Refrakční chirurgiePRK, LASIK, LASEK, femto LASIK, SMILE (small incision lenticulextraction), LRI, phakic IOL, keraring,FerraraprstenecAgarwal and Jacob, Color Atlas of Ophthalmology: The Quick-Reference Manual for Diagnosis and Treatment:Q&A Companion, 2nd Ed. (ISBN 978-1-60406-211-3), copyright 2010 Thieme Medical Publishers.All rights reserved. Usage subject to terms and conditions of license.
LASEK Eye Surgery:How It WorksReviewed by Brian S. Boxer Wachler, MDLike This Page? Please Share!On This Page: LASEK vs. LASIK LASEK vs. PRK What toexpect during and after LASEK surgery Risks andcomplicationsLASEK eye surgery is a variation of PRK to correct myopia(nearsightedness), hyperopia (farsightedness) and astigmatism.LASEK combines certain methods from both LASIK and PRK.LASIK remains the most popular laser eye surgery, but forpeople who are not suitable LASIK candidates, PRK or LASEKmay be better options and produce comparable outcomes toLASIK.Like other types of laser refractive surgery, LASEK works byreshaping the cornea using an excimer laser, allowing lightentering the eye to be properly focused onto the retina forclearer vision without eyeglasses or contact lenses.
The fundamental difference in how LASIK, PRK and LASEK areperformed concerns how the eye is prepared for the lasertreatment:LASEK EYE SURGERYDuring LASIK, a thin circular "flap" is created on the eye'ssurface using a microkeratome or a femtosecond lasersurgical tool. The surgeon then folds back the hinged flap toaccess the stroma and reshape the corneal tissue using anexcimer laser.
The flap is then returned to its original position and servesas a natural bandage, keeping the eye comfortable as itheals. The flap adheres securely without stitches, andhealing occurs relatively quickly.During PRK, instead of creating a corneal flap as in LASIK,the surgeon completely removes the extremely thin outerlayer of the cornea (epithelium, which is like a clear "skinlayer" covering the cornea), using an alcohol solution, a"buffing" device or a blunt surgical instrument. Theunderlying corneal stroma is then reshaped with an excimerlaser. A new epithelial layer grows back within five days.The LASEK procedure involves a little of both LASIK andPRK. Like in PRK, the corneal epithelium is separated fromthe underlying stromal layer. But instead of completelyremoving and discarding this tissue, as in PRK, the LASEKsurgeon pushes an ultra-thin "flap" of epithelium off to oneside of the cornea, where it remains attached to the eye (likethe thicker flap of corneal tissue created during LASIKsurgery).After the laser treatment is finished, the epithelial tissue isrepositioned on the surface of the eye to cover the laseredstroma, and a bandage contact lens is placed on the eye tokeep the epithelium in place as it heals.
BEST CANDIDATESmyopia, hyperopia and/or astigmatism, ineligible for LASIKProcedure time: about 10 minutes per eyeTypical results: 20/20 vision without glasses or contactlensesRecovery time: several days to several weeks for visionto stabilizeCost: about 1,500 to 2,500 per eyeAnother laser eye surgery, called epi-LASIK or e-LASIK, is verysimilar to LASEK. But instead of using alcohol to loosen theepithelium like in LASEK, in epi-LASEK the surgeon typicallyuses a blunt, plastic blade to separate the epithelial sheet fromthe eye. This avoids the possibility of a reaction from the alcohol,which can kill epithelial cells.LASIK, PRK and LASEK all have high success rates and similarvision outcomes. One is not necessarily better than the other inthe long term, but vision tends to be more hazy in the first weekwith LASEK than with LASIK and PRK.
