Manifest Refraction Part 1

What are objective types of refraction?

auto refraction

retinoscopy

wavefront guided

What are subjective types of refraction?

manifest/BCVA refraction

trial frame refraction

What is dry refraction? How does this affect accommodation?

refraction done without cycloplegic drops

accommodation is active but controlled during testing

How is accommodation controlled during dry refraction?

using distance targets

Why do we want accommodation to be controlled during refraction?

prevent overminusing patient

What is damp refraction? How does this affect accommodation?

refraction done with tropicamide

accommodation is paralyzed, still some residual

What is wet refraction? How does this affect accommodation?

refraction done with use of cyclopentolate

accommodation is fully paralyzed

What is the disadvantage of damp/wet refraction?

pupil is dilated so you may not achieve 20/20 during refraction

What is the goal of manifest refraction?

provide the most plus/least minus refraction that provides BCVA

Why do we not want to over-minus the patient?

patient has to accommodate to see clearly, causing eye strain + could impact BV or near vision

What are the steps of refraction?

1. retinoscopy

2. Check monocular Vas

2. monocular sphere check

3. Cyl power

4. Cyl axis

5. cyl power

6. monocular sphere check

7. binocular balance

8. binocular sphere

9. final acuity check

What letter size do you use when using retinoscopy?

20/400 with red/green filter

How do we control accommodation without using drops?

fog patient or do 3-eyed retinoscopy

What is "fogging" for retinoscopy?

where you over plus the left eye 1.5-2D before starting ret on the right eye

What is 3 eyed retinoscopy?

When you neutralize the right eye then the left, then go back and recheck the right before removing your working distance

If the patient was originally accommodation when you scoped the right eye, what motion and what lens will you need to add when checking the right eye again with 3-eyed retinoscopy?

with motion, add plus

What are the goals of the first monocular sphere check ?

eliminate any over-minus

maximize acuity before JCC

center circle of least confusion on retina

If your patient sees 20/20 after retinoscopy, what is your next step?

add plus to blur entire line and add minus to regain clarity

If your patient sees 20/25 or 20/30 after retinoscopy, what is your next step?

add 0.50D of plus first

if plus does not help:

add 0.50D of minus

If your patient is seeing 20/25 after retinoscopy and you add +0.50D of plus and they said it is clearer, what do you do next?

add another +0.50D until plus starts to reduce clarity, the start showing +/-0.25D options

If your patient is seeing 20/25 after retinoscopy and you add -0.50D and they said it is clearer, what do you do next?

add another -0.25D of minus to see if it improves vision

If your patient is seeing 20/40 or worse after retinoscopy, what is your next step?

monocular bichrome

What is the monocular bichrome test/how is it performed?

20/20-20/40 chart over red-green filter

add +0.50 of viewing eye and have patient compare letters on red vs green side and add appropriate lenses until both sides look equal

If you are doing a monocular bichrome test and the patient says the green side looks better, what does this mean the patient was and what do you do?

patient is overminused, add +0.25D

If you are doing a monocular bichrome test and the patient says the red side looks better, what does this mean the patient was and what do you do?

patient is overplused, add -0.25

If you are doing monocular bichrome on a myopic patient and no lens results in both sides looking equal, what do you do?

stop at the first lens that makes the green look better

If you are doing monocular bichrome on a hyperopic patient and no lens results in both sides looking equal, what do you do?

stop at the last red response (last lens that makes the red look better)

What is a Jackson Flip Cross Cylinder (JCC)?

A sphere-cylindrical lens that has equal and opposite power in perpendicular meridians

What do the red dots indicate on JCC?

minus cylinder axis therefore the location of the plus power

When determining cyl power, what position should the JCC be in?

parallel/power position

If you are doing cyl power check with JCC and your patient picks the red dots, what does that mean?

increase minus cyl

If you are doing cyl power check with JCC and your patient picks the white dots, what do you do?

decrease the minus cylinder

When you fully correct astigmatism, what will the patient state?

that both choices look the same

If you add in an extra -0.50D of cyl, what do you have to do to the sphere power?

add in +0.25D

If you add in an extra +0.50D of cyl, what do you have to do to the sphere power?

add in -0.25D

Why do we adjust the sphere power for every two clicks of cyl power?

too keep the circle of least confusion on the retina

If you have -0.25D of cyl in the JCC and the patient indicates that both flips look the same, what do you do?

KEEP the -0.25 and adjust axis

When checking cylinder axis, what position is the JCC in?

straddle position

If you have <1.00D of cyl, how much do you turn the axis wheel?

20º until patient reverses, then 10º

If you have >1.00D of cyl, how much do you turn the axis wheel?

10º until patient reverses, then decrease

If you scope a large amount of cyl on a patient, what step can you skip and what step would you start with instead?

skip the first cyl power check and start right at axis check

After JCC, what acuity line should your patient be reading (if no pathology/problems).

20/20 or close to it

What is the goal of the monocular sphere recheck after JCC?

to get 20/20 acuity with the mostplus/least minus sphere lens

How do you perform the monocular sphere check after JCC if patient is seeing 20/20?

offer the patient +0.25 and -0.25 to see which the prefer

How do you perform the monocular sphere check after JCC if patient is NOT seeing 20/20?

offer patient +0.50 and -0.50D to see which one helps and then offer that sign lens in 0.25D steps to maximize acuity

Why is binocular balance done?

patients may have accommodated during refraction and amount of accommodation can differ between both eyes, leading to an unbalance Rx where one eye will always be out of focus

binocular balance eliminates this

What does binocular balance ensure?

that both eyes will have equally clear retinal images when viewing together

If the refraction is unbalanced and not fixed, what are the potential outcomes?

reduced stereo acuity

central suppression

asthenopia (eyestrain)

PT complaints

amybopia in child if significant

During binocular prism balance what prism does the right eye get?

BD

During binocular prism balance what prism does the left eye get?

BU

If you are doing binocular balance and the patient says the upper image is better, what do you do?

add +0.25 to the right eye

If you are doing binocular balance and the patient says the lower image is better, what do you do?

add +0.25 to the left eye

How many clicks should you be adding for the binocular balance with prism?

1-2 clicks

If you have to add more than a couple of clicks during the prism binocular balance, what might be the case?

patient has unequal VAs and one eye sees better

astigmatism correction is off in "worse" eye

What must you never do after finding binocular balance?

change the sphere power of just one eye

What do you do after checking binocular balance?

binocular subjective sphere

What is the final sphere determination for the patient?

binocular subjective sphere

How do you perform binocular subjective sphere?

add plus in both eyes until 20/20 is too blurry to read

switch line and decrease plus until patient can guess 1-2 letters

than offer minus up to -0.75D

If your patient is easily seeing 20/20 during binocular subjective sphere, what can you do?

show them the 20/15 line as a bonus row

What do you do if a patient reports that adding a click of minus makes the letters darker and smaller, but not clearer?

they do not need that minus

When do you do the prism binocular balance?

after second monocular sphere check