1
Q
What are the sequence of events (steps) when determining refractive error during an eye exam?
A
Step 1
-Measure Vision and VA (with old Rx if Px has one)
Step 2
-Objective refraction (retinoscopy/autorefractor)
-Measure VA with final ret result
Step 3
-Subjective refraction
-Refine the sphere
-Refine the cylinder axis then cylinder power
-May need to refine the sphere once more
-Measure VA with new Rx
2
Q
What is Best Vision Sphere (BMS)?
A
Sphere of maximum plus or minimum minus power which gives the best VA WITHOUT ANY CYLINDER
3
Q
How much reduction would 0.5 dioptres of Astigmatism give?
A
1 line reduction
So… 1 diopter of Astigmatism would give a 2 line reduction
4
Q
Formula to calculate BMS?
A
BMS = sphere + (1/2 x cylinder)
5
Q
What is Best Vision Sphere (BVS)?
A
It is the sphere of maximum plus or minimum minus power which gives best VA when a cylinder is in the trial frame
NOTE : the cylinder can be correct or incorrect
6
Q
Why is over-minussing bad for myopes?
A
Over-minussing is a problem for myopes that have accommodation as too much -ve power simulates hyperopia (rays of light converge to a point behind the retina), but a Px that has accommodation can use their accommodation to converge the rays of light to a point on the retina so their VA may be as good with a higher -ve power compared to a more +ve power
NOTE : for older Px’s who don’t have accommodation, introducing the wrong sign lens power is ok as their VA will be worse
7
Q
Why is over-plussing bad for hyperopes?
A
Over-plussing may be a problem if the Px’s eye is habitually accommodating as it might be difficult to get the Px’s accommodation to relax
8
Q
What power lens should we give to myopes?
A
Minimum minus
9
Q
What power lens should we give to hyperopes?
A
Maximum plus
10
Q
What is Step 1 of Refining The Sphere?
A
-Determine VA before you offer any sphere (or refine the current sphere)
-DIrect the Px’s attention to the smallest line of letters they can see
11
Q
What is Step 2 of Refining The Sphere?
A
-Offer both +0.50DS and -0.50DS
-ALWAYS OFFER PLUS BEFORE MINUS
-Ask the Px “is it better with or without?” and make a mental note of what the Px said
“with” - as you introduce the lens
“without” - as you remove the lens
-The -0.50DS lens should be offered for a shorter period of time than +0.50DS (2 seconds VS 4 seconds)
12
Q
Why should you offer the -0.50DS lens for a shorter period of time compared to the +0.50DS lens?
A
-ve lenses simulate hyperopia and will use the Px’s accommodation
It’s faster to switch on accommodation than switching it off
13
Q
What if the Px is hesitant or if their responses are contradicting?
A
Increase the power to ±0.75DS
If the same thing happens increase the power ±1.00DS
REDUCE STEP SIZE DOWN TO ±0.50DS ASAP
14
Q
What is Step 3 of Refining The Sphere?
A
Interpret the patient’s response, make appropriate decision and take this action
-If the Px says “it’s better with” the +0.50DS, offer the full +0.50DS
-But if the Px says “it’s the same” only offer +0.25DS
-If the Px says “it’s better with”, only offer the full -0.50DS if VA improves by a line (3 letters or more)
-If the Px says “it’s the same”, DO NOT OFFER MINUS POWER
-Same procedure with ±0.75DS or ±1.00DS
15
Q
Step 3 of Refining The Sphere with -0.75DS
A
1 line improvement = offer -0.25DS
2 line improvement = offer -0.50DS
3 line improvement = offer full -0.75DS
So… 4 lines of improvement would be needed to offer the full -1.00DS
16
Q
What is Step 4 of Refining The Sphere?
A
-Repeat steps 1-3
-If you added +ve power in Step 3, now only offer +ve power until VA measurements become worse
-If you added -ve power in Step 3, now only offer -ve power until there is no further improvement in VA measurements
17
Q
When should you stop adding +ve power?
A
Keep adding +ve power until VA measurements become worse
18
Q
When should you stop adding -ve power?
A
Keep adding -ve power until there is no further improvement in VA measurements
19
Q
What is Step 5 of Refining The Sphere?
A
Endpoint for BMS/BVS determination
-Now switch to the weakest power flippers (±0.25DS)
-Offer both powers (asking same questions as before and holding it in place for the same time as before)
-Endpoint is reached when :
+0.25DS produces blur (Px says “it’s worse”)
-0.25DS makes no difference (or makes VA worse)
20
Q
What is Step 6 of Refining The Sphere?