After a thorough eye exam, your eye surgeon will advise you onthe best type of laser eye surgery for your individual needs andrequirements.LASEK vs. LASIKThe hinged flap made in LASEK surgery is created in theepithelial layer of the eye and is much thinner than the cornealflap created in LASIK (which contains both epithelial and deeperstromal tissues).This is of particular importance if you have a naturally thincornea that makes you a less-than-ideal LASIK candidate.In LASEK, an ultra-thin flap is created onthe eye's surface, unlike the thicker flap inLASIK.The LASEK technique avoids any corneal flap-related LASIKcomplications and lessens the likelihood of removing too muchcornea with the excimer laser and compromising the structuralintegrity of the eye. By avoiding a deeper flap, there also isslightly less risk of developing dry eyes after LASEK eye surgery.
LASEK also may be a better option if you have a high degree ofmyopia (which requires more tissue removal from the centralcornea to correct the refractive error), or if your occupation orhobbies puts you at high risk of an eye injury and dislodging thecorneal flap created in LASIK surgery.It's important to note, however, that LASEK typically involvesmore discomfort and a longer recovery time compared withLASIK surgery.LASEK vs. PRKLASEK is very similar to PRK. Both involve lifting the extremelythin epithelium to access the deeper corneal tissues, instead ofcreating a thicker corneal flap as in LASIK surgery.The key difference between LASEK and PRK is that LASEKpreserves and then replaces the epithelial layer whereas in PRKthe epithelium is completely removed and discarded and a newepithelial layer grows back over the next few days followingsurgery.Initially, many surgeons thought that by preserving theepithelium LASEK would have a faster recovery time than PRK.In practice, however, many surgeons have found that the
replaced epithelial layer in LASEK often takes longer to healcompared with the growth of a new epithelial layer after PRK.As such, PRK remains the most popular of the "surface ablation"techniques (PRK, LASEK and epi-LASIK).LASEK Eye Surgery: What To ExpectBefore. Your eye surgeon will perform a thorough eye exam andgeneral health check to see if you are a suitable candidate forLASEK eye surgery. Many eye surgeons will recommend LASEKonly if you are not suited to LASIK eye surgery.If you wear contact lenses, your doctor typically will instruct youto stop wearing them for a period of time before takingmeasurements for laser eye surgery as contacts can change thenatural shape of your cornea.As you won't be able to drive yourself home from the surgery,you'll need to arrange someone to drive you. You'll also need toorganize time off work — around a week in typical cases — asyour eyes heal and your vision begins to improve.During. Numbing anesthetic drops are first applied to your eye.Then your surgeon makes a circular cut in the corneal
epithelium using a fine blade (trephine). The trephine leaves asmall arc-shaped area of the circle uncut, so the epithelial "flap"that's created remains attached to the eye. A diluted alcoholsolution is placed over the eye for approximately 30 seconds,which loosens the edges of the epithelium and enables thesurgeon to gently push the loosened flap of epithelium to theside.The excimer laser is then positioned over the eye to reshape thecorneal stroma and correct your vision. After the laser treatmentis completed, the epithelial flap is repositioned on the eye.A special contact lens that acts as a protective bandage is thenplaced over your eye.LASEK eye surgery is performed on a walk-in, walk-out basis,and should take about 15 minutes per eye. You are awake for theprocedure and shouldn't feel any pain, but your surgeon maygive you a mild sedative to help you relax.Vision recovery after LASEK may beslower than for other procedures, but thereis less risk of complications such as dryeye.
