2 Disclosures Purpose financial disclosure: To educate optometrists No current financial interest or consulting fees related to any products discussedPurposeTo educate optometristsFamiliarize with possible post-operative complications of LASIK and PRKLASIK is a surgery, and all surgery has some riskTerrence S. Spencer, M.D.
4 Outline Briefly Review Corneal anatomy Refractive Surgery vs. Corneal refractive surgeryHistory of Refractive SurgeryBasics of corneal refractive surgeryPRK and LASIKFlap creating technology - Intralase.Complications and what to do.
6 Corneal Anatomy Corneal Transparency: Stroma: Ground substance: Based on highly organized systemStroma:Layers of fibroblasts between sheets of lamella.Ground substance:Maintain proper position of the fibrils equidistant from each otherOpacity (or scar):Forms when organization of structure is disrupted
7 What is Refractive Surgery Photo-Refractive KeratectomyLASIKCK: conductive keratoplastyPhakic IOL’s – Visian Staar ICLRefractive lens exchange or cataract surgeryPresbyopia-correcting & Toric IOLsCorneal implantsIntracor 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 suction1898:keratotomy experiment in rabbits.
10 History of Refractive Surgery Svyatoslav Fyodorov (Moscow)Early1970s: boy on bicycle (-6 D)1974: started doing RK on humansRadial incisions “relax” tension on peripheral cornea to flatten the centerLate 1970s: US surgeons started performing RK
11 History of Refractive Surgery Conveyer operating theater in Soviet Union
12 History of Refractive Surgery Jose BarraquerThe father of modern refractive surgerySeveral inventionsBorn in Spain, but moved to Bogotá, Columbia in 1965
14 History of Refractive Surgery Keratomileusis (Jose Barraquer)1949: 1st publication on changing shape of cornea to change refractionCryolatheLayer of cornea removedStained and FrozenLathedSutured back in placeSutures removed weeks later
15 History of Refractive Surgery Microkeratome: (Barraquer)Allowed for in situ correctionALK: Automated Lameller Keratoplasty (Luis Ruis)Microkeratome 1st makes an incomplete flapMicrokeratome readjusted for the power cut.Never gained great popularity
16 History of Refractive Surgery Laser: Light Amplification by Stimulated Emission of Radiation1917: theorized by Albert Einstein1960: first successful laser
17 History of Refractive Surgery Laser: Wavelength of light is determined by the type of gas or solid mediumExample: 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 invented1970’s: Etching silicone computer chips1982: Rangaswamy Srinivasin (IBM): excimer laser can ablate tissue without causing heat damage1983: Steven Trokel (NYC) patented excimer laser use for vision correction193 nm (ultraviolet)
19 History of Refractive Surgery Photorefractive keratectomy (PRK)1st eye surgery done with excimer laser1987 in Berlin: Dr. Theo Seiler
23 PRK PhotoRefractive Keratectomy Other names for PRK First performed in 1987Removal of tissue with excimer laserOther names for PRKLASEK (laser epithelial keratomileusis)The epithelium layer is placed back on the stroma after corrective laser is completedEpi-LASIKA device called an epikeratome is used to remove the epithelium
25 Photorefractive Keratectomy (PRK) Step 1:Epithelium is removeddiluted alcohol, brush, vibrating blade, laserDiscarded or replacedStep 2:Excimer laser correctionsculpting the corneaEither flattening or a steepening pattern +/- astigmatism correction
26 PRK post-op expectations Soft bandage contact lensPlaced immediately following treatmentHelps with patient comfortActs as a protective barrier for the healing processEpithelium closes in ~ 3-7 daysEpithelial healing lineVisible where leading edges of epithelium meet in center of corneaCan induce temporary astigmatism. It can takes weeks to months to stabilize.
28 LASIK- laser assisted in-situ keratomileusis The removal of tissue is done with excimer laserIn-Situ (latin)In place in the bodyKeratomileusisKerato (Greek): corneaMileusis: 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 laserAblates the corneal stroma to correct the refractive error.
30 LASIK SURGERY BASICS After excimer laser treatment Cornea irrigated with sterile salineExamine for any debrisIrrigate until the interface is clear of any debris.Flap is positioned back into the original position in the corneal bedSmooth 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 systemDenotes a factor of ( )Femtosecond = 1 quadrillionth of a secondCategory: ultrashort pulse (ultrafast) laser
35 Femtosecond laser Advantage of ultra-short pulse lasers Extremely preciseCuts material by ionizing it at the atomic levelPulses are too brief to transfer heat to the material being cutNo damage to surrounding tissueFemtosecond 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 factorsCorneal thickness, steepness, and/or diameterFS laser produces precisely beveled edge architecture to enable secure flap positioningResists displacementLess risk of epithelial ingrowth.
