- the direct ophthalmoscope magnifies the retinal fundus this many times

- ends up being only 5 degree field of view

14x

- this type of ophthalmoscope provides less magnification than the direct but a 5x larger field of view (25 degrees)

Panoptic Ophthalmoscope

- located in the nasal half of the retina

- 1.5 mm in diamater (used to compare other structures)

- slightly pink and oval (normal)

- has the physiologic cup

- may be surrounded laterally by pigmented crescents

- should be evaluated for color, clarity and cupping

Optic Disc

Retinal pathology

- small white depression devoid of nerve fibers in the center of the optic disc where retinal vessels emerge (central retinal artery)

Physiologic Cup

- the optic disc is smaller and the optic cup may appear non-existent in these people

Hyperopic patients

- the optic disc is larger and the optic cup may appear more prominent in these people

Myopic patients

- these may be seen around the lateral margins of the optic disc particularly in myopic patients

Pigment crescents

- the loss of nerve fibers and piling up of reflective astrocytes on top of the optic disc

- disc appears white

Pallor

- pallor is a sign of this eye pathology and may be due to a lesion between the retina and lateral geniculate body

- diagnosis based on presence of disc pallor and decreased visual acuity

Optic atrophy

Disc Pallor

- loss of nerve fibers and piling up of astrocytes

Optic Atrophy w/ decreased visual acuity

- swelling of the optic disc due to increased intracranial pressure

- margins are blurred and disc becomes elevated

- clarity is preserved till it advances

- flame-shaped hemorrhages and soft exhudates develop as it worsens

- usually affects both eyes

- many people have no symptoms

Papilledema

- retardation of axoplasmic flow at the level of the lamina cribrosa from increased intracranial pressure

- occlusion of capillaries and venules that leads to hemorrhages and edema in between axons

Mechanisms of Papilledema

- can be confused with papilledema

- produces optic disc swelling, unilateral ocular pain with eye movement, acute loss of central vision, and afferent pupillary defect

- most patients are young females and they gradually recover

Optic Neuritis

Papilledema

- swelling of optic disc w/ increased intracranial pressure

- flame-shaped hemorrhages and soft exudates develop as it worsens

from retardation of axoplasmic flow or occlusion of capillaries and venules

- can be confused with papilledema

- caused by decreased blood flow to the optic disc through the posterior ciliary arteries

- sudden, painless, monocular blindness and optic disc swelling

- most cases occur w/ diabetes and hypertension

- can be caused by temporal arteritis in pt's >60 yrs

Anterior Ischemic Optic Neuropathy (AION)

Anterior ischemic optic neuropathy (AION)

- decreased blood flow to the optic disc

- sudden, painless, monocular blindness and optic disc swelling

found w/ diabetics, hypertension, temporal arteritis (rare)

- results when there is an increased cup to disc ratio more than 50% as a result of increased intraocular pressure

Glaucomatous cupping

Glaucomatous cupping

- increased cup to disc ratio of more than 50% as a result of increased intraocular pressure

- superior, inferior, nasal, temporal

Branches of Central Retinal Artery

- nourished by retinal branches of the central retinal artery

Retinal nerves

- nourished by diffusion from the choroidal circulation

Photoreceptors

- as the central retinal artery passes through the lamina cribrosa it shares the same vascular wall with its corresponding vein

- it causes this finding in about 50% of large veins at the disc margin in normal individuals

- disappear early in the course of increased intracranial pressure (papilledema?)

Spontaneous pulsations of the retinal veins

- when a posterior ciliary artery emerges at the optic disc margin

- not part of the central retinal artery circulation but supplies part of the retina like it

Cilioretinal artery

Cilioretinal artery

- supplies part of retina but is part of the posterior ciliary circulation

Which is darker on an ophthalmoscope exam; arteries or veins?

Veins

- ratio of size (caliber) of the retinal arteries to the retinal veins

2/3 : 1

- these two things are visible in the retinal arteries and occur in a 1/4 to 1 ratio

- arterial wall is invisible

Light Reflex : Column of Blood