Test 1: Surgical Management of Glaucoma

Question 1

rationale for surgery in glaucoma

Answer 1

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

Question 2

laser procedures

Answer 2

laser iridotomy
laser trabeculoplasty
selective laser trabeculoplasty
cyclophotocoagulation

Question 3

surgical procedures

Answer 3

filtration surgery

aqueous shunts

Question 4

argon laser trabeculoplasty

Answer 4

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

Question 5

advantage of laser surgery

Answer 5

noninvasive

reduce dependence on drops

Question 6

disadvantages of laser surgery

Answer 6

inflammation

IOP spikes

Question 7

ALT mechanism

Answer 7

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

Question 8

primary open angle glaucoma and ALT

Answer 8

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

Question 9

pseudoexfoliative glaucoma and ALT

Answer 9

effective

effect can diminish quicker than in non-pseudoexfoliative patients

Question 10

pigmentary glaucoma and ALT

Answer 10

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

Question 11

post op ALT management

Answer 11

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)

Question 12

SLT

Answer 12

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

Question 13

mechanism of SLT

Answer 13

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

Question 14

ALT vs SLT IOP spike

Answer 14

ALT: 3.4%
SLT: 4.5%

Question 15

ALT vs SLT PAS formation

Answer 15

ALT: 1.2%
SLT: 1.1%

Question 16

ALT vs SLT ALT treatment within 1 year

Answer 16

ALT: 5.7%
SLT: 3.4%

Question 17

ALT vs SLT SLT treatment within 1 year

Answer 17

ALT: 4.6%
SLT: 6.7%

Question 18

ALT vs SLT trabeculectomy within 1 year

Answer 18

ALT: 8.0%
SLT: 9.0%

Question 19

laser iridotomy is used in

Answer 19

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)

Question 20

laser iridotomy technique

Answer 20

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

Question 21

complications of laser iridotomy

Answer 21

inflammation
IOP spike
iris bleeding
cataracts over site

Question 22

laser iridotomy pre-op meds

Answer 22

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)

Question 23

cyclodestruction

Answer 23

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

Question 24

three main types of procedures to destroy ciliary body

Answer 24

diathermy
cyclocryotherapy
cyclophotocoagulation

Question 25

diathermy

Answer 25

electrode needles deliver current to produce diathermy burns burns applied in 2 rows, 3-4 mm apart many side effects so not currently used

Question 26

cyclocryotherapy

Answer 26

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

Question 27

cyclophotocoagulation

Answer 27

contact diode laser 0.5-1.0 mm from limbus | 16-18 laser applications evenly spaced over 270 degrees

Question 28

side effects of cyclophotocoagulation

Answer 28

``` uveitis pain hyphema hypotony phthisis bulbi ```

Question 29

endocyclophotocoagulation

Answer 29

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

Question 30

filtration surgery

Answer 30

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

Question 31

antimetabolites

Answer 31

5-fluorouracil 5-FU | mitomycin-C MMC

Question 32

5-FU

Answer 32

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)

Question 33

MMC

Answer 33

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

Question 34

blebs and surgery

Answer 34

bleb forms under superior conj and aqueous percolates under the conj

Question 35

filtration surgery sutures

Answer 35

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

Question 36

filtration surgery post op meds

Answer 36

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

Question 37

atropine in filtration surgery is used to

Answer 37

increase patient comfort deepen anterior chamber reduces risk of posterior synechia

Question 38

intraoperative complications of filtration surgery

Answer 38

``` retrobulbar hemorrhage conjunctival buttonhole scleral flap shrinkage tearing or avulsion of the scleral flap iris and ciliary processes bleeding suprachoroidal hemorrhage ```

Question 39

early postoperative complications of filtration surgery

Answer 39

``` 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 ```

Question 40

late postoperative complications of filtration surgery

Answer 40

``` filtration failure (wound fibrosis, encapsulated bleb) cataract bleb leak blebitis endophthalmitis hypotony maculopathy ```

Question 41

aqueous shunts

Answer 41

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

Question 42

aqueous shunts are reserved for eyes which

Answer 42

have a failed trabeculectomy with antimetabolites conjunctival scarring preventing a scleral flap neovascular glaucoma

Question 43

micro invasive or minimally invasive glaucoma surgery

Answer 43

trabectome canloplasty (not really minimal) trabecular bypass stent

Question 44

trabectome

Answer 44

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

Question 45

trabectome success

Answer 45

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

Question 46

trabectome vs trabeculectomy

Answer 46

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

Question 47

canaloplasty

Answer 47

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

Question 48

canaloplasty versus trabeculectomy

Answer 48

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

Question 49

trabecular microbypass shunt

Answer 49

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