After. You can return home after a brief period of rest followingLASEK surgery. Most people report mild to moderate discomfortin the first few days after LASEK.You will need to keep the "bandage" contact lens on your eye forapproximately four days while the surface epithelial cells healand regenerate. Your doctor also will prescribe topical steroidsand antibiotics for at least three weeks to aid healing andminimize the risk of infection.Generally, visual recovery after LASEK (and epi-LASIK) issignificantly slower than after LASIK and often slower than therecovery after PRK. Initial visual recovery can take up to a weekwith LASEK (as opposed to 24 hours in typical LASIK cases) andfinal outcomes can be seen anywhere from a few weeks toseveral months.LASEK and PRK outcomes are similar to LASIK results. Mostpeople achieve 20/20 vision after laser eye surgery, and nearlyall achieve 20/40 visual acuity or better. Depending on yourdegree of refractive error, you may still need to wear eyeglassesor contact lenses, but the prescription will be significantly lower.Like LASIK and PRK, LASEK eye surgery is not necessarily asolution for presbyopia, a naturally occurring age-related loss of
near vision. Your doctor will be able to advise whether you're asuitable candidate for presbyopia surgery instead.LASEK Risks and ComplicationsLASEK and PRK complications are similar to LASIKcomplications. Side effects can include vision disturbances suchas:Your EyePinionOf these professions, which one requires the bestvision?ChefRefereeBaseball playerSurgeonCabdriverAirline pilotVoteView ResultsBlurry vision, halos and glareSignificant overcorrection, undercorrection or regressionwhich may require further surgery or reliance on eyeglassesor contact lenses for some or all activitiesDry eyesEye infection and irritation
While LASEK avoids the corneal flap-related risks of LASIK, thereare some complications exclusive to LASEK surgery.In some cases, the thin epithelial flap created during LASEK isnot strong enough to be replaced over the treated area and willbe removed completely as it would have been in PRK. Typically,this does not pose a risk, but if you have a very high prescriptionfor myopia you may have a greater likelihood of experiencinghazy vision.The alcohol solution used during LASEK causes tissue damage toepithelial cells that slows the healing process immediately aftersurgery. Recovery after epi-LASIK typically is faster because noalcohol is used to create the epithelial sheet.LASEK eye surgery offers a safe and effective alternative toLASIK but typically is performed only if you are not a goodcandidate for LASIK eye surgery, owing to the faster visualrecovery and minimal discomfort associated with LASIK.An experienced eye doctor will be able to advise you whenLASEK is the best vision correction surgery for your individualneeds. AAVWhat is Femto-Lasik?
Femto-Lasik or Z-Lasik is the most efficienttechnology currently available within thefield of laser eye surgery. Lasik stands for‘laser-assisted in situ keratomileusis’ – themethod involved in this type of procedure.Femto represents the technology, in thiscase the most recent type of laser: theFemtosecond.The Femtosecond laser method involvesthe cutting of a microscopically thin flap onthe surface of the cornea, after which theExcimer laser is used to correct anyexisting refractive errors. With Femto-Lasik,we can easily and successfully treat eyedioptre prescriptions between -12 and 6.Say a rapid farewell to your glasses, makea no-strings attached appointment today. ahref "http://www.vimeo.com/36132179" http://www.vimeo.com/36132179 /a
The Focus Eye Clinic uses the WavelightEX500 Excimer laser and the Ziemer Z8Femto laser. Both of these devices areconsidered state-of-the-art.The combination of both of these devicesguarantees predictable and reliable resultsand extreme precision using a quick,painless and safe technique.Advantages of Femto-Lasik1. Optimal safety :Highly reduced risk of complicationswhen cutting the corneal flap.Reduced risk of infection andinflammationLarger treatable surface for increasedstabilityReduction in retreatment rates2. Thinner flap:The Femto-Lasik allows for such a thin,uniformly cut corneal flap that
complications are practically nonexistent. With these thinner flaps, morecorneal tissue is left behind, meaningnot only an increase in long-termcorneal stability, but also theopportunity to correct higher refractiveerrors.3. Even flap thickness:When using the Femto-Lasik, thesurgeon knows beforehand whichform, thickness, measurements andcapacity each flap entails. This is animportant issue when consideringtreatment for higher refractive errors.When using a scalpel, a surgeon canonly know how the flap will look afterthe cut has been made.4. Other benefits:Eyeball measurements are of littleimportance for Femto-Lasik laser eyesurgery.You will heal in a shorter span of time
