Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Contact Lens I > Contact Lens 1: Intro to SCL > Flashcards

Contact Lens 1: Intro to SCL Flashcards

1
Q
  1. When should Single Vision Sphere CLs be used? (ie, w/what cylinder power)?
  2. When should Single Vision Toric CLs be used?
A
  1. Less than or equal to 0.50 DC

2. Greater than or equal to 0.75 DC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

CL History: Leonardo Da Vinci

  1. What Manual did he write?
  2. What Optical Principle did he describe?
  3. What did he figure out by immersing an eye in a bowl of water?
A
  1. Codex of the Eye (Manual D)
  2. The Optical Principle in regards to CONTACT LENS
  3. Will Change Corneal Power
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

CL History: Rene Descartes

  1. What did Descartes do?
A
  1. Created a Water-filled tube in contact w/eye. End of tube made of Clear Glass.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Contact Lens Material

  1. Chronologically, what 4 materials were made?
A
  1. Glass
  2. Polymethyl Methacrylate (PMMA)
  3. Soft
  4. Gas Permeable (GP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Glass Contact Lenses

  1. Who made the first scleral, non-optical Contact Lens?
  2. Who made the first optically useful Scleral CL?
A
  1. Frederick Muller

2. Eugen Fick and Eugene Kalt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

First Optically Useful CL

  1. What was it made of?
  2. The space b/w CL and eye was filled with what?
  3. What was it useful for? (what kind of cornea)
A
  1. Glass Shell placed on the eye
  2. It fills with Liquid (“Tear Lens”)
  3. for Irregular Corneas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Use of a Rigid Material On an Irregular Cornea

  1. Main site of refraction is now where?
  2. Irregularities in the Passage of light from Air/Tearfilm are what?
  3. Soft Materials do not do what?
A
  1. the Air/CL Interface.
  2. are Lost
  3. don’t produce this effect.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. Who introduced plastic?
    a. What did he make with the CL?
    b. What did this provide?
A
  1. William Feinbloom
    a. Made a CL w/a GLASS CENTER and a PLASTIC OUTER EDGE

b. An Adjustable Periphery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Poly(Methyl Methacrylate) (PMMA)

  1. What kind of plastic is it?
  2. What is it resistant to?
  3. What is it free from?
A
  1. TRANSPARENT Plastic
  2. Shatter-resistant
  3. Bisphenol A (BPA)-Free
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

PMMA CLs

  1. Who designed an All-PMMA Scleral CL?
  2. Who Accidentally Conceptualized CORNEAL PMMA Lenses?
A
  1. Frederick Ridley (Ophthalmologist)

2. Kevin Tuohy (Optician). He patented it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. What 4 things can happen to the CORNEA after YEARS of PMMA Wear?
A
  1. Corneal Neovascularization
  2. Corneal Edema
  3. Polymegathism
  4. Pleomorphism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. Who Created SCLs made from HEMA?
    a. Are they clear or solid?
    b. Impurities?
    c. Permeable to what?
A
  1. Otto Wichterie
    a. Transparent
    b. Free of Impurities
    c. to Oxygen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Soft Lens Manufacture

  1. Who Created SPIN CASTING?
    a. Who patented it
A
  1. Wichterie

a. Bausch and Lomb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Use of a Rigid Material on an Irregular Cornea

  1. Main site of Refraction is now what?
  2. What is lost in the Passage of light from the Air/cornea interface?
  3. What Materials DO NOT produce this effect?
A
  1. Air/Contact Lens Surface
  2. Irregularities
  3. Soft Materials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Gas Permeable

  1. 1970s: Rigid GP Materials introduced
    a. CAB? (What material is it)?
    b. What is Silicone Acrylate?
  2. What is better about these CLs compared to the Soft CLs? (2)
A
  1. a. Cellulose Acetate Butyrate
    b. Silicone + PMMA
  2. Superior Optics and Better O2 Transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

SCL Fabrication

  1. Physical Construction for what?
  2. Optical Parameters for what?
  3. Cost Effective…?
A
  1. For COMFORT
  2. Vision
  3. Need to make a Profit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

3 Methods of Fabrication?

A
  1. Cast Moulding, Lathe Cutting, Spin-Casting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Spin-Casting Manufacturing

  1. What do we start with first?
  2. Monomers are introduced into what?
  3. What does the Centrifugal Force and Gravity do?
  4. What does the MOLD Define?
A
  1. Liquid Monomers
  2. Into a Spinning Mold
  3. Defines BACK SURFACE SHAPE and BOZR
  4. the FRONT SURFACE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Spin Casting (2)

  1. What 4 things are produced by SLOWER ROTATIONS?
  2. What about faster rotations?
A
  1. a. Smaller Diameters
    b. Thicker Centers
    c. Flatter Base Curves
    d. Plus Powers
  2. The OPPOSITE is true for Faster Rotations
20
Q

