Refraction Lecture Powerpoint

Question 1

Presbyopia is a ____ refractive error

Answer 1

FALSE

Question 2

Hyperopia

Answer 2

Far-sightedness, eyeball is too short (axial) or cornea is not curved sufficiently (curvature), corrected by a convex lens (positive power) that increases the eyes refractive power by converging the light

Question 3

Myopia

Answer 3

Near-sightedness, eyeball is too long (axial) or cornea is excessively curved (curvature), corrected by a concave lens (negative power) that reduces the eyes refractive power by diverging the light rays

Question 4

The majority of refraction is done by….

Answer 4

…the cornea (fine tuned by the lens)

Question 5

What is the shape of the lens for distance viewing?

Answer 5

Flat

Question 6

The lens of the eye cannot make a ___ shape but can go ____ to view distances

Answer 6

concave, flat

Question 7

Myopia is corrected by what type of lens? What about hyperopia? Astigmatism?

Answer 7

Concave, convex, cylindrical

Question 8

Most common cause of amblyopia and 3 other common onees

Answer 8

• Strabismus
• Refractive disorder
• cataract
• ptosis

Question 9

Refraction

Answer 9

Ability of eye to bend light so image is focused on the retina

Question 10

Concave lens

Answer 10

A lens with negative optical power that causes the dispersing of oncoming light, used in nearsighted patients

Question 11

Convex lens

Answer 11

A lens with positive optic power that causes converging of the oncoming light, used in farsighted patients

Question 12

Ametropia (refractive errors)

Answer 12

Optical imperfections that prevent the eye from properly focusing light causing blurred vision, including nearsightedness, farsightedness, or astigmatism, very common up to 1/3 of patients >40, worldwide common cause of poor visual acuity and blindness

Question 13

Worldwide #1 cause of blindness

Answer 13

Cataracts

Question 14

Visual acuity

Answer 14

Diagnosed via a snellen chart, a patient with less than 20/25 in either eye has impaired visual acuity, done by healthcare professional often in children and then annual beyond 61

Question 15

Treatments of ametropia (3)

Answer 15

• Eye glasses
• Contact lens
• Lasik surgery (refractive surgery)

Question 16

Orthoptist

Answer 16

Specialize in diagnosis and treatment of binocular vision problems such as strabismus

Question 17

Factors influencing light focusing on the retina

Answer 17

• Cornea is extremely curved
• Refraction thru the aqueous humor is minimal
• Lens accommodates and can adjust accordingly
• Refraction thru vitreous humor is minimal
• Length of eyeball matters to bring focus to the

Question 18

Emmetropia

Answer 18

When the eye is able to bring distant objects to a point of focus on the retina without a refractive aid

Question 19

Presbyopia

Answer 19

A loss of lens elasticity preventing it from becoming as convex that causes difficulty seeing near things (rolling lens, flat lens is no problem), not considered a true refractive error

Question 20

When an object is close, the lens refractive power must ____

Answer 20

increase (accommodate)

Question 21

Elderly must read things by holding the media….

Answer 21

….farther away than a child would

Question 22

___% of people have a refractive error (ametropia)

Answer 22

70%

Question 23

Astigmatism

Answer 23

Misshapen cornea resulting in 2 or multiple focal lines that focus in front, behind, or on the retina

Question 24

OD

Answer 24

Right eye

Question 25

OS

Answer 25

Left eye

Question 26

Sphere, cyl, axis, add

Answer 26

• Refers to the degree of optical error in the glasses
• corresponds to astigmatism
• corresponds to astigmatism
• Added to bifocals to adjust in presbyopia

Question 27

LASIK

Answer 27

Laser assisted in situ keratomileusis, used for hyperopia, myopia, and astigmatism, laser alters shape of the cornea, can have complications including dry eyes, overcorrection or undercorrection, induced astigmatism, wrinkles in flap, or halos

Question 28

Amblyopia

Answer 28

Disorder of visual development caused by optical, physical, or ocular alignment defect in childhood, brain selects better image to the eventual detriment of vision in the other eye (lack of development in the visual pathway), most common cause of uniocular vision loss in patients less than 45 years of age, if not treated before age of 7 permanent visual loss occurs

Question 29

Esotropia

Answer 29

When the strabismis affected eye moves inward

Question 30

Exotropia

Answer 30

when the strabismis affected eye moves outward

Question 31

Cataract

Answer 31

Clouding of lens obstructing passing light, leading source is aging, can be congenital, traumatic, or drug induced, prevented with sun glasses, has loss of visual acuity and contrast sensitivity, as well as an absent red reflex

Question 32

Cataract treatment (1)

Answer 32

-Surgical removal of lens and replacement with plastic lens (that can’t accommodate like the natural one but can sometimes have different optic settings)