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Glaucoma > Surgical Procedures > Flashcards

Surgical Procedures Flashcards

1
Q

What does laser stand for?

A

light amplification by stimulated emission of radiation

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2
Q

What is coherence?

A

spatial-precise focusing widths of several microns, temporal-monochromatic wavelength

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3
Q

What is fluence?

A

flux integrated over time, energy delivered per unit area (spot size, power/wattage, exposure time)

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4
Q

What do resonance mirrors do?

A

allow amplification of the laser energy as the photons bounce back and forth between two mirrors within an optical cavity or tube

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5
Q

3 main types of laser-tissue interactions:

A

photothermal, photochemical, photoionization

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6
Q

What is photothermal?

A

photocoagulation and photovaporization, rise in temperature that denatures proteins

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7
Q

What is photochemical?

A

photoradiation (PDT) and photoablation (Excimer), formation or destruction of chemical bonds

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8
Q

What is photoionization?

A

electrons stripped from tissue creates expanding plasma cloud and ensuing acoustic shock wave disrupting tissues (Nd:YAG)

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9
Q

3 unique characteristics of lasers:

A

coherent, monochromatic, collimated

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10
Q

What is coherence?

A

strong correlation between the electric fields across the beam (cross section)

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11
Q

What is monochromatic?

A

specific wavelength absorbed by specific tissue, allows for tissue selectivity

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12
Q

What is collimated?

A

minimal divergence of the beam (energy is stable across the whole beam) these two features allow for specific application to ophthalmology as small spot sizes can be used and specific tissues targeted

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13
Q

What wavelength do red (blood) tissues absorb?

A

blue and green laser light

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14
Q

What wavelength do brown (pigment) tissues absorb?

A

yellow, blue and green

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15
Q

Which wavelengths penetrate deeper?

A

longer wavelengths

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16
Q

Cornea absorbs

A

UV/100-280 nm (excimer)

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17
Q

Hemoglobin absorbs

A

yellow/555, green/542 (Nd:YAG)

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18
Q

Xanthphyll absorbs

A

blue/400

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19
Q

Melanin absorbs**

A

blue/400 (argon/green) – absorption decreases with increased wavelength

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20
Q

Water absorbs

A

infrared (YAG, diode)

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21
Q

What is a peripheral iridotomy?

A

creates opening in iris for alternate flow of aqueous

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22
Q

What is an indication for a PI?

A

narrow angle/iris bombe

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23
Q

What is the benefit of a PI?

A

helps prevent future ACG but IOP may increase in some and not without complications

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24
Q

What may cause a PI to fail?

A

choroidal thickening, abnormal iris activity secondary to peripheral iris roll (not true bombe)

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25
Q

What is a laser peripheral iridotomy?

A

superior or temporal hole within iris crypt

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26
Q

What do you prescribe before a LPI?

A

pilocarpine 2% to make iris stretched tight

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27
Q

Why might both Nd:YAG and argon lasers be used for a LPI?

A

allows for photocoagulation, argon laser burns tissue and allows the Nd:YAG laser to poke a hole in it, reduces risk of bleeding

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28
Q

Which laser is more effective in a light iris for a LPI?

A

YAG

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29
Q

Difference between temporal and superior LPI:

A

superior may have more visual symptoms than temporal because tear prim can refract light under lid and actually focus it onto retina; temporal image is severely defocused resulting in decreased sensation; temporal may also have less pain

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30
Q

What is the post-op care for a LPI?

A

check IOP before they leave, steroid QID, pilocarpine, potentially hypotensive

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31
Q

Why use a steroid in LPI post op?

A

prevents scarring and closure

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32
Q

What are LPI complications?

A

IOP spike, hyphema, corneal epi/endo burns and edema, correctopia, iritis, lens opacity, monocular diplopia, retinal burns, LPI scarring over

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33
Q

What is a laser peripheral iridoplasty?