A
-Measure VA with BMS/BVS and proceed to address any possible astigmatism (i.e. introduce a cyl if none exists, or refine the one that already exists e.g. from retinoscopy)
21
Q
Why do we use the JCC?
A
For the subjective correction of Astigmatism or refinement of the cylinder axis and cylinder power already in place from retinoscopy/autorefractor
22
Q
What is the aim of using the JCC?
A
To try and reduce the Interval of Sturm
23
Q
What is the JCC?
A
A crossed cylindrical lens
+ve and -ve cylinders combined with their axis at 90 degrees from each other
24
Q
How do you find the axis of the -ve cyl?
A
Look at the red markings
Can be a different colour bu usually red
25
What power acts along the axis of the -ve cyl?
+ve power
and vice versa
26
What do the white circles mean on the JCC?
The white circles are located 45 degrees away from each axis
-One white circle must be in line with the handle for the JCC to twirl properly
27
How do you write the powers of the JCC in sphero-cylindrical format?
Write the +ve power as the sphere
The cylinder power should be twice (double) the power of the sphere and have the opposite sign
e.g.
+0.25/-0.50 x ...
+0.50/-1.00 x ...
28
What does it mean when one of the four dots (white circles) is next to the handle?
When one of the 4 dots is next to handle, this means the principal meridians of the lens are both 45 degrees from the handle
29
What are the 3 choices of targets?
1st choice : Concentric circles
"Verhoeff's rings"
2nd choice : Dot target
3rd choice : Letters that are just above the resolution limit
Use circular letters
30
For all of the choices of targets why is it important for the size of the targets to be the correct size?
The targets shouldn't be too big, otherwise the task for the Px will be to easy
Also if the targets are too small then it will be quite hard for the Px to determine which option is better
31
Why are all of the choices of targets circular?
Target used is circular as it contains all orientations i.e. not just horizontal and vertical
32
What must always be on the retina?
Circle of Least Confusion (CLC)
33
Once Refining The Sphere has been completed, where is the Circle of Least Confusion (CLC)?
On the retina
34
Why do you not need to compensate the Sphere power when using the JCC?
CLC does not move relative to retina when the JCC is introduced
Why? Because the mean sphere of the JCC is plano (zero) [sphere + ½cyl= 0]
e.g. +0.25 + (1/2 x -0.50) =
+0.25 + -0.25 = 0
35
What happens to the Interval of Sturm and the Circle of Least Confusion (CLC) if you introduce the JCC at the wrong axis?
Interval of Sturm gets bigger
Circle of Least Confusion (CLC) stays on the retina
36
What do we (practitioner) ask the Px?
I'm going to show you 2 lenses
Could you tell me which lens makes the circles look clearer, sharper and rounder?
If the circles look equally blurry that's ok, just say that it's the same
37
What are the rules for sphere power compensation when adding a -ve cylinder from the trial case?
For every extra -0.50DC added (making the cylinder power more -ve), add +0.25DS to the sphere power (making the sphere power more +ve)
For every -0.50DC removed (making the cylinder power more +ve), add -0.25DS to the sphere power (making the sphere power more -ve)
38
How do you Refine the cylinder axis?
-Hold the handle of the JCC along the axis of the cylinder already in the trial frame
-Ask the Px "1 or 2?"
-Move the axis of the cylinder in the trial frame towards the -ve axis of the JCC
39
When can you stop cylinder refinement?
You MUST have observed at least one reversal before you know the axis endpoint
You CANNOT determine the axis endpoint at the first "same" response
Stop when "1 or 2?" is the same for the Px (when the circles look equally blurred)
40
How much should I initially rotate the cylinder axis?
Depends on the starting cylinder power
41
How much should you rotate the cylinder axis by when the power is 0.25DC?
30°
42
How much should you rotate the cylinder axis by when the power is 0.50DC?
20°
43
How much should you rotate the cylinder axis by when the power is 0.75DC?
15°
44
How much should you rotate the cylinder axis by when the power is 1.00DC-2.00DC?
10°
45
How much should you rotate the cylinder axis by when the power is 2.25DC or more?
5°
46
What power JCC should you use?
