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3F: Surgery Final > Final Review > Flashcards

Final Review Flashcards

1
Q

what does LASER stand for

A

Light amplification of stimulated emission of radiation

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2
Q

Characteristic properties of photons

A
  • in the interaction of radiation with matter, radiation behaves like particles called photons. PHOTONS=PARTICLES
  • photons are always moving with the speed of light in a vacuum. Attempt to stop a photon=absorption
  • photons travel in straight lines
  • photons have a zero rest mass but never occur at rest
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3
Q

Electron volt

A

Energy carried by a single photon

-the amount of energy that an electron gains while moving through a potential difference of 1 V

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4
Q

Electrons that orbit the atomic nucleus exist

A

ONLY IN DISCRETE ENERGY LEVELS

Bohr atom model

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5
Q

An electron can jump to a _____ energy level by emitting a photon

A

Lower

Bohr

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6
Q

A electron can jump to a _____ energy level by absorbing a photon

A

Higher

Bohr

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7
Q

Spontaneous emission

A
  • An electron that stays in an excited state for <8-10s and then jumps to a LOWER LEVEL emitting a photon in the process
  • an atom will absorb only photons whose energy is the exact amount needed to raise electrons up by 1 energy level and will release that same wavelength of enegery as we photon
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8
Q

Stimulated emission

A

If a photon of the precise wavelgnth passes Ana electron in an elevated energy level of equal gain in energy, that electron will emit a photon of that same wavelgnth, direction, phase, coherence, and polarization

Two photons will leave for each photon that enters=amplifying the beam

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9
Q

Fluorescence and Phosphofluorescence

A
  • stand out because the luminous flux EMITTED at the fluorescent wavelengths by a fluorescent substance may be FAR GREATER than the luminous flux INCIDENT at those wavelengths
  • the energy that drives the fluorescent radiation comes from an incident HIGHER FREQUENCY radiation (UV)
  • when a metastable state with a long lifetime is populated by incident radiation, the material may continue to glow or emit radiation long after the original source is removed
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10
Q

What is the distinction between fluorescence and phosphofluoresence

A

Matter of time

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11
Q

Population inversion: electrons at LOWER energy levels ____protons

A

Absorb

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12
Q

Population inversion: electrons at HIGHER levels _____protons

A

Emit

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13
Q

Application occurs when

A

Mor eeelctrons are at an elevated state than at a lower energy state

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14
Q

Cavity oscillator

A
  • optical cavity
  • 2 parallel Mirrors=feedback loop with active medium between the mirrors. Mirrors have optical coating-reflective proptosis
  • builds the strength of the avalanche
  • stimulated emission causes application of the signal within the optical resonator
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15
Q

Q switching

A
  • NANOSECOND DURATION
  • higher power intensity
  • shutter or light modulator
  • energy builds and is then released in sudden bursts
  • plasma formation
  • PHOTODISRUPTIVE EFFECT
  • less affected by pigmentation
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16
Q

Laser light characteristics

A

Coherence
Monochromatic
Collimated

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17
Q

Photochemical effects

A

Photoradiation

Photoablation

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18
Q

Photoradiation

A
  • Photochemical
  • IV administration of photosensitizing agent taken up by target tissue-free radicals
  • PDT therapy
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19
Q

Photoablation

A

Photochemical

  • pigment independent
  • higher energy UV light=excimer laser (cleaves bonds)
  • NON THERMAL
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20
Q

Photothermal effects

A

Photocoagulation

Photovaporization

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21
Q

Photocoagulation

A

Phototheramal

  • ALT
  • targets melanin and hemoglobin
  • denatures protein, contracts collagen, coagulates blood
  • 10-20 decrease C increase in temp
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22
Q

Photovaporization

A

Photothermal

  • targets melanin
  • water turned into steam, tissue turned to CO2 and H20
  • 60-100* C increase in temp
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23
Q

Mechanical disruption

A

Photodisruption

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24
Q

Photodisruption

A
  • mechanical disruption
  • YAG CAP/LPI/VITREOLYSIS
  • reduces tissue to plasma, modules stripped of electron. NO COAGULATION** (why there is blood on LPI with Nd:YAG 1064 vs using Argon)
  • PIGMENT INDEPENDENT
  • explosive force
  • pulse travels back towards surgeon
  • 15,000* C increase in temp
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25
Q

Pigment dependent lasers

A

Argon

Diode

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26
Q

Pigment independent laser

A

Nd:YAG 1064nm
Femtosecond
Excimer

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27
Q

Nd:YAG characteristics

A
  • 1064nm
  • solid state laser (level 4)
  • Q switched
  • continuous or short pulsed
  • neodymium YAG
  • photodisruptive
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28
Q