A

laser therapy inducing cicatricial iris-retraction of the iris stroma peripherally to pull it away from the angle in angle closure or plateau iris

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34
Q

What are indications of a laser peripheral iridoplasty?

A

angle closure non-responsive to LPI, plateau iris, malignant glaucoma post RD

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35
Q

What laser is used for a laser peripheral iridoplasty?

A

argon laser 200-400mW with 5 to 10 spots per quadrant

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36
Q

What is the post op of a laser peripheral iridoplasty?

A

similar to LPI, keep on steroids and watch for complications

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37
Q

Why should you recommend surgical treatment to patients?

A

non-adherence, challenges maintaining multiple medications, lack of medical control, laser or microinvasive tx before advanced incisional surgery, patient understands risks and benefits, operate before blindness

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38
Q

What is an argon laser trabeculoplasty?

A

A scar in the trabecular meshwork

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39
Q

How does the ALT work?

A

blue-green argon laser used on anterior TM and absorption by pigment in TM yields shrinkage of collagen in trabecular lamellae expanding schlemm’s canal

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40
Q

How does an ALT expand Schlemm’s?

A

two laser spots are made within the TM and cause contraction of the TM in between the two laser spots, pulls schlemm’s canal towards anterior chamber and allows for more outflow

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41
Q

What is the mechanism of the ALT?

A

reduces debris by upregulating phagocytosis

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42
Q

What are indications for an ALT?

A

particularly effective in pigmentary and pseudoexpoliative glaucoma because laser is absorbed by more pigment

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43
Q

What is the pre-treatment of an ALT?

A

apraclonidine 1% or brimonidine 0.2%

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44
Q

What is the ALT procedure?

A

topical anesthetic, 3 mirror gonio lens, treatment 180 or 360 degrees, 50-100 burns, 50 microns size, 0.6-1.0 watts, 0.1 sec exposure time, treat in anterior TM

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45
Q

What are ALT complications?

A

IOP spike, iritis, PAS, heme, K edema/burns, limited repeatability

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46
Q

Why does an ALT have limited repeatability?

A

once you scar that area of TM, you’ve damaged the tissue, don’t want to scar the entire TM

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47
Q

What was discovered in the glaucoma laser trial of 1984?

A

eyes treated with ALT before meds had IOP 1.2 mmHg lower, better VF, fewer cup changes; 30% of ALT had initial IOP increase with 12% being over 10 mmHg

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48
Q

What laser is used in a SLT?

A

q-switched ND:YAG laser, frequency doubled selective for pigment (1064 nm wavelength down to 532 nm) 3 ns oulse, 400 micron spot size, 40-50 spots per 180 degrees

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49
Q

What is q switching?

A

really rapid pulse of energy, prevents burning of tissue (not a hot laser)

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50
Q

What is the mechanism of SLT?

A

induces cytokine release from melanosomes, macrophage activity decreases TM debris and MMP activity increases porosity of TM endothelium; potential vasoactive effect on endothelial cells

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51
Q

Explain the SLT laser impact:

A

large spot size with low energy per area (fluence) so no coagulative damage aka cool laser

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52
Q

What does Dr. Dork call the SLT mechanism?

A

scrubbing bubbles of the TM, clean out TM so we increase aqueous outflow via macrophage activity

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53
Q

Is SLT repeatable?

A

yes but 2nd treatment tends to show less effect and 3+ treatments not very effective

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54
Q

Is SLT better in more or less pigmented angle?

A

more, more pigment=more absorption of energy

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55
Q

What are SLT complications?

A

risk of IOP spike, more energy absorbed=more risk of complications

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56
Q

What technique should you consider with SLT?

A

treat 180 degrees then go back and do the other 180 at f/u

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57
Q

What is the SLT post-op?

A

NSAID qid 2-5 days or nothing, continue hypotensives

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58
Q

Why do we not use a steroid in an SLT?

A

we do NOT want to inhibit the response, we want the immune response to break up inflammation

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59
Q

When does the max IOP response of a SLT occur?

