Transcript Complications in refractive surgery

Complications in refractive
surgery
Modified by Corina van de Pol, O.D., Ph.D.
July 28, 2001
James Colgain, OD
Mitch Brown, OD, FAAO
Complications of PRK
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refractive
– over/undercorrection
– Regression
– Central Islands
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laser
– Decentered ablation
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healing
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–
–
–
Epithelial compromise
Corneal infection
Corneal haze
Corneal scar
infection - rare 1:5,000
Over/under-correction
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Cause:
– inaccurate refraction
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unstable
CTL warpage especially in HCL or GPHCL
undetected pathology (KCN)
– unpredictable healing
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induced cylinder
occult autoimmune disorder
Over/under-correction
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Treatment:
– based on refractive stability
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change no greater than 0.5D over 1 month
wait longer in higher myopes and hyperopes
most surgeons wait at least 3 months
ok to treat interim over-correction with SCL
– UCVA >20/40
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based on expectations, patient desire
Regression
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<0.25D myopic regression over 1 year
– US Navy study (n=100)
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Retreatment possible
– based on refractive stability and visual
symptoms/complaints
Central islands
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Cause:
– plume/debris
– water
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Rare in Lasik, rarer still with scanning lasers
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Not as prevalent with newer software and
scanning lasers
Central islands
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Treatment:
– observe
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>90% of islands resolve spontaneously
– customized ablation
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based on height and diameter of island
Epithelial compromise
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Cause:
– underlying basement dystrophy
– prior trauma
– dry eye
– smoking
Epithelial compromise
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Treatment:
– patient selection
– copious tears
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consider punctal occlusion
– bandage CTL
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proper fit
– Acuvue 8.8 for K<40
– Acuvue 8.4 for K>40
– topical antibiotic until epithelium healed
Corneal infection
Rare (<1:5,000)
 Worked up and treated like CTL-related
microbial keratitis
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– if <2 mm, mid-periphery to limbus,
consider empiric therapy with
fluoroquinolone
– if >2 mm and/or central/paracentral,
consider scraping for culture and sensitivity
and aggressive topical fortified antibiotics
(cefazolin and tobramycin)
Corneal haze
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Cause:
– unclear
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? UV exposure
? Over-exuberant healing response
Corneal haze
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Treatment:
– unclear
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based on vision and refraction
probably no treatment required if not visually
significant
if K's are steepening and refraction shifting
toward myopia, consider trial of FML
– >95% of haze clears eventually
Corneal scar
Unresolved haze, refractory to FML
 Potential for vision loss
 Consider PF
 Consider corneal scraping
 Consider mitomycin-C or thio-tepa
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Complications of LASIK
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refractive
– over/undercorrection
– induced astigmatism
– central islands - rare
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laser
– decentered
– less with tracking
– more with longer
ablations
– angle kappa and
visual axis?
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flap
– buttonhole in pupil
– free cap if small
– epithelial defects
especially with older
patients and dry eyes
– wrinkles, striae
– decentration
– inflammation (DLK)
– epithelial ingrowth
(primary and secondary)
– infection - rare 1:5,000
Buttonhole
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Cause:
– steep K (>46), greater risk
– cornea "buckles" during microkeratome
pass, creating central area where blade
exits cornea then re-enters. This is often
in the visual axis and is disastrous to vision
if the ablation occurs.
– May re-cut deeper in cornea in 3-6 months
Buttonhole
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Treatment:
– do NOT perform laser ablation
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irregular astigmatism WILL be induced
– replace flap or don’t lift at all
– allow cornea to heal (at least 3 months)
– re-cut thicker flap and decenter entry of
the MK so as not to disturb initial plane
Free cap
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Cause:
– flat K (<40D) these are at greater risk
– microkeratome travels completely across
flap
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no hinge created
– ALK used to be performed in this fashion
– Surgeon MAY proceed if he bed, cap and
area for ablation are normal
– Always necessary to mark cornea so the
epi side is placed up when repositioned
Free cap
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Treatment:
– save free cap in antidessication chamber
– complete laser ablation
– replace cap, aligning with preplaced marks,
epithelium UP
– consider suture (usually not required) and
bandage CTL
Epithelial defects
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Cause:
– pre-existing condition
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ABM dystrophy
recurrent erosion
prior trauma
dry eye
– greater suction and torquing motion
– dry surface during microkeratome pass
Epithelial defects
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Treatment:
– patient selection
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pre-existing epithelial conditions listed above
are relative contraindications to LASIK.
