Test 1: Surgical Management of Glaucoma Flashcards
rationale for surgery in glaucoma
laser and glaucoma surgery is indicated after maximal medical therapy doesn’t result in adequately lowered IOP
laser procedures
laser iridotomy
laser trabeculoplasty
selective laser trabeculoplasty
cyclophotocoagulation
surgical procedures
filtration surgery
aqueous shunts
argon laser trabeculoplasty
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
advantage of laser surgery
noninvasive
reduce dependence on drops
disadvantages of laser surgery
inflammation
IOP spikes
ALT mechanism
scarring causes shrinkage of TM opening the intratrabecular spaces increasing outflow
laser alters TM’s biochemical and reduce aqueous resistance
primary open angle glaucoma and ALT
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
pseudoexfoliative glaucoma and ALT
effective
effect can diminish quicker than in non-pseudoexfoliative patients
pigmentary glaucoma and ALT
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
post op ALT management
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)
SLT
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
mechanism of SLT
mechanism increases monocytes and macrophages which clear pigment and debris from TM
ALT vs SLT IOP spike
ALT: 3.4%
SLT: 4.5%
ALT vs SLT PAS formation
ALT: 1.2%
SLT: 1.1%
ALT vs SLT ALT treatment within 1 year
ALT: 5.7%
SLT: 3.4%
ALT vs SLT SLT treatment within 1 year
ALT: 4.6%
SLT: 6.7%
ALT vs SLT trabeculectomy within 1 year
ALT: 8.0%
SLT: 9.0%
laser iridotomy is used in
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)
laser iridotomy technique
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
complications of laser iridotomy
inflammation
IOP spike
iris bleeding
cataracts over site
laser iridotomy pre-op meds
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)
cyclodestruction
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
three main types of procedures to destroy ciliary body
diathermy
cyclocryotherapy
cyclophotocoagulation
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
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
cyclophotocoagulation
contact diode laser 0.5-1.0 mm from limbus
16-18 laser applications evenly spaced over 270 degrees
side effects of cyclophotocoagulation
uveitis pain hyphema hypotony phthisis bulbi
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
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
antimetabolites
5-fluorouracil 5-FU
mitomycin-C MMC
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)
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
blebs and surgery
bleb forms under superior conj and aqueous percolates under the conj
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
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
atropine in filtration surgery is used to
increase patient comfort
deepen anterior chamber
reduces risk of posterior synechia
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
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
late postoperative complications of filtration surgery
filtration failure (wound fibrosis, encapsulated bleb) cataract bleb leak blebitis endophthalmitis hypotony maculopathy
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
aqueous shunts are reserved for eyes which
have a failed trabeculectomy with antimetabolites
conjunctival scarring preventing a scleral flap
neovascular glaucoma
micro invasive or minimally invasive glaucoma surgery
trabectome
canloplasty (not really minimal)
trabecular bypass stent
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
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
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
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
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
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