-If VA when starting JCC (with or without cyl in the trial frame) is poorer than 85 VAR (6/12),
use the higher powered JCC (±0.50DC)
-Also use higher powered JCC if Px responses during BVS/BMS determination were
hesitant/conflicting, even if VA better than 85 VAR
RETURN TO SMALLEST JCC POWER (±0.25DC) ASAP
47
How do you refine the cylinder power?
-Hold the axis markings (red and white) along the axis of the cylinder in the trial frame
-Ask "1 or 2?"
-Depending on the Px responses, change the cylinder power appropriately
e.g. if the Px preferred the white line - make the cylinder power more +ve
if the Px preferred the red line - make the cylinder power more -ve
48
When do you need a reversal?
YOU ONLY NEED A REVERSAL WHEN REFINING CYLINDER AXIS
WE DON'T NEED A REVERSAL WHEN REFINING CYLINDER POWER
49
What power of JCC would you choose if the Px's VA is VAR 85 (6/12) or better?
+0.25/-0.50
(±0.25)
50
What power of JCC would you choose if the Px's VA is poorer than VAR 85 (6/12)?
+0.50/-1.00
(±0.50)
51
What power of JCC would you choose if the Px's has low vision?
+0.75/-1.50
(±0.75)
OR
+1.00/-2.00
(±1.00)
52
When should you check VA during the JCC procedure?
Check VA if you change the cylinder power by 0.50DC or more OR if you change the cylinder axis enough that VA may have improved by a line or more (5 points or more)
53
Should you recheck sphere power after the JCC procedure?
Only recheck sphere power if the cylinder power changes by 0.50DC or more
(sphere compensation)
54
How do you do JCC (power) with no cylinder in place from objective refraction?
-Use BMS and measure VA
-Use the VA to determine if there is any astigmatism present
e.g. VA = 95 ≈ 1DC of uncorrected astigmatism
e.g. VA = 85 ≈ 2DC of uncorrected astigmatism
55
How do you do JCC (axis) with no cylinder in place from objective refraction?
Place the handle of the JCC at 90°/180°/135°/45° and work from there to bracket off the axis
56
What do you do once you have completed the JCC procedure?
-Try +1.00DS blur test
Add a +1.00DS lens
57
What does the +1.00DS blur test do?
-Simulates +1.00DS of myopia
-Px's distance vision will definitely be reduced
58
What should you expect when you do the +1.00DS blur test and why should you expect this?
Should expect a 4 line reduction in VA (3-5 lines is ok though)
Should expect this as 0.25DS of myopia reduced VA by one line
59
How many lines does a 0.25DS of myopia equate to?
0.25DS of myopia equates to a one line reduction
60
What does the +1.00DS blur test confirm?
Confirms that you have not over-minussed (myopic Px) or under-plussed (hyperopic Px)
61
What do you do if there is only a 2 line reduction with the +1.00DS blur test?
Recheck sphere power and adjust then check cylinder power and axis
62
Outline the steps for a full monocular refraction for a beginner
1) Unaided vision
2) Perform retinoscopy (objective refraction)
Don't forget to add the WD allowance
3) VA with the final ret result
4) Begin subjective refraction
Refine the sphere
5) VA after refining the sphere
6) Refine cylinder axis
7) VA after refining cylinder axis
8) Refine cylinder power (may need to compensate sphere power)
9) VA after refining cylinder power
10) *may need to recheck cylinder axis and then VA*
11) Write down final subjective refraction result
12) VA with final subjective refraction
13) Repeat for the other eye
63
Outline the steps for a full monocular refraction for someone that knows what they're doing
1) Unaided vision
2) Perform retinoscopy (objective refraction)
Don't forget to add the WD allowance
3) VA with the final ret result
4) Begin subjective refraction
Refine the sphere
5) Refine cylinder axis
6) Refine cylinder power (may need to compensate sphere power)
7) *may need to recheck cylinder axis and then VA*
8) Write down final subjective refraction result
9) VA with final subjective refraction
10) Repeat for the other eye
64
What steps can we miss out on a full monocular refraction when we know what we're doing compared to a beginner?
We don't need to check VA after sphere refinement, cylinder axis refinement and cylinder power refinement
65
Is the refractive index greater for shorter wavelengths or longer wavelengths of light?
And how does this relate to the Duochrome test?
Refractive index is slightly greater for shorter wavelengths of light
So green is refracted greater than red
Order of colours that appear on the retina : Green, Yellow, Red
66
What does the Duochrome target look like?
Black circles/black dots on red and green background
67
Why are red and green colours used for the Duochrome target?
