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tecture is consistently delivered in an optimal alignment for separation. 6.3 Histology of the EpiLASIK Cut For the evaluation of the cleavage plane of Epi- LASIK human corneas that were not suitable for transplantation were obtained from the Bristol eye bank. e corneo-scleral buttons were placed in an articial anterior chamber. EpiLASIK cuts were performed on these human corneas with the EpiVision microkeratome (Gebauer/Cooper- Vision). In 5 eyes the epithelium and the stromal beds were embedded for light and electron mi- croscopy in paraformaldehyde. In 5 corneas the epithelium was used to test for cell viability with Trypan blue. 6.3.1 Light Microscopy For light microscopic examinations the epithelial aps were embedded immediately aer the sepa- ration. e epithelial ap showed that the epithe- lium was uniformly thick along its entire length. e epithelial layer retained its typical stratica- tion and integrity. ere was no disruption of the basal membrane in any of the specimens. e stromal bed appeared to be very smooth with smooth cutting edges (Fig. 6.2). 6.3.2 Transmission Electron Microscopy e epithelial ap and the stromal bed for trans- mission electron microscopy were embedded in glutaraldehyde. e ap demonstrated that the epithelial layer was separated beneath the level of the basement membrane (between the lamina lucida and Bowman’s membrane. e epithelium consisted of healthy-looking cells with intact basal membrane. e intracellular organelles and intercellular desmosomal connections looked very healthy and there are no evident morpho- logical abnormalities. Basal epithelial cells rested on the prominent basal lamina, which consisted of an apparently structureless lamina lucida and an electron-dense lamina densa with occasional focal disruptions. In some places, the disruptions were associated with the formation of small blebs surrounded by a cell membrane. e basal cells of the epithelial disk had a normal morphol- ogy with minimal evidence of trauma or edema (Fig. 6.3). Fig. 6.2 Histology aer EpiLA- SIK: light microscopy 6.3 Histology of the EpiLASIK Cut 67 6 68 EpiLASIK 6.3.3 Scanning Laser Microscopy Corneas were also embedded for scanning laser microscopy. e wound edges showed a very smooth cut at the edges. e surface is very regu- lar without any disruptions of Bowman’s mem- brane (Fig. 6.3). 6.3.4 Cell Vitality To maintain the surface of the cornea and induce minimal wound healing reactions aer laser ab- lation, minimal harm to the epithelium should be applied during the separation and the whole surgical period. In LASEK the vitality of the epi- thelium is dependent on the ethanol concentra- tion and the exposure time. Aer 0 s of 20% etha - nol less than 1% of all epithelial cells are dead, aer 15 s 8%, aer 30 s 21%, aer 45 s 54%, and aer 60 s more than 97% of all epithelial cells are dead. Most surgeons use ethanol exposure times of 20–30 s, which result in 10–20% of cell deaths and more cells that are stimulated. In contrast to this, aer EpiLASIK, around 95% of all cells are vital directly aer the cut. e high amount of vi- tal cells in connection with the intact basal lam- ina should reduce the wound healing reactions, although more studies to evaluate the wound healing are necessary (Fig. 6.2). 6.4 EpiLASIK: the Surgery 6.4.1 Preoperative Evaluation As in all keratorefractive techniques all patients have to undergo a full ophthalmic examina- tion before treatment (primary and enhance- ment surgery). is includes a detailed history and a complete examination with manifest and cycloplegic refractions, slit lamp microscopy, keratometry, corneal topography, applanation to- nometry, pachymetry, determination of scotopic pupil size, and dilated fundus examination. e use of contact lenses was discontinued 4 weeks and 2 weeks before examination and surgery for hard and so lenses respectively. Fig. 6.3 Histology: electron microscopy. SEM scanning electron microscope, TEM transmission electron microscope Patients with diabetes mellitus, a rheumatic disease, an autoimmune condition, or a derma- tological disease possibly aicting the eyes (e.g., rosacea) were excluded, as were patients with se- vere keratoconjunctivitis sicca, a corneal disease (e.g., keratoconus), or another pathological eye condition. A scotopic pupil larger than 7.0 mm was also an exclusion criterion. 6.4.2 Indication for Refraction • Myopia up to –8.0 D, • Hyperopia up to +3.0 D, • Astigmatism up to –5.0 D. 6.4.3 Inclusion Criteria • Age (at least 18 years old), • Stable refraction (changes less than 0.5 D within 2 years), • Signing of informed consent. 6.4.4 Exclusion Criteria • No stable refraction; • Refraction outside the indication (see above); • Corneal disease (e.g., keratoconus, acute in - ammation); • Glaucoma; • Scotopic pupil larger than the intended abla - tion zone; • Patients with systemic disease like diabetes mellitus, rheumatic disease, autoimmune condition, or dermatological disease possibly aicting the eyes (e.g., rosacea); •Pregnancy. 6.5 EpiLASIK Technique Figure 6.4 shows the EpiLASIK technique using the EpiVision by Gebauer/CooperVision. Af- ter the application of anesthetic eye drops (e.g., mepivacaine) twice within 1 min, the patient is positioned on the operating table of the laser sys- tem. e eyes are disinfected with Octeniso so- lution and aerwards draped with a sterile drape. e eye is kept open during surgery with a ster- ile speculum. For every eye a new blade is used. Fig. 6.4 Clinical images 6.5 EpiLASIK Technique 69 6 70 EpiLASIK Aer the microkeratome has been positioned preassembled on the cornea, the suction of the keratome is turned on. One drop of cooled ster- ile BSS is applied to the cornea and the micro- keratome and the separation of the epithelium is made automatically by the microkeratome. Aer the microkeratome head goes back to its origin, the suction is turned o and the keratome is re- moved. e separated epithelium is pushed back with a blunt epithelial peeler to its hinge posi- tion and the eye is centerd beneath the laser. e laser ablation is carried out, and the wound bed is rinsed thoroughly with BSS. en the epithe- lium is replaced carefully, so that the epithelium is adapted well to the wound edge without any wrinkles. Aer the wound edges have been dried with a sponge a bandage contact lens is applied for the xation of the epithelium for 3 days. 6.5.1 Surgical Technique: Pearls • Cut correct angle of hand piece, • Cut with not too much upward or downward pressure exerted by user, • No tilting of the microkeratome, • Use recommended speculum. Aer laser treatment: • Wash wound bed thoroughly with cooled bal - anced salt solution, • Completely dry around wound bed especially hinge area, • Replace Epi-ap, • Dry surface of ap and surrounding tissue be - fore applying bandage contact lens, • Using a swab, press gently on the surface of bandage contact lens to ensure all excess uid is expressed from under the lens. 6.5.2 EpiLASIK Microkeratome Settings Exemplary for the Gebauer/ CooperVision EpiVision • Flap size 9.0 mm • Hinge 0.5 mm • Speed 1.0 mm/s • Oscillation 10,000 rpm 6.5.3 High Myopia: Mitomycin C Wound healing reaction is one major problem that occurs aer surface ablation. Especially in the case of higher intended corrections the typi- cal subepithelial haze may appear. Aer EpiLA- SIK the wound healing reaction is reduced, as a healthy epithelium minimizes the induction of wound healing mediators like growth factors or cytokines. But there is still a higher induction of wound healing reaction in the case of higher in- tended corrections. Mitomycin C (MMC) is an alkylating sub- stance. DNA synthesis is inhibited, preformed DNA is degraded, and lysis of nuclei is induced. DNA synthesis inhibition by the cross linking of DNA requires the lowest concentrations of MMC and is the most