Consider surface PRK for above conditions
– copious irrigation during procedure
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wet cornea just prior to keratome pass
– bandage CTL
– intraoperative defects may end up being
areas of RCE during healing phase
Flap striae
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May result in irregular astigmatism and lost
BCVA
Cause:
– technique
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flap laid back with poor attention to detail
not smoothed properly
more significant in higher myopes
– patient
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rubbed eye/flap during day one to week one
possible to dehisce flap completely in first 24-48 hours
Flap Striae at 6 weeks post-op
Flap striae
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Treatment:
– technique
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meticulous attention to smoothing flap at time
of ablation and positioning with attention to
“gutter” and pre-op marker alignment
consider "pressing" flap
consider refloating flap if visually significant
rarely, suturing required to stretch flap
– patient
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clear shield at night for first week
caution patient not to rub eye
– use tears for irritation
Flap de-centration
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Cause:
– eye torques when suction applied
– may result in decentered ablation
– the larger the ablation zone - especially in
hyperopes the more significant this issue
– prior to treatment, the surgeon may view
the area of ablation on most lasers to
determine whether the bed area is OK for
the treatment
Flap de-centered nasally ~1.5mm
Flap decentration
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Treatment:
– if ablation can be performed without hitting
flap edge, consider proceeding
– if ablation cannot be accomplished without
hitting flap edge, abort laser, replace flap,
allow cornea to heal (at least 3 months)
and recut deeper, centered flap possibly
using a different MK
Inflammation
Received the most press as potential
complication following LASIK
 Called many names:
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– Diffuse lamellar keratitis (DLK)
– Sands of the Sahara syndrome (SOS)
– May occur in “groups or outbreaks”
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Causes (many potential, none proven):
– metallic debris, meibomian secretions,
staph toxin, keratome oil, infection
Early DLK @ 1 day P/O
DLK @ 6 weeks P/O
Inflammation
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Treatment (stage-dependent):
– stage
– stage
– stage
Forte
– stage
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I: increased frequency of FML
II: switch to Pred Forte
III: lift flap, irrigate and add Pred
IV: stage III Rx and pray
vision loss probable
Epithelial ingrowth
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Causes (2 types):
– nests of cells deposited under flap during
procedure
– migration of epithelium at flap edge
Epithelial cells under flap
Epithelial ingrowth
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Treatment:
– observe for progression
– if progressive, lift flap, scrape with
Weckcell, irrigate well and reposition flap
– may require lifting flap more than once
– risk of epithelial ingrowth increases each
time flap is lifted
– More risk with older patients and poorer
epithelium
– follow up, early detection and treatment
critical to the best outcome
Infection (lamellar keratitis)
Potentially the most devastating
complication associated with LASIK
 Fortunately, a rare complication
(<1:5,000)
 Causes:
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– poor Betadine prep
– poor lid/lash drape
– bad luck
– post op introduction of infectious agent
Infection
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Treatment:
– consider lifting flap to scrape for culture
and sensitivity
– consider aggressive topical fortified
antibiotics (cefazolin and tobramycin)
Flap Dislodgment after Lasik
Rare: no real studies just reported
events
 No one knows when the flap heals
 Able to lift some patients 3 years out
 Events leading to flap dislodgment or
striae from trauma after 30 days
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– Airbag, cat and dog scratch, cardboard box
edge, fingernail scratch during fight, retinal
buckle surgery, tree branch hitting cornea,
snowball hit eye
PRK
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Advantages
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Disadvantages
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safer
longer track record
costs less
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slower recovery
more discomfort
corneal haze
limited range
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LASIK
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Advantages
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faster recovery
less discomfort
less follow-up
enhancements
easier
high myopia
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Disadvantages
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increased risk
late flap
displacement
increased cost
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PRK vs. LASIK
Same destination; Different journey
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PRK
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Day one:
“Oowww!”
Less surgical risk
Slower recovery
80% 20/20
Haze
No flap
0.2 – 0.3% risk
visual loss (>2 lines)
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LASIK
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Day one: “Wow!”
Greater surgical risk
Quicker recovery
80% 20/20
No haze
Flap
0.2 – 0.3% risk
visual loss (>2 lines)
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