Test 1: Surgical Management of Glaucoma Flashcards

(49 cards)

1
Q

rationale for surgery in glaucoma

A

laser and glaucoma surgery is indicated after maximal medical therapy doesn’t result in adequately lowered IOP

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2
Q

laser procedures

A

laser iridotomy
laser trabeculoplasty
selective laser trabeculoplasty
cyclophotocoagulation

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3
Q

surgical procedures

A

filtration surgery

aqueous shunts

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4
Q

argon laser trabeculoplasty

A

lowers IOP due to focal contraction or shrinking f the TM
initial success is ~ 60-97%
ALT not effective if TM not visible
generally 180 degrees treated per session
repeat ALT is not effective
glaucoma laser trial compared initial treatment of glaucoma with meds vs ALT - showed that eyes did slightly better with initial laser versus medication first

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5
Q

advantage of laser surgery

A

noninvasive

reduce dependence on drops

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6
Q

disadvantages of laser surgery

A

inflammation

IOP spikes

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7
Q

ALT mechanism

A

scarring causes shrinkage of TM opening the intratrabecular spaces increasing outflow
laser alters TM’s biochemical and reduce aqueous resistance

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8
Q

primary open angle glaucoma and ALT

A

success rate ~80-97%
some investigators show a reduction in number of meds needed following procedure
effect wears off overt time with a failure rate of 10% per year
show to be successful in 32% of eyes after 10 years

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9
Q

pseudoexfoliative glaucoma and ALT

A

effective

effect can diminish quicker than in non-pseudoexfoliative patients

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10
Q

pigmentary glaucoma and ALT

A
good IOP lowering 44-80% at 1 year to ~45% at 5 years
younger patients (40+ years) seem to show better response 
trabeculoplasty over iridotomy still preferred
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11
Q

post op ALT management

A

IOP’s measured within 30-60 min following surgery (IOP spike generally pretreated with iopidine)
glaucoma meds used for 4-6 weeks following surgery util laser has attained maximal effect
post-op meds include topical steroids, typically qid x 4 days
PAS can occur in 46% of patients (no effect on IOP if not occluding over 330 degrees)

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12
Q

SLT

A

shown to be as effective as ALT
can be used on patients with previous ALT with success
repeatable
SLT doesn’t destroy TMa dn does’ show scar tissue
lowers IOP by ~ 30%
laser effects lasts 1-5 years (subsequent treats don’t achieve same efficacy as initial treatment)
spot size - 400 microns with duration of 0.3ns
apraclonidine or brimonidine placed in the eye to decrease the risk of a IOP spike
performed with a Q switch 532 Nd:YAG laser

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13
Q

mechanism of SLT

A

mechanism increases monocytes and macrophages which clear pigment and debris from TM

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14
Q

ALT vs SLT IOP spike

A

ALT: 3.4%
SLT: 4.5%

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15
Q

ALT vs SLT PAS formation

A

ALT: 1.2%
SLT: 1.1%

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16
Q

ALT vs SLT ALT treatment within 1 year

A

ALT: 5.7%
SLT: 3.4%

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17
Q

ALT vs SLT SLT treatment within 1 year

A

ALT: 4.6%
SLT: 6.7%

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18
Q

ALT vs SLT trabeculectomy within 1 year

A

ALT: 8.0%
SLT: 9.0%

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19
Q

laser iridotomy is used in

A
used in glaucoma with pupillary block
acute angle closure 
chronic angle closure 
malignant  glaucoma (aqueous misdirection)
aphakic or pseduophakic pupillary block 
prophylactic iridotomy 
pigmentary dispersion syndrome 
nanophthalmos (narrow, crowded anterior chamber angles)
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20
Q

laser iridotomy technique

A

involves creating a full thickness hole in the peripheral iris with an argon or YAG laser
argon laser produces thermal burn in pigmented tissue which cauterizes wound
YAG laser photo disrupts with shock waves and can show bleeding (used in less pigmented eyes)
site shown to be under upper lid to avoid glare
non-superior site ideal (avoids obscuration from gas bubbles)
typically performed within iris crypt

