Advanced Case Analysis (Final Set)

Front 1

New Course: Advanced Case Analysis

Front 2

make sure you go through the lectures too; flashcards just for memory stuff, not calculations.

Front 3

is the AC/A high or low if the near phoria is more eso than the far? what if it is more exo?

Back 3

if near is more eso than far: high AC/A if near is more exo than far: low AC/A

Front 4

describe Dr. Smith's method of calculating AC/A in your head in clinic

Back 4

take the difference between the phoria at near and the phoria at far (absolute value). then multiply it by the working distance in meters (usually .4). then you either add or subtract that value from the pd in centimeters. if the near phoria is more eso than the far phoria then you add, if the near phoria is more exo than the far phoria then you subtract.

Front 5

how can you look for a verticle deviation on cover test

Back 5

ask the pt to tell you if the bead is moving up and down, side to side, or diagonally. if they report that it is moving up and down or diagonally then they definately have a vertical phoria.

Front 6

why do you need to know that AC/A clinically before you make any chages from the manafest

Back 6

you want to know how it is going to affect their vergence ranges, their phorias, and the PRA/NRA.

Front 7

what phoria values at distance and near would be high enough that Dr. Smith recommends checking the compensating ranges even if they don't complain of any symptoms? what should you do if you do check the compensating ranges?

Back 7

distance: 4 or more eso or exo near: 4 or more eso, 9 or more exo -if you do find a phoria at these levels or higher, then you check the compensating range (BI range for eso deviations and BO for exo). when you check the compensating range you determine if they meet sheard's criteria.

Front 8

does percival's use the break or the recovery values

Back 8

for this class use the break. for national boards use the blur.

Front 9

what is percival's criteria

Back 9

take the smaller range (BO or BI) and multiply it by two. it should be equal to or greater than the larger of the two ranges.

Front 10

if you give a 1 eso pt 3 BO, what will their phoria be

Back 10

2 exo

Front 11

how does rxing BO affect the vergence ranges on a pt

Back 11

decrease BO range; increase BI range

Front 12

would the gradient or the near far AC/A typically be lower

Back 12

gradient should be lower than distance to near AC/A. when you do a near/far AC/A there is a priximal component stimulating extra accommodation that you don't get with a gradient AC/A

Front 13

what are the two things that could limit PRA

Back 13

relative accommodation, or relative divergence. when you see a pt with a low PRA you need to determine if it is limited due to vergence or accommodation.

Front 14

how can you calculate the point where PRA would be limited by vergence based on other binocular findings

Back 14

determine the AC/A of the BI line (graphical analysis) (use blur if you have blur and break if you don't; think zone of clear single binocular vision). divide the BI first blur value at near (or the break value if no blur) by the AC/A. the quotient is the expected PRA net (assuming accommodation doesn't limit the value) -think of BI values as exo -same process for determining the NRA from the BO ranges.

Front 15

are the BI lines and the BO lines (think graphical analysis) going to be parallel (same AC/A) as the phoria line

Back 15

for clinical calculations the BI line is usually pretty much parallel to the phoria line (you can use AC/A of phoria for BI calculations clinically), but the BO line is usually not parallel to the phoria line.

Front 16

what does the BCC tell you about an add for a pre-presbyopic pt

Back 16

BCC is the MOST plus they will accept at near. there may be times that you need to rx more than that, but they are not going to like it and both you and they need to be aware of that.

Front 17

what does the BCC tell you about an add power for a presbyopic pt

Back 17

BCC is a good lens to rx for a presbyope.

Front 18

what type of AC/A should you use when thinking about a plus add and how it is going to affect vergence

Back 18

gradient AC/A is a more realistic value than near/far for an add power because that is basically what you are doing with an add.

Front 19

what is probable error

Back 19

1 Probable error is 25% of the population above (or below) the mean of the pop. Each finding is normal if it is within plus or minus 1 probable error (PE) of the mean

Front 20

what is standard deviation

Back 20

you take each individual score and subtract it from the mean. then that number is divided by the total number of scores (averaged). it is an average of the difference of the individual scores from the mean.

Front 21

what is the equation for standard score and how do you interperate the result

Back 21

Standard Score (SS) = [Test score – Population Mean (M)] / PE (probable error) When result is between -1 and 1, the finding is considered normal -the standard score allows different tests with different means and standard deviations to be compared directly to one another

Front 22

how do you know if your distance phoria is statistically worse than your near phoria for dwayne white classification

Back 22

you need to convert each data point into a standard score to see which is worse. you can't just compare the raw data because the near and far phorias each have different mean values and probable errors. if the difference in the standard score of the near and far phoria is greater than 1, then you can say that one is statistically "worse" than the other. -(Z score is the same as standard score, only you divide by the standard deviation instead of the probable error)

Front 23

is eso and exo positive or negative in optometry

Back 23

eso: positive exo: negative -think of a dioptric line for an emmetrope, you would need to add plus to get conjugate focus closer to your nose. or think of MEM, to get their conjugate focus closer to their nose you would use a plus lens.

Front 24

if you are making a dwayne white classification based on standard scores, how do you know if the near value is "worse enough" to be classified as worse than the far (CI vs. basic exo for example)

Back 24

if the difference in their standard scores is greater than 1, it is statistically significant and you can apply a dwayne white classification.

