myopia and more

Question 1

affect of NS on vision

Answer 1

cause myopic shift even before they cause a decrease in BCVA

Question 2

cortical cataracts effect on vision

Answer 2

hyperopic shift

Question 3

elevated glucose levels and vision

Answer 3

cause myopic or hyperopic shift. will be symmetric between the two eyes and most often >1.00D

Question 4

pseudophakic patients and blood sugar shifts

Answer 4

CANNOT have refractive shift due to elevated blood glucose

Question 5

inherited myopia

Answer 5

myopia inherited from parents

Question 6

risks for the development of myopia in kids based on whether their parents have myopia

Answer 6

• no parents with myopia: <10%
• one parent with myopia: 20-25% chance
• both parents with myopia: 30-40% chance

Question 7

nocturnal myopia

Answer 7

occurs in dimly illuminated surroundings due to minimal visual clues to guide the amount of accommodation that is necessary. this type of myopia particularly causes issues with night driving. Remember that distance vision doe snot require accommodation; however, if there are minimal visual cues to guide accommodation, accommodation will be suspended at an intermediate distance, resulting in a more myopic Rx (the eye will be too powerful)

Question 8

absolute presbyopia and night myopia

Answer 8

there is no accommodation that could induce night myopia in an absolute presbyope, however could experience it due to an increase in SAs due to dilated pupils in dimly lit condition

Question 9

pseudo myopia

Answer 9

occurs when an uncorrected hyperbole accommodates to neutralize his RX, but then accommodates too much, resulting in a myopia RX. Dry refraction will show a low amount of myopia, but cyclo refraction will reveal the uncorrected hyperopia. pts with this are often RXed a low plus RX for near only to alleviate symptoms. the low minus RX should NOT be RXed, as it will exacerbate symptoms

Question 10

things that can cause a myopic shift

Answer 10

NS
increased blood glucose 
scleral buckle 
diamox 
NSAIDs
topamax

Question 11

pinhole

Answer 11

increases the depth of focus and depth of field. this increase in depth of focus will improve the patients VA if the reduced VA is due to uncorrected refractive error. in other words, theoretically the patient should have the same VA through the pinhole as at the end of the refraction.

Question 12

what are pinhole acuities limited by

Answer 12

media opacities an other ocular pathologies

Question 13

assuming the patient is not wearing his glasses and is an absolute presbyope, at what distance will this patient see most clearly? his Rx is -2.00Ds OU

Answer 13

1/2.00=50cm

the range of clear vision for a patient extends form the near point (the closest point an object can be placed in front of the eye and still be seen as clear when the eye is fully accommodated) and the far point (the farthest point an object can be placed in front of the eye and still seen as clear)

Question 14

far point

Answer 14

determined by taking the reciprocal of the patients refractive error.

Question 15

near point

Answer 15

determined by taking the reciprocal of the maximal amount of accommodation the patient can exert. in an absolute presbyope, the near point and the far point will coincide.

Question 16

far point location

Answer 16

in front of the eye for a myopic patient and behind the eye for a hyperopic patient and infinity for emmetropic patient

Question 17

which mode of correction is most appropriate to minimize RSM for a high myope with an axial length of 26mm

Answer 17

glasses

Question 18

what is a normal axial length

Answer 18

24mm

Question 19

Knapps law

Answer 19

glasses should be rxed for axial ametropes in order to minimize RSM. refractive ametropes are best corrected with CLs which minimize RSM

Question 20

RSM

Answer 20

is the ratio of the retinal image size in a corrected eye to the retinal image size in a gullstrand emmetropic eye. when RXing, the goat lis to maintain an RSM of appx 1. according to Knapps law, this is achieved in a refractive ametropes when the lens is placed at the entrance pupil of the eye (very near the cornea), and an axial ametrope when the lens is placed at the anterior focal point of the eye (appx 15mm from the cornea)

Question 21

axial ametropes should be corrected with

Answer 21

glasses

Question 22

refractive ametropes should be corrected with

Answer 22

CLs

Question 23

pathological myopia

Answer 23

>6.00D SE or axial length >26.5mm. 
posterior staphyloma
lacquer cracks
Fuch's spots
obliquely inserted ONHs
lattice 
RDs (both types)
CNVMs
PPCs
premature cataracts 
glaucoma

Question 24

angioid streaks

Answer 24

similar to lacquer cracks as they also represent a break in Bruchs membrane that increases the risk of development of a CNVM. recall that angioid streaks are associated with PEPSI (PXE, ED, Paget’s disease, sickle cell anemia, idiopathic)

Question 25

the COMET study

Answer 25

correction of myopia eval trial

evaluated whether +2.00D PaLs slow the progression of myopia compared to single vision lenses in kids ages 8-12 with 0.75D to 2.50D myopia, a near EP, and an accommodative lag. after 3 years, patients in the PAL progressed 0.87D compared to 1.15D progression in the SV lens group. There was poor compliance in the PAL group. Although this difference in progression between the 2 groups was statistically significant, it is not clinically significant

Question 26

biggest things to think about with adults and myopic shifts

Answer 26

NS and DM