Subjective Refraction Overview and Pre-presentation

Question 1

why prescribe? 4

Answer 1

1. improve VA
2. improve binocular function
3. prevent ambylopia
4. improve general function

Question 2

what are the goals of refraction? (4)

Answer 2

1. clear vision
2. comfortable vision
3. rapid adaptaion
4. do no harm

Question 3

what are the 4 phases of refraction divided into?

Answer 3

1. pre-presenation
2. starting points
3. refinement
4. end points

Question 4

what is the most important tool of refraction?

Answer 4

clinical reasoning....
too bad its hte most useless class lol

Question 5

what gives us hints as to the pts refractive error?

Answer 5

1. age
2. externals
3. case history
4. entrance tests: VA, CT
5. other tests: amp of acc, bruckner, direct ophthalmoscopy, keratometry

Question 6

when does tearing occur?
when do headaches (HA) occur?
when does dist blur occur?

Answer 6

• hyperopia, astig
• myopia, hyperopia, astig, presby
• myopia, astig, sometimes if high hyp in adults w/ reduced acc

Question 7

what happens if the pt says that tilting the gl makes things clearer?

Answer 7

change the cyl

Question 8

the pt says “pulling the gl away from my face makes things clearer” what do yo udo

Answer 8

increase the plus

Question 9

for CT, eso may be assiociated w / what? exo may be associate w/ what?

Answer 9

• eso w/ uncorrected hyperopia or an over-minused pt

- exo (esp at near) w/ uncorrected or undercorrected myopia

Question 10

what might low amp be ass w/?

Answer 10

hyperopia

-can also be ass w/ primary anomalies of the acc system

Question 11

what does bruckner test provide info on?

Answer 11

ref error 
-hyp or myop?
-astig?
-aniso?
strabismus
media opacity

-abt all 3 types of amblyopia

Question 12

when you have a clear view of the pts fundus (blur=0) w/ a direct oscope, the lens in the oscope head has neutralized the sum of 4 things:

Answer 12

1. pts ametropia (discrepancy)
2. pts acc
3. your ametropia (discrep)
4. your acc

Question 13

what do you need to consider to predict VA

Answer 13

distance VA
near VA
pts age and epidomiology

Question 14

for eggers chart, what can you predict refractive error for most accurately?

Answer 14

myopia and astig

-more difficult for hyperope bc of acc

Question 15

for eggers chart, what do you predict the D to drop?
spherical component: 
-from 20/20-20/50 =? 
-20/70 = ?
20/100 =?

Answer 15

0. 25D per line
1. 25 D
2. 50 D

Question 16

for eggers chart, what do you predict the D to drop?
cylindrical component: 
20/20-20/50=?
20/70=?
20/100=?

Answer 16

0. 50D cyl per line
1. 50D
2. 00D

-values in minus cyl, apply to power but say nothing about axis

Question 17

how does static retinoscopy asses the eye? what is it useful for?

Answer 17

asses the eye as if it is a passive optical device. it is useful for predicting the rx that will give clear vision

Question 18

how does static retinoscopy asses sphere, cyl, power, cyl axis?

Answer 18

objective assessment

Question 19

what can the quality of the static recinoscopy reflex give?

Answer 19

some info about corneal/integrity/shape and opacities along visual axis

Question 20

how can static retinoscopy monitor accomodation?

Answer 20

can monitor acc indirectly by observing pupil size-measure when pupil at its largest to avoid over minusing

Question 21

why can some argue that retinoscopy is the most important step in the exam process?

Answer 21

the essence of the exam process is to determine if decreased vision or visual function is due to ref error or bad eye/bad brain. you can’t do that if you don’t know if there is sig ref error

Question 22

when can you prescribe based on static in pt?

Answer 22

that cannot give reliable subjective responses

Question 23

for what type of pts is autorefraction reasonably accurate

Answer 23

esp for pt w/ limited acc or under cycoplegia (esp for cyl power and axis)

Question 24

what does autorefraction do esp to young pts?

Answer 24

may over minus.

difficult to use in young pt or others who cant sit in device

Question 25

what is keratometry not used for? what is it used for instead?

Answer 25

not generally used as starting point in a ‘routine’ refraction

• used to guide contact lens fitting
• used occ as an adjunct test when there is reason to do so (high cyl, irreg cyl, poor VA or refraction endpoint, scissor reflex on ret, diagnostic value, monitor for progression)

Question 26

what is toricity

Answer 26

difference in corneal curvature in different meridians

Question 27

when do k’s help predict the cyl in the Rx-java’s rule

Answer 27

if cornea has > 1.0D of ‘toricity’