Coa

Front 1

Prism in a hype topic lens is?

Back 1

Two prisms base to base

Front 2

What is the formula to determine focal length?

Back 2

Don't know

Front 3

Macula is loaded with?

Back 3

The macula is loaded with a great number of color sensitive cells (cones) in order to increase the acuity of the central field of vision.

Front 4

What is the center of the macula?

Back 4

The very center of the macula, the fovea, is avascular (no blood vessels), and no nerve fibers run above the cones in this bulls-eye of maximum acuity that is a mere 1.5 mm across.

Front 5

Why does the macula appear darker in fundus photos?

Back 5

The macular area appears darker than the surrounding retina on fundus photos. This is because the underlying pigment layer (RPE) is more dense in the macula.

Front 6

On a fundus photo the macula is located where?

Back 6

macula is anatomically slightly lower than the center of the optic nerve. Since the optic nerve enters each eye nasally, a photo of the posterior pole will have the optic nerve to the left of the macula in a photo of the left eye

Front 7

What are the two phot receptor cells in the retina?

Back 7

The photoreceptor cells are of two types: rods and cones

Front 8

Are there more rods or cones?

Back 8

Rods far outnumber cones, approximately 20 to 1. This is because the 130 million rods are scattered over the peripheral retina, which makes up the vast majority of the surface area of the retina compared to the small area of central vision in the macula.

Front 9

What colors do rods perceive?

Back 9

Rods only perceive in black and white, and they are most sensitive to the blue end of the spectrum.

Front 10

Where are the cones concentrated?

Back 10

cones in the macula.

Front 11

Is the vision in peripheral range good?

Back 11

No This means that the acuity of the peripheral retina is very low, less than 20/400.

Front 12

Are rods sensitive to low or bright light?

Back 12

Low light. The rods are very sensitive to low light levels, but not instantly. The dark adaptation process, which involves the chemical rhodopsin, is 80 percent complete after 30 minutes in the dark

Front 13

What is the Purkinje shift?

Back 13

As light dims and the eye converts from photopic (bright illumination) vision to scotopic (dim illumination) vision, the eye becomes less sensitive to colors at the "warm" end of the visual spectrum (cone sensitivity), and it becomes more sensitive to light at the "cool" end of the spectrum (rod sensitivity).

Front 14

What is Retinitis pigmentosa?

Back 14

an inherited disease that slowly atrophies rod function until the patient is only left with only cone function and tunnel vision. Massive doses of vitamin A have slowed the degenerative process in some of these patients.

Front 15

Cones are?

Back 15

Cones are color sensitive and are concentrated in the macula

Front 16

What are the three different types of cone cells?

Back 16

red light sensitive, blue light sensitive, and green light sensitive.

Front 17

Persons with normal color vision are termed?

Back 17

trichromats, they have normal function with all three types of cone pigments.

Front 18

A person missing one type of cone pigment would be a?

Back 18

dichromat (3% of the population),

Front 19

If someone is anomalous trichromat that means?

Back 19

persons with "color blindness" are really color deficient meaning one of the cone types functions below normal.

Front 20

What is The most common type of deficiency ?

Back 20

congenital red/green deficiency that occurs in varying degrees in about 9 percent of the male population and in only about .5 percent of the female population.

Front 21

Why is plaquenil a high risk medication?

Back 21

Plaquenil (chloroquine) has been shown to be toxic to the photoreceptors at doses above 400mg a day. Changes in color vision serve as an early warning of damage to the retina. A decrease in retinal sensitivity and visual acuity can follow within months of changes in color vision if the Plaquenil dosage is not reduced or discontinued.

Front 22

What are the twp types of color vision tests performed?

Back 22

Color vision tests for clinical use come in two types: color plate tests and hue tests. An anomaloscope is used for color vision research.

Front 23

How are color plates useful?

Back 23

All will tell you if there is normal color perception or if there is a red-green deficiency

Front 24

Farnsworth D-15 is a?

Back 24

hue tests that consist of colored caps (the number in the name refers to the number of caps in the test). The caps are mixed in random order and the patient is asked to place them in smooth order according to hue. Results are recorded on a chart, and a scoring process reveals the type and the degree of the defect.

Front 25

The Retinal Pigment Epithelium (RPE) lies where?

Back 25

RPE lies beneath the neurosensory retina. This layer of concentrated pigment cells is what gives the retina colorati

Front 26

The central retinal artery and the central retinal vein branch from the?

Back 26

the ophthalmic artery and come into the eye through the optic nerve head. Each then branches from the optic nerve head to serve four main quadrants of the retina. These vessels provide the blood supply for the inner two thirds of the retina.

Front 27

Why doesn't the fovea has no overlying blood vessels?

Back 27

so that no light is blocked over this small, highly sensitive area of central vision.

Front 28

The outer third of the retina is served by the blood vessels of the?

Back 28

Choroid

Front 29

VER: Tests the function of the visual cortex and the pathway leading to it.

Back 29

VER: Tests the function of the visual cortex and the pathway leading to it. This test is useful for testing unexplained visual loss (malingering), visual potential in newborns, optic nerve disease, and pathway abnormalities.

Front 30

ERG: Tests the function of the rods and cones. This test is useful for evaluating retinitis pigmentosa, cone dystrophies, and unexplained visual loss.

Back 30

ERG: Tests the function of the rods and cones. This test is useful for evaluating retinitis pigmentosa, cone dystrophies, and unexplained visual loss.

Front 31

EOG: Test the rods and cones and the RPE layer. This test is useful for evaluating Best's disease, vitelliform macular degeneration, and retinal toxicities (e.g. Plaquenil).

Back 31

EOG: Test the rods and cones and the RPE layer. This test is useful for evaluating Best's disease, vitelliform macular degeneration, and retinal toxicities (e.g. Plaquenil).