38 A pulse of laser energy is focused to a precise spot inside the cornea IntraLase PhotodisruptionA pulse of laser energy is focused toa precise spot inside the corneaA microplasma is created, vaporizingapproximately 1 micron of corneal tissue1 Micron
39 IntraLase Photodisruption 2 MicronsAn 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 keratometryReduction of induced irregular astigmatismOptimizes stromal bed for wavefront guided vision correctionIncreased flap stability (less slipped flaps)
50 Differential Diagnosis Cont. 5)Corneal infiltrate6)Corneal ulcer7)Herpetic lesion8)Epithelial Basement Membrane Dystrophy (EBMD)9)Micro striae vs. Slippped flap or folds10)Prominent corneal nerves
51 Differential Diagnosis Cont. Other considerations:Corneal scar – look back at pre-op exam findingsCorneal EdemaArcus senilisLoose epithelium
52 Most Common Post-op findings Dry eye/ SPK or PEKTear film debris interfaceoily or small spotsOther Interface debrissterile fiber, eyelashPost operative reticular haze in interfacePre-existing Corneal scarCorneal scarring at flap edge
53 Less Common findings Diffuse Lamellar Keratitis Epithelial ingrowth “Sands of the Sahara”Epithelial ingrowthInfectious infiltrateSterile infiltrateInfectious Ulcer or infiltrateFungal infection (rare)Peripheral infiltrate, not in flap interface – can be due to corneal neovascularizationHerpetic lesionSurgical stress may re-activate a dormant virus
55 WHERE is the Opacity? Biomicroscopy (Slit Lamp) Assessment Depth? Look carefully with the optic sectionSurface – EpithelialIt should stainFlap interfaceIt won’t StainStromalIt won’t stain. Is it anterior, posterior?EndothelialEndothelial 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 / PRKExam findings: SPK/PEKCan dramatically effect visual acuity.If not quickly resolvedCan lead to poor healing and a “non-perfect” visual outcome.DES can lead to Myopic regressionWhich then requires an enhancement which could lead to more dry eye!
58 Dry Eye Management Artificial tears q30min-1hr Punctal plugs Preservative freeConsider Celluvisc or ointment at bedtimePunctal plugsTemporary collagenPermanent - SiliconeRestasis- 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 steroidLoteprednol (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 managementConsider BLOOD PLASMA TEARSAutologousContains nutrients, platelets, proteins, minerals, antibodies, imunoglobulins
62 Under the surfaceIf 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 KeratitisEpithelial ingrowthPost op corneal haze in interfaceSlipped flapButton hole flapExample: Interface haze d/t endothelial cell deficiency
67 Diffuse Lamellar Keratitis (DLK) AKA- Sands of the SaharaWhite blood cells in the flap interface.EtiologyInflammatory response to surgical trauma,Reaction to solutionsPovidone-iodineDistilled water used on surgical instrumentsSurgical marking penMicrokeratome oilBacterial endotoxinscarboxymethylcellulose drops,Meibomian gland secretionsdetergents, contaminated air particulatesIdiopathic (UNKNOWN cause)
68 Diffuse Lamellar Keratitis (DLK) Increased incidence withAtopic, allergic patientsBlepharitis.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 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!!
73 DLK Grade DLK Classification system Stage 1- Faint sterile infiltration of infammatory cells at the flap edge within the interfaceStage 2- More central diffuse patternStage 3- inflammatory cells within the visual axis lead to reduced visual acuityStage 4-(rare) Collagenase release and stromal melting and subsequent loss of BSCVA.
74 DLK GradeDLK 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 daysGrade 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 PrednisoneFlap lifted and irrigated.
76 DLK Management If severe photophobia CycloplegiaALWAYS REMEMBER TO MONITOR IOP WHILE ON STEROIDS!!!
81 Epithelial IngrowthTrauma induced by lifting the flap activates the epithelial cellsA disrupted edge may create a path for migration of epi cellswhich then multiply and continue to grow into the flap interface.
85 Assessment of Epithelial Ingrowth Assessment of the cellsCan have different appearancesSheet-like, globular, cysticMeasure and document at each visitIs 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?
87 Management of Epithelial Ingrowth If the cells are progressive, abundant, central or affecting visionSend back to BHREI for lift and scrape a.s.a.p.If minimal, at the edge and not affecting vision – MONITOR, but carefullyIf it doesn’t appear aggressive, follow up in 3 weeks.If appears aggressive, follow up in 1 weekMuro 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 edgeEpithelial 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 ectasiaSimilar to KCNVery rare under today’s conservative standards for patient selection
91 Post Operative Reticular Haze Late onset6 wks to 6 mo post opCan affect both PRK and LASIK patientsCan reduce visual acuityIf 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!!
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 ingrowthIf off visual axis, not affecting vision, and the flap edge/gutter is not exposed, can often leave it alone.Early post opA 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 resolveMay have long term visual affectsMay have normal visual outcome with proper treatmentOver time, vision can improve even with some residual stria post lift.
98 Button Hole Flap Complication Manage it like PRKWait 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 UlcersTreat aggressively (Fluoroquinolone or fortified antibiotics) and monitor daily.May leave a scar
100 Less Common Post op Concerns Surgical traumacan 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 MicrostriaeTear film debris in interfaceDoes it need immediate management?DLKSlipped flapInfectious keratitisAggressive epithelial ingrowth
104 When in doubt, send it out SUMMARYWhen in doubt, send it outBHREI is more than happy to see a patient for an evaluation, please send them back to us if you have any concerns.