4-TF

Question 1

Regarding TF of pts undergoing VEGF injections, does the mean change in VA occur (slow/quickly)? Maximized after about how many injections?

What was the mean VA of those entering the MARINA study?

Answer 1

• quickly; maximized after ~4-6 injections

- 20/80-

Question 2

Three important tests before refracting a LV pt: [PRK]

Answer 2

• Pinhole VA - can be misleading in LV pts!
• Retinoscopy
• Keratometry - useful if no reflex seen on ret, IDs high cyls

Question 3

Give the number of appropriate conditions that lead to the following refractive trends:

• Myopia (3):
• Hyperopia (4):
• Astigmatism (4):
• What’s the RED FLAG?!

Answer 3

Myopia: cataracts, degenerative myopia, ROP
Hyperopia: WET AMD, aphakes, coloboma, microcornea
Astigmatism: Pseudophakes, PK, KConus, albinism
-Red flag - UNCONTROLLED DIABETIC!!

Question 4

When TF refracting a pt; their entering VA is 10/100 - what’s the JND? What two lenses will you bracket with?

Answer 4

10/100 ==> 20/200 –> 200/100 = 2.00; bracket w/ +/-1.00

Question 5

Say the pt picks the -1.00 bracket lens - what lens do you put in the TF to continue bracketing?

Answer 5

-2.00 - change it initially by the ENTIRE JND; recheck VA to readjust bracketing lens

Question 6

Given the appropriate JCC power; give the range of VA that you should use to determine what power JCC lens you pick to refract the pt's astigmatism: 
\+/-0.25
\+/-0.50
\+/-0.75
\+/-1.00

Answer 6

+/-0.25: 20/50 or better
+/-0.50: 20/60-20/100
+/-0.75: 20/125-20/200
+/-1.00: 20/200 or worse

Question 7

To refine the AXIS of the JCC, use the ____
To refine the POWER of the JCC, use the ___ ___

-Most important thing to keep in mind when changing the cyl power lenses?

Answer 7

handle (and chase red lines as if they're dots)
red dots (MINUS cyl axis --> recall: POWER is 90 deg away!!)
i.e. red dots at 90? POWER at 180!

-MAINTAIN S/E

Question 8

Given a pt is +13.00 -2.00 x090 OU, what refraction method will you use? Why?

-What must you make sure to include when writing the final Rx?

Answer 8

trial clip - because any HIGH power is crucial to compensate for BACK VERTEX DISTANCE!

-write BVD = 12mm (or whatever the back vertex distance is!)

Question 9

What “test” do you do if trying to decide whether to recommend new Rx when the pt thinks it dramatically improves their vision?

Answer 9

“SO WHAT” test
-Bernell lens double flipper - use placebo (old Rx) on one side, new Rx on the other - see if they really do prefer the new Rx (by a lot - and record in chart)

Question 10

What are the four ways to determine Feq for 1M? How to do each of them?

Answer 10

1) Kestenbaum’s rule - invert distance snellen in better eye (20/100 –> 100/20 = 5D)
2) Near acuity method - place +2.50 add over dist Rx; give near card @ 40cm, calculate w/ INVERTED D/L–> so letter size/dist (2.5M/0.40m)
FEQ = M/m
3) Acuity reserve rule? 2x Kestenbaum’s (ideal for COMFORTABLE reading)
4) Inverse of CPS (critical print size - MAX speed) - MNRead card

Question 11

Using the MNRead card to find the critical print size (MAX reading speed), what’s the minimum amount of words per minute (WPM) required for actual reading COMPREHENSION?

-Bear in mind: LV pts may require mag __-__X LARGER than their acuity limit to achieve reasonable reading speed

Answer 11

85WPM minimum - greater obv. better

2-3X larger

Question 12

Regarding lighting - if I bring a light 3x closer to the print I’m trying to read - it’s effectively how much brighter?

Answer 12

9x brighter!! - based on the inverse square law

Question 13

Do amsler to detect SCOTOMAS….

• scotomas to the right of fixation affect _____
• to the left of fixation affect ____
• inferior to fixation affect ____
• which scotoma is the most COMMON (careful!!!)

Answer 13

• right = reading - majority of scotomas (~34%) are here
• left = finding the next line when reading
• inferior = mobility (stairs, etc)

-SUPERIOR scotoma - most common! 39% (right is next @ 33%)

Question 14

Test distance for amsler?

• Add required over dist Rx?
• Each square = how many degrees?
• How many TOTAL degrees in central fixation are assessed assuming amsler is placed @ proper working distance?
• T/F: physiological blind spot will be masked by amsler

Answer 14

30cm –> +3.00add
1 deg/square
-At 30 cms, this grid measures central 20 DEGREES in central fixation - 10 squares on all sides of dot
-FALSE - it’s 15.5 degrees out - you’re only measure 10 deg in all directions! it’s OUTSIDE of the grid!

Question 15

What word defines when amsler squares bend OUTWARDS? What are pathologies that may cause this?

What word defines when amsler lines look smaller? What are pathologies that may cause this?

Answer 15

MACROPSIA - PRs pushed closer together - squares bend out - tumors, or anything that takes up space

MICROPSIA - PRs pushed apart - lines smaller/closer to each other - macular edema

so the spacing of the PRs in INVERSE to what the pt sees - overall distortion = metamorphopsia

Question 16

Amsler has very good _____, but very low ____ (has many false negatives)

Answer 16

good specificity (few false positives) - 98%
poor sensitivity (many false negatives "just kidding you don't have AMD") - 9-50%

Question 17

What’s the MAIN REASON why sensitivity of Amsler is so low??

Answer 17

FILLING-IN phenomenon**: features perceived in the absence of neural input - think of the blind spot! .

-using the PRL away from the edge of the scotoma can also be a cause

Question 18

Amsler grading: define each grade
G1: metamorphopsia: \_\_\_\_
G2: metamorphopsia: \_\_\_\_
G3: scotoma: \_\_\_\_
G4: scotoma: \_\_\_\_

Answer 18

G1: mild meta: LESS THAN 6deg in dia, NOT affecting fixation
G2: mod meta: GREATER than 6 deg in dia AND/OR involving fixation
G3: minimum scotoma: LESS THAN 6deg dia, NOT affecting fixation
G4: significant scotoma: GREATER THAN 6deg in dia, or ANY scotoma involving fixation REGARDLESS OF SIZE!!