Subjective Refraction

Question 1

When would it be appropriate to perform subjective refraction

Answer 1

• To determine a prescription through which the patient can see comfortably.
• To assess the patient’s blur discrimination
• When you cannot perform objective testing
  e.g., due to media opacities or pinhole pupils.

Question 2

the vertical focal line is formed at the point where the

Answer 2

horizontal rays focus

Question 3

the horizontal focal line is formed at the point where the

Answer 3

vertical rays focus

Question 4

the dioptric midpoint between the 2 focal lines is called

Answer 4

COLC

Question 5

plus lenses move focal lines ___ towards the retina

Answer 5

anteriorly
hyperopes MR is posterior to R thus moves forward

Question 6

minus lenses move focal lines __ towards the retina

Answer 6

posteriorly
myopes MR is anterior to R thus move back

Question 7

we can estimate the potential change in spherical refinement error in the following patients except ?

a. myopia
b. non accommodating hyperopia
c. absolute hyperopia
d. accommodating hyperopia

Answer 7

D

Question 8

on JCC, the red and white denotes which cylinder axis respectively ?

Answer 8

minus, plus cyl axis

Question 9

The cylinder axis is where the power is not. given the minus cyl axis lies at 180, while the plus cyl axis lies at 90, where are the respective cyl powers ?

Answer 9

minus cyl power = 90
plus cyl power = 180

Question 10

given the cylinder axis found during retinoscopy is 90, which two axis would you bracket during JCC cyl axis refinement ?

Answer 10

(90 + 45) and 90-45

Question 11

what is the order of subjective refraction ?

Answer 11

initial sph refinement OD
initial cyl axis refinement OD
cyl power refinement OD
second sph refinement OD
- repeat all steps for OS
binocular balance
binocular sph refinement

Question 12

When increasing the cyling by -0.50D, the sph power adjustment is ___ to keep the COLC on the retina

Answer 12

+ 0.25D

Question 13

when changing cyl power, which focal line are we moving

Answer 13

front focal line

Question 14

if a patient has a VA of 20/40 after best sphere, what is the estimated uncorrected astigmatism ?

Answer 14

1.50 D

Question 15

when using a fan chart, what components of the prescription are used to start the procedure

Answer 15

sph equivalent, no cyl

Question 16

during axis refinement the patient mentions all lines of the fan chart are equally dark, whats the finding

Answer 16

no astigmatism or COLC is on the retina (unfavorable)

Question 17

if a pt is 0.50D myope along 30M and 2.50 myope along 120M, which focal line is closest to retina

Answer 17

30M has lowest refractive error, the equivalent focal line is 120 FL, thus closest to R

Question 18

when performing axis refinement, the doctor sees an angle of 45, the patient will see an angle of ?

Answer 18

180-45 = 135

Question 19

given from dr perspective the 120 FL is closest to the retina, then the focal line nearest R for pt perspective is ?

Answer 19

(180-120) =60 FL
the orientation of the clearest line on the fan chart (from pt perspective) is the same as the orientation of focal line nearest the retina (from pt perspective)

Question 20

pt perspective: 70 FL is nearest retina
doctor perspective: (180- 70) = 110 FL nearest retina
what is the meridian nearest retina from dr perspective ?

Answer 20

110-90 = 20

Question 21

The meridian nearest the retina from dr perspective represents

Answer 21

cyl axis

Question 22

if the pt says the clearest line is at 30, what is the meridian from doctors perspective

Answer 22

dr perspective FL = 180-30 = 150
dr perspective meridian = 150- 90 = 60M
60M

Question 23

After cyl axis refinement, to correct cyl power, decreased the number of choice by providing 2 blocks that are _______ to achieve equal appearance of clear and dark

Answer 23

90 degrees apart

Question 24

what are two instances when 2 blocks appear equal to the pt:

Answer 24

1. succesfully corrected astig
2. COLC is on the retina, uncorrected astigmatism is still present

Question 25

if block appear equal, how can you confirm the astigmatism is fully corrected ?

Answer 25

place additional +1.00SPH to move the entire IOS, if equal pt voices equal blur

Question 26

if block appear equal, how do you know if COLC was left uncorrected ?

Answer 26

place additional +1.00 SPH and pt voices one block clearer than another > recheck cyl power

Question 27

when undergoing second sph refinement, what line VA should you stop at if pt can go to 20/20

Answer 27

beyond 20/20 until they reach best VA

Question 28

under duochrome tests, a hyperopic patient would report which target as clearest and dark

Answer 28

green, shorter AL

Question 29

under duochrome tests, a myopic patient would report which target as clearest and dark

Answer 29

red , longer AL

Question 30

would you perform binocular balance on a presbyopic pt?

Answer 30

yes, to ensure equal ADD OU

Question 31

does the eye accommodate more or less under binocular conditions

Answer 31

more

Question 32

what is exophoria

Answer 32

under converged eye under monocular conditions (outward turn), require more convergence when testing binocularly

Question 33

what is esophoria

Answer 33

the eye turns inwards under monocular conditions

Question 34

which of the binocular balancing techniques are the least reliable in represent daily encounters? a. succesive alternate occlusion b. vertical prism dissociation c. septum techniques d. polaroid techniques e. A and b

Answer 34

E successive alt occlusion occluding an eye leads to convergence of the open eye and this is a false reality as the pupil isn't in that position during primary gaze VPD is the same as occluding one eye without actually doing it

Question 35

Given then prism is base up, where is the image

Answer 35

image appears down

Question 36

when performing humphriss binocular balancing technique, the blurred eye under a +1.00D lens has a central retinal blur of how many degrees ?

Answer 36

2-3

Question 37

during polaroid techniques, if a filter blocks transmission of the light reflecting from a letter, what color with the letter be?

Answer 37

black letter against white background

Question 38

during polaroid techniques, if a filter allows transmission of the light reflecting from a letter, what color with the letter be?

Answer 38

white letter on white background

Question 39

when a letter appears black, what does this represent

Answer 39

the absence of light, blocked light transmission

Question 40

which technique doesn't require fogging lenses

Answer 40

polarized duochrome