important mechanism. DNA re- pair mechanisms do not tend to be inuenced. Mitomycin C has been used for several years in refractive surgery. In the rst reports inves- tigators tried to reduce the wound-healing re- actions aer PRK and LASEK. MMC (0.02%) was applied for 2 min in most studies. e rst studies showed a reduction in haze and a slight overcorrection appeared. erefore, the intended correction was reduced by 10–15%. In EpiLASIK we use MMC in corrections with ablation depths of more than 100 µm to reduce the wound-healing reaction. e application time was primarily also 2 min with 0.02% MMC. As the clinical trials and wound-healing mod- els showed that a shortened application time is enough, we now use an application time of 30 s. e intended correction is also reduced by an average of 15%. is setting results in almost no haze and also does not inuence the visual recov- ery and time course of the surgery. 6.5.4 Bandage Contact Lens Aer the EpiLASIK, the epithelial ap is put back to minimize pain and minimize the wound-heal- ing reaction. As the epithelium is only a very thin layer a bandage contact lens is needed for the xation of the epithelial ap. Problems of contact lenses: • Risk of infections, • Edema, • Foreign body sensation, • Pain, • Reduced visual acuity. erefore, it is important to minimize the appli- cation time of the contact lens. Many dierent contact lenses have been evaluated aer refrac- tive surgery. e perfect contact lens must have two major features: good oxygen permeability and perfect tting. e oxygen permeability of the new genera- tion of so contact lenses has improved a great deal. e Dk/t value of standard so contact lenses is between 20 and 40. But these Dk/t val- ues would still result in corneal edema aer some days. e new silicone hydrogel contact lenses like the Fokus Night and Day (CIBA Vision) and the Pure Vision (Bausch & Lomb) have much higher Dk/t values (over 100). erefore, the oxygen permeability to the cornea is better com- pared with the standard contact lenses. But, even if the oxygen permeability is very good, we no- ticed cell debris beneath the contact lens in some patients and that they had pain. We compared the immediate postoperative period of a silicon hydrogel contact lens (Pure Vision, base curve 8.6) with a atter standard contact lens (Biomed- ics 55, base curve, 8.9, OSI; Fig. 6.5). e higher myopic patients in particular had less pain and a faster visual recovery with the Biomedics con- tact lens. In myopic excimer laser surgery the cornea is made atter. If the contact lens is too steep, the epithelial ap can move beneath the contact lens and the cell debris will result in pain. erefore, a contact lens with a atter base curve is benecial. e silicone hydrogel lenses are only available with base curves up to 8.6; there- fore, conventional contact lenses with atter base curves may be superior (8.9 or even 9.1). 6.5.5 Postoperative Examinations and Medication All patients undergo postoperative examinations 30 min aer surgery. e tting of the contact lens and the underlying epithelial ap should be assessed at the slit lamp. Dislodged aps should be repositioned during this visit. All patients Fig. 6.5 Comparison of two dierent contact lenses 6.5 EpiLASIK Technique 71 6 72 EpiLASIK are scheduled for routine follow-up visits aer 1 and 3 days, aer 1 week, and aer 1, 3, 6, and 12 months aer EpiLASIK. e bandage contact lens was routinely removed on the third post- operative day. In about 85% of all surgeries the epithelial surface was intact with slight irregu- larities. If the ap was not rmly attached a new contact lens was applied to the eye for a further 2 days. Aer this time, no further contact lens was necessary in over 98% of all surgeries. e follow-up visits involved a detailed ophthalmo- logic examination including manifest refraction, slit lamp microscopy, corneal topography, and tonometry. e postoperative therapy until removal of the bandage contact lens consists of: • Unpreserved topical antibiotics (e.g., neomy - cin, polymyxin-B) ve times a day, • Corticosteroids (e.g., dexamethasone 0.1%) ve times a day, • Lubrication (carbomer) six times a day. Diclofenac eye drops and tablets (50 mg) were handed out to the patient as rescue medication in case of pain. erapy aer re-movement of the contact lens: • Lubrication (carbomer) ve times daily, • Corticosteroids (e.g., dexamethasone 0.1%) four times daily for 2 weeks and two times daily for a further 2 weeks. 6.6 Clinical Experiences EpiLASIK is becoming more and more popular. Up to now several thousand EpiLASIK surger- ies have been carried out all over the world us- ing the three available devices. In our clinic we have performed over 600 EpiLASIK procedures within the last 12 months. e average age of the patients was 32.5 years (range: 18–52, 60% women, 40% men). e Gebauer/CooperVision EpiVision microkeratome was used in all cases. e excimer laser employed in this study was the MEL 80 by Carl Zeiss Meditec. 6.6.1 Conventional EpiLASIK e preoperative refraction was between –1.5 and –8.0 D spherical equivalent (SE; mean –4.75) and the astigmatism was up to 4 D. e preop - erative and postoperative refractions are listed in Table 6.1. All EpiLASIK surgeries were carried out without any intraoperative pain. During the suc- tion of the microkeratome all patients reported blurred vision, but none of the patients reported a “lights out” phenomena, which is common in LASIK. In one eye a free ap appeared. is surgery was converted into a PRK. All other Epi- LASIK surgeries were without any intraoperative complications. ere were no holes in the epithe- Table . Refractive results of EpiLASIK for myopia. SE spherical equivalent, UCVA uncorrected visual acuity, BCVA best corrected visual acuity EpiLASIK 1day 3 days 1 week 1 month 3 month 6 month 1 year SE 0.23 –0.11 –0.12 –0.11 –0.10 UCVA 20/30 20/40 20/20 20/18 20/18 20/18 20/18 Haze 0 0 0 0.22 0.19 0.11 0.07 Percentage within ± 0.5 D 0.56 0.86 0.92 0.92 0.91 Percentage within ± 1.0 D 0.93 0.97 0.97 0.98 0.97 Loss of Snellen lines >2 lines (%) 00000 lial aps and there were also no incomplete or stromal cuts. During the postoperative course, no infec- tions, stromal inltrates or similar interface ap- pearances were visible, as seen aer LASIK. Al- though the epithelial cells were visible under the contact lens aer 2 days, aer the re-movement of the contact lens no epithelial defect was vis- ible. Aer the re-movement of the contact lens, in 15% of eyes the ap was a little bit loose, and therefore a new contact lens was given for fur- ther 2 days. Aer this time, the epithelium was stable. No epithelial instability occurred in any of the eyes treated during the entire postoperative time. 6.6.2 Refractive Results e refractive results were very encouraging. Fig- ure 6.6 shows the comparisons of the intended and the attained correction (SE) aer 6 months. Aer 1 week, 56% of all patients were within ±0.5 D and 93% were within ±1.0 D SE around emmetropia. is increased during the rst month to 86% of all patients within ±0.5 D and 97% were within ±1.0 D SE around emmetropia. Twelve months aer surgery 91% of all patients were within ±0.5 D and 9% were within ±1.0 D SE around emmetropia (Table 6.1). Initially a slight hyperopic shi of +0.23 D could be determined aer 1 week, which was only temporary. Aer 1 month the refraction was –0.11 and was stable at the 3-, 6-, and 12-month follow-up visits (Fig. 6.7). One year aer Epi - LASIK, 93% of all patients had an astigmatism ≤0.5 D and 99% had an astigmatism ≤1.0 D. To evaluate the astigmatic results aer EpiLASIK, vector analysis was calculated according to the Alpins method. e surgically induced astigma- tism 12 months aer EpiLASIK was 1.04 of the intended astigmatism correction. e index of success according to Alpins, which is dened as the quotient of the remaining astigmatism and Fig. 6.6 Achieved vs. attempted refraction aer EpiLASIK for myopia. One year postoperatively 6.6 Clinical Experiences 73 6 74 EpiLASIK the intended correction, with an ideal value of 0, had a value of 0.21. 6.6.3 Safety Safety of a refractive procedure is the changes in postoperative best-corrected visual acu- ity (BCVA) in comparison to the preoperative BCVA. One week aer EpiLASIK 13% of all patients lost one line of Snellen visual acuity, 43% of all patients were unchanged, and 44% gained one or two lines. Aer 1 month 2% lost one line, 42% were unchanged, and 56% gained one or two lines (Fig. 6.8). None of the patients lost more than two lines of Snellen visual acuity 1 week aer EpiLASIK and during the rest of the follow-up. Fig. 6.7 Postoperative refraction aer EpiLASIK for myopia Fig. 6.8 Safety aer EpiLASIK for myopia 6.6.4 Uncorrected Visual Acuity (UCVA Ecacy) Ten minutes aer EpiLASIK all patients had an UCVA of 20/40 or better. On day 1, the average visual acuity was 20/30 with a range of 20/60 to 20/15. On day 3 the visual acuity dropped slightly, due to edema through the contact lens, to an av- erage visual acuity of 20/40 with a range from 20/80 to 20/15. One week aer EpiLASIK most of the patients already had a good visual acuity with an average of 20/20 (range 20/30 to 20/15). is increased continuously. Aer 1 month all patients had a visual acuity of 20/25 with an av- erage of 20/18).is was stable throughout the whole year (Table 6.1). At 12 months 85% had a visual acuity of 20/20 or better (Fig. 6.9). 6.6.5 Postoperative Pain Postoperative pain is one of the key issues in re- fractive surgery. e postoperative pain was eval- uated using the visual analog scale. erefore, the patients were given a scale with ten units, from 0 to 10. e patients quote 0 if they do not have any pain and 10 if they have maximal pain. e patients noted their subjective pain values for the rst 14 h and then every 12 h. About 25% of all patients had no pain during the whole follow-up. e other patients ranged from foreign body sen- sation up to pain. e maximal pain score was on average 3.5 (SD±3.2) and started 3.0 h (SD±3.1) aer the surgery. ere were two dierent peaks of the pain values. e rst peak was aer 3 h, when the pain started, and aer 3 days, when the foreign body sensation got worse. Patients noted that above all wearing the contact lens was un- pleasant, and that aer the removal of the contact lens the pain disappeared. 6.6.6 Corneal Haze One major problem of the PRK was the wound healing reaction with the development of subepi- thelial haze, especially in the case of higher in- tended corrections. is haze formation was re- duced with LASEK technique, but still occurred. e subepithelial corneal haze was classied subjectively using slit lamp examination accord- ing to its degree with values between 0 and 4 on the basis of the current scale (Hanna): 0 = No haze, completely clear cornea, 0.5 = Low trace haze, seen only with indirect illumination, 1 = Clouding at the slit-lamp, visible with direct and indirect illumination, 2 = Moderate haze, well visible, 3 = Distinctive haze with clearly reduced intraocular insight, 4 = Very strong haze, iris details not visible on the basis of clouding of the cornea. e mean maximal haze value was 0.31±0.30 (range 0 to 1). One month aer EpiLASIK, the Fig. 6.9 Ecacy aer EpiLASIK for myopia 6.6 Clinical Experiences 75 6 76 EpiLASIK mean haze value was 0.27±0.31 (range 0 to 1), at 3 months it was 0.19±0.29 (range 0 to 1), and at 6 months it was 0.19±0.21 (range 0 to 0.5). ere were no eyes with signicant haze (i.e., worse than grade 1) throughout follow-up aer re- treatment. 6.6.7 Corneal Sensitivity Dry eye problems aer refractive surgery are a common problem. Aer LASIK this can persist for years. e main reason is that with LASIK the nerve bers in the stroma are cut with the micro- keratome. In EpiLASIK, patients also complain of dry eye symptoms during the rst weeks aer surgery, as the sub-epithelial nerve ber bundles and stromal nerves are disrupted during EpiLA- SIK surgery and the procedure results in a sig- nicant reduction in corneal sensation. Corneal sensation, measured with the Co- chet-Bonnet aesthesiometer, is signicantly re- duced 3 days, 7 days, and 14 days aer surgery (p<0.01). e loss of corneal sensation is greatest 3 days aer surgery and corneal sensation in - creased during the rst month aer EpiLASIK. Aer 1 month, 3 months, and 6 months no sig - nicant dierence was found between preopera- tive and postoperative sensation. ere was no signicant dierence in sensation among dier- ent areas of the cornea aer EpiLASIK. 6.7 Customized Ablation: Wavefront-Guided or Wavefront-Optimized In a perfect, aberration-free optical system all light rays would focus on one point. is would result in a perfect wavefront. But the human eye is not a perfect optical system. e human cornea is naturally prolate. Conventional laser systems use similar energy to treat both centrally and peripherally resulting in oblate ablations due to less tangential peripheral treatments. e change from prolate to oblate results in higher amounts of spherical aberrations in wavefront measure- ment. Although most patients are very happy aer refractive surgery, some patients have visual problems, especially in ambient light, like glare or halos. e induction of higher order aber- rations is the main reason for these symptoms; however, this may be reduced with wavefront- guided ablation. Another possibility for reducing the induc- tion of spherical aberrations may be the wave- front-adjusted (optimized) ablation proles. In these proles more relative energy would be used to treat the peripheral cornea to compensate for the prolate shape. In a prospective study, we com- pared the visual outcome aer wavefront-guided with the results aer wavefront-optimized abla- tion in 60 eyes in 30 patients. e laser used in this study was the Concept 500 from WaveLight Technology. e microkeratome was the EpiVi- sion by Gebauer/CooperVision. 6.7.1 Refractive Results e SEs before EpiLASIK were –4.13±1.38 D in the wavefront-guided group (range: –2.5 to –6.75 D) and –5.01±1.86 in the wavefront-opti - mized group (range: –2.5 to –7.63 D). ere was no statistically signicant dierence. One month aer EpiLASIK, SE was +0.08 D±0.21 D in the wavefront-guided group and +0.21 D±0.31 D in the wavefront-optimized group, at 3 months 0.13 D±0.25 D and 0.13 D±0.29 D respec - tively, and at 6 months –0.06 D±0.18 D and –0.03±0.21 D respectively. Six months aer LASEK all 30 eyes in both groups were within ±1.0 D of emmetropia, and 90% of all eyes in the wavefront-guided group and 87% of all eyes in the wavefront-optimized group were within ±0.5. 6.7.2 Visual Outcome Uncorrected visual acuity (UCVA) was improved and reached at least 20/25 in all eyes following EpiLASIK in both groups. It was 20/20 or better in 93% of all eyes aer wavefront-guided and 90% of all eyes aer wavefront-optimized ablation. Best corrected visual acuity (BCVA) was 20/20 or better in all 30 eyes in both groups 6 months aer treatment. Before surgery, 24% of [...]... improved from 6.22 (±2 .51 ) to 5. 94 (±2. 65) in the wavefront-guided group and from 6.33 (±2.63) to 6.01 (±2 .55 ) in the wavefront-optimized group However, none of these differences were statistically significant Also, the Pelli Robson Chart test improved slightly from 1.4 25 log contrast sensitivity (±0.093) to 1 .52 4 (±0.9 15) in the wavefront-guided and from 1.422 (±0.093) to 1 .50 3 (±0.08 85) in the wavefrontoptimized... 6.8.1 Refractive Results (Re -surgery) The SE before primary surgery was –6 .53 ±1.22 D (range: –4. 25 to –8.0 D) Before EpiLASIK enhancement the SE was –1.22 D±0 .57 D (range: –0.38 to –2.0 D) One month after re-treatment, SE was +0 .57 D±0 .51 D (range: 0.00 to 1. 25) , at 3 months it was 0.20 D±0.28 D (range: –0.12 to 0. 75) , and at 6 months it was 0. 25 D±0.36 D (range: 0. 