LASIK: COMPLICATIONS AND THEIR MANAGEMENT

1. LASIK: COMPLICATIONS AND
THEIR MANAGEMENT
Dr. Rujuta GoreDr. Rujuta Gore
Dr. Mrudula BhaveDr. Mrudula Bhave

2. LASIK: Possible complications
Intraoperative
Microkeratome related
Flap related
Early postoperative
Late postoperative
Refractive complications

3. Intraoperative complications
Inadequate exposure
Inadequate suction

4. Incomplete Cut
A lamellar cut that does not reach the limit scheduled by
the operating program
Causes:
Loss of suction
Block of keratome by drape or dust in its gears
Power failure
Prevention:
Precise preoperative check of the instrumentation
Adequate exposure
Continuous power supply

5. Mx Incomplete Cut
Unexpected stop- reverse the run direction, remove the
suction ring
Complete block- suspend the suction, gently remove
microkeratome and suction ring in a direction away from
hinge
Sufficient room for refractive ablation- proceed
If insufficient- replace the flap; postpone by 3-6 months

6. Thin/ Perforated cut (buttonhole)
Mechanical Causes:
Inadequate suction
Incorrect ring size
Poor blade quality
Excessively dry cornea
Loose epithelium
Edematous epithelium
Anatomical causes:
Very steep corneas
Irregular astigmatism

7. Results:
Inability to perform laser ablation
Risk of epithelial ingrowth in interface and possible
melting
Risk of irregular astigmatism

8. Mx Thin Cut
Prevention:
Avoid excessive use of anaesthetic eyedrops that may weaken
the epithelium
Change the blade after every cut
If flap can be raised, ablation can be performed, paying
attention to alignment, avoiding folds while repositioning

9. Mx Thin Cut
Management:
Minimal manipulation
Replace the thin flap or buttonholed flap while carefully
managing the epithelial edge
Inspect the flap and verify adherence
Wash the interface carefully
Therapeutic contact lens

10. Flap cut around 360° (Free Cap)
Etiology-
Large (>14.5mm) , flat cornea
(<41.0D)
Poor assembly of microkeratome
Inadequate suction
Removal of suction ring with cap
still adhered to it
Reduced intra op IOP
Prevention:
Corneal marking for proper
alignment

11. Mx Free Cap
Keep the flap in antidessication chamber, epithelial side
down
Proceed with ablation
Stromal surface should not be hydrated
Align flap with preop markings
Sutures not required
OR Flap may be discarded; apply a contact lens to aid
epithelial regrowth

13. Early Postoperative
Complications

14. Flap related complications
Causes:
Excessive dehydration due to prolonged surgical time
Manipulation with forceps, swabs and other instruments
not suitable for LASIK
Prevention:
Alleviate anxiety
Flap must not be allowed to dry
Time between lifting and reposition minimum
Avoid excessive interface irrigation
Speculum removal-gentle
Protect the hinge when OZ is large

15. Flap Complications
Displacement of flap
Wrinkled flap (micro and macrostriations)
Interface debris
Flap edema
Flap shrinkage
Flap stretching
Decentration

16. Displacement of flap
Causes:
Incomplete adhesion to stroma
Squeezing of eyes while drape and
speculum removal
Excessive movements of eye/
rubbing
Dryness of eye
Accidental trauma while instilling
drops
Mx:
Immediate refloating of flap into
position

17. Wrinkled flap
Causes:
Rubbing
Instilling eyedrops
Incorrect flap positioning
Extremely thin flap
Dehydration of stromal
surface due to prolonged
exposure
Rough handling of flap
Use of vasoconstricting
agents like phenylephrine
or brimonidine to
minimize SCH

18. Striations: What are they?
Microstriations: folds in Bowman’s membrane. Cause
minimal visual deficit
Macrostriations: folds in the flap. Reduce VA due to
irregular astigmatism, halos, starbursts

19. Mx Striations
Micro- can be observed
Macro- Flap should be lifted again, interface should be
washed and flap replaced
Flap should be smoothed with a Merocel soaked in BSS,
perpendicular to orientation of striations
Contact lens may be applied

20. Striations: consequences and Mx
Striae become permanent as epithelium fills the spaces in
the folds
Mx
Soak the epithelial surface by instilling distilled water. This
creates edema and loosens the cells for removal
Remove the epithelium with a spatula
Then raise the flap and irrigate the interface with BSS, and
distilled water
Reposition
Apply contact lens

21. Persistent striations
May apply continuous 10-0 Nylon suture to mechanically
smoothen the flap
PTK to remove epithelium between striae
PTK (10μm) on stromal surface of flap

