Optics Notes

Question 1

Real Object, definition

Answer 1

• emits diverging light
• object distance is negative
• object vergence is negative

Question 2

Real Image, definition

Answer 2

• When converging light leaves a refracting surface.
• image distance is positive
• image vergence is positive

Question 3

Virtual object; definition

Answer 3

• when converging light is incident on a surface
• object distance is positive
• object vergence is positive

Question 4

Virtual Image; definition

Answer 4

• when diverging light leaves a refracting surface
• image distance is negative
• image distance is negative

Question 5

Lens Clock

Describe what the red and black scale indicate.

Answer 5

The pointer shows your focal power

Red scale: concave surface = minus power
Black scale: convex surface = plus power

Question 6

Chief rays pass through the ______ _______

Answer 6

Optical center

Question 7

What are the rules for light rays in refraction?

1. A focal ray becomes ________
2. A parallel ray becomes ________
3. A chief ray is ______ _________.

Answer 7

Focal ray becomes a parallel ray.
Parallel ray becomes a focal ray.
A chief ray is not deviated.

Question 8

Positive power lens; definition

Answer 8

• secondary focal length is positive

- primary focal length is negative

Question 9

Negative power lens; definition

Answer 9

• secondary focal length is negative

- primary focal length is positive

Question 10

Where do oligodendrocytes provide myelination to the axons?

Answer 10

Posterior to the laminar cribrosa

Question 11

Which cells are found in the PNS, providing myelination?

Answer 11

Schwann cells are found in the PNS, not in the optic nerve.

Question 12

What is the circle of zinn formed by?

Answer 12

Formed by anastomoses of the SPCAs

Question 13

Define intraocular optic nerve

Answer 13

Pre-laminar and laminar layers; supplied by the circle of zinn and other branches of the SPCAs

Question 14

Define intraorbital optic nerve

Answer 14

Post laminar area; supplied by branches from the central retinal artery and the pial mater arterial plexus

Question 15

Intra-cranial optic nerve

Answer 15

Supplied by branches of the ophthalmic, anterior cerebral, anterior communicating, and internal carotid arteries.

Question 16

Which glial tissues separates the pre-laminar optic nerve fibers from the choroid?

Answer 16

The border tissue of Jacoby. A continuation of the glial tissue known as the intermediary tissue of Khunt.

Tight junctions within the glial tissue help protect the optic nerve fibers from fluid that leaks from the fenestrated choroidal vessels.

Question 17

Superior colliculus

Answer 17

Aid in saccadic eye movement.

Question 18

Pretectal nucleus

Answer 18

Aids in pupil movement.

Question 19

Define anterior knees of Wilbrand

Answer 19

Inferior nasal fibers that cross through the optic chiasm and then loop anteriorly into the contralateral optic nerve before entering the optic tract.

Question 20

Posterior knees of wilbrand

Answer 20

Superior nasal fibers that loop posteriorly into the ipsilateral optic tract before crossing through the optic chiasm.

Question 21

Optic chiasm location

Answer 21

Located within the circle of Willis. The internal carotid artery and posterior communicating arteries travel along the lateral edges of the optic chiasm. The pituitary gland is located to the optic chiasm.

Question 22

Where do macular fibers travel?

Answer 22

The middle of the optic tract.

Question 23

LGN: magnocellular layers

Answer 23

Layers 1 & 2. Located inferiorly. Contains large magno cells.

Question 24

LGN: parvocellular layer

Answer 24

Layers 3 to 6. Extended superiorly that contain medium parvo cells.

Question 25

Koniocellular layers

Answer 25

Contain small cells located between each layer.

Question 26

Where do crossed fibers of the optic tract synapse?

Answer 26

LGN layers 1, 4, 6

Question 27

Where do uncrossed fibers of the optic tract synapse?

Answer 27

LGN layers 2, 3, 5

Question 28

Define optic radiations

Answer 28

Fibers that leave the LGN and travel to the primary visual cortex. V1

Inferior radiations go to the temporal lobe. Superior radiations go to the parietal lobe.

Question 29

What are other names for the primary visual cortex and where is it located?

Answer 29

Aka V1, brodmann’s area 17, striate cortex.

On the medial surface of the occipital lobe.

Question 30

Define calcarine fissure

Answer 30

Divides the internal posterior position of the occipital lobe into anterior and posterior sections.

Question 31

Define cuneus gyrus

Answer 31

The superior portion of the visual cortex in the occipital lobe. Superior fibers terminate here. Also superior macular fibers.

Question 32

Lingual gyrus. Define.

Answer 32

The inferior portion of V1 in the occipital lobe. Inferior retinal fibers terminate here. Inferior macular fibers as well.

Question 33

Optic chiasm, blood supply

Answer 33

Supplied by Circle of Willis and branches of the internal carotid artery.

Question 34

Optic tracts, blood supply.

Answer 34

Supplied by the anterior choroidal branch of the middle cerebral artery.

Question 35

LGN, blood supply

Answer 35

Supplied by the anterior choroidal and posterior cerebral arteries.

Question 36

Optic radiations, blood supply.

Answer 36

Supplied by the anterior choroidal, middle cerebral, and posterior cerebral arteries.

Question 37

Primary visual cortex, blood supply.

Answer 37

Supplied by the posterior cerebral artery and the middle cerebral artery. This gives a dual blood supply.

Question 38

Post-chiasmal lesion.

Answer 38

Produces homonymous visual field defects (same side). The more posterior a post chiasmal lesion is located, the more congruous the visual field defects are between the eyes.

Example: right lesion = left visual field defect of both eyes.

Question 39

Temporal lobe lesion.

Answer 39

Temporal lesions cause superior visual field defects. “Pie in the sky.” This is because lesions in the temporal lobe damages the inferior retinal fibers forming Meyers Loop.

Question 40

Parietal lobe lesions.

Answer 40

Cause inferior visual field defects. “Pie on the floor.” Lesion in the parietal lobe damages the superior retinal fibers (and associated with the asymmetric OKN response).