1. LASIK & PRK: Potential Post-op Corneal Opacities
Terrence S. Spencer, M.D.
February, 2013

2. Disclosures Purpose financial disclosure: To educate optometrists
No current financial interest or consulting fees related to any products discussed
Purpose
To educate optometrists
Familiarize with possible post-operative complications of LASIK and PRK
LASIK is a surgery, and all surgery has some risk
Terrence S. Spencer, M.D.

3. Tunnel on the Peter Norbeck Scenic Byway

4. Outline Briefly Review Corneal anatomy
Refractive Surgery vs. Corneal refractive surgery
History of Refractive Surgery
Basics of corneal refractive surgery
PRK and LASIK
Flap creating technology - Intralase.
Complications and what to do.

5. Corneal Anatomy

6. Corneal Anatomy Corneal Transparency: Stroma: Ground substance:
Based on highly organized system
Stroma:
Layers of fibroblasts between sheets of lamella.
Ground substance:
Maintain proper position of the fibrils equidistant from each other
Opacity (or scar):
Forms when organization of structure is disrupted

7. What is Refractive Surgery
Photo-Refractive Keratectomy
LASIK
CK: conductive keratoplasty
Phakic IOL’s – Visian Staar ICL
Refractive lens exchange or cataract surgery
Presbyopia-correcting & Toric IOLs
Corneal implants
Intracor procedure

8. History of Refractive Surgery
Ancient Chinese:
Slept with sandbags on eyes to flatten the cornea
’s:
A variety of devices to modify the shape of cornea with pressure or suction
1898:
keratotomy experiment in rabbits.

10. History of Refractive Surgery
Svyatoslav Fyodorov (Moscow)
Early1970s: boy on bicycle (-6 D)
1974: started doing RK on humans
Radial incisions “relax” tension on peripheral cornea to flatten the center
Late 1970s: US surgeons started performing RK

11. History of Refractive Surgery
Conveyer operating theater in Soviet Union

12. History of Refractive Surgery
Jose Barraquer
The father of modern refractive surgery
Several inventions
Born in Spain, but moved to Bogotá, Columbia in 1965

13. Lathe (for background info only)

14. History of Refractive Surgery
Keratomileusis (Jose Barraquer)
1949: 1st publication on changing shape of cornea to change refraction
Cryolathe
Layer of cornea removed
Stained and Frozen
Lathed
Sutured back in place
Sutures removed weeks later

15. History of Refractive Surgery
Microkeratome: (Barraquer)
Allowed for in situ correction
ALK: Automated Lameller Keratoplasty (Luis Ruis)
Microkeratome 1st makes an incomplete flap
Microkeratome readjusted for the power cut.
Never gained great popularity

16. History of Refractive Surgery
Laser: Light Amplification by Stimulated Emission of Radiation
1917: theorized by Albert Einstein
1960: first successful laser

17. History of Refractive Surgery
Laser: Wavelength of light is determined by the type of gas or solid medium
Example: YAG laser – crystal of Yttrium-Aluminum-Garnet = 1064 nm

18. History of Refractive Surgery
Excimer (Excited Dimer of Argon and Flourine) Laser:
1968: Excimer laser invented
1970’s: Etching silicone computer chips
1982: Rangaswamy Srinivasin (IBM): excimer laser can ablate tissue without causing heat damage
1983: Steven Trokel (NYC) patented excimer laser use for vision correction
193 nm (ultraviolet)

19. History of Refractive Surgery
Photorefractive keratectomy (PRK)
1st eye surgery done with excimer laser
1987 in Berlin: Dr. Theo Seiler

21. History of Refractive Surgery
1990: Laser In-Situ Keratomeleusis (LASIK)
Epithelium intact = less pain from exposed nerves
Combines flap (ALK) with excimer laser (PRK)