22. Interface debris
Causes:
Debris from cannula, syringe, microkeratome, sponge
Mx:
Inspect the interface and flap before removing drape
and speculum
Edge irrigation
Lift flap and reposition after irrigation

23. Microbial Keratitis
Rare but potentially devastating complication
Incidence: 1:5000(0.02% to 1%)
Common organisms:
Staph aureus (early onset infections)
Mycobacterium chelonae (late onset infections)
Candida, Fusarium (later onset)
Predisposing factors:
Poor steririlization
Poor compliance to postop instructions
Poor hygiene

24. Symptoms:
Increased light sensitivity
Pain
Redness
Foreign body sensation
Decreased vision
Microbial Keratitis

25. Clinical signs:
Corneal infiltrate
Epithelial ingrowth
Epithelial defects
AC reaction
Hypopyon
Microbial Keratitis

26. Laboratory tests:
Scrapings: from stromal bed
Smears
Culture
Management:
In case of interface infiltrate, lifting of flap and removal of all
infective foci
Irrigation with 50mg/mL vancomycin or 35mg/mL amikacin
Intensive fortified antibiotic and antifungal therapy as per
the lab results
Mx Microbial Keratitis

27. In cases of resistant bacterial infection, flap removal and
intensive medical therapy has been found useful
In cases of resistant fungal infection, an aggressive
approach consisting of amputation of the flap, daily
debridemant of the bed, intensive topical and systemic
antifungals may be required
Eyes not responding to medical therapy and those
presenting late with large infiltrates may need ALK or TPK
Mx Microbial Keratitis

28. Prevention:
Treatment of blepharitis preoperatively
Sterile technique
Careful clearing of all cannulas and syringes using fresh
sterile distilled water
Prophylactic postop topical antibiotic
Avoid swimming for 1month postoperatively
Microbial Keratitis

29. Diffuse lamellar keratitis
Also known as ‘Sand of Sahara’
Non infectious complication
Infiltration of inflammatory cells in interface

30. Possible causes:
 Retained meibomian secretions
 Metallic debris
 Talc from gloves
 Lubricants on the microkeratome or blades
 Topical medications such as anesthetics
 Endotoxins
 IL 1 released from corneal epithelial cells following cell
injury or death

31. Linebarger staging of DLK
Stage 1
Fine white cells of granular appearance distributed in
wave like fashion in periphery of flap
Frequently occurs on day1
No decrease in BCVA
Mx:
Frequent
administration of
topical steroids

32. Stage 2
Whitish cells of granular or wave like appearance in
visual axis and possibly at the periphery
Typically seen 2 or 3 days post Lasik
No decrease in BCVA
Mx:
Frequent
administration of
topical steroids
Linebarger staging of DLK

33. Stage 3
Increased density of cells in visual axis, more clumped
than wave like
Transparent peripheral cornea
Seen on day 3 0r 4
Patient may describe fogginess of vision
Linebarger staging of DLK
Mx:
Raise the flap and
thoroughly irrigate
with BSS
Frequent
administration of
topical steroids

34. Stage 4
Central corneal melting at interface by release of
collagenase by aggregated inflammatory cells
Scarrings and folds in visual axis
VA is decreased, hyperopic
shift
Irregular astigmatism
Mx:
When repair process has
concluded, consider anterior
lamellar keratoplasty
Linebarger staging of DLK

35. Late Postoperative
Complications

36. Epithelialization of interface
Causes:
Prolonged manipulation
of the flap
Excessive use of
instruments at the
interface
Poor flap edge adhesion
Epithelial abrasion at
flap edge
Flap misalignment
Buttonholes
Spillover of ablation at
bed margin

37. Results:
Decreased visual acuity
Irregular astigmatism
Discomfort
Risk of stromal melt

38. Machat classification of Epithelial Ingrowth
Grade 1:
Small white aggregates with
smooth outlines
Limited to 2mm from the
flap edge
Often outlined by white
demarcation line along the
front of epithelial
progression
No treatment required
Normally disappear within
2-4 months

39. Grade 2:
Pearly white aggregates
with blurred edges
Located within 2mm
from the flap edge
Ingrowth is thicker
My progress toward
centre of pupil
Requires observation
Machat classification of Epithelial Ingrowth

40. Grade 3:
Ingrowth is marked with
multicellular thickness
Extent exceeds 2mm from
the flap margin
Thinning or melting of flap
may occur
Machat classification of Epithelial Ingrowth

41. Prevention:
Avoid prolonged manipulation of flap
Clear any epithelium, tags, or debris from stromal bed
prior to flap reposition
Shield hinge area
Apply contact lens when epithelial defects are observed
Femtosecond laser flap is better

42. Mx
For peripheral few aggregates: NdYAG laser
30-40 pulses; 0.6-1.2mJ; beam focussed slightly
posteriorly with respect to the epithelial growth
Sufficient for blocking progression

