Foveola- (0.35mm dia.). 

densest population of cones that have the smallest cross-sectional diameter of all the photoreceptors/Red and Green sensitive cones only No rods or Blue cones. 

Fovea- (1.5 mm dia

shallow depression in the center of the macular region The curved wall of the depression is known as the clivus.  High concentration of cones and is capillary free

Parafovea

contains the largest accumulation of retinal bipolar and ganglion cells (0.5mm dia. Annulus outside fovea).

Perifovea-

area begins where the ganglion cell layer if four cells thick & ends where it is one cell thick (1.5mm dia.).   

Ora Serrata

the peripheral termination of the retina. Made up of dentate bays and dentate processes with the post posterior of pars plan

Optic Nerve head 

site where ganglion cell axons accumulate & exit the eye.  Lacks all retinal elements except NFL and an internal limiting membrane ~ because it contains no photoreceptors, it does not elicit a response, and therefore represents the physiological blind spot.

Major blood vessels

The outer retinal layers receive their nutrition from the choroidal capillary bed, the inner layer from the central retinal artery

dominate the central retina

cones

Cone peak @ fovea 

dominate most of the retinal area

Rods

Rod peak, a ring @ ~ 15 degrees temporal retina & 25 degrees nasal retina. (No rods located at the center of fovea or optic disc    

Central retina

peripheral retina

Central retinal is dominated by cones, has the most ganglion cells per area, and yet it is a fairly small portion of entire retina.

The periphery is designed for detecting gross form & motion, while the central area is specialized for visual acuity.  The periphery makes up most of the retina, & rods dominate

Retina is the site...

Retina is the route that...

The retina is the site of transformation of light energy into a neural signal & contains the first three types of cells (photoreceptor, bipolar, & ganglion) in the visual pathway

the route where visual information form the environment reaches the central nervous system for interpretation

Photoreceptors

the rods and cones are special sense cells containing photopigments that absorb photons of light.  (Rods are more active in dim illumination; cones are more active in well lit conditions.)

Photoreceptors; OUTTER SEGMENT

 made up of a stack of membranous discs and in rods, these are enclosed by the cell membrane.  Visual pigment molecules are located in the disc membranes. 

Photoreceptors: connecting cilium

  extends from the innermost disc, joining the outer segment with the inner segment.  Acts as a conduit between them.

Photoreceptors: Inner segment 

composed of ellipsoids, closer to the outer segment and contains mitochondria; and myoid, closer to the cell body and is the site of protein synthesis.

Photoreceptors: nucleus 

 contained within the cell body

Photoreceptors : axon 

an inner fiber containing microtubules running inward from the cell body

ribbon synapses with bipolar and horizontal cells

the outermost retinal layer, is a single cell thick and consists of pigmented hexagonal cells.  Basal surface is next to choroids and apical surface faces neural retina.

Bipolar cells: Dydrentic end

Bipolar cells: nuclues

synapses with photoreceptor and horizontal cells

is large and contains little cell body cytoplasm

Bipolar cells: axon terminal end

bipolar cells: cell body

dyad synaps and synapses with ganglion and amacrine cells

lies betwen the dendritic end an the axon terminal end

Horizontal cells tranfers info with____

horizontal cells connect via---

transfer in horizontal direction parrallel to retinal surface

connect via synapse w/ PR, BPolar and other horizontal cells

Amacrince cells connect via ____

amacrine modulate info how___

Connect via complex of synapse w/ axon of BP, dedrites, and soma of ganglion and IPlexiform nuerons and  other amacrine

modulate info that reaches ganglion

Retinal layers : RPE

-development
-where its located
-morphology
-features 

-arises from nueral ectoderm
-outter most layer ( sclera)
- single layer of hexagonal ( from columnar to cubodial to ora serrate)

-melanin, gap junctions,lipofuscin to phagocytize 

Layer: Photoreceptor 
-outer
-inner

-features 

-visual pigments in stacked disk

-inner contains cell organelles

- Muller cells seperate inner seg, RPE microvilli and outter seg of PR integrate

more active in dim

disc made inner and displace out

loughed off and phagocytized by RPE

usually "cone" shaped, with disc wider at tip

outter seg short that that of rod and may not reach RPE

disc shed at end of day

Layer: External Limiting membrane

- consists of
-features

- looks like 

-Consist of intercell. junction b/w PR and b/t PR and Muller
-tight junctions provide barrier

