Myopia

Question 1

by 2050, how much of the world population is expected to have myopia

Answer 1

50% = 1 billion humans

Question 2

what is the leading cause of visual loss worldwide

Answer 2

myopia

Question 3

what is emmetropization

Answer 3

newborns are hyperopic, but their RE decreases during adolescents

Question 4

In the first 3 years of life, which are the most dramatic growth of ocular components

Answer 4

cornea, AC depth, crystalline lens and axial length

Question 5

how is emmetropia formed

Answer 5

the coordinated growth of ocular components

Question 6

what is the most common cause of developed ametropia

Answer 6

increased vitreous depth - longer axial length

Question 7

what is the greatest risk factor for myopia

Answer 7

two myopic parents

Question 8

what are the possible risk factors to myopia

Answer 8

1. diet
2. near work
3. intelligence
4. stress
5. lack of outdoor activities

Question 9

what are the studies done upon near work and myopia that is not significant

Answer 9

• near work
• reading
• religious boys at school
• screens ( iphone est 2007, myopia rose before the time)

Question 10

what is a possible theory associated with near work and myopia

Answer 10

increased screen time with less outdoor time

Question 11

what is most common form of myopia

Answer 11

axial length myopia

Question 12

if children spend more time outdoors then

Answer 12

Children w/ 2 myopic parents and spend more time outdoors = chances of developing myopia is lower (about 20%, compared to 60% to those who spend LESS time outdoors)

Question 13

why does each diopter of myopia matter

Answer 13

• less visual disability when uncorrected
• better option and outcomes thru surgical myopia correction
• higher risk of blindness is assoc. w/ higher levels of myopia

Question 14

higher myopes are at a greater risk of

Answer 14

• cataract
• glaucoma
• retinal detachment

Question 15

the greatest myopia related cause of irreversible vision loss is

Answer 15

myopic macular degeneration

Question 16

myopia progression is the following

Answer 16

• 6 to 7 yr olds progress 2x faster than 11-12yr old - refractively and axial length
• girls progress 10% faster than boys
• children w/ 2 myopic parents have onset 35% faster than 0 myopic parents
• children in Asia progress 50% faster than USA

Question 17

can the environment influence the axial length of the eye

Answer 17

yes! hyperopic retinal defocus stimulates elongation
- the rays from distant object are focused posterior to R and then brain signals to elongate to eye to focus light on retina

Question 18

what kind of defocus does myopic lenses create and how does it affect axial length

Answer 18

hyperopic retinal defocus - increased AL growth

Question 19

what kind of defocus does hyperopic lenses create and how does it affect axial length

Answer 19

myopic retinal defocus - decreased AL

Question 20

what is the significance of peripheral retina

Answer 20

visual signals from peripheral retina can impact emmetropization at fovea, possibly developed refractive error

Question 21

how does the hoya DIMS lens work

Answer 21

forms myopic defocus peripherally to decreased axial growth

Question 22

what is orhto K

Answer 22

• retainers for the eyeball
• continued wear overnight so pt doesnt have to wear lenses during daytime
• temp reduces myopia

Question 23

what is the mechanism associated with ortho K

Answer 23

flat rigid lens > flattens central region of cornea > steepens peripheral cornea > leads to less power > increases radius

Question 24

what happens with ortho K myopically

Answer 24

slows myopic progression

Question 25

what is the main goal of refractive surgery

Answer 25

obtain myopic defocus

Question 26

what is assoc w lasik

Answer 26

• laser forms epithelial flap
• remove epithelium and stroma
• reposition epithelial flap
• slows myopic progression

Question 27

what occurs in multifocal CLs

Answer 27

adding plus power to the near region of lens will cause rays to pass through that zone to focus anteriorly of the retina
- thus myopic defocus

Question 28

what are the 3 myopia controls and the significance

Answer 28

atropine, soft bifocal, ortho - K
all slow myopia progression to a degree, but doesn’t eliminate

Question 29

what are the possible mechanisms assoc with time outside and reduced myopia

Answer 29

• less accommodation in outdoor environment
• pupil constriction in bright environments (pinhole effect of our eyes)
• sunlight exposure releases retinal transmitter (dopamine) > inhibits eye growth

Question 30

what is radial keratometry

Answer 30

• series of cuts in 4, 8 or 10
• scar tissue unevenly heals > cataract > pulls on cornea > flattened cornea > decrease of myopia
• uneven healing > irregular and oblique astig

Question 31

what is PRK

Answer 31

• laser used to reshape cornea
• corneal epithelium removed to reach stroma

Question 32

what is lasik procedure

Answer 32

• same as PRK but the epithelium is moved aside so laser can reshape stromal bed

Question 33

what the advantage oD LASIK

Answer 33

immediately better BVA

Question 34

what are the complications to refractive surgery

Answer 34

• reduced BCVA (best corrected)
• red. contrast sensitivity
• red. corneal sensitivity
• reading glasses may be req
• increased dry eye
• reduced night vision
• halos around light during immediate months
• thinner cornea

Question 35

what is the reduced corneal sensitivity from refractive surgery caused by

Answer 35

corneal nerve damage, will not all regenerate

Question 36

does the axial length of the eye get changed during lasik

Answer 36

no, thus risk of retinal tears/ holes are still present
- the only take away is a thinner/flatter cornea > leads to higher risk of corneal perforation