7.1 Refractive Error

Question 1

Define refractive error

Answer 1

Light is not bent perfectly to hit the retina precisely

Question 2

Myopic refractive error

Answer 2

Light hits IN FRONT of the retina

Question 3

Hyperopic refractive error

Answer 3

Light hits BEHIND the retina

Question 4

Emmetropic refractive error

Answer 4

Trick question! NONE. Emmetropes have NO REFRACTIVE ERROR as the light hits retina perfectly

the white here if light hit retina perfectly

Question 5

Which has the MOST refractive power: cornea, crystalline lens, or retina

Answer 5

Cornea 2/3rd refractive power of whole eye (think light hits big dome: large surface area)

Question 6

What spectacle lens in front of emmetrope helps light to hit retina?

Answer 6

Plano DS (needs nothing as light already hits retina)

Question 7

What spectacle lens in front of myopic eye helps light to hit retina?

Answer 7

Minus lens aka CONCAVE

Question 8

What spectacle lens in front of hyperopic eye helps light to hit retina?

Answer 8

Plus lens/ AKA CONVEX

Question 9

Is an EMMETROPIC eye long or short?

Answer 9

Neither! It’s perfect length for light to hit retina perfectly

Question 10

Is a MYOPIC eye long or short?

Answer 10

Long (the retina is so far away the light end short and can’t reach that long)

Question 11

Is a HYPEROPIC eye long or short?

Answer 11

Short (the retina is bunched too close so the light surpasses it)

Question 12

Myopia aka

Answer 12

Nearsightedness (sight of the near, none of the far)

Question 13

Hyperopia aka

Answer 13

Farsightedness (sight of the far, none of the near)

Question 14

Mnemonic for Myopia refractive error

Answer 14

MINUS Myopia Increased length Nearsightedness Upclose Short light to retina

Question 15

Concave corrects what refractive error

Answer 15

Minus lens is concave, corrects myopia

Question 16

Mnemonic for hyperopic refractive error

Answer 16

PLUS Past the retina Long away sight Unique Short eye

Question 17

Convex corrects what refractive error

Answer 17

Plus lens is convex, corrects hyperopia

Question 18

With the rule astigmatism is @ what meridian in the plus cyl (vs minus cyl)

Answer 18

090 plus cyl (vs 180 in minus cyl)

Question 19

Against the rule astigmatism is @ what meridian in plus cyl (vs minus cyl)

Answer 19

180 in plus cyl (vs 090 in minus cyl)

Question 20

What lens corrects for astigmatism

Answer 20

Cylinder

Question 21

Oblique astigmatism

Answer 21

Range of 30deg on either side of 180 or 90,if outside that it is oblique

Question 22

Irregular astigmatism

Answer 22

Two meridians are not 90 deg away from each other (think looks like L instead of figure 8)

Question 23

Oblique astigmatism vs Irregular astigmatism

Answer 23

Oblique is Outside range of 30deg to either side of 90 or 180, Irregular is isosceles triangle is not 90 deg between each meridian

Question 24

Define presbyopia

Answer 24

Cilliary body muscles to crystalline lens get week with age, won’t all lens to bend, blows out near vision

Question 25

Monocular precautions

Answer 25

Protect one good eye with shatter resistant lenses (polycarbonate spectacle lenses)

Question 26

Aphakia is

Answer 26

No implant to replace when the crystalline lens came out (uncommon)

Question 27

Pseudophakia means

Answer 27

Implant inside eye after crystalline lens removed after cataract surgery (super common almost 100%)