ANATOMY OF THE LENS

ANATOMY OF THE LENS

let's see anatomy of the lens there's no

blood supply or innervation so it

depends on aqueous for nutrient delivery

and waste removal.

we know that what it

does reflects like some interesting

concept. I guess you look at it with

aging terms of changes sometimes there's

a myopic shift sometimes there's a hyper

optic shift. we know it's always

increasing in curvature but the very

changes in index of refraction can alter

the actual refractive effect of that

Size at birth

versus size in adults so those are sort

of important anatomic considerations if

you're cataract surgeon just remembering

that in adult size is really about five

millimeters thick at most so you got

about five millimeters of depth before

you're puncturing a posterior capsule

with whatever instrument you're using

all right the capsule elastic membrane

type for collagen just remember its

thinnest posterior to four microns

pretty impressive how strong it is

despite its  thin nature there. you

can see it's thickest equatorial and

centrally about 14 microns as annuals

microfibrils composed of elastic tissue

they originate for the non pigmented

epithelium of the ciliary body the

insert in a continuous fashion

equatorial region you can see they

insert just a little bit more central

anteriorly versus posteriorly and with

age of course the fibers regress the

equatorial fibers will progressively

they mostly just an tear in poster

fibers  lenz epithelium is a single layer and of course there's active replication and

the anterior equatorial region as we all

know the newly formed cells as we know

they migrate equatorially and posterior

lis forming new lines fibers losing

their organelles that through that

process and of course because they have

no organelles they depend on glycolysis

class let's see

so those highlights here of course no

cells are lost from the lens the oldest

form the nucleus so you'll see that

fetal or embryonic suture pattern and

newest form the outermost aspect at the

you know the cortex we've seen the lens

sutures onyx those who have looked on

slit lamp exam major digitation z--

their the apical and basal cells. we see

optical zones when you look at a lens so

you might notice that there's sort of

this delineation of an endo nucleus a

central lens component versus the EPI

nucleus or cortical material when you

look at cataracts or a similar finding

except it's not a clear lens obviously

it's a cloud at the some degree there's

no morphologic distinction between the

cortex and nucleus though you know we

have these surgical delineations that we

talk about or discuss when you actually

look at it from a pathology assessment

histologically  there's really no

differentiation lens up to the Lens  cells

 those lens cells look the same

let's see crystalline proteins that make

up a lot of what is left over once the

lens has eliminated its organelles you

see some fascinating concepts about it

and

maybe you should read about this

sometime it's not super exciting as

that I know as you age you start to lose

some of the it says here maybe it's the

next slide here membrane structural

proteins and skeletal proteins or

anything highlight that I could take off

of here while you're reading it here it

is  the increase of water with age this is actually you

know important to understand as we get

older protein aggregates into large

particles they become water insoluble

that's going to result in opacity Claire

reduce clarity or cataract so scatter

they scatter lights of course certain

amount of this process appears to be

normal with maturation of lens cells the

seeing clear lenses with the excess of

it results in the cataract formation.