Red and green colours are used since they appear equally bright to the Px
68
Why are red and blue not used for the Duochrome target?
The blue background would look quite dark relative to the red one and this would interfere with the test result
69
What would you ask the Px when doing the Duochrome test?
Ask the Px :
"on which colour do the black dots look clearer and rounder, or do they look the same on both colours?"
70
What does it mean if the Px says the black dots look clearer/rounder on the red background?
What should we do?
-Red light is focussed near the retina
-The eye is in myopic defocus (over-plussed)
-So we would try adding -0.25DS to the trial frame (only leave it in if it improves VA)
71
What does it mean if the Px says the black dots look clearer/rounder on the green background?
What should we do?
-Green light is focussed near the retina
-The eye is in hyperopic defocus (over-minussed)
-So we would try adding +0.25DS to the trial frame (only leave it in if VA stays the same, if VA reduces don't add it in)
72
What if the Px responds "the same" to the Duochrome test?
What does this mean?
-Suggests no change is required
-Ideally we would want this but it is ok to start JCC with black dots being clearer/rounder on the green
-NEVER start JCC with the black dots being clearer/rounder on the red
73
When would we do the Duochrome test?
At the end of refining the sphere
74
If the Px responds "the same" to the Duochrome test, what can we do to check this?
What would we expect?
Add +0.25DS
-Rings on the red should look clearer
And then add -0.25DS
-Rings on the green should look clearer
75
What should we do if the rings on the red look clearer in the Duochrome test?
If rings on red look clearer, add -0.25D and ask the same question. If still “red”, add -0.50 and recheck. If still “red”, add -0.75 and recheck
76
What should we do if the rings on the green look clearer in the Duochrome test?
If rings on green look clearer, add +0.25D and ask the same question. If still “green”, add +0.50 and recheck. If still “green”, add +0.75 and recheck
77
When can the Duochrome test become unreliable?
-When the Px initially reports “same”, but -0.25DS gives “red” and/or +0.25DS gives “green”
-Px requires 1.00DS change before switching form green to red (or vice versa)
-Avoid Duochrome with older Px's
78
Why may it be ok to stop when the Px says the black dots look clearer/rounder on the red background if they are young?
Young Px's have accommodation, so they can accommodate and bring the CLC onto the retina
79
When is the +1.00DS test used and what does it check?
Used at the end of subjective refraction
Final check to ensure. that we have not under-plussed (a hyperopic eye) or over-minussed (a myopic eye)
80
What does the +1.00DS test do?
-A +1.00DS will artificially generate -1.00DS of myopia which causes/should lead to a 4 line reduction in VA as -0.25D of uncorrected myopia (real or artificial) leads to a 1 line reduction in VA (however fall can be anywhere between 2 to 7 lines)
81
In what Px's would you use the +1.00DS test and why?
(older or younger)
-Test is only needed in younger Px's as...
-Cannot really under-plus old hyepropes as their VA will reduce as they don't have any accommodation to overcome the residual hyperopia
-If you over-minus an old myope, their VA will reduce as they don't have any accommodation to overcome the extra, unnecessary minus power
82
What part of subjective refraction does the Fan and Block Technique replace?
Alternative to JCC
All steps before and after JCC during subjective refraction still apply
83
What part of the Fan and Block Technique is for cylinder axis and what part is for cylinder power?
Fan - cylinder axis
Block - cylinder power
84
What sign of cylinder does the Fan and Block Technique work with, +ve or -ve?
Only works with -ve cylinders, not +ve cylinders
85
What 2 things does the Fan and Block Technique rely upon?
1) Making a prediction of the amount of astigmatism that the eye may have (0.50DC = 1 line)
2) The axis of the -ve cylinder will need to be in line with the most clearest lines
86
Give the steps on how to perform the Fan and Block Technique
Step 1
-Remove the cylinder in place from objective refraction (e.g. retinoscopy)
-Determine the BMS
Step 2
-Estimate the remaining astigmatism and then add 1/2 of this amount as +ve sphere to the BMS
Step 3
-Direct the Px to the fan chart
-Ask the Px "which lines look more clearer?"
-Turn the pointer so that it is in line with the most clearest line
-The limbs of the pointer should look equally out of focus
Step 4
-Check that the rear focal line is on the retina
Step 5
-Add a cylinder with its axis in line with the blurred lines (parallel to the blurred lines)
Step 6
-Refine the cylinder power by increasing cylinder power until the blocks are equally clear
-Ask the Px "are the blocks equally clear?"
