
- high metabolism
- area of mitosis (forming new lenticular fibers throughout life)
lens thickness changes with age
lens tends to thicken as you age
causes more pressure against the iris, leading to aqueous flow problems
what is the lens substance made up of
lenticular fibers
describe fibrillar projections
anterior to posterior, form new lenticular ones and earlier ones get pushed towards center and lose nuclei
how many sides does a lenticular cell have and what lines them up?
6 sided cell with interdigitations to keep the cells lines up but to allow some movement
what are the 2 main lens zones ?
- inner zone (nucleus)- older cells
- outer zone (cortex) -newer cells
what lens gradient changes occur with age?
the cortex to nucleus gradient is smoother in a younger lens
development of the lens at 1-2 months
embryonic nucleus: round structure right in the center of the nucleus
development of lens at 3-8 months:
fetal nucleus- forms around the other
development of the lens at birth and on
adult nucleus- always adding throughout life
what are lens sutures?
all fibers that meet in close proximity along these sutures (at the poles) instead of all meeting in one spot