Nd:YAG 532

A
  • 532nm
  • Freqyency doubling and Q switches
  • photocoagulation/sublethal photostimualtion pigment dependent
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29
Q

UV range

A

200-400

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30
Q

UVC

A

200-280

31
Q

UVB

A

280-315

32
Q

UVA

A

315-400

33
Q

Visible light

A

400-780

34
Q

IRA

A

780-1400

35
Q

IRB

A

1400-3000

36
Q

IRC

A

3-1000um

37
Q

Near infrared

A

IRA

780-1400nm

38
Q

Far infrared

A

IRB and IRC
1400-3000nm
3-1000um

39
Q

UV light absorbed within the

A

Cornea

<400nm

40
Q

Visible light absorbed with in the

A

Retina

400-700

41
Q

Near infrared light absorbed within the

A

Retina

700-1400

42
Q

Far infrared light absorbed within the

A

Cornea

1400nm+

43
Q

Tissue variables

A

Melanin
Hemoglobin
Xanthophyll

44
Q

Melanin

A
  • absorbs across entire visible spectrum

- absorbers infrared less effectively

45
Q

Hemoglobin

A

Absorbed green and blue wavelengths very well

46
Q

Xanthophyll

A

Absorbs blue well

Use red or IR for macula

47
Q

Class I ANSI standard

A

Very low powered laser (<0.5 uW)

  • no eye or skin hazard from full day exposure
  • no labeling requirements are needed
  • lasers inside CD/DVD players
48
Q

Class II ANSI standard

A

Low powered laser (<1mW)

  • no eye hazard from intrabeam exposure within short period of time
  • basic laser pointers/surveying lasers
49
Q

Class IIIa

A
  • visible beam with power <5mW
  • damage on accidental exposure through optical aid
  • more powerful laser pointers
50
Q

Class IIIb

A
  • Eye and skin hazard

- viewed only through diffuse reflection from distance over 50mm for <10s with diffuse image diameter greater than 5.5mm

51
Q

Class IV lasers

A
  • eye andskin hazard from intrabeam and diffuse relcfection

- fire hazard

52
Q

What class is an Nd:YAG 532nm (freq doubled)

A

Class IIIb

53
Q

Which class of lasers is an Nd:YAG 1064

A

Class IV

54
Q

Laser safety

A

Governing bodies and professional organizations
-ANSI,FDA, OSHA

Administrative controls
-laser safety officer

Practice guidelines
-american society for laser medicine and surgery (ASLMS)

Protective equipment
-warning signs, skin protection, smoke evacuation

55
Q

What grading system uses Roman numerals to describe the degree to whch the angle is closed

A

Sheie’s system

56
Q

Which grading system uses numeral to describe the degree to which the angle is open

A

Shaffer

57
Q

Which are pathological? Iris processes or peripheral synechiae

A

Synechiae

58
Q

What is the general mechanism of action for a laser trabeculoplasty

A

Increase Aqueous outflow mainly through the TM

59
Q

Indications for laser trabeculoplasty

A 
POAG
NTG
OHTN
PDG
PSG
60
Q

Positive predictors for laser trabeculoplasty

A

<40yo
Moderate to heavy TM pigment
Clear cornea

61
Q

Thermal relaxation time

A

Time required by melanin to convert electromagnetic energy into thermal
-1 MICROSECOND

62
Q

Argon laser trabeculoplasty: mechanical or biological MOA?

A

Both

63
Q

What are the pre op drops for ALT and SLT

A

Alphagan 15-30m prior

Proparacaine

64
Q

Can you repeat an ALT

A

Highly recommended NOT to-increases complication and 50% need filtration surgery to lower IOP within 6 months of repeated ALT

65
Q

SLT: mechanical or biological MOA?

A

Biological only

66
Q

Is SLT a cold or hot laser and why

A

Cold

Thermal relation time is not met, so no burns occur

67
Q

Is SLT a safe and effective initial therapy?

A

Yes

-based upon multiple studies

68
Q

SLT laser settings

A 
Energy-0.8-1.2mJ
Spot size-400microns fixed
Duration-3ns fixed
Pulses-1
Amount of burns ~100/360
69
Q

What are the post opt drops of SLT

A

Alphagan

NO STEROIDS!! Oral Tylenol PRN or optical NSAID if absolutely needed

70
Q

What is the time frame for an SLT to be the most successful

A

12-60m

-80% @ 1 yearand 50% at 5 years

71
Q

Will an SLT be successful if the patient DI not repsond to a PGA

A

No

Alvarados insights

72
Q

Should you perform an SLT on patient’s with pigment dispersion syndrome/glaucoma?

A

Yes-be more cautious

-10-20* at a time-test area

73
Q

Can you repeat an SLT

A

Yes

-no as effective the second time

3F: Surgery Final (5 decks)

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