Step 7
-Confirm that the cylinder power that makes the blocks equally clear is accurate and correct
-Try a slightly higher cylinder power, the right block should become more clear
87
In Step 1 of the Fan and Block Technique, what does the BMS mean in terms of the CLC?
Ensures CLC is on the retina
88
What does Step 2 of the Fan and Block Technique do?
Places the rear focal line on the retina
89
What do you do in Step 4 of the Fan and Block Technique to check whether the rear focal line is on the retina?
Add a +1.00D lens
-If the rear focal line is on the retina then all the fan lines will look blurred
-If the front focal line is on the retina then the +1.00D lens will not make the lines blurred
90
Does the -ve cylinder impact the position of the rear focal line?
What does the -ve cylinder do in terms of the interval of sturm?
No, the -ve cylinder doesn't impact the position of the rear focal line
it makes the interval of sturm smaller by reducing of the distance of the front focal line and by moving the CLC closer to the retina
91
What should you do if one limb of the pointer is clearer than the other in Step 3 of the Fan and Block Technique?
-The pointer is not in line with the most clearest line
-Rotate the pointer to a different line
92
For the Fan and Block Technique, what if the Px has no astigmatism?
All the lines will appear equally clear on fan chart with a sphere alone and the acuity will be VAR 105 or better
93
For the Fan and Block Technique, what if the clarity of the blocks reverses when you change the cyl power by -0.25DC [i.e. blocks are never equally clear]?
Choose the lower cyl power unless the higher powered cyl gives better acuity
94
For the Fan and Block Technique, what if the fan lines are not all equally clear at the end?
Recheck the cyl power and axis using the fan and block charts as all lines should appear equally clear
95
Give the advantages of the Fan and Block Technique
-Px can see the picture getting better as astigmatism is corrected
(end point is well defined - all the fan lines are equally clear)
-Easier way to explain how astigmatism works to a Px and an easier way to understand astigmatism as a student
96
Give the disadvantages of the Fan and Block Technique
-Near focal line has to be on the retina
-When the Px has low astigmatism/very small amounts of astigmatism there will be lots of clear lines so the Px may struggle to identify the clearest line
-Determining cylinder axis is not as accurate compared to JCC
97
Formula to calculate Meridional Power
S + C.(Sin^2θ)
S - Sphere power (D)
C - Cylinder power (D)
θ - difference between cyl axis and the meridian of interest
98
What is the Meridional Power formula used for?
Used for working out the power along a non-principle meridian
99
Define what Resiual Ametropia is (when using the JCC)
Difference between actual ametropia in each meridian and the combined power of the JCC and the trial frame lenses in each meridian
100
What does the Px's responses actually mean when performing cylinder refinement (JCC)?
The response that the Px will say is which combination will make the circles clearer/sharper/rounder
In other words, they will say the combination that corrects more of the eyes ametropia (leaving less residual ametropia)
101
When the Px says the circles look equally blurred, what does this actually mean (JCC)?
This occurs when both positions of the JCC leave the same residual ametropia
102
What is the Resultant?
Give an example
Combined power of 2 sph/cyl lenses that have the same principal meridians
Example :
+1.00/-1.00 x 160
+0.50/-0.75 x 160
Resultant = +1.50/-1.75 x 160
103
What 3 terms do we divide a Rx into and calculate in order to combine different lenses together that don't have the same principal meridians?
(Astigmatic Decomposition)
-M
-J180
-J45
104
Formula to calculate M
What is M?
(Astigmatic Decomposition)
M = S + C/2
M - mean sphere
105
Why does M = 0 for a JCC lens?
E.g. +0.25/-0.50
M = S + C/2
M = +0.25 + (-0.50/2) = 0 (plano)
106
Formula to calculate J180
What is J180?
(Astigmatic Decomposition)
J180 = -0.5C*cos(2A)
2A - 2 x Axis
J180 - amount of WTR astigmatism
107
Formula to calculate J45
What is J45?