A

4-6 weeks, 20% IOP decrease (5-6 mmHg)

60
Q

What do the microscopic images of ALT vs SLT show?

A

ALT laser burn to the tissue causes the adjacent tissue to stretch, SLT has no effect on tissue

61
Q

Compare SLT and ALT:

A

equal efficacy with reduced side effects using SLT, may do SLT after ALT

62
Q

SLT/MED study results:

A

60% of eyes having SLT 360 degrees had IOP decrease >30%

63
Q

What was the LiGHT study?

A

laser in glaucoma and ocular hypertension trial

64
Q

What was the primary and secondary outcome of the LiGHT study?

A

primary- quality of life, secondary clinical effective ness (target IOP) and visual function

65
Q

Results of LiGHT study:

A

equal QOL between med and SLT group, glaucoma symptom score worse in med group, overall cost more in med group, more visits at target IOP in SLT program, slightly more disease progression in med group

66
Q

Why might an SLTdo better than medication?

A

non concern for adherence, no change with diurnal efficacy

67
Q

What are the SLT review points?

A

effective, no photocoagulative damage to TM, repeatable, upregulates phagocytic activity, targets melanosomes (want less intense tx in pts with excessive pigment

68
Q

What is the endolaser to CP (ECP)

A

uses endoscopic delivery of argon or green laser to ciliary body

69
Q

Where does the ECP work?

A

limbal or pars plana entry

70
Q

What is ECP often performed in conjunction with?

A

vitreoretinal surgery

71
Q

What are ECP complications?

A

pain, iritis w/ synechiae, hypotony, phthisis, zonular damage, reduced accom, pupil distortion, CME, IOP spike, RD, conjunctival burn, choroidal detachment, intraocular heme, endophthalmitis

72
Q

What is cyclophotocoagulation CPC?

A

diode laser therapy to CB with trans-scleral approach, similar to ECP but is administered outside the eye, used as a last ditch effort

73
Q

Which has more pain CPC or ECP?

A

CPCe

74
Q

Where is the CPC performed?

A

laser probe applied at limbus to cause trauma to ciliary processes to reduce aqueous production

75
Q

What are CPC complications?

A

uveitis, K edema, pain, uveitis, hyphema, phthisis bulbi, high IOP spikes permanently, reduction in central VA

76
Q

When is CPC indicated?

A

poorly controlled OAG or MMG, use as cryo cycloablation, advanced glaucoma after filter, secondary glaucoma (like neovascular), instead of endolaser

77
Q

What is a goniotomy?

A

superficial incision into uveal TM, removes obstruction to aqueous outflow

78
Q

When is goniotomy indicated?

A

congenital glaucoma– poor formation of TM resulting in reduced outflow

79
Q

When should a goniotomy be performed?

A

between 1 month and before 2 years

80
Q

What tool is used for a goniotomy?

A

laser or phaco probe (trabecutome) hx done with scapel like tool

81
Q

What is the newest form of goniotomy therapy?

A

kahook dual blade, MIGS

82
Q

What is a trabeculectomy?

A

opening made from sclera through or above TM into anterior chamber for direct drainage of aqueous into sub conj bleb

83
Q

What is the standard for advanced/significant incisional surgery for glaucoma?

A

trabeculectomy

84
Q

Where does a bleb drain?

A

conjunctival and episcleral veins

85
Q

What are the two anti-metabolites and what do they do?

A

mitomycin C and 5FU, chemotherapeutic agents that reduce scarring after the procedure

86
Q

Explain mitomycin C:

A

used more often now, less pain, MMC soaked sponge place over sx site or via injection during procedure, then thorough lavage

87
Q

Explain 5-flurouracil:

A

injected in area daily for 1 week after sx procedure

88
Q

Trab + antimetabolite risks:

A

less risk of failure, greater risk of over filtration and leak, risk of too much aqueous draining resulting in low IOP

89
Q

What is the trabeculectomy post op?