Lathe Cutting

  1. What is it?
A
  1. a Machine for shaping wood, metal or other material by way of a Rotating drive that turns the piece being worked against Changeable cutting tools
21
Q

Soft Lens Manufacturing Lathing

  1. What do you start with?
  2. Method is similar to what?
  3. What Strict Controls are needed?
  4. What 2 things have to be done after it’s completed?
  5. Lens is sealed in what?
  6. Packaged product is then what?
A
  1. an ANHYDROUS Button
  2. to RGPs
  3. Strict control of the Environment, ESPECIALLY of HUMIDITY
  4. Cleaning and Hydration
  5. in Normal Saline
  6. Autoclaved (121 degrees Celsius for 15 minutes)
22
Q

Soft Lens Manufacturing Lathing

  1. What button is it?
  2. Goes to which Lathe first?
  3. Then it’s transferred to what other lathe?
A
  1. Polymer Button
  2. Back surface Lathe
  3. Front surface lathe (then Anhydrous lens edge is polished, inspected, hydrated in saline, inspected, then INSERTED into GLASS VIAL w/SALINE…then Autoclaved and Dispatched individually)
23
Q

Cast Moulding

  1. Technology?
  2. What tools are there?
  3. What happens?
A
  1. Dominant Technology in HIGH-VOLUME MANUFACTURE
  2. Male and Female Tool (Molds are created)
  3. Monomers introduced into female mould, then male and Female mould are put together, Excess Polymer Squeezed out, UV radiation done, Then Anhydrous lens is removed from Mold, and Final stages are like those for Spin Casting
24
Q

SCL Manufacturing Methods

  1. Lathe Cutting
    a. Advantages
    b. Disadvantages
  2. Spin Casting
    a. Advantages
    b. Disadvantages
  3. Cast Moulding
    a. Advantages
    b. Disadvantages
A
  1. a. Wide Parameter Availability
    b. Expensive
  2. a. Consistency; Low Cost
    b. Limited Parameter Availability
  3. a. Quality
    b. Limited Parameter Availability
25
Q

Pre-Fit Examination

  1. History: What 3 important things should be noted?
  2. What else
A
  1. Visual Demands, Cosmetic Demands, and Previous Lens Wear

2. Examination

26
Q

What are some problems with Glasses? (Visual Demands)

6 categories…

A
  1. Frame/Lens Weight
  2. Lens Fogging
  3. Slipping/Sliding/Not Staying Put
  4. Discomfort
  5. Aberrations and Reduced VF
    a. Oblique Astig and power error when looking away from Optical Center
    b. Blurry Distorted Peripheral Vision results, limiting visual field
  6. Mag/Minification/Aniso
27
Q

Cosmetic Demands

  1. Why do you want to wear Contact Lenses? (5)
A
  1. No Frames
  2. Mag/Min/Aniso
  3. Enhance Eye Color
  4. Change Eye Color
  5. Conceal Abnormality
28
Q

Previous Lens Wear

  1. Type: What are three important Questions to ask?
  2. What do we need to know for Current Lens Wear? (7)
A
  1. When, For how Long, and Reason for Dropout.
  2. a. Brand/Type
    b. Solution
    c. Comfort
    d. Vision
    e. Sleep
    f. AWT
    g. WTT
29
Q

Examination

  1. What 3 things should we do for Examination? (Basically, what do we do when we check most patients’ eyes?)
A
  1. Refractive Status
  2. Binocular Vision Status
  3. Ocular Health/Anatomy
30
Q

Examination: Refractive Status Considerations

  1. Distortion: What 2 things about the image does it Affect?
    a. As Power INCREASES from Center to Periphery of a Spectacle Lens, what else increases?
    b. Plus Lenses –> ?
    c. Minus Lenses –> ?
A
  1. Image Size/Shape
    a. Magnification also Increases (+ or -)
    b. More (+) Mag off Center (Pin cushion)
    c. More (-) mag (minification) off Center (Barrel)
31
Q

Examination: Refractive Status Considerations

  1. Anisometropia
    a. In Glasses, Difference in Prescription (Anisometropia) can cause a difference in what?

b. What about in CLs?
c. Considerations in what?