- looks like fenestrated sheet 

Layer: Outter nuclear layer

-contains

-cone nuclei

-rod nuclei

- rod and cone cell bodies 

-cone nuclei in single layer close to ELM/larger than rod

- rod nuclei in several row inner to cone nuclei

Layer: Outter plexiform layer

-external band

-internal band

- inner fibers of rods and cones

- synapes between PR and INL ( triads that are 2 postsynaptic horiz. cell flankinf bipolar dendrite at cone pedicle)

Layer: Inner nuclear layer

-horizontal

-amacrin

-bipolar

-nuclei found next to OPL

-nuclei found next to IPL

-dendrite in OPL, axon in IPL

Layer: Inner plexiform layer
- connects via
- contains

-midget bipolar

-via between axons of biploar cells and dendrites of ganglion cells

-the synapse b/w 1 order and 2 order nureon in the visual path

-inner half of IPL

Layer: Ganglion Cell layer

-Contains

-usually a single...except

- contains nuclei of ganglion and number a displaced amacrine.

-single layer EXCEPT at macula and temporal side of optic disk

number of ganglion cells diminish toward ora serrata.

Layers: Internal limiting membrane
-what boundary
-termination of
-continuous with
-present over __ but changes at ___

- green, red and blue cones

- rods for dark

Cell type: ON bipolar

- ___ bipolar that __ in response to increasing light intensity
-terminates where 

-cone bipolar, depolarize with light intensity

-terminates in the inner half of IPL

cell type: parasol ganglion cells
- ___ganglion cell

- recieves excitatory inputs from 

- unisratified ganglion cell

- input froom  diffuse bipolar cells

cell type : amacrine cells
-class
- connections where

- how many types
 

- retinal interneurons 
- connect in the IPL amoung bipolar / glaglkion and other ganglion cells  

- 30 types

-Sampling unit defined in terms of
- structural basis defined by 

- Ganglion cell w/ largest tile and lowest density...

- terms of info output

- by the ganglion cells

- will have  a larger sampling unit

-smallest sampling unit located..
- dominated by ...

- parasol has the highest ratio of __ in the retina 

- a midget ganglion cell

- 2 parasol ganglion cells

In order the  retinal circulartion (5)

-Fovea is indicated how
-Fundus photo concerns the ___

, ____ and ____ 

- indicated becuase region is darker

- corcerns, uniformity of background, vessels and apperance of optic nerve head

-Cenral Retinal Artery is the ___ ___ system.

-connection with
-anastosomes with
- obsctruction of any branch will 

-end arterial system
- no other arterial system
- no major and minor branches

- deprive the inner retina of blood supply 

-Arterial and venous

- one venule
- deep cap. extend furthest into fovea
-superficial cap. enter fovea last 

-Foveal center lacks ___ 

- foveal cones supplied via
 

Retinal capillaries are specialized to ___

this is accomplished by the presence of ___

 create a blood-retinal barrier

 overlapping endothelial cells and tight junctions 

-All __ and all branched of the ___ converge at the optic nerve head

- there are __ arterial and 4 __ branches from the nerve head that create __ superia and 2 __ branches of both central retinal artery and vien

-ganglion cells axons, central retinal artery

-4,4,2,2,

-The optic disc( optic nerve head) is the site where ___

-The nearve head and optic nerve consist primarily of axon bundles seperated by ...

-Nerve head is divided into what three parts?

-sheaths of glial cells and connective tissue

-laminar portion, prelaminar portion, postlaminar portion

- Laminar portion defined by

-Prelaminar portion is the 

- Postlaminar portion 

-defined by scleral fibers that intersect the axons as they exit at the lamina cribosa

- nerv head proper, between the lamina cribosa and the  vitreous

- the 1st mm of the optic nerve behind the eye

Meniscus of Khunt

- located where

- is the what of the ILM

-looks like the 

-at the center of the nerve head

-thickest part of the ILF of Elschnig

- a cup or depression in the optic disc

-Ganglion cells on the nasal side of the fovea also axons running...

-axons from all other ganglion cells ..

-temporal to the fovea , the ___ divides the ganglion cells whose axons run below the fovea from those whose axons run above it 

- running directly to the nerve as the papillomacular bundle

-follow paths around the fovea

-horizontal raphe

- a blind spot is located where

- the lamina cribosa is weaker than

- behind the cribosa

- perceptual counter part of the nerve head. It is temporal to the fovea

- rest of the sclera

-the optic never had 2 blood supplies: central artery branches and plaxis 

Two theories in origin of feild defects in glaucoma

1.  vascular defects at the optic nerve head 

2. structural changes in the lamina cribosa