Vertical Imbalance

Question 1

Vertical Imbalance

Answer 1

Difference in Total Power at 90 degrees x reading levelDivided by constant of 10 (Prentice’s Rule)

Question 2

6 ways to correct VI

Answer 2

1. Two pairs of glasses 2. Prism segments 3. Fresnel press-on prisms 4. Dissimilar segments 5. R-compensated segments 6. Slab-off prisms

Question 3

Fresnel Principal

Answer 3

A series of small plastic prisms lying adjacent to each other on a thin platform of plastic Much thinner than a conventional ophthalmic prism 6 month life span Quarter increments 0.25, 0.50, 0.75 etc

Question 4

What are the rules for Prism Segments?

Answer 4

Prism goes in both eyes Use increments of 0.5D, 1D, 1.5D Never see, rare, in glass only, ugly, expensive, long time to make Doesn’t matter which increment you use for each eye Goal is to cancel prism in chosen eye

Question 5

When do you use Fresnel prisms?

Answer 5

Better for high diopters When you need quarter DioptersNot clearest vision, lose visual acuityAphakias, post cataract patients with no lenses

Question 6

When do you use Slab - off prism?

Answer 6

When the vertical balance is present with antimetropia Meaning two different signs for each eye with a big difference between the powers

Question 7

Slab off/ Bicentric Grinding

Answer 7

1. Get the Vertical Prism 2. Most Minus BD / Least Plus BU 3. Prescribe Slab off Prism -MM BU in same eye to neutralize -LP BU in same eye to neutralize

Question 8

How many choices are there for R-Compensated Segments?

Answer 8

7 choices One has to be R-4 R-4, R-5, R-6, R-7, R-8, R-9, R-104mm - 10mm

Question 9

What are R-Compensated segs?

Answer 9

Round segs that have the bottom or top cut off in order to change where the OC ends up

Question 10

When do you use R-Compensated Segs?

Answer 10

Only good for small amounts of vertical imbalance Can only separate the OCs by 6mm Glass durabilityBig in the Midwest

Question 11

Do you know the BTS’s for doing dis-similar segs?

Answer 11

1. TK/Kryptok/Round 22 = 11mm 2. Any fuses FT = 5mm 3. Ribbon Seg/Bar Seg 22 x 19 = 4.5mm // 22 x 14 = 7mm 4. Curve Top/Panoptik = 3.5mm 5. Round 22 = 11mm // Round 25 = 12.5 mm6. FT one piece = 5mm 7. Executive = 0 8. Ultex A and AA = 19mm 9. Blended/Seamless 22=11 mm 28=14 mm 10. Ultex B = 11 mm FT 45/ Welsh FT/ Thin Line 35 = 0

Question 12

For which VI corrections do you use MMLP?

Answer 12

Dis-Similar Segs R-Compensated Segs Slab off Prism

Question 13

Which lens has the VI?

Answer 13

Minus Lens has the imbalance in the strongest lens Plus lens has the imbalance in the most plus, always base up

Question 14

Explain the need for intermediate vision.

Answer 14

Their is an inevitable loss of accommodation that results in the loss of clear vision at arm’s length, 20” to 30”. As presbyopia advances with age after 40, the add power becomes greater than the person’s accommodation. They get an intermediate blur at arm’s length. Bifocal is too strong to see further out than arm’s length and their accommodation is not strong enough to bring that area into focus.

Question 15

What do we have to correct intermediate vision?

Answer 15

Progressives Trifocals Bifocals SV lenses for specific purpose like sheet music

Question 16

What are examples of occupational progressives?

Answer 16

Zeiss Gradal RD, the Varilux Interview, Sola Access, Hoya Tact II, AO Technica, and the Shamir Office

Question 17

Intermediate Vision definition

Answer 17

Distance will vary -16” to 24” SV - piano glasses Bifocal -top intermediate/bottom reading Trifocal -three focal lengths Usually prescribed after 2.00 add, not always Age dependent/use dependent

Question 18

Donders

Answer 18

Ophthalmologist charted how much accommodation people had at various ages 60 yr old, +1 D left

Question 19

11 Common Trifocal Types

Answer 19

1. Executive 2. Flat Top 3. E.D. Trifocal 4. Progressives 5. Smart Seg 6. Occupational/Vocational Lenses 7. Double Flat Top 8. Double Round or Basketball Seg 9. Double Executive or E Line 10. Quadrifical 11. Rede-Rite