22. Procedure Descriptions

23. PRK PhotoRefractive Keratectomy Other names for PRK
First performed in 1987
Removal of tissue with excimer laser
Other names for PRK
LASEK (laser epithelial keratomileusis)
The epithelium layer is placed back on the stroma after corrective laser is completed
Epi-LASIK
A device called an epikeratome is used to remove the epithelium

25. Photorefractive Keratectomy (PRK)
Step 1:
Epithelium is removed
diluted alcohol, brush, vibrating blade, laser
Discarded or replaced
Step 2:
Excimer laser correction
sculpting the cornea
Either flattening or a steepening pattern +/- astigmatism correction

26. PRK post-op expectations
Soft bandage contact lens
Placed immediately following treatment
Helps with patient comfort
Acts as a protective barrier for the healing process
Epithelium closes in ~ 3-7 days
Epithelial healing line
Visible where leading edges of epithelium meet in center of cornea
Can induce temporary astigmatism. It can takes weeks to months to stabilize.

27. PRK for Athletes

28. LASIK- laser assisted in-situ keratomileusis
The removal of tissue is done with excimer laser
In-Situ (latin)
In place in the body
Keratomileusis
Kerato (Greek): cornea
Mileusis: to shape

29. LASIK SURGERY BASICS TWO STEPS OF LASIK 1: Corneal flap
Microkeratome or Femtosecond laser.
Layer includes epithelium, Bowman’s membrane, some anterior stroma.
The corneal flap is then folded back.
2: Excimer laser
Ablates the corneal stroma to correct the refractive error.

30. LASIK SURGERY BASICS After excimer laser treatment
Cornea irrigated with sterile saline
Examine for any debris
Irrigate until the interface is clear of any debris.
Flap is positioned back into the original position in the corneal bed
Smooth out any micro-striae

31. LASIK Immediately after LASIK surgery: Patient’s vision is foggy
cornea edema may cause difficulty to see any striae, debris etc.
Some small particles in the flap interface are not visible until the one-day post-op visit.

33. Concerns with LASIK Microkeratome:
Flap creation with a blade is responsible for the majority of the possible procedural complications

34. What is femtosecond laser?
Femto- is a prefix in the metric system
Denotes a factor of ( )
Femtosecond = 1 quadrillionth of a second
Category: ultrashort pulse (ultrafast) laser

35. Femtosecond laser Advantage of ultra-short pulse lasers
Extremely precise
Cuts material by ionizing it at the atomic level
Pulses are too brief to transfer heat to the material being cut
No damage to surrounding tissue
Femtosecond lasers are “cold” lasers

36. The IntraLase® laser is a femtosecond laser
How does a laser cut a flap?
To truly embrace the IntraLase method and to understand why IntraLase will benefit your practice and patients, it makes sense to first discuss the differences between the technology you currently employ, the microkeratome, and the technology you will be soon using, blade free IntraLase.

37. Femtosecond Laser Laser pulse is focused to desired corneal depth
Depth and hinge placement are adjustable based on individual patient factors
Corneal thickness, steepness, and/or diameter
FS laser produces precisely beveled edge architecture to enable secure flap positioning
Resists displacement
Less risk of epithelial ingrowth.

38. A pulse of laser energy is focused to a precise spot inside the cornea
IntraLase Photodisruption
A pulse of laser energy is focused to
a precise spot inside the cornea
A microplasma is created, vaporizing
approximately 1 micron of corneal tissue
1 Micron

39. IntraLase Photodisruption
2 Microns
An expanding bubble of gas & water is created separating the corneal lamellae

40. IntraLase Photodisruption
The bi-products of photodisruption (CO2 & water) are absorbed by the mechanism of the endothelial pump, leaving a cleavage plane in the cornea

41. Intralase Photodisruption
The speed of the new 30kHz laser allows tighter spot placement. The faster laser fires ahead of the photodisruption process producing a more homogenous bubble pattern and resulting in easier flap lifts.
Tighter spot placement facilitates easier flap lifts

42. IntraLase Photodisruption to create horizontal cleavage plane

43. The Planar Flap IntraLase provides uniform flap thickness
Independent of patient keratometry
Reduction of induced irregular astigmatism
Optimizes stromal bed for wavefront guided vision correction
Increased flap stability (less slipped flaps)

44. Post-operative flap edge

45. One day post op

46. Intralase 1Day post op

47. Intralase Contraindicated in eyes with a corneal scar.
Laser may not penetrate through the opacity
May cause a gas bubble breakthrough or a tear in the flap underneath the scar

48. Corneal opacities after LASIK

49. Differential Diagnosis
1)Superficial Punctate Keratitis (SPK)
2)Diffuse Lamellar Keratitis (DLK)
3)Epithelial ingrowth
4)Interface debris
Tear film –oily deposits
Cloth fiber
Cilia, Eyelash
Sponge particles
Mascara
Etc

50. Differential Diagnosis Cont.
5)Corneal infiltrate
6)Corneal ulcer
7)Herpetic lesion
8)Epithelial Basement Membrane Dystrophy (EBMD)
9)Micro striae vs. Slippped flap or folds
10)Prominent corneal nerves

51. Differential Diagnosis Cont.
Other considerations:
Corneal scar – look back at pre-op exam findings
Corneal Edema
Arcus senilis
Loose epithelium

52. Most Common Post-op findings
Dry eye/ SPK or PEK
Tear film debris interface
oily or small spots
Other Interface debris
sterile fiber, eyelash
Post operative reticular haze in interface
Pre-existing Corneal scar
Corneal scarring at flap edge

53. Less Common findings Diffuse Lamellar Keratitis Epithelial ingrowth
“Sands of the Sahara”
Epithelial ingrowth
Infectious infiltrate
Sterile infiltrate
Infectious Ulcer or infiltrate
Fungal infection (rare)
Peripheral infiltrate, not in flap interface – can be due to corneal neovascularization
Herpetic lesion
Surgical stress may re-activate a dormant virus

55. WHERE is the Opacity? Biomicroscopy (Slit Lamp) Assessment
Depth? Look carefully with the optic section
Surface – Epithelial
It should stain
Flap interface
It won’t Stain
Stromal
It won’t stain. Is it anterior, posterior?
Endothelial
Endothelial folds from a very edematous cornea. Unlikely with LASIK. More common with PRK

56. Dry Eye Syndrome If not quickly resolved
The Most Common adverse side effect of LASIK / PRK
Exam findings: SPK/PEK
Can dramatically effect visual acuity.
If not quickly resolved
Can lead to poor healing and a “non-perfect” visual outcome.
DES can lead to Myopic regression
Which then requires an enhancement which could lead to more dry eye!

57. DRY EYE SYNDROME Surface epithelium will stain Symptoms:
Sodium Fluorescein dye
Rose Bengal, Lissamine green
Symptoms:
Less pain than expected d/t nerve damage
Affects visual acuity.
Like looking through textured glass. Vision appears grainy, foggy.

58. Dry Eye Management Artificial tears q30min-1hr Punctal plugs
Preservative free
Consider Celluvisc or ointment at bedtime
Punctal plugs
Temporary collagen
Permanent - Silicone
Restasis- one drop BID

59. Dry Eye Management Doxycycline (oral)
Anti-inflammatory effect as well as improve proper meibomian gland function.
Nutritional supplements – Fish Oil & Flax seed oil 2000mg daily.
Consider low-potency steroid
Loteprednol (Lotemax)
Fluorometholone (FML)

60. Severe Dry Eye Severe Dry eye patients Consider BLOOD PLASMA TEARS
If not improving with all of the typical dry eye management
Consider BLOOD PLASMA TEARS
Autologous
Contains nutrients, platelets, proteins, minerals, antibodies, imunoglobulins

61. Blood Plasma Tears

62. Under the surface
If it doesn’t stain, consider that it may be something in the interface.

63. Interface Debris Location – in the flap interface It WILL NOT STAIN.
Tear film debris - in interface- looks oily or has small spots.

64. Interface Debris Powder-like debris from tissue ablation
It can look like DLK or Epithelial cells.
Refractile or glistening appearance.
Document. It shouldn’t look different at the next visit.
If it grows, it may be DLK or epithelial ingrowth.

65. Interface Debris Cont. Particle/spec:
If no inflammation and not affecting vision, leave it alone.
Flap lift to irrigate can increase risk of epithelial ingrowth.
If affecting vision, we lift and irrigate, a.s.a.p.

66. More Flap Interface Complications
Diffuse Lamellar Keratitis
Epithelial ingrowth
Post op corneal haze in interface
Slipped flap
Button hole flap
Example: Interface haze d/t endothelial cell deficiency

67. Diffuse Lamellar Keratitis (DLK)
AKA- Sands of the Sahara
White blood cells in the flap interface.
Etiology
Inflammatory response to surgical trauma,
Reaction to solutions
Povidone-iodine
Distilled water used on surgical instruments
Surgical marking pen
Microkeratome oil
Bacterial endotoxins
carboxymethylcellulose drops,
Meibomian gland secretions
detergents, contaminated air particulates
Idiopathic (UNKNOWN cause)

68. Diffuse Lamellar Keratitis (DLK)
Increased incidence with
Atopic, allergic patients
Blepharitis.
Pre-treat bleph with oral Doxycycline, lid scrubs, topical medications before LASIK and PRK.
Can occur with corneal trauma even many years post-LASIK
Can occur when we do PRK over an old LASIK flap.
DOES NOT OCCUR WITH PRK ALONE (no flap, no DLK)
Can be detected as early as the one day post op visit. Look at the flap interface very carefully!
Can look like SPK but DOES NOT STAIN!!

69. Diffuse Lamellar Keratitis (DLK)

70. Diffuse Lamellar Keratitis (DLK) and Intralase flap technology
Incidence of significant DLK
0.1% of LASIK patients with the microkeratome
Slightly more risk with early model of Intralase

71. DLK

72. DLK

73. DLK Grade DLK Classification system
Stage 1- Faint sterile infiltration of infammatory cells at the flap edge within the interface
Stage 2- More central diffuse pattern
Stage 3- inflammatory cells within the visual axis lead to reduced visual acuity
Stage 4-(rare) Collagenase release and stromal melting and subsequent loss of BSCVA.

74. DLK Grade
DLK usually starts within 24 hours, and peaks at about post-op day 5

75. DLK Management Consult back with BHREI
Grade 1-Manage with Pred Forte 1% q2h and see every 3-5 days
Grade 2-3 Pred Forte q1-2h. Consider stronger Durezol. The patient is to be seen every 24 hours until DLK begins to regress.
Grade 3-4+ Refer back to BHREI.
Pred Forte or difluprednate (Durezol)
May need oral Prednisone
Flap lifted and irrigated.

76. DLK Management If severe photophobia
Cycloplegia
ALWAYS REMEMBER TO MONITOR IOP WHILE ON STEROIDS!!!

77. Epithelial Cell Ingrowth

78. Epithelial Ingrowth Surface epithelial cells in the flap interface.
More common with enhancements than with primary LASIK
With each additional surgery or flap lift, the risk increases.

79. Epithelial Ingrowth

80. Epi-ingrowth with MK
Epi cells in interface

81. Epithelial Ingrowth
Trauma induced by lifting the flap activates the epithelial cells
A disrupted edge may create a path for migration of epi cells
which then multiply and continue to grow into the flap interface.

82. Epithelial Ingrowth

83. Epithelial Ingrowth

84. More Epitheilial Ingrowth

85. Assessment of Epithelial Ingrowth
Assessment of the cells
Can have different appearances
Sheet-like, globular, cystic
Measure and document at each visit
Is it at the edge or a central island?
Is it progressive or stable?
Is it affecting vision?
Is it creating surrounding tissue scarring or edge melt?

86. More Epithial Cell Ingrowth

87. Management of Epithelial Ingrowth
If the cells are progressive, abundant, central or affecting vision
Send back to BHREI for lift and scrape a.s.a.p.
If minimal, at the edge and not affecting vision – MONITOR, but carefully
If it doesn’t appear aggressive, follow up in 3 weeks.
If appears aggressive, follow up in 1 week
Muro 128, 5% may help to seal the flap edge by compacting the corneal layers. QID.

88. Epithelial Ingrowth Less Common with IntraLase
Due to inverted bevel-in side cut

89. Irregular flap edge
Epithelial cells in flap edge can have a toxic by-product.
Ingrowth can cause scarring and even lead to corneal melt.
Pred Forte may be applied if the flap edge is becoming irregular. PF Q2h follow every 5-7 days to monitor for increasing melt.
Scar will not go away, even with treatment. Just try to control more damage.

90. Apical Scar from ectasia
Corneal ectasia
Similar to KCN
Very rare under today’s conservative standards for patient selection

91. Post Operative Reticular Haze
Late onset
6 wks to 6 mo post op
Can affect both PRK and LASIK patients
Can reduce visual acuity
If caught early-on, treat with Pred Forte q1-2h then qid. Takes weeks to months to clear. If longer term therapy (more than a month) switch to FML or Alrex.
Don’t forget to monitor IOP!!

92. Corneal Haze

93. Additional complications
Flap stria vs folds
Can be obvious or very fine (micro-striae)
If off visual axis, rarely effects vision
Central micro-striae can effects visual acuity, but often does not.

94. Flap Striae Vs Folds

95. Flap Stria Management If affecting vision
Send back to the surgeon for lift and smooth a.s.a.p.
Each additional lift increases risk of epi ingrowth
If off visual axis, not affecting vision, and the flap edge/gutter is not exposed, can often leave it alone.
Early post op
A Q-tip stretch technique can smooth out the small peripheral wrinkles without having to do a lift.

96. Slipped Flap Requires a surgical intervention (lift and stretch) ASAP
Wrinkles don’t always fully resolve
May have long term visual affects
May have normal visual outcome with proper treatment
Over time, vision can improve even with some residual stria post lift.

97. Slipped Flap

98. Button Hole Flap Complication
Manage it like PRK
Wait for corneal surface to heal and refraction to stabilize.
PRK once fully healed.
Usually patients do well, may have a central scar with decreased BCVA.

99. Less Common Concerns Corneal Infiltrates Infectious Ulcers
Treat with Pred Forte and Zymar or Combo drop (TobraDex)
monitor closely.
Infectious Ulcers
Treat aggressively (Fluoroquinolone or fortified antibiotics) and monitor daily.
May leave a scar

100. Less Common Post op Concerns
Surgical trauma
can stress the corneal nerves and lead to a re-activation of corneal HSV.
HSK. Usually is contraindication for LASIK surgery.
If you see this post LASIK, start antiviral therapy immediately

101. Other Final Considerations EBMD
EBMD- maps can look like striae.
Post op LASIK -If the epithelium is loose it can slough and create discomfort, slow the healing.
If they have dry eye, can cause painful recurrent corneal erosions.
Important to look closely pre-op to identify EBMD and consider PRK instead.

102. SUMMARY Very careful exam on the 1-day and 1-week post op.
If there is an opacity, consider the following:
What is it?
Where is it?
Surface vs interface (fluorescein stain or no stain)

103. SUMMARY Can it be left alone? Does it need immediate management?
Visually insignificant Microstriae
Tear film debris in interface
Does it need immediate management?
DLK
Slipped flap
Infectious keratitis
Aggressive epithelial ingrowth

104. When in doubt, send it out
SUMMARY
When in doubt, send it out
BHREI is more than happy to see a patient for an evaluation, please send them back to us if you have any concerns.

105. THANK YOU!!
Questions?

106. Stopped enrolling after 17 eyes due to 2 eyes with very severe haze and loss of 3 lines of BCVA