Terrence S. Spencer, M.D. Disclosures financial disclosure:financial disclosure: –No current financial interest or consulting fees related to any products discussed Purpose To educate optometristsTo educate optometrists –Familiarize with possible post-operative complications of LASIK and PRK –LASIK is a surgery, and all surgery has some risk
Tunnel on the Peter Norbeck Scenic Byway
Outline Briefly Review Corneal anatomyBriefly Review Corneal anatomy Refractive Surgery vs. Corneal refractive surgeryRefractive Surgery vs. Corneal refractive surgery History of Refractive SurgeryHistory of Refractive Surgery Basics of corneal refractive surgeryBasics of corneal refractive surgery –PRK and LASIK Flap creating technology - Intralase.Flap creating technology - Intralase. Complications and what to do.Complications and what to do.
Corneal Transparency:Corneal Transparency: –Based on highly organized system Stroma:Stroma: –Layers of fibroblasts between sheets of lamella. Ground substance:Ground substance: –Maintain proper position of the fibrils equidistant from each other Opacity (or scar):Opacity (or scar): –Forms when organization of structure is disrupted
What is Refractive Surgery Photo-Refractive KeratectomyPhoto-Refractive Keratectomy LASIKLASIK CK: conductive keratoplastyCK: conductive keratoplasty Phakic IOL’s – Visian Staar ICLPhakic IOL’s – Visian Staar ICL Refractive lens exchange or cataract surgeryRefractive lens exchange or cataract surgery –Presbyopia-correcting & Toric IOLs Corneal implantsCorneal implants Intracor procedureIntracor procedure
History of Refractive Surgery Ancient Chinese:Ancient Chinese: –Slept with sandbags on eyes to flatten the cornea ’s: ’s: –A variety of devices to modify the shape of cornea with pressure or suction 1898:1898: –keratotomy experiment in rabbits.
History of Refractive Surgery Svyatoslav Fyodorov (Moscow) 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
History of Refractive Surgery Conveyer operating theater in Soviet UnionConveyer operating theater in Soviet Union
History of Refractive Surgery Jose BarraquerJose Barraquer – –The father of modern refractive surgery Several inventionsSeveral inventions –Born in Spain, but moved to Bogotá, Columbia in 1965
Lathe (for background info only)
History of Refractive Surgery Keratomileusis (Jose Barraquer)Keratomileusis (Jose Barraquer) –1949: 1 st publication on changing shape of cornea to change refraction –Cryolathe Layer of cornea removedLayer of cornea removed Stained and FrozenStained and Frozen LathedLathed Sutured back in placeSutured back in place Sutures removed weeks laterSutures removed weeks later
History of Refractive Surgery Microkeratome: (Barraquer)Microkeratome: (Barraquer) –Allowed for in situ correction ALK: Automated Lameller Keratoplasty (Luis Ruis)ALK: Automated Lameller Keratoplasty (Luis Ruis) –Microkeratome 1 st makes an incomplete flap –Microkeratome readjusted for the power cut. –Never gained great popularity
History of Refractive Surgery Laser: Light Amplification by Stimulated Emission of Radiation –1–1–1–1917: theorized by Albert Einstein –1–1–1–1960: first successful laser
Laser: Wavelength of light is determined by the type of gas or solid mediumLaser: Wavelength of light is determined by the type of gas or solid medium –Example: YAG laser – crystal of Yttrium- Aluminum-Garnet = 1064 nm
History of Refractive Surgery Excimer (Excited Dimer of Argon and Flourine) Laser: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)
History of Refractive Surgery Photorefractive keratectomy (PRK)Photorefractive keratectomy (PRK) –1 st eye surgery done with excimer laser –1987 in Berlin: Dr. Theo Seiler
History of Refractive Surgery 1990: Laser In-Situ Keratomeleusis (LASIK)1990: Laser In-Situ Keratomeleusis (LASIK) –Epithelium intact = less pain from exposed nerves –Combines flap (ALK) with excimer laser (PRK)
PRK PhotoRefractive KeratectomyPhotoRefractive Keratectomy –First performed in 1987 –Removal of tissue with excimer laser Other names for PRKOther names for PRK –LASEK (laser epithelial keratomileusis) The epithelium layer is placed back on the stroma after corrective laser is completedThe 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 epitheliumA device called an epikeratome is used to remove the epithelium
Photorefractive Keratectomy (PRK) Step 1:Step 1: –Epithelium is removed diluted alcohol, brush, vibrating blade, laserdiluted alcohol, brush, vibrating blade, laser Discarded or replacedDiscarded or replaced Step 2:Step 2: –Excimer laser correction sculpting the corneasculpting the cornea Either flattening or a steepening pattern +/- astigmatism correctionEither flattening or a steepening pattern +/- astigmatism correction
PRK post-op expectations Soft bandage contact lensSoft 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 daysEpithelium closes in ~ 3-7 days Epithelial healing lineEpithelial 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.
PRK for Athletes
LASIK- laser assisted in-situ keratomileusis Laser-AssistedLaser-Assisted –The removal of tissue is done with excimer laser In-Situ (latin)In-Situ (latin) –In place in the body KeratomileusisKeratomileusis –Kerato (Greek): cornea –Mileusis: to shape
LASIK SURGERY BASICS TWO STEPS OF LASIKTWO STEPS OF LASIK 1: Corneal flap1: Corneal flap –Microkeratome or Femtosecond laser. –Layer includes epithelium, Bowman’s membrane, some anterior stroma. –The corneal flap is then folded back. 2: Excimer laser2: Excimer laser –Ablates the corneal stroma to correct the refractive error.
LASIK SURGERY BASICS After excimer laser treatmentAfter 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 bedFlap is positioned back into the original position in the corneal bed –Smooth out any micro-striae
LASIK Immediately after LASIK surgery: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.
Concerns with LASIK Microkeratome:Microkeratome: –Flap creation with a blade is responsible for the majority of the possible procedural complications
What is femtosecond laser? Femto- is a prefix in the metric systemFemto- is a prefix in the metric system –Denotes a factor of ( ) Femtosecond = 1 quadrillionth of a secondFemtosecond = 1 quadrillionth of a second –Category: ultrashort pulse (ultrafast) laser
Femtosecond laser Advantage of ultra-short pulse lasersAdvantage of ultra-short pulse lasers –Extremely precise Cuts material by ionizing it at the atomic levelCuts material by ionizing it at the atomic level –Pulses are too brief to transfer heat to the material being cut No damage to surrounding tissueNo damage to surrounding tissue –Femtosecond lasers are “cold” lasers
The IntraLase ® laser is a femtosecond laser How does a laser cut a flap?How does a laser cut a flap?
Femtosecond Laser Laser pulse is focused to desired corneal depthLaser pulse is focused to desired corneal depth Depth and hinge placement are adjustable based on individual patient factorsDepth 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 positioningFS laser produces precisely beveled edge architecture to enable secure flap positioning –Resists displacement –Less risk of epithelial ingrowth.
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 IntraLase Photodisruption
An expanding bubble of gas & water is created separating the corneal lamellae 2 Microns IntraLase Photodisruption
The bi-products of photodisruption (CO 2 & water) are absorbed by the mechanism of the endothelial pump, leaving a cleavage plane in the cornea IntraLase Photodisruption
IntraLase Photodisruption to create horizontal cleavage plane
IntraLase provides uniform flap thicknessIntraLase 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) The Planar Flap
Post-operative flap edge
One day post op
Intralase 1Day post op
Intralase Contraindicated in eyes with a corneal scar.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
Differential Diagnosis Cont. Other considerations:Other considerations: –Corneal scar – look back at pre-op exam findings –Corneal Edema –Arcus senilis –Loose epithelium
Most Common Post-op findings Dry eye/ SPK or PEKDry eye/ SPK or PEK Tear film debris interfaceTear film debris interface –oily or small spots Other Interface debrisOther Interface debris –sterile fiber, eyelash Post operative reticular haze in interfacePost operative reticular haze in interface Pre-existing Corneal scarPre-existing Corneal scar Corneal scarring at flap edgeCorneal scarring at flap edge
Less Common findings Diffuse Lamellar KeratitisDiffuse Lamellar Keratitis –“Sands of the Sahara” Epithelial ingrowthEpithelial ingrowth Infectious infiltrateInfectious infiltrate Sterile infiltrateSterile infiltrate Infectious Ulcer or infiltrateInfectious Ulcer or infiltrate Fungal infection (rare)Fungal infection (rare) Peripheral infiltrate, not in flap interface – can be due to corneal neovascularizationPeripheral infiltrate, not in flap interface – can be due to corneal neovascularization Herpetic lesionHerpetic lesion –Surgical stress may re-activate a dormant virus
WHERE is the Opacity? Biomicroscopy (Slit Lamp) AssessmentBiomicroscopy (Slit Lamp) Assessment –Depth? Look carefully with the optic section Surface – EpithelialSurface – Epithelial –It should stain Flap interfaceFlap interface –It won’t Stain StromalStromal –It won’t stain. Is it anterior, posterior? EndothelialEndothelial –Endothelial folds from a very edematous cornea. Unlikely with LASIK. More common with PRK
Dry Eye Syndrome The Most Common adverse side effect of LASIK / PRKThe Most Common adverse side effect of LASIK / PRK –Exam findings: SPK/PEK –Can dramatically effect visual acuity. If not quickly resolvedIf not quickly resolved –Can lead to poor healing and a “non-perfect” visual outcome. DES can lead to Myopic regressionDES can lead to Myopic regression –Which then requires an enhancement which could lead to more dry eye!
DRY EYE SYNDROME Surface epithelium will stainSurface epithelium will stain –Sodium Fluorescein dye –Rose Bengal, Lissamine green Symptoms:Symptoms: –Less pain than expected d/t nerve damage Affects visual acuity.Affects visual acuity. –Like looking through textured glass. Vision appears grainy, foggy.
Dry Eye Management Artificial tears q30min-1hrArtificial tears q30min-1hr –Preservative free –Consider Celluvisc or ointment at bedtime Punctal plugsPunctal plugs –Temporary collagen –Permanent - Silicone Restasis- one drop BIDRestasis- one drop BID
Dry Eye Management Doxycycline (oral)Doxycycline (oral) –Anti-inflammatory effect as well as improve proper meibomian gland function. Nutritional supplements – Fish Oil & Flax seed oil 2000mg daily.Nutritional supplements – Fish Oil & Flax seed oil 2000mg daily. Consider low-potency steroidConsider low-potency steroid –Loteprednol (Lotemax) –Fluorometholone (FML)
Severe Dry Eye Severe Dry eye patientsSevere Dry eye patients –If not improving with all of the typical dry eye management Consider BLOOD PLASMA TEARSConsider BLOOD PLASMA TEARS –Autologous –Contains nutrients, platelets, proteins, minerals, antibodies, imunoglobulins
Blood Plasma Tears
Under the surface If it doesn’t stain, consider that it may be something in the interface.If it doesn’t stain, consider that it may be something in the interface.
Interface Debris Location – in the flap interfaceLocation – in the flap interface It WILL NOT STAIN.It WILL NOT STAIN. –Tear film debris - in interface- looks oily or has small spots.
Interface Debris Powder-like debris from tissue ablationPowder-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.
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.
More Flap Interface Complications Diffuse Lamellar KeratitisDiffuse Lamellar Keratitis Epithelial ingrowthEpithelial ingrowth Post op corneal haze in interfacePost op corneal haze in interface Slipped flapSlipped flap Button hole flapButton hole flap Example: Interface haze d/t endothelial cell deficiency
Diffuse Lamellar Keratitis (DLK) AKA- Sands of the SaharaAKA- Sands of the Sahara White blood cells in the flap interface.White blood cells in the flap interface. EtiologyEtiology –Inflammatory response to surgical trauma, –Reaction to solutions Povidone-iodinePovidone-iodine Distilled water used on surgical instrumentsDistilled water used on surgical instruments Surgical marking penSurgical marking pen Microkeratome oilMicrokeratome oil Bacterial endotoxinsBacterial endotoxins carboxymethylcellulose drops,carboxymethylcellulose drops, Meibomian gland secretionsMeibomian gland secretions detergents, contaminated air particulatesdetergents, contaminated air particulates –Idiopathic (UNKNOWN cause)
Diffuse Lamellar Keratitis (DLK) Increased incidence withIncreased incidence with –Atopic, allergic patients –Blepharitis. Pre-treat bleph with oral Doxycycline, lid scrubs, topical medications before LASIK and PRK.Pre-treat bleph with oral Doxycycline, lid scrubs, topical medications before LASIK and PRK. Can occur with corneal trauma even many years post-LASIKCan occur with corneal trauma even many years post-LASIK Can occur when we do PRK over an old LASIK flap.Can occur when we do PRK over an old LASIK flap. DOES NOT OCCUR WITH PRK ALONE (no flap, no DLK)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 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!!Can look like SPK but DOES NOT STAIN!!
Diffuse Lamellar Keratitis (DLK)
Diffuse Lamellar Keratitis (DLK) and Intralase flap technology Incidence of significant DLKIncidence of significant DLK –0.1% of LASIK patients with the microkeratome –Slightly more risk with early model of Intralase
DLK Grade DLK Classification systemDLK 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.
DLK Grade DLK usually starts within 24 hours, and peaks at about post-op day 5DLK usually starts within 24 hours, and peaks at about post-op day 5
DLK Management Consult back with BHREIConsult 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)Pred Forte or difluprednate (Durezol) May need oral PrednisoneMay need oral Prednisone Flap lifted and irrigated.Flap lifted and irrigated.
DLK Management If severe photophobiaIf severe photophobia –Cycloplegia ALWAYS REMEMBER TO MONITOR IOP WHILE ON STEROIDS!!!ALWAYS REMEMBER TO MONITOR IOP WHILE ON STEROIDS!!!
Epithelial Cell Ingrowth
Epithelial Ingrowth Surface epithelial cells in the flap interface.Surface epithelial cells in the flap interface. More common with enhancements than with primary LASIKMore common with enhancements than with primary LASIK With each additional surgery or flap lift, the risk increases.With each additional surgery or flap lift, the risk increases.
Epi-ingrowth with MK Epi cells in interface
Epithelial Ingrowth Trauma induced by lifting the flap activates the epithelial cellsTrauma induced by lifting the flap activates the epithelial cells A disrupted edge may create a path for migration of epi cellsA disrupted edge may create a path for migration of epi cells –which then multiply and continue to grow into the flap interface.
More Epitheilial Ingrowth
Assessment of Epithelial Ingrowth Assessment of the cellsAssessment of the cells –Can have different appearances Sheet-like, globular, cysticSheet-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?
More Epithial Cell Ingrowth
Management of Epithelial Ingrowth If the cells are progressive, abundant, central or affecting visionIf 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 carefullyIf 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.
Epithelial Ingrowth Less Common with IntraLaseLess Common with IntraLase –Due to inverted bevel-in side cut
Irregular flap edge Epithelial cells in flap edge can have a toxic by-product.Epithelial cells in flap edge can have a toxic by-product. Ingrowth can cause scarring and even lead to corneal melt.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.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.Scar will not go away, even with treatment. Just try to control more damage.
Apical Scar from ectasia Corneal ectasiaCorneal ectasia –Similar to KCN –Very rare under today’s conservative standards for patient selection
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!!
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.
Flap Striae Vs Folds
Flap Stria Management If affecting visionIf 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.If off visual axis, not affecting vision, and the flap edge/gutter is not exposed, can often leave it alone. Early post opEarly post op –A Q-tip stretch technique can smooth out the small peripheral wrinkles without having to do a lift.
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.
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.
Less Common Concerns Corneal InfiltratesCorneal Infiltrates –Treat with Pred Forte and Zymar or Combo drop (TobraDex) –monitor closely. Infectious UlcersInfectious Ulcers –Treat aggressively (Fluoroquinolone or fortified antibiotics) and monitor daily. –May leave a scar
Less Common Post op Concerns Surgical traumaSurgical trauma –can stress the corneal nerves and lead to a re-activation of corneal HSV. HSK. Usually is contraindication for LASIK surgery.HSK. Usually is contraindication for LASIK surgery. If you see this post LASIK, start antiviral therapy immediatelyIf you see this post LASIK, start antiviral therapy immediately
Other Final Considerations EBMD EBMD- maps can look like striae.EBMD- maps can look like striae. Post op LASIK -If the epithelium is loose it can slough and create discomfort, slow the healing.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.If they have dry eye, can cause painful recurrent corneal erosions. Important to look closely pre-op to identify EBMD and consider PRK instead.Important to look closely pre-op to identify EBMD and consider PRK instead.
SUMMARY Very careful exam on the 1-day and 1-week post op.Very careful exam on the 1-day and 1-week post op. If there is an opacity, consider the following:If there is an opacity, consider the following: –What is it? –Where is it? Surface vs interface (fluorescein stain or no stain)Surface vs interface (fluorescein stain or no stain)
SUMMARY Can it be left alone?Can it be left alone? –Visually insignificant Microstriae –Tear film debris in interface Does it need immediate management?Does it need immediate management? –DLK –Slipped flap –Infectious keratitis –Aggressive epithelial ingrowth
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.BHREI is more than happy to see a patient for an evaluation, please send them back to us if you have any concerns.