and your sight will improve much morequickly.Visual results are excellent.During the procedure, the Femto-Lasiklaser exercises less pressure on theeye. This means the patient willexperience very little discomfort.Will Femto-Lasik work for me?Nearly everyone with nearsightedness(myopia), farsightedness (hypermetropia)or astigmatism can be treated using theFemto-Lasik method.You are between 18 and 60 years oldYou are in good healthRefractive errors between -12 and 6Refractive errors have not undergone anychanges during the past year
People who suffer from very dry eyes orhave thin corneas are often not consideredfor Femto-Lasik surgery. They would bebetter served using the alternative butexcellent PRK method.For age related vision problems, otherwiseknown as presbyopia, Femto-Lasik is notthe ideal solution. We would recommendmultifocal lens implants.Treatment should be postponed duringpregnancy or when breast feeding. We willnot carry out Femto-Lasik procedures onpatients with the following pathologies: viraleye infections, herpes, diabetes mellitus,keratoconus and any pathologies requiringcortisone therapy.Still not sure? Come and have a chat. Makeyour obligation-free appointment today.Femto-Lasik pricing
Focus Eye Clinic puts transparent pricinginto practice. You pay the advertised pricefor Femto-Lasik treatment using the latesttechnology.Treatment for one eye costs 1,750. Botheyes will cost 3,250. A no-strings pretreatment consultation with one of oursurgeons is completely free.Femto-Lasik: practicalinformationThe entire Femto-Lasik procedure ascarried out at the Focus Eye Clinic – fromarrival to discharge – takes approximately 2hours.Before the procedureOn the day of your Femto-Lasik procedurewe will repeat all preoperative
measurements. You will then be given alight sedative. Your eyes will beanesthetised with a local anaesthetic.There is therefore no need for a fullanaesthetic.During the procedureNursing staff will help you onto theoperating table situated within the FemtoLasik treatment room.They will thoroughly disinfect youranesthetised eyes and cover them with asterile dressing. Your eyelashes will bemoved aside and your eyes once againanesthetised using a local anaesthetic. Aneyelid holder will be put into place, makingit impossible for you to blink or close youreyes.Cutting the corneal flap takes just 26seconds using a device placed directly ontothe eye. It is via this device that the Femto
Laser forms the flap. Don’t worry: nothingyou do can change the position of or adjustthis device.After the flap has been formed the surgeonuses the Wavelight-Excimer laser to treatthe refractive error. For this, you will needto look into a fixation light for 1 second;after you have done this the laser willautomatically follow the movements of youreye.Finally, the flap is put back, thoroughlyrinsed and pressed into place.After the procedureYou will be taken to a rest and relaxationarea where you will stay for approximately30 minutes. On the day of the procedureitself you should not drive. Please bringsomeone with you! We do not recommendyour using public transport systems.Postoperative medication consists of eye
drops. You will also receive protectiveglasses which you are required to wear forthe following 24 hours.AftercareYou will come for a control visit one day,one week and two to three months after theprocedure. These visits are included in thelisted price.What risks?Femto-Lasik laser eye surgery is safer thandaily contact lens use. Currently, the mostapplicable risk is that of Femto-Lasikretreatment. However, the chance of thisoccurring is less than 0.5%.As in all types of surgery there is a limitedrisk of infection and inflammation. You willreceive eye drops and protective glasses toreduce such risk.
Older techniques could sometimes lead topermanent dry eyes. The state-of-the-artFemto-Lasik method, together withsufficient preoperative care, has drasticallyreduced this risk. Any temporary decreasein tear production can be treated withlubricating eye drops and tear duct(lacrimal) plugs.There is no risk of decreased night vision.In fact, the opposite is true; laser treatmentincreases contrast in low light conditions.FAQWhat is an Excimer laser?With the Excimer laser, thin layers of thecornea are evaporated by way of photoablation.This makes it possible to:
change the corneal profileflatten the cornea in cases ofnearsightednessmake the cornea more rounded in cases offarsightednesseven out the cornea in cases ofastigmatismThe newest computer technology cancalculate the correct corneal profileautomatically, as well as the correct dosesof photo ablation. The Wavelight EX500Excimer laser uses “Perfect PulseTechnology” to guarantee both safety andprecision. The 6-sigma tracking systemfollows all eye movement during theprocedure.Reliability and predictability are guaranteedby way of high resolution calibration foreach procedure. Aspheric laser ablationmeans improved night vision.