A
  1. a. in Image Size (Aniseikonia)
    b. Has a Much Lesser Effect on Magnification
    c. In Amblyopia Prevention/Management
32
Q

Examination: Refractive Status Considerations

  1. Astigmatism
    a. Type (2)?
    b. Direction (3)?
    c. What else?
A
  1. a. Regular vs. Irregular
    b. WTR (180), ATR or Oblique
    c. Magnitude, Corneal vs. Internal
33
Q

Examination: Refractive Status Considerations

  1. Regular Astigmatism?
    a. Seen in what 2 things?
  2. Irregular Astigmatism?
    a. Refracted Rays have no what?
    b. What lenses?
A
  1. 2 Principal Meridians Separated by 90 Degrees
    a. Glasses or Soft CLs
  2. Refraction in Different Meridians Conforms to no Geometrical Plan
    a. Have No Planes of Symmetry
    b. Gas-Permeable Lenses
34
Q

Examination: Refractive Status Considerations

  1. Magnitude of Astimatism
    a. Less than 0.50 DC: What CLs should be used?

b. Greater than or Equal to 0.75 DC?
2. Source of Astigmatism? (2)

A
  1. a. Spherical Soft CLs
    b. Toric Soft CLs
  2. Corneal vs. Lenticular
35
Q

Which Material has Poorer O2 Transmissibility; PMMA or HEMA?

A
  1. PMMA
36
Q

CLs can ONLY Correct for what Prism?

a. How much diopters?
b. What Base Orientation?

A

Only for VERTICAL PRISM

a. 2-4 diopters
b. Base Down

37
Q
  1. What does BI prism do to the Image?

2. MYOPES Must Converge and Accommodate MORE/LESS in CLs than with Spectacles?

A
  1. Shifts the Image OUT!

2. MORE

38
Q

Examination: Refractive Status Considerations

  1. Refraction
    a. RECORD VERTEX DISTANCE on ANY MANIFEST REFRACTION THAT IS MORE THAN OR EQUAL TO WHAT?
  2. If BCVA is REDUCED in Either Eye, Discuss Risk of loss of what?
    a. Must be especially careful in what 2 things?
A
  1. a. +/- 4.00 D
  2. of Vision Associated w/CL Wear
    a. in Informed Consent and Documentation thereof; it may not be worth the Risk
39
Q

Examination: Refractive Status Considerations

  1. Corneal Curvature
    a. Sagittal depth is the measurement from what?
A
  1. a. the Flat plane at a given diameter to the HIGHEST Point of a Concave surface of the CL; Also described as the degree of Corneal Elevation for a Given Chord Diameter
40
Q

Examination: Refractive Status Considerations

  1. Sagittal Depth
    a. What 2 FACTORS determine How STEEP or FLAT an Eye is?
A
  1. Corneal Curvature (Keratometry of “K” Values) and Corneal Size: Horizontal Visible Iris Diameter (HVID)
41
Q

Examination: Refractive Status Considerations

  1. Keratometry
    a. Measure what area of the Cornea?

b. What else does it measure?
c. Record to the Nearest what?
d. Comment on what?
e. 2 ways to record the values?

A
  1. a. The CENTRAL 3 mm of the Cornea
    b. CORNEAL TORICITY
    c. to the Nearest Eighth
    d. on Mire Clarity
    e. Both Meridians, or ONLY Specifying the Vertical (Always specify the Vertical Meridian Last)
42
Q

Examination: Refractive Status Considerations

  1. Keratometry
    a. If the Cornea is TOO Steep, what can be done?
    b. If it’s TOO FLAT?
A
  1. a. Use +1.25 D Lens on OBJECTIVE SIDE of Keratometer and ADD 8.00D to your result
    b. Use -1.00DS Lens on OBJECTIVE SIDE of Keratometer and SUBTRACT 6.00D from your result
43
Q

Examination: Refractive Status Considerations

  1. HVID
    a. What is it a measurement of?
    b. Approximation of what?
    c. What 2 things should we use?
    d. What’s the Avg?
A
  1. a. Limbus to Limbus Measurement of the Iris
    b. of Corneal Diameter
    c. Slit Lamp mm Gauge or PD ruler
    d. 11-12 mm
44
Q

Examination: Refractive Status Considerations

  1. Pupil Size
    a. Measure in what 2 situations?
A
  1. a. Dim and Bright

b. *Also, Look at Colors, Multifocals, and Prosthetics

45
Q

Examination: Refractive Status Considerations

  1. Palpebral Fissure Width (Palpebral Aperture)
    a. Distance b/w what 2 things?
    b. What considerations?

c. What is considered small?
d. Medium?
e. Large?

A
  1. a. Upper and Lower Lid in Primary Gaze
    b. I & R Considerations
    c. Less than 9.0 mm
    d. 9.0-10.5 mm
    e. more than 10.5 mm
46
Q

Examination: Refractive Status Considerations

  1. Ocular Health Considerations
    a. What 5 things?
A
  1. Allergies
  2. Dry Eye/MGD
  3. Anterior Segment Scarring
  4. Ocular Infection/Inflammation
  5. Uncontrolled Diabetes
47
Q

Examination: Refractive Status Considerations

  1. Fluorescein Staining Assessment: Rinse it out before applying CLs, ESPECIALLY when LENSES are made from what material?
A
  1. HYDRAGEL LENSES!!

Contact Lens I (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions