151
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Fam HB, Lim KL. Corneal elevation indices in normal and keratoconic eyes. J Cataract Refract Surg 2006; 32:1281-7. [PMID: 16863962 DOI: 10.1016/j.jcrs.2006.02.060] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Accepted: 03/06/2006] [Indexed: 11/29/2022]
Abstract
PURPOSE To determine an index that distinguishes keratoconus and keratoconus-suspect eyes from normal eyes with Orbscan (Bausch & Lomb) corneal elevation maps. SETTING Department of Ophthalmology, Tan Tock Seng Hospital, Singapore, and iLaser Centre, Island Hospital, Penang, Malaysia. METHODS In this initial phase of this multicenter nonrandomized retrospective study, 1 eye of 166 normal subjects, 15 keratoconus patients, and 11 keratoconus suspects was examined at 1 clinic. The anterior best-fit sphere (BFS), posterior BFS, anterior elevation, posterior elevation, and maximum and minimum keratometries were analyzed. Two indices with the highest sensitivity and specificity classifying these conditions were identified using receiver operating characteristic curves. These 2 indices were evaluated in a subsequent validation study using 1 eye of 221 normal subjects, 43 keratoconus patients, and 23 keratoconus suspects from another clinic. RESULTS The anterior elevation and anterior elevation ratio (anterior elevation ratio = anterior elevation/anterior BFS) best classified the different groups. An anterior elevation ratio of 0.5122 mm or less had 99% sensitivity and 95.2% specificity while a ratio 16.5 mum or less had 80.1% sensitivity and 80.8% specificity in discriminating normal eyes from keratoconus and keratoconus suspects. The results were similar in the validation study. In addition, these anterior elevation and anterior elevation ratio cutoff values had high sensitivity and specificity in identifying keratoconus suspects from normal eyes in the validation study. CONCLUSION Anterior corneal elevation parameters are clinically relevant measures for detecting keratoconus and suspected keratoconus eyes.
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Affiliation(s)
- Han-Bor Fam
- From The Eye Institute, Tan Tock Seng Hospital, Singapore
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152
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Affiliation(s)
- Colin C K Chan
- The Eye Institute, Level 3, 270 Victoria Parade, Chatswood, NSW 2067, Australia
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153
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Bilgihan K, Ozdek SC, Sari A, Hasanreisoğlu B. Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities. J Cataract Refract Surg 2006; 32:1264-9. [PMID: 16863959 DOI: 10.1016/j.jcrs.2006.02.056] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Accepted: 02/12/2006] [Indexed: 11/29/2022]
Abstract
PURPOSE To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus (<350 microm) and corneal ectasia after laser in situ keratomileusis (LASIK) and to treat anterior stromal opacities. SETTING Ophthalmology Department, School of Medicine, Gazi University, Ankara, Turkey. METHODS Thirteen eyes (5 keratoconus, 3 macular dystrophies, 1 post-LASIK ectasia, 1 post-LASIK interstitial keratitis, 3 post-herpetic keratitis sequelae) of 13 patients were included in this prospective study. The treatment group was divided into corneal ectasia and stromal opacity groups. A donor stromal button approximately 350 microm thick received a 100 microm excimer laser ablation on the endothelium. The remaining cornea (epithelium, Bowman's membrane, and stroma) was punched with a 7.5 or 7.7 mm trephine. After transepithelial ablation of the host cornea to 200 mum thickness, the corneal button was sutured with interrupted 10-0 monofilament nylon. Sutures were removed between 3 months and 6 months postoperatively. Preoperative and postoperative simulated keratometric cylinders and corneal thickness values were compared using the Wilcoxon signed rank test. The postoperative spherical equivalent refraction and best spectacle-corrected visual acuity (BSCVA) between the groups were compared using the Mann-Whitney U test. RESULTS The mean follow-up was 27.6 months +/- 8.3 (SD). All patients gained 2 lines or more of BSCVA, and no patient lost a line. The mean corneal thickness was 381.2 +/- 88.2 microm preoperatively, which significantly increased to 534.9 +/- 96.6 microm postoperatively (P < .05). The mean preoperative simulated keratometric cylinder was 7.44 +/- 7.18 diopters (D); postoperatively, it decreased to 2.61 +/- 1.73 D (P < .05). There was no significant difference in postoperative spherical equivalent refraction or BSCVA between the groups (P > .05). CONCLUSIONS This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.
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Affiliation(s)
- Kamil Bilgihan
- Ophthalmology Department, School of Medicine, Gazi University, Ankara, Turkey.
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154
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Donoso R, Castillo P. Correction of high myopia with the PRL phakic intraocular lens. J Cataract Refract Surg 2006; 32:1296-300. [PMID: 16863965 DOI: 10.1016/j.jcrs.2006.03.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 03/15/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE To assess the predictability, efficacy, safety, and complications of the PRL (CIBA Vision) phakic intraocular lens (pIOL) in the correction of high myopia. SETTING Clínica Oftalmológica Pasteur, Santiago, Chile. METHODS This prospective study comprised 53 eyes of 39 patients who received a PRL pIOL. The spherical equivalent (SE), uncorrected visual acuity (UCVA), efficacy index (postoperative UCVA/preoperative best spectacle-corrected visual acuity [BSCVA]), safety index (BSCVA/preoperative BSCVA), intraocular pressure (IOP), iridocorneal angle, and distance between the crystalline lens and PRL were prospectively assessed during the follow-up period. RESULTS The mean patient age was 39 years. The mean power of the implanted pIOL was -12.73 diopters (D) +/- 2.87 (SD) (range -20.00 to -7.00 D), for a preoperative SE of -17.27 +/- 4.58 D (range -31.50 to -8.75 D). The mean preoperative BSCVA was 0.50 +/- 0.70 (logMAR equivalent), and the mean follow-up was 8 +/- 9.4 months. The mean postoperative SE was -0.23 +/- 1.05 D; 71.2% of eyes were within +/-1.00 D. Sixty percent of patients had UCVA of 20/40 or better, and 88.2% of patients had BSCVA of 20/40 or better. Ninety-two percent maintained or gained 1 or more lines of BSCVA; 5.7% lost more than 1 line. There was no significant change in IOP (P = .40), and the mean distance between the crystalline lens and pIOL was 370 microm (ultrasound) and 604 microm (optical coherence tomography). Late complications included 1 case each of retinal detachment and lens subluxation. CONCLUSIONS Although PRL implantation in high myopia was predictable and effective, retinal detachment and IOL subluxations occurred. Other posterior chamber pIOLs should be used until the complications associated with the PRL pIOL are resolved.
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155
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Abstract
PURPOSE OF REVIEW The aim of this article is to review the causes, risk factors, management, and future research directions for corneal ectasia after laser in situ keratomileusis. RECENT FINDINGS Complex corneal biomechanical processes influence the integrity of the normal and postoperative cornea, and developing an understanding of these processes facilitates recognition of risk factors for ectasia after laser in-situ keratomileusis. Currently identified risk factors include keratoconus, high myopia, low residual stromal bed thickness from excessive ablation or thick flap creation, and defined topographic abnormalities such as forme fruste keratoconus and pellucid marginal corneal degeneration. Ectasia can also rarely occur in patients without currently identifiable risk factors, and future identification of at-risk patients may be facilitated by corneal interferometry and corneal hysteresis measurements. Utilization of intraoperative pachymetry measurements at the time of surgery and confocal microscopy prior to enhancement to measure residual stromal bed thickness should avoid unanticipated low residual stromal bed thickness. Management options for ectasia after laser in situ keratomileusis include intraocular pressure reduction, rigid gas permeable contact lenses, and intracorneal ring segments, in addition to corneal transplantation. In the future, collagen cross-linking may reduce corneal steepening and improve refractive error. SUMMARY When ectasia develops, early recognition and proper management are essential to prevent progression, to promote visual rehabilitation, and to reduce the need for corneal transplantation for these patients.
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Affiliation(s)
- J Bradley Randleman
- Emory University Department of Ophthalmology and Emory Vision, Atlanta, Georgia 30322, USA.
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156
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Flanagan GW, Binder PS. Role of flap thickness in laser in situ keratomileusis enhancement for refractive undercorrection. J Cataract Refract Surg 2006; 32:1129-41. [PMID: 16857499 DOI: 10.1016/j.jcrs.2006.01.095] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 01/13/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE To determine which preoperative and/or perioperative factors determine the need for an enhancement for refractive undercorrection in laser in situ keratomileusis (LASIK) for spherical or spherocylindrical myopia. SETTING Clinical refractive surgery outpatient facility. METHODS In this nested case-control study within a retrospective cohort, 3850 of the 9777 eyes operated on between January 1996 and August 2005 who met the selection criteria were studied. Only patients whose refractive goal was plano were included. Control eyes were those whose latest spherical equivalent (SE) refraction was within +/-0.37 diopters (D) of emmetropia. Cases were defined as enhancements for undercorrection with an SE refraction worse than or equal to -0.50 D performed less than 6 months following the primary surgery. RESULTS Factors associated with enhancement included increasing patient age (odds ratio [OR] = 1.048, P<.001), decreasing follow-up time (OR = 0.994, P<.001), increasing minus laser sphere (OR = 0.700, P<.001) and cylinder settings (OR = 0.718, P<.001), female sex (OR = 1.112, P = .046), and corneal toricity (OR = 1.237, P = .012). The Summit laser had a significant risk for enhancement (OR = 1.726, P<.001) compared with the Visx laser, whereas the Wavelight Allegretto had a lowered risk (OR = 0.630, P = .049). Enhancement risk with the Autonomous was no different from that with the Visx (OR = 1.120, P = .342). Increasing flap thickness (OR = 1.009, P<.001) was more strongly associated with enhancement risk than residual stromal bed thickness. CONCLUSIONS After controlling for patient age, time to follow-up or surgery, corneal cylinder, sphere and cylinder laser settings, laser manufacturer, patient sex, and corneal thickness, increasing flap thickness was found to be a more important predictor of enhancement for refractive undercorrection than residual stromal thickness.
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Affiliation(s)
- Gerald W Flanagan
- Gordon Binder and Weiss Vision Institute, San Diego, California, USA.
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157
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Binder PS. One thousand consecutive IntraLase laser in situ keratomileusis flaps. J Cataract Refract Surg 2006; 32:962-9. [PMID: 16814054 DOI: 10.1016/j.jcrs.2006.02.043] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 10/10/2005] [Indexed: 11/18/2022]
Abstract
PURPOSE To measure laser in situ keratomileusis (LASIK) flap dimensions created with the IntraLase FS (IL) laser (Intralase Corporation). SETTING Private practice, San Diego, California, USA. METHODS Consecutive LASIK flaps created with the IL were measured with subtraction ultrasound at primary and enhancement surgeries. Data were stored in Outcomes Analysis Software and analyzed using MS Excel (Microsoft Corporation) and SSPS software. RESULTS The mean achieved flap thickness exceeded the attempted by 9.4 to 34.3 mum. The standard deviation varied from +/-10.2 to +/-21.7 mum. Preoperative corneal thickness and power did not affect achieved flap thickness. Seventy-three percent of mate eye flaps were within +/-15 mum of each other for the 90 mum attempted. The same flaps measured at enhancement were thicker than the primarily measured flaps (n = 58). Diffuse lamellar keratitis and slipped flaps were eliminated with experience. There were no decentered or irregular flaps, epithelial defects, or flap perforations. CONCLUSIONS Compared with published results of mechanical microkeratomes, the IL reduced the standard deviation of flap thickness as well as the achieved range. It eliminated physical complications associated with mechanical flap creation, and the impact of preoperative pachymetry and corneal power, thereby permitting more myopia to be corrected without risking deep ablations.
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Affiliation(s)
- Perry S Binder
- Gordon Binder and Weiss Vision Institute, San Diego, California 92122, USA.
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158
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Malecaze F, Coullet J, Calvas P, Fournié P, Arné JL, Brodaty C. Corneal Ectasia after Photorefractive Keratectomy for Low Myopia. Ophthalmology 2006; 113:742-6. [PMID: 16650667 DOI: 10.1016/j.ophtha.2005.11.023] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 11/14/2005] [Accepted: 11/15/2005] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE To alert ophthalmologists of the possibility of an aggravation of forme fruste keratoconus after photorefractive keratectomy (PRK). DESIGN Clinical case report. INTERVENTION Standard bilateral PRK for low myopia. MAIN OUTCOME MEASURES Corneal topography, corneal thickness, and visual acuity. RESULTS Corneal ectasia occurred bilaterally after PRK. Retrospective analysis of preoperative videokeratography indicated the existence of forme fruste keratoconus on the left eye. CONCLUSIONS This article is the first case report of a bilateral corneal ectasia after PRK for low myopia. Even if there is no direct proof to demonstrate that PRK has worsened the evolution of keratoconus, the safety of the PRK procedure in forme fruste keratoconus must be considered.
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159
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Klein SR, Epstein RJ, Randleman JB, Stulting RD. Corneal Ectasia After Laser In Situ Keratomileusis in Patients Without Apparent Preoperative Risk Factors. Cornea 2006; 25:388-403. [PMID: 16670474 DOI: 10.1097/01.ico.0000222479.68242.77] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate patients who developed ectasia with no apparent preoperative risk factors. METHODS Potential cases of patients who developed ectasia without apparent risk factors were identified by contacting participants in the Kera-Net (n = 580), ASCRS-Net (n = 450), and ISRS/AAO ISRS-Net (n = 525) internet bulletin boards from April to October 2003. Cases were included if ectasia developed after laser in situ keratomileusis in the absence of apparent preoperative risk factors. Reported cases were excluded for the following reasons: (1) calculated residual stromal bed less than 250 microm, (2) preoperative central pachymetry less than 500 microm, (3) any keratometry reading greater than 47.2 diopters (D), (4) a calculated inferior-superior value greater than 1.4, (5) more than 2 retreatments, (6) attempted initial correction greater than -12.00 D, (7) an Orbscan II "posterior float" (if obtained) greater than 50 microm, and (8) surgical/flap complications. RESULTS A total of 27 eyes of 25 patients were submitted for consideration. Eight eyes (8 patients) met our inclusion criteria. Mean age was 27.7 years (range, 18-41 years). Preoperative manifest refraction spherical equivalent was -4.61 D (range, -2.00 to -8.00 D); steepest keratometric reading was 43.86 D (range, 42.50-46.40 D); keratometric astigmatism was 0.93 D (range, 0.25-1.90 D); and preoperative central pachymetry was 537 microm (range, 505-560 microm). The mean calculated ablation depth was 82.8 microm (range, 21-125.4 microm), and mean calculated residual stromal bed was 299.5 microm (range, 254-373 microm). Mean time to recognition of ectasia onset was 14.2 months (range, 3-27 months) postoperatively. At the time of ectasia diagnosis, the mean manifest refraction spherical equivalent was -1.23 D (range, +0.125 to -3.00) with a mean of 2.72 D (range, 0.75-4.00 D) of astigmatism. CONCLUSIONS Ectasia can occur after an otherwise uncomplicated laser in situ keratomileusis procedure, even in the absence of apparent preoperative risk factors.
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Affiliation(s)
- Shawn R Klein
- Cornea Service, Department of Ophthalmology, Rush University Medical Center, Chicago, IL 60612, USA
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160
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Eisner RA, Binder PS. Technique for measuring laser in situ keratomileusis flap thickness using the IntraLase laser. J Cataract Refract Surg 2006; 32:556-8. [PMID: 16698470 DOI: 10.1016/j.jcrs.2006.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Accepted: 07/26/2005] [Indexed: 10/24/2022]
Abstract
Measurement of laser in situ keratomileusis flap thickness is required to estimate residual bed thickness. Historically, flap thickness has been assumed, estimated based on microkeratome head labeling, guessed based on flap handling characteristics, or calculated by subtraction pachymetry. We describe a method for measuring flap thickness before actual flap elevation using the IntraLase laser.
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161
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Cheng ACK, Rao SK, Tang E, Lam DSC. Pachymetry Assessment With Orbscan II in Postoperative Patients With Myopic LASIK. J Refract Surg 2006; 22:363-6. [PMID: 16629068 DOI: 10.3928/1081-597x-20060401-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare central corneal thickness after LASIK for myopia, using ultrasonic pachymetry and Orbscan II measurements, and to evaluate changes in these measurements over time. METHODS Central corneal thickness measurements obtained by ultrasonic pachymetry and Orbscan II (Bausch and Lomb, Rochester, NY) in patients who underwent myopic LASIK between July 2002 and May 2003 were analyzed. The two measurements were assessed preoperatively and postoperatively at 1 day and 1, 3, 6, and 12 months. RESULTS In 237 eyes, using the correction factor 0.93, no significant difference was noted in the preoperative central corneal thickness measured by ultrasonic pachymetry (561.89 +/- 28.66 microm) and Orbscan pachymetry (562.28 +/- 28.18 microm) (P =.713). Postoperatively, the difference was statistically significant at day 1 and 1, 3, and 6 months (P < .001), but was not significant at 12 months (P = .130). CONCLUSIONS Orbscan II measurements of central corneal thickness after myopic LASIK are less than those measured by ultrasonic pachymetry; however, this difference decreases with time and may not be significant after 1 year.
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Affiliation(s)
- Arthur C K Cheng
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, Kowloon, Hong Kong, People's Republic of China.
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162
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