How does the Femto-Lasik laserwork?The Ziemer Z8 Femto laser works using theprinciple of photo disruption: using infraredlaser energy, the surgeon creates a patternof tiny, overlapping spaces immediatelyunder the surface of the cornea. The laseroperates at extremely high speeds:impulses of 1 quadrillionth of a second, or 1femtosecond.These highly accurate laser impulses splitthe corneal tissue at a molecular levelwithout creating heat or touching thesurrounding tissue. As the laser moves upand down across the eye a completecorneal flap is formed. After the flap hasbeen created the surgeon lifts it with aspecially designed instrument. The Excimerlaser is then used to shave away thin slicesof the cornea and in doing so correctrefractive errors. Finally, the surgeon setsthe flap back into place.
What are the Femto-Lasik-options:A-Cat, T-Cat and Lasik-Extra?A-Cat: Femto-Lasik with aberrometryWe now possess sophisticated diagnosticdevices which can register extremely subtlerefractive errors. These aberrations are sotiny that glasses or contact lenses cannothelp. Treatment of specific aberrations (theA-Cat option) can offer more night visioncontrast to those people with widenedpupils. The surgeon will discuss this optionwith you should he consider it applicable.T-Cat: Femto-Lasik with topographyA cornea is usually regular in form(spherical and toric). For some patients,such as those with keratoconus,asymmetrical or irregular astigmatism canonly be seen when using topographicalimaging. If the surgeon thinks you are a
candidate for topography, he will tell youabout the T-Cat option.Lasik-Extra: AvedroWhen using Femto-Lasik therapy forhypermetropia and presbyopia, vision canstart to decline within a few years. Untilrecently, this meant retreatment.Thanks to the Avedro UV Crosslinkingtechnique, retreatment is no longernecessary. With this technique, we treat theeye after the Lasik procedure with UV lightto encourage the attachment of collagenfibres onto the cornea. This means that thenew corneal form will be stable.
Refrakční chirurgie Photorefractive KeratectomyPhotorefractive keratectomy (PRK) is one of the refractive procedures using excimer laser toablate the cornea. It corrects myopia, hypermetropia, presbyopia, and astigmatism. In myopia,the central corneal stroma is ablated to flatten it; in hypermetropia and presbyopia the corneais made steeper by ablating the desired zone. TechniqueUnder topical anesthesia the epithelium is debrided. The patient fixates at the target in themicroscope. The desired amount of corneal tissue is ablated using the nomogram made withthe patient’s data. The eye is taped following the procedure or a contact lens is placed.Postoperative medications include antiinflammatory and lubricating drops. Selected Complications of Photorefractive KeratectomyDecentered AblationD ecentration of the ablation zone by 1 mm or more occurs due to improper patient fixation,centration, or eye movement during the procedure. PresentationPatients present with decreased visual acuity, diplopia, glare, halos, induced astigmatism . ManagementSome decentrations will lessen with time and remolding. Those that do not improve requirecorneal topographic studies. Visual symptom improvement may be attempted with weakmiotics, contact lens, or re-treatment.Central IslandsA portion of the central corneal tissue is raised, leading to area of higher central cornealrefractive power surrounded by an adjacent area of paracentral stroma. It has an elevation ofat least 1 diopter with a diameter of more than 1 mm as compared with the paracentral flatarea. It is seen less often now with the increasing use of flying spot laser systems. PresentationPatients present with visual distortion, double vision, decreased vision.518