21
Q

complications of laser iridotomy

A

inflammation
IOP spike
iris bleeding
cataracts over site

22
Q

laser iridotomy pre-op meds

A

pilocarpine 1 or 2% to stretch iris and help lower IOP (maintain following ACG)
apraclonidine (iopidine) or brimonidine (alphagan P) to minimize IOP rise and minimize bleeding (vasoconstrictive effect)
topical steroids to reduce inflammation (also given post-op too)

23
Q

cyclodestruction

A

used when IOP cannot be controlled through medical or surgical intervention
reduces when amount of aqueous production to match decreased outflow ability
usually reserved for eyes with little to no vision

24
Q

three main types of procedures to destroy ciliary body

A

diathermy
cyclocryotherapy
cyclophotocoagulation

25
diathermy
electrode needles deliver current to produce diathermy burns burns applied in 2 rows, 3-4 mm apart many side effects so not currently used
26
cyclocryotherapy
nitrous oxide cryotherapy tips is placed 1-1.5 mm from limbus three to four applications are made per quadrant cyroprobe tip is held in place for 30-45 seconds once reaches -80 degrees celsius creates an icefall which extends into CB and creates cell death generally 2 quadrants initially treated intense uveitis occurs in all cases managed with topical steroids and cycloplegics severe post-op pain may also be present hyphema common in NVG hypotony and phthisis bulbi may also occur due to high side effects, not performed on humans
27
cyclophotocoagulation
contact diode laser 0.5-1.0 mm from limbus | 16-18 laser applications evenly spaced over 270 degrees
28
side effects of cyclophotocoagulation
``` uveitis pain hyphema hypotony phthisis bulbi ```
29
endocyclophotocoagulation
process involves applying argon laser to visualized ciliary processes under direct visualization works well limited to eyes undergoing cataract surgery ophthalmic laser microendoscope (laser and fiber optics for video) good option for patients using glaucoma meds and needing cataract surgery have a lot of inflammation afterwards - so use a lot of steroids
30
filtration surgery
indicated when medical therapy doesn't meet IOP goals trabeculetomy involves removal of a partial portion of limbal tissue containing cornea, sclera, and TM below a scleral flap an antimetabolite may be used to reduce scar formation antimetabolites may be placed on a cotton pledget or piece of methyl cellulose sponge over the wound site for a specified time period
31
antimetabolites
5-fluorouracil 5-FU | mitomycin-C MMC
32
5-FU
a fluorinated pyrimidine antagonist which inhibits fibroblast proliferation by suppressing DNA synthesis side effects include wound leak and corneal epithelial changes can be injected as a series of 5 mg injections over the course of 2 weeks (if not used during surgery)
33
MMC
an antibiotic which causes cross linking of DNA and may inhibit RNA synthesis at higher concentrations giving it antineoplastic and cytotoxic properties applied intraoperatively on a cellulose sponge prior to entering the anterior chamber (MMC very toxic to corneal endothelium) side effects much higher than with 5-FU results in an avascular and acellular bleb
34
blebs and surgery
bleb forms under superior conj and aqueous percolates under the conj
35
filtration surgery sutures
releasable sutures are used for aqueous titration initially sutures are snug to prevent a flat anterior chamber and hypotony laser suture lysis may be employed to gradually open the wound suture lysis should be performed within 2 weeks of the surgery
36
filtration surgery post op meds
results in an avascular acellular bleb 1% red drops q2h while awake for 2 weeks and tapered over 4-8 weeks topical antibiotic used for 2 weeks or until removal of releasable sutures 1% atropine used qd for bid for 2+ weeks until inflammation resolves
37
atropine in filtration surgery is used to
increase patient comfort deepen anterior chamber reduces risk of posterior synechia
38
intraoperative complications of filtration surgery
``` retrobulbar hemorrhage conjunctival buttonhole scleral flap shrinkage tearing or avulsion of the scleral flap iris and ciliary processes bleeding suprachoroidal hemorrhage ```
39
early postoperative complications of filtration surgery
``` hyphema excessive inflammation endophthalmitis choroidal effusion suprachoroidal hemorrhage deep anterior chamber with elevated IOP (sclerostomy blockage - viscoelastic, tight sutures) shallow anterior chamber with low IOP (wound leak, over filtration, iridocyclitis, CB detachment) ciliary block glaucoma ```