A

DO NOT USE GLC MEDS, every appointment VA, IOP, slit lamp, day 1 start steroid-antibiotic and possible atropine (decrease over filtration and pushes iris toward angle), week 2 switch to steroid only, month 1 steroid taper, monthe 2 dilate, end steroid

90
Q

Bleb evaluation (ELVIS):

A

elevation (not too much), location (11 or 12 oclock), vascularization (not too much), infection (creamy white), seidel

91
Q

Bleb management:

A

massage, needling, laser suture lysis, revision of surgery

92
Q

What is the bleb massage?

A

pressure on globe 180 degrees away form the bleb, pushes aqueous out and into bleb

93
Q

What is bleb needling?

A

break up scar tissue on top of bleb

94
Q

What is bleb laser suture lysis?

A

break open suture to open up the flap a bit more

95
Q

What are trab complications?

A

flat anterior chamber, high IOP/failure, heme, infection/blebitis, endophthalmitis, choroidal effusion (over-filtration), K edema, bleb rupture

96
Q

How do you stop an active seidel?

A

double pressure patch, large diameter CL (22mm), consider atropine

97
Q

How do you stop over-filtration?

A

autologous injection (coagulative factors can seal the inside of the bleb), simmons shell

98
Q

How do you manage high IOP after bleb surgery?

A

consider massage, increase steroids, revision

99
Q

What are filtering devices?

A

trab w/ tube and reservoir, device rests where bleb is and contains perforations to allow aqueous to percolate out, tube keeps it open, goo for neovascular component or if pt is at risk for their bleb opening up

100
Q

Valved vs valveless drainage:

A

valve-ahmed, less- molteno, baerveldt

101
Q

What is the ahmed valve?

A

silicone tube with one or two polypropylene plates, valve opens at pressure of 12 and closes at 8-10

102
Q

What is the molteno and baerveldt?

A

molteno is most widely used, silicone tube w/ 1 or 2 polypropylene plates 13 mm in diatere, the baerveldt is a silicone tube with large diameter 250-350 mm^2 barium impregnated silicone plate

103
Q

What are glaucoma drainage device complications?

A

similar to that of trabs, ocular motility disturbance, tube or plate extrusion, tube migration (contact with iris or cornea), complications usually require surgical revision

104
Q

What is a viscocanalostomy VCL?

A

small sclerostomy into roof of schlemm’s canal, catheterization and viscoelastic fluid irrigated through canal

105
Q

What does a VCL do?

A

dilates canal and collector channel to increase aqueous outflow, possible mild bleb formation

106
Q

What is the VCL efficacy?

A

initial 1 year equivalent effect to trab with lower side effects and complications, esp in congenital, not as effective as trab in some studies of POAG

107
Q

What is the success rate of VCL?

A

60% success rate at 60 months, may need ancillary laser procedure

108
Q

What is iTrack?

A

current US product, ab-externo ciscovanalostomy with cataract surgery

109
Q

What are MIGS procedures?

A

micro invasive glaucoma surgery increasing aqueous outflow through small incisional surgeries, commonly in conjunction with cataract surgery, mostly ab interno

110
Q

What is ab-interno?

A

excision of TM through corneal incision (internal)

111
Q

What is ab-externo?

A

excision of TM through sclera and conjunctiva (external)

112
Q

What are FDA approved MIGS?

A

iStent, Hydrus, Xen 45 gel, cypass, omni 360

113
Q

What MIGS are approved in conjunction with cataract surgery?

A

hydrus and istent

114
Q

What is OMNI?

A

ab interno, combines canaloplasty with trabeculotomy, probe goes 360 and injects viscoelastic to stretch it open and then pulls tubing that pulls open the TM, can be done with cataract surgery or alone

115
Q

What does OMNI treat?

A

three sources of outflow resistance, TM, schlemms and collector channels

116
Q

What are OMNI complications?