ManagementManagement consists of waiting and watching and corneal topographic study. Retreatmentwith the excimer laser may be helpful in selected cases.Disabling Glare or Halos PresentationS ome patients complain of glare and halos around light, especially in scotopic conditions.These symptoms are more pronounced with smaller ablation zones. They may also be seenwith decentered ablations, epithelial ingrowths, and corneal haze. ManagementM anagement consists of constricting the pupil using miotics, topical brimonidine, andsecondary ablation with increasing diameter.Delayed Epithelial Healing PresentationN onhealing epithelium even after 3 to 4 days postoperatively is commonly due to a large areaof debridement, severe dry eye and prophylactic antibiotic and antiinflammatory eye drops,diabetes mellitus, and other autoimmune disorders. Patients present with watering,discomfort, redness, pain, and photophobia. ManagementManagement consists of contact lens wear until reepithelialization, liberal use of lubricatingdrops, and treatment of the underlying cause. Excess nonsteroidal antiinflammatory drugs andcorticosteroids should not be used. The patient may be followed up daily until healing.Infectious KeratitisInfectious keratitis is unusual, with bacterial causes most common. The inflammation typicallycauses redness of the eye with a focal infiltrate. Management includes culturing and antibioticuse directed towards the suspected organism until culture results are known.Haze and Regression PresentationThe healing process of activated keratocytes laying down new collagen fibers leads to cornealhaze. The higher the correction the greater the risk of haze developing. Maximum haze isnoticed between 1 and 3 months postoperatively and decreases with time. Corneal steepeningleads to regression due to the changes in refractive power of the cornea.
ManagementT opical steroids reduce the incidence of haze and regression. Patients having decreased visualacuity may benefit from re-treatment. Laser In Situ KeratomileusisL aser in situ keratomileusis (LASIK) is keratorefractive surgery for the treatment of highmyopia, hyperopia, and astigmatism. TechniqueA corneal flap is created by corneal lamellar incision using a microkeratome or thefemtosecond laser. The flap is then reflected and the corneal stroma is reshaped using theexcimer laser. The flap is repositioned and realigned correctly after the procedure and allowedto adhere back on its own. It is used in the healing process. Visual recovery is quicker, with lessscarring and regression compared with PRK because the epithelial surface is not debrided andthe Bowman layer is not ablated. Selected Complications of Laser In Situ KeratomileusisDebris after LASIK PresentationI nterface debris is common and often results from meibomian gland secretions or makeup ormascara. These are typically not visually significant unless they occupy a large area and createan interface scar.To prevent debris, it is important to operate in a lint-free environment, use nonfragmentingsponges, and have patients clean their lids well before surgery to remove all makeup andmascara (Fig. 19.1). ManagementNo intervention is needed unless enough debris is present that it is at risk of forming aninterface scar or the debris degrades the vision.Flap Striae PresentationThe patient with flap striae may have monocular diplopia due to irregular astigmatism in thepresence of microstriae. It may be a result of mild or significant LASIK flap displacement (Fig.19.2).
ABFig. 19.1 (A) Mascara in theinterface after LASIK. (B) Moderatemascara in the interface. This istypically not visually significant. (C)Metal flecks in the interface, which istypically not reactive or visuallyCsignificant.
ABFig. 19.2 (A) Striae across the visual axis from a displaced flap. (B) Peripheral striae thatare not always visually significant, yet can occasionally cause induced asymmetricastigmatism. (Continued on page 524)CDFig. 19.2 (Continued) (C) Significant striae in the visual axis. (D) Severe striae frombunching of the flap. PreventionA lignment of the created trough by even placement of the corneal cap over the stromaevenly in all directions can help reduce the incidence of striae. Some surgeons advocatemaking a mark on the epithelium prior to creation of the flap to help with postoperativealignment, yet care must be taken that the epithelium does not shift in relationship tothe stroma when using these marks to realign the flap.