(Astigmatic Decomposition)
J45 = -0.5C*sin(2A)
2A - 2 x Axis
J45 - amount of oblique astigmatism
108
Steps to combine 2 or more sph/cyl lenses that do not have the same principal meridians
1) Calculate M, J180 and J45 for each lens
2) Calculate ∑M, ∑J180 and ∑J45
3) Calculate Resultant Sphere
4) Calculate Resultant Cylinder
5) Calculate Resultant Axis
109
Formula to calculate Resultant Sphere
Resultant Sphere = ΣM + √[ (ΣJ180)^2 + (ΣJ45)^2 ]
110
Formula to calculate Resultant Cylinder
Resultant Cylinder = -2*√[ (ΣJ180)^2 + (ΣJ45)^2 ]
111
Formula to calculate Resultant Axis
Resultant Axis = 0.5tan-1 (ΣJ45 / ΣJ180)
112
Give a list of the sources of uncertainty in subjective refraction measurements and categorise them whether they are intrinsic or extrinsic factors
-Pupil size (intrinsic factor)
-Uncertainties in the powers of trial case lenses (extrinsic factor)
-Errors in trial case lens vertex distance (extrinsic factor)
113
How is pupil size a source of uncertainty in subjective refraction measurements?
Pupil size influences depth of field
114
How is uncertainties in the powers of trial case lenses a source of uncertainty in subjective refraction measurements?
-Powers of trial case lenses may not be exactly what they say
(e.g. a +3.00DS has a tolerance of !±0.09D, so the power could be anywhere between +2.91D - +3.09D)
115
How is errors in trial lens vertex distance a source of uncertainty in subjective refraction measurements?
-Ocular refraction vs Spectacle refraction
-Need to take into account vertex distance (distance of the correcting lens to the cornea) as a change in vertex distance may change the power
116
What is depth of field?
The vergence range over which there is no perceptible defocus
117
Do larger pupils have a smaller or larger depth of field?
Smaller
118
Do smaller pupils have a smaller or larger depth of field?
Larger
119
What does it mean if a pupil has a larger depth of field?
We can change the lens power by a greater amount without the Px noticing
120
What does it mean if a pupil has a smaller depth of field?
We can change the lens power by a small amount without the Px noticing
121
When and why is binocular balancing of accommodation performed?
Performed after a monocular refraction to relax and balance accommodation in the two eyes
122
Who does binocular balancing of accommodation not need to be performed on?
-Px's that don't have accommodation (Px's older than 60)
-Pseudophakes
-Px's with a dominant eye
123
What are Pseudophakes?
People that have an artificial lens (IOL - Intraocular Lens) implanted to replace the natural lens
(tend to have a myopic Rx)
124
What is the aim of binocular balancing of accommodation?
-Make the spherical correction in conditions similar to the Px's normal viewing situation so that vergence and pupil size are in their normal binocular state
-Also makes sure the eye is not proximally accommodating (proximal accommodation) because of an occluder
125
What can binocular balancing of accommodation do?
Balance accommodation in Px's with unequal monocular VA
126
Give the steps for the procedure of binocular balancing of accommodation
1) Fog the LE until VA is reduced by 3 or 4 lines less than the RE (eye being tested)
Typically +0.75 DS or +1.00 DS is required
2) Repeat BVS using +0.25DS flipper in the RE
3) If it is better or the same, add the +0.25DS to the sphere power and repeat step 2 until the patient says that it is better without the extra +0.25DS
4) Remove the fog from the LE then fog the RE by 3 or 4 lines and repeat steps 2 and 3 for the LE until you have the most plus, and least minus in both eyes
127
What type of Px's is binocular balancing of accommodation particular good with and why?
Hyperopes as hyperopes accommodate with an occluded
128
When performing BVS/BMS where do you instruct the Px to look?
Instruct the Px to look at the lowest line they can see
129
What does adding +0.25DS or +0.50DS to an eye that is close to/at the final Rx do?
Relaxes accommodation
This is why the Px responds "the same"
130
Do you record the subjective refraction result and then record the binocular balancing of accommodation result?
No, you would only record the binocular balancing of accommodation result at the very end
131
What should the Rx be in a Px with a dominant eye?
Rx needs to be spot on as you would not do binocular balancing of accommodation
VA and Refractive Correction 1
flashcards
Decks in class (7)
# Cards
-
Vision and VA/VA Measurement Uncertainty/Measuring Visual Function At Near/External and Internal Factors Affecting VA144
-
Ametropia and Astigmatism/Refractive Correction/Refractive Error/Myopia Management246
-
Retinoscopy127
-
Reversibility Of Light and The Far Point of Accommodation/Accommodation132
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Subjective Refraction131
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The Visual Acuities/Different Systems For VA Measurement139
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Visual Development78