75 to –0. 25 D) Six months after EpiLASIK... laser photorefractive keratectomy for myopia; refractive and visual results Ophthalmology 1994;101: 155 8– 156 3; discussion 156 3– 156 4 Febbraro J-L, Buzard KA, Friedlander MH Reoperations after myopic laser in situ keratomileusis J Cataract Refract Surg 2000;26:41–48 Fernandez AP, Jaramillo J, Jaramillo M Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less... eyes were within ±0 .5 D of emmetropia and 100% were within ±1.0 D 6.8.2 Visual Outcome Uncorrected visual acuity (UCVA) was improved and reached at least 20/ 25 in all eyes following EpiLASIK enhancement (6-month follow-up) and 85% had an UCVA of 20/20 or better Best corrected visual acuity (BCVA) was 20/20 or better in all 20 eyes both before and 6 months after re-treatment Before re -surgery 10% of all... had a visual acuity of 20/ 15 or better in the wavefront-guided and 20% in the wavefront-optimized groups This increased to 50 % after wavefront-guided EpiLASIK and to 48% in the wavefront-optimized group None of the eyes lost one line of the pre-EpiLASIK BCVA All patients reported improved visual acuity Sixty percent of all eyes in the wavefront-guided and 47% in the wavefront-optimized groups had the... Uusitalo H Repeated photorefractive keratectomy for undercorrection and regression J Refract Surg 2002;18: 155 –161 22 Pop M, Aras M Photorefractive keratectomy retreatments for regression; one-year follow-up Ophthalmology 1996;103:1979–1984 23 Pop M, Payette Y Photorefractive keratectomy versus laser in situ keratomileusis; a control-matched study Ophthalmology 2000;107: 251 – 257 24 Rozsival P, Feuermannova... In the wavefront-guided group hoRMS increased from 0.26 (±0.12) to 0.31 (±0.14) and in the wave-optimized group hoRMS increased from 0.27 (±0.13) to 0.32 (±0. 15) Third order aberrations increased from 0.20 (±0.09) to 0.23 (±0.10) in the wavefront-guided and from 0.19 (±0.08) to 0.22 (±0.13) in the wavefront-opti- Undercorrection and regression of the initial surgical effect are well-known phenomena... LASIK, LASEK, and EpiLASIK is currently between 5 and 10% of all myopic corrections up to –6 D Several techniques can be used to treat residual myopia after myopic excimer laser refractive surgery Laser in situ keratomileusis enhancement after initial LASIK 77 78 6 EpiLASIK is effective and safe in correcting the remaining refractive error by re-lifting or re-cutting the flap [4, 6, 15, 20] However,... ethanol-assisted mechanical versus transepithelial excimer laser debridement J Refract Surg 2000;16 :51 9 52 2 Kim S-Y, Sah W-J, Lim Y-W, Hahn T-W Twenty percent alcohol toxicity on rabbit corneal epithelial cells; electron microscopic study Cornea 2002;21:388–392 Lee JB, Seong GJ, Lee JH, et al Comparison of laser epithelial keratomileusis and photorefractive keratectomy for low to moderate myopia J Cataract. .. acuity as before and 40% of the wavefront-guided and 53 % of the wavefront-optimized groups even gained one line The mesoptometer tests stayed nearly the same in both groups Without a glare source it improved slightly in the wavefront-guided group from an average of grade 6.39 (±1.72) to 6.31 (±1.78) and in the wavefront-optimized group from an average of grade 6. 45 (±1.68) to 6.33 (±1. 75) With a glare . follow-up of ex- cimer laser photorefractive keratectomy for myo- pia; refractive and visual results. Ophthalmology 1994;101: 155 8– 156 3; discussion 156 3– 156 4. 6. Febbraro J-L, Buzard KA, Friedlander. the wavefront-guided and 47% in the wavefront-optimized groups had the same postoperative Snellen visual acuity as be- fore and 40% of the wavefront-guided and 53 % of the wavefront-optimized. a glare source it improved from 6.22 (±2 .51 ) to 5. 94 (±2. 65) in the wavefront-guided group and from 6.33 (±2.63) to 6.01 (±2 .55 ) in the wave- front-optimized group. However, none of these dierences
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