ManagementMicrostriae may be observed if not visually significant. If they are visually significant,the surgeon may need to lift the flap, clean the interface from any cells or debris, andstretch the cap by stroking it with Merocel wipes (Medtronic, Minneapolis, MNwww.medtronicophthalmics.com/Ophthalmics Catalog 2007 2008 LR.pdf) until thegutter is well aligned.Diffuse Lamellar KeratitisDiffuse lamellar keratitis (DLK) is a sterile inflammation of the flap interface occurring inthe first week after LASIK. The condition has also been known as “shifting sands”phenomenon or “sands of the Sahara.” PresentationSevere DLK may occur in 1 out of 5000 cases, and mild DLK in 1 in 50 cases in mostcenters. Stage 1 : Defined by the presence of white granular cells in the periphery of the lamellarflap, outside the visual axis (Fig. 19.3 ). Stage 2: Defined by migration of cells in the center of the flap, involving the visualaxis, in the flap periphery, or in both. It is more frequently seen on day 2 or 3. Theresult of central migration of cells in stage 1 gives the so-called shifting sandsappearance. This occurs in 1 in 200 cases (Fig. 19.4). Stage 3: The aggregation of more dense, white, and clumped cells in the central visualaxis, with relative clearing in the periphery. This is often, but not always, associatedwith a subtle decline in visual acuity by 1 or 2 lines and a subjective description of hazeby the patient. The frequency of stage 3 may be as high as 1 in 500 cases (Fig. 19.5).ABFig. 19.3 (A) Stage 1 diffuse lamellar keratitis (DLK) with mild cell in the peripheral flap.(B) Stage 1 DLK with mild cell in the peripheral flap—high magnification.
AFig. 19.4 (A) Stage 2 diffuse lamellar keratitis (DLK) with cells in the periphery andcentral portion of the flap. No significant clumping of the cells is seen in stage 2. (B)Stage 2 DLK—high magnification.Fig. 19.5 Stage 3 diffuse lamellarkeratitis with cells that are nowaggregating, typically slightly below thecenter of the visual axis.B
ABCFig. 19.6 (A) Stage 4 diffuse lamellar keratitis (DLK) with stromal melting. (B) Stage 4DLK. (C) Stage 4 DLK with irregular astigmatism with flattening due to tissue loss wherethe cells had aggregated, typically slightly below the visual axis. Stage 4 : The presence of stromal melting, often associated with permanent scarringand visual morbidity. There is fluid collection in the central lamellae with bullae
formation and stromal volume loss. A hyperopic shift occurs due to central tissueloss, along with the appearance of corrugated “mud cracks,” which are a seriousfinding. The incidence is 1 in 5000 cases (Fig. 19.6).Fig. 19.7 Lifting and gentle irrigation of the flap is idealmanagement for stage 3 diffuse lamellar keratitis (DLK), typically atday 3 or day 4 after the surgery. Management Stages 1 and 2: Topical prednisolone acetate 1% every hour and steroid ointment(fluoromethalone) at bedtime. Follow up in 24 to 48 hours. Stage 3 : Lifting the flap, debulking the inflammatory reaction by careful irrigation of the bedand undersurface of the cap. It is usually done on day 3 or 4 after the procedure (Fig. 19.7). Stage 4 : No definitive successful treatment identified. If white cells are still present, thengentle irrigation may be helpful in reducing tissue necrosis. Otherwise, waiting for epithelialhyperplasia may allow improvement in irregular astigmatism. Rigid gas-permeable contactlenses are often helpful for visual rehabilitation. Wavefront-directed surface treatment withmitomycin C can be considered after full epithelial hyperplasia has occurred, usually at 1year postoperatively.Epithelial IngrowthG rowth of epithelium into the interface between the flap and the stroma results in irregularastigmatism and loss of best corrected visual acuity. The presence of the epithelial cells in theinterface can be safely followed without intervention in the majority of cases. The epithelial
cells in the interface can block the supply of nutrients to the underlying stroma and result innecrosis of the flap, extrusion of the
similar to LASEK. But instead of using alcohol to loosen the epithelium like in LASEK, in epi-LASEK the surgeon typically uses a blunt, plastic blade to separate the epithelial sheet from the eye. This avoids the possibility of a reaction from the alcohol, which can kill epithelial cells. LASIK, PRK and