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Contact lens Year 2 > Unit 2 > Flashcards

Unit 2 Flashcards

1
Q

Indications for GP and hybrid lenses

A
  • Needs excellent VA/Sharpness * Custom designed lenses
  • Borderline and mild dry eyes
  • Irregular corneal surface
  • Poor VA with glasses and soft lenses * Vision fluctuation with soft toric lenses * High myopia, hyperopia, astigmatism * Ortho K
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2
Q

Contraindications for GP and hybrid

A
  • Ocular inflammation/infection
  • Allergies
  • Pinguecula/pterygium
  • Corneal hypoesthesia (loss of sensitivity)
  • Poor lens handling/cleaning/maintenance (too young, elderly) * Immunosuppression
  • Needs horizontal prism
  • Sports (GP Lenses)
  • Hybrids - Lenticular Astigmatism (could be corrected with GP) * Dust/chemical vapors
  • Sensitive to foreign body (FB) sensations
  • Pregnancy (possibly) – can cause dry eyes and hypoesthesia
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3
Q

What are the main benefits that patients recieve from RGP lens

A

-Cover corneal astigmatism
-Better clarity
-Mild dry eye
-More oxygen getting to the eye

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4
Q

what are some benefits for the practice that are associated with fitting RGP lenses

A

Less required stoarge space
Build rapport with px due to all follow up appts

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5
Q

What is the amount of Low DK and what type of CLs

A

25 to 50 (daily wear and myopes)

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6
Q

What is the amount of High DK and what type of CLs

A

51 to 100 (Daily wear and hyperopes)

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7
Q

What is the amount of DK and for what type of CLs

A

> 100 (extended wear)

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8
Q

Surface treatment

A

-Plasma treatment (electrical surface structure)
-when RGPs contain plasma it makes it hydrophilic (water loving)

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9
Q

Refractive index for flurosilicone acrylate

A

1.42 to 1.46

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10
Q

refractive index of newer material (HDS)

A

may be 1.51 to 1.54

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11
Q

Material properties

A

-wettability
-frictoin (more silicone we have, less friction)
-Oxygen permeability (DK)
-Oxygen transmission (Dk/T)
-Refractive index
-Modulus (flexure of lens)
-Luminance transmission (light)
-Surface hardness

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12
Q

How to manufacture RGP CLs

A

1.Button of plastic material
2. Lathe cut the base curve (BC) on the back surface
3. Polish the back surface
4. Block the lens * Uses a wax
5. Cut the front surface of the lens
6. Polish the lens
7. Surface treatment (optional)

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13
Q

RGP physical parameteres

A

-power
-diameter
-base curve
-centre thickness
-peripheral curves

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14
Q

how to measure RGP diamter?

A

V-gauge
CL loupe

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15
Q

PCR

A

Peripheral curve radius

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16
Q

PC

A

peripheral curve

17
Q

Indications for hybrid

A

-similar to RGP candidates
-Additional good candidates due to soft skirt

18
Q

poor candidate for hybrid

A

soft skirt - beacuse less tear exchange

19
Q

which manufacture is the major supplier of hybrid lenses

A

synergeyes

20
Q

Older deisgn cons

A

-lower Dk/t
-limited parameters (limited GP / skirt options)
-poor bonding of soft skirt to GP

21
Q

types of lens deisgns

A

-for regular corneas
-astigmatism
-kerataconus
-post surgical (oblate)
-presbyopia

22
Q

Synergeyes Material for soft skirt?

A

Silicone hydrogel (larafilcon A)
Dk- 84

23
Q

synergeyes - Matieral for GP centre / diameter and DK

A

-Petrafocon A
-diamter ; 8.5mm
-DK: 130

24
Q

hyperbond junction

A

keeps the RGP and soft skirt together

25
Q

what is Tangible hydrapeg coating used for

A

wettability
makes it very slippery so its hard to remove

26
Q

synergeyes hybrid lenses- OVERALL DIAMTER

A

14.5MM

27
Q

rgp diamteres

A

9.6 to 10.6 mm

28
Q

sclera diamter

A

more than 15mm

29
Q

RGP modality

A

1-2 years replacement
-some materials are approved for RGP extended wear

30
Q

hybrid modalitity

A

6 month replacement
-softer lens so more debris can get in there
-NO extended wear for hybrids

31
Q

RGP wearing schedule

A

-start with 1-2 hours and increase over days
-max of 14-16 hours a day in general but depends on the px (dry eyes or allergy)

32
Q

Hybrid wearing schedule

A

Day 1: up to 6 hours
Day 3-5: 8 hours
Day 6+: as eye care professional reccomends

33
Q

what CLs to use for severe dry eye?

A

SCLERAL

34
Q
A

Contact lens Year 2 (8 decks)

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