Front 25

How do you convert standard score into a percent of the normal population (i.e. how rare is the finding)

Back 25

Convert standard score into Z score (take SS and multiply by 0.6745). then you look up the probability using either a table in a statistics book called standard normal probabilities or use excel using the following formula: =NORMSDIST(z) (where z is the Z score)

Front 26

what is a type 1 finding in normative analysis and give some examples

Back 26

known as a physiological finding. scaled on a continuum from inferior to normal to superior. MORE IS BETTER. -examples: amplitudes of accommodation and vergence, relative accommodation and vergence findings, facility

Front 27

what is a type 2 finding in normative analysis and give some examples

Back 27

known as a postural finding. scaled on a continuum from hypo-activity to normal to hyper-activity. hypo AND hyper findings are bad -examples: crossed cylinder test, dynamic retinoscopy, AC/A ratios, phorias and fixation disparity.

Front 28

what is the probability of having a bad type 1 finding due purely to chance? what about a bad type 2 finding

Back 28

type 1: 25% type 2: 50% -in either the probability of being abnormal is 50%, but abnormal is not bad for superior findings with type 1.

Front 29

what is sheard's comfort criteria

Back 29

they should have twice the phoria in the opposite vergence range direction to be comfortable

Front 30

does sheard's use the blur or the break values

Back 30

if you have the blur use the blur, if you don't use the break.

Front 31

how do you calculate how much prism to rx if a pt doesn't meet sheard's criteria

Back 31

you calculate the number that they would need to pass and subtract the number that they do have; then you divide that number by three.

Front 32

describe seven ways you could determine the amount for an add on a pre-presbyope

Back 32

1. BCC 2. take 0.25 off the BCC 3. rx based on what you want the phoria to be 4. rx so that you don't shift the balance between whichever is larger the BI or the BO range. 5. based on sheard's 6. based on percival's 7. based on MEM (accommodative lag)

Front 33

how do you determine how much prism to rx if the pt doesn't meet percival's criteria

Back 33

take twice the smaller vergence range and subtract it from the larger range. then divide that number by three and that is how much prism you would rx. the direction of the prism is the direction of the larger range (if they have a larger BO range rx BO prism)

Front 34

what is the krimsky test

Back 34

like hirschberg, but you place prism in front of the eye until the reflex is even

Front 35

what should you do if you are doing the red lens test and the pt reports red, but you are not sure if the pt is seeing pink (red and wite) or is suppressing and really only seeing red

Back 35

cover one eye and ask them if the color chages when you do that.

Front 36

what is a clinical test you can do to tell if their asigmatism induces enough prismatic effect when they look through the bottom of the lens to cause a problem

Back 36

put a red lens over one eye and bring a white light from primary gaze down into reading position. if the light splits into two, then they should get slab off prism.

Front 37

what amount of induced vertical prism caused by a difference in power in down gaze should you start thinking about slab off prism clinically

Back 37

1.5 prism diopters of induced vertical prism

Front 38

if you are suspicious of what condition you should repeat NPC multiple times

Back 38

CI, their break and recovery will deteriorate with repeat testing; normals will not.

Front 39

do low AC/A conditions tend to adapt to prism?

Back 39

no, that is part of the problem with CI. vergence is not adapting and keeps drifting back towards the edge of panam's fusional area, then accommodation kicks in a little more and gets tighter and tighter. since they don't adapt to vergence very well, they will not usually adapt to prism very much.

Front 40

how much do you expect your recovery values to be

Back 40

1/2 to 2/3 the blur value

Front 41

what should you always make sure is accurate before you start a VT program

Back 41

correct the ametropia. if their glasses rx is not right on, you need to correct their rx and bring them back in 1 month to see if that has straighted out there binocular problems. you don't want to start therapy if all they needed was an accurate rx.

Front 42

what does the NPC recovery tell you about the BO recovery

Back 42

if NPC recovery is greater than 40 cm you expect BO recovery to be negative.

Front 43

describe the meachanism for low AC/A and for high AC/As

Back 43

high: accommodative adaptation is not working. as the phasic system gets tired it starts to lag. when the lag gets toward the edge of depth of focus accommodation is signaled to increase; this signal also goes to convergence (which has normal adaptation and was not laging) and convergence increases low: vergence adaptation is not working. as the phasic system gets tired vergence starts to lag until it gets toward the edge of panam's fusional area. then convergence increases and accommodation gets tighter and tighter. -this is why low AC/A pts don't adapt to prism (their vergence adaptation is not working) and why high AC/A pts do adapt to prism (their vergence adaptation is working quite well). generally divergence excess pts don't adapt to prism like CEs do. -this is also why plus works well for high AC/A pts, because it works as the adaptive component

Front 44

what type of ogle curve is most commonly associated with CE

Back 44

type II

Front 45

would a high AC/A pt tend to have high or low recoveries? why?

Back 45

high. because they adapt to vergence so well. you can tell if they are going to adapt to BO prism by doing their recoveries.

Front 46

for divergence excess, what potential problem do you run into at near if you rx prism and how could you fix it

Back 46

if the prism is greater than their phoria at near you could make them eso at near. you could fix this with a bifocal.

Front 47

what could you do for a divergence excess pt instead of giving them prism

Back 47

overminus them at distance and take advantage of the high AC/A

Front 48

approximately what range of AC/A is considered normal

Back 48

4-6

Front 49

what kind of phorias do you expect to find with fusional verdence dysfunction (general binocular dysfunction)

Back 49

normal phorias with a normal AC/A

Front 50

what does it tell you if you have a different vertical phoria at distance and near

Back 50

you expect it to be the same. if not it is almost always because you have an over or under-acting oblique

Front 51

what is it called if you have a vertical deviation due to a over or under-acting oblique

Back 51

cyclovertical deviation

Front 52

if you have unilateral aphakia and you have the pt in contacts but the image size difference is still too large for them to fuse what can you do

Back 52

reverse galilean telescope over the CL. overplus them and them provice a minus compensating lens in front of the eye and you will get minification of the image. works fantastically.