A

hyphema, inflammation/debris from TM, K edema

117
Q

Why is a hyphema from OMNI a good thing?

A

means reflux from episcleral plexus

118
Q

What should you try with K edema?

A

rhopressa, it has a secondary application to Fuch’s

119
Q

What is OMNI post op?

A

normal cataract type post op meds, it’s better in a day or 2

120
Q

What is iStent?

A

small implant draining aqueous directly to Schlemm’s canal, used in conjunction with cataract sx

121
Q

How is the iStent placed?

A

placed via small temporal corneal incision, placed into inferonasal quadrant and has improved result when closer to collector channels

122
Q

What is the IOP decrease of iStent?

A

moderate, 4 mmHg

123
Q

What is the iStent 2 efficacy?

A

24 months 75% had IOP reduction of 20% or more w/o meds (62% in cataract only)

124
Q

What was the mean IOP decrease in iStent 2?

A

6.9 mmHg vs 5.4 in cataract only

125
Q

What is iStent supra?

A

drains to suprachoroidal space, under investigation now

126
Q

What is the hydrus microstent?

A

schlemm’s canal scaffolding device, dilates schlemm’s canal and allows alternate pathway into schlemms (90 degrees of schlemms), in conjunction with phaco IOL sx

127
Q

What is the IOP decrease of the hydrus?

A

4 mmHg

128
Q

What is the Xen45 gel stent

A

soft gel tube that allows aqueous drainage into sunconjunctival bleb, creates alternate pathway for aqueous to exit the eye

129
Q

Is Xen45 gel externo or interno?

A

ab interno, approved on severe/refractory GLC

130
Q

What is the Xen45 gel efficacy?

A

75% had IOP decrease of 20% or more on same or fewer meds, mean IOP decrease 9.1 mmHg

131
Q

What is the added benefit of Xen45 gel?

A

reduction in topical meds by average of 1.1 meds

132
Q

What is the variability in procedure for Xen gel?

A

externo and interno, placement in sub-conj or sub-tenon space, conjunctival flap opened or not, use of mitomycin c

133
Q

What is a common complication solution for Xen?

A

needling is common

134
Q

What is the cypass micro-stent?

A

shunt placed in anterior chamber to drain aqueous to supraciliary space, not on the market anymore

135
Q

Is cypass interno or externo?

A

interno

136
Q

What is the pressure gradient between the anterior chamber and supraciliary space?

A

3.5 mmHg, allows for good IOP decrease w/o hypotony, accessing similar pathway to uveal-scleral outflow

137
Q

What is the cypass efficacy?

A

72.5% of eyes maintained 20% IOP reduction or greater at 24 months without meds (58% in cataract), 61% had diurnal IOP b/w 6 and 18 (43.5% in cataract)

138
Q

How does cypass compare to cataract surgery alone?

A

32% improvement in IOP reduction

139
Q

How did cypass do with acuity and hypotony?

A

only 3% hypotony in first 30 days post op, 8.8% lost >10 letters vs 15% in cataract

140
Q

Why was cypass recalled?

A

voluntary recall in 2018, some patients had decreased K endothelial cell count, esp if stent was not advances as far into TM, company decided K endo cell loss not appropriate in mild GLC

141
Q

What is the preserflo microshunt?

A

drains aqueous to subconj/sub-tenon’s bleb

142
Q

Is preserflo interno or externo?

A

externo, slightly more invasice but less invasice than trab with the formation of a bleb

143
Q

What is different about preserflo and FDA?

A

currently in trials, not in conjunction with cataract surgery, comparing efficacy against trabeculectomy

144
Q

What is the preserflo efficacy?

A

mean IOP remaining below 15 mmHg, 50% IOP reduction at 3 year mark, 60% of patients are medicine free

145
Q

Preserflo microshunt vs Xen gel:

A

comparable to slightly better IOP control and med reduction with preserflo microshunt

Glaucoma (4 decks)

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