Question 20

Executive Trifocal

Answer 20

Glass or plastic, one piece, 7mm intermediate segment height

Question 21

Flat Top Trifocal

Answer 21

Glass or Plastic, fused or one piece Plastic Only =7x25 7x28 8x35Glass Only 9x35 7x35 1st measurement is distance btw first 2 lines

Question 22

E.D. Trifocal

Answer 22

Plastic only, executive with a flat top segment Near Rx in FT segment Intermediate under executive line

Question 23

Progressives

Answer 23

All one-piece, segment on the front Many different sizes and configurations Intermediate section small with distortion on each side Keyhole

Question 24

Smart Seg

Answer 24

Made by SolaA FT design that incorporates an intermediate portion at the top of the segment30mm x 24 mm 30mm length of FT 24= 12 mm intermediate 12 mm near

Question 25

Occupational/Vocational Lenses

Answer 25

Lenses designed for a specific function They often will fill a special need required for a hobby/employment

Question 26

Double FT

Answer 26

22mm, 25mm, 28mm diameter only Glass or plasticThe upper segment may be for near vision or intermediate

Question 27

Double Round or Baseball seg

Answer 27

Round 22mm or 25mm segments Glass or plastic Top round segment could be intermediate or near

Question 28

Double Executive or E line

Answer 28

Glass or plastic Intermediate or Near Then Distance Then Near The Distance portion is 10-14mm long

Question 29

Quadrifical

Answer 29

Vision Ease Glass only A double FT and smart seg on the bottom

Question 30

Rede-Rite

Answer 30

Essentially, an upside down Ultex Looks like an OliveUpside down Ultex A

Question 31

What type of intermediate lenses would you recommend for piano players who need to read sheet music?

Answer 31

Single Vision intermediate

Question 32

Who would wear trifocals?

Answer 32

Progressive non-adapt

Question 33

Who would wear occupational lenses?

Answer 33

Musicians, IT, laboratory personnel

Question 34

Vertex distance

Answer 34

From the front surface of the cornea to the back of the lens

Question 35

Ideal vertex distance

Answer 35

13.75mm

Question 36

Reason for Vertex Distance Compensation

Answer 36

If a person with a +/-5.00 Diopter or greater lens is refracted at one distance and the glasses are fitted at a different distance, a disparity in visual acuity will exist

Question 37

How do you determine the length that focused light rays hit inside the eye? Using your knowledge of vertex distance compensation, how far do focused light rays hit inside the eye if the optician fits the glasses at 14mm?

Answer 37

100mm-distance optician first glasses at = distance focused light rays hit the eye 100mm is the retina

Question 38

Four rules of Vertex Distance Compensation?

Answer 38

A minus lens moved inward INCREASES it’s effective power A minus lens moved outward DECREASES its effective power A plus lens moved inward DECREASES its effective powerA plus lens moved outward INCREASES its effective power

Question 39

What’s the relationship between focal length and lens power?

Answer 39

Shorter Focal Length = stronger lens power Longer Focal Length = weaker lens power

Question 40

A high hyperope patient was examined at 8mm and fit at 13 mm, did you move inward or outward? Which rule?

Answer 40

Moved outwards/away Increases its effective power You need the opposite So you need a weaker lens

Question 41

Vertex Compensation

Answer 41

When the frame does not sits at the same vertex distance as the phoropter/trial frame did during the examination Manipulating Focal Length

Question 42

Four Rules Simplified

Answer 42

Plus Moved away gets stronger Plus Moved Closer gets weaker Minus moved away gets weaker Minus moved closer gets stronger

Question 43

Shamir office

Answer 43

Shamir Computer™ is designed to provide patients with a wide field of near viewing with clear vision up to 5 feet, which is a far greater depth of field than that offered by conventional reading lenses. It is ideal for patients working at a computer or who are primarily stationary at their desk/workstation throughout the day. Professions that may benefit from Shamir Computer™ include architects, post office clerks, software engineers, data entry clerks, graphic designers, pianists and more.

Question 44

Reverse Slab-off increments for Younger

Answer 44

1.5, 2, 2.5, 3, 3.5, 4, 5, 6