40
late postoperative complications of filtration surgery
``` filtration failure (wound fibrosis, encapsulated bleb) cataract bleb leak blebitis endophthalmitis hypotony maculopathy ```
41
aqueous shunts
glaucoma drainage implants drainage plate sutured to sclera with the distal tube implanted into he anterior (most common) or posterior chamber plate serves as a diffusion device to allow aqueous to accumulate under the conj
42
aqueous shunts are reserved for eyes which
have a failed trabeculectomy with antimetabolites conjunctival scarring preventing a scleral flap neovascular glaucoma
43
micro invasive or minimally invasive glaucoma surgery
trabectome canloplasty (not really minimal) trabecular bypass stent
44
trabectome
an ab interno technique (no conj dissection therefore superior conj undisturbed for filtration surgery if needed) uses microelectrocautery to ablate a strip of tissue (nasal 60 degrees to 120) from the TM and schlemm's canal, allowing aqueous direct access to the eye's drainage system inserted into eye through a 1.88 mm temporal clear corneal incision tip is inserted through the TM into schlemm's canal features protective footplate that prevents the heat generated during electrocautery from damaging non-targeted tissues it also guides the tip smoothly through schlemm's canal, while ablating the targeted trabecular and juxtacanalicular tissues simultaneous irrigation and aspiration remove the debris and maintain a stable anterior chamber
45
trabectome success
yielded a 30-40% reduction in IOP with end pressures in the mid teens, one to two fewer meds postoperatively, with little to no vision threatening complications one study concluded although the success rate was lower with the trabectome, the excellent safety profile for the procedure makes it a viable option for glaucomatous eyes with more modest IOP goals or in which the risks of trabeculectomy are of particular concern
46
trabectome vs trabeculectomy
one study showed two groups and included more than 100 eyes and were followed for about 2 years the authors concluded that, although the success rate was lower with the trabectome, the excellent safety profiled the procedure makes it a viable option for glaucomatous eyes with more modest IOP goals or in which the risks of trabeculectomy are of particular concern
47
canaloplasty
maximall invasive an ab externo technique that combines non penetrating deep sclerectomy with dilation of schlemm's canal conj dissection and formation of a scleral flap are required the goal of the procedure is to increase conventional outflow by catheterizing and viscodilating schlemm canal transient hyphema was the most common complication, occurring in 10.2% of eyes
48
canaloplasty versus trabeculectomy
one study showed patients in the trabeculectomy group three fewer meds 12 months postoperatively, whereas patients in the canaloplasty group required 2 fewer meds there was no significant difference between the two groups regarding surgical failures, which was defined as an eye requiring re-operation transient hyphema was the most common complication in the canaloplasty group, and choroidal effusion was the most common complication in the trabeculectomy group hypotony, maculpathy and suprachoroidal hemorrahge occurred infrequently in the trabeculectomy group and did not occur in the canaloplasty group the authors concluded that trabeculectomy resulted in lower IOP and less post op meds and canaloplasty resulted in a significant reduction in IOP and post op meds without long term potential risks of a filtration bleb
49
trabecular microbypass shunt
approved in 2012 the trabecular micro bypass stent is for use in conjunction with cataract surgery in patients with mild to moderate POAG similar to the trabectome, implantation of an iStent is an ab intern procedure with the need for conj dissection the micro-device was developed to bypass the TM and inner wall of schlemm's canal to reestablish outflow when the iStent was combined with phacoemulsification, a statistically higher % of patients achieved an IOP less than 21 mmHg without meds vs phacoemulsification alone in patients with mild to moderate glaucoma the incidence of complications was low in both groups, and no serious adverse complications specifically related to the iStent occurred