43. Mx
For extensive aggregates:
Raise the flap closest to epithelial growth
Debride the stromal surface and undersurface of flap edges
with microspatula
In severe ingrowth with melting and folds it is better to
remove the flap and allow healing

45. Refractive Complications

46. Irregular astigmatism
Causes:
Wrinkles or folds in flap
Interface debris
Epithelial ingrowth
Decentration
Results:
VA decreased by 2 or more lines
Mx:
Retreatment is directed to underlying cause

47. Undercorrection
There is residual, unexpected refractive error in first
postoperative month
More frequent in high myopia above 10 to 12D
It is easier to correct residual myopia than to correct
hyperopia from overcorrection

48. Causes of undercorrection:
Incorrect preoperative refraction (most common)
Difficulty in performing precise refractive
evaluation(severe myopia with staphyloma)
Incorrect laser calibration
Environmental condition in OT
Incorrect data entry
Incomplete or decentered ablation
Incorrect interpretation of nomogram
Unstable ametropia
Undercorrection

49. Mx:
 Retreatment should be considered 2 to 3 months
later, after refractive stability
 Preferably under aberrometric guidance
Options:
 Lifting the flap and reablation
 Usually performed within 3 to 4mths of first treatment
 Lamellar technique or recutting a new flap(for
myopia greater than 10D)
 Performed atleast 6months after initial treatment
 May not be possible due to already thinned cornea
 Surface ablation technique(PRK)

50. Overcorrection
1 month after surgery ,there is refractive correction
that exceeds the expected value
Causes:
Incorrect preoperative refraction
Incorrect data entry
Poor control of humidity levels in laser room(too
dry)

51. Mx:
 Lifting the flap and reablation
 It is possible to repeat the treatment for hyperopic
values in 2 to 3months
 Paraperipheral ablation of anterior stromal bed is
done
 Hyperopic surface photoablation
 Hyperopia of 1 to 3D can be corrected
 Conductive keratoplasty

52. Regression
Indicates that the refractive result of Lasik is not
stable with continuing loss of effect over a few
months
Normally stops between 1 and 3 mths after surgery
More frequent in myopia >10D
Frequently seen in severe hyperopia and astigmatism

53. Causes:
May be due to combination of epithelial hyperplasia
and remodeling of stroma
Management:
Treatment options as for undercorrection
Enhancement procedures to be considered only after
refraction is stable
Regression

54. Corneal Ectasia
Progressive relaxation of
the cornea with an
increase in radius of
curvature along with
thinning
Progressive deterioration
of patient’s VA

55. Pathophysiology:
Collagen fibres in anterior third of cornea have greater
tensile strength
In LASIK, cut is performed in the anterior third
Corneal weakening by 0-33%
Ectasia: delamination and interfibril fracture
Corneal Ectasia

56. Risk factors-
Keratoconus
Pellucid marginal degeneration
Forme fruste keratoconus
Residual stromal bed less than 250μm in diseased corneas
Refractive instability and family history of keratoconus
should arouse suspicion
Corneal Ectasia

57. Results:
Thinning and bulging of cornea
Myopic shift
Irregular astigmatism
Reduced UCVA and BCVA
Corneal Ectasia

60. Diagnostic criteria for corneal ectasia:
1. Inferior topographic steepening of >5D compared with
immediate postoperative appearance
2. Loss of >2snellens line of UCVA
3. Change in manifest refraction >2D(sph/cyl)
4. Posterior float higher than 0.08 mm
Corneal Ectasia

61. Prevention:
Alternative approach- PRK/ Phakic IOL
Preoperative:
Topography:
In asymmetric cornea –test should be repeated several times
CL wearers should stop using CL 2-3wks before topography
Rule out keratoconus
Pachymetry:
Most important to plan ablation
Corneal Ectasia

62. Intraoperative:
Measure flap thickness and posterior stroma during
surgery, both before and after the ablation
Corneal Ectasia

63. Mx:
Collagen crosslinking
RGP contact lens
Intrastromal rings
Lamellar keratoplasty
Penetrating keratoplasty
Corneal Ectasia

64. Decentered Ablation
Causes:
Poor patient fixation due to
nervousness or
oversedation
Difficulty seeing target due
to blurred vision(high
corrections)

65. Results:
Loss of BCVA
Irregular astigmatism
Night vision problems
Ghosting, glare
Decentered Ablation

68. Treatment:
For mild degrees of decentration, a small diameter
ablation may be performed at the edge of the original
optical zone to enlarge the optical zone in pupillary axis
A series of 3 small diameter ablations may be placed at the
edge of decentered ablation followed by PTK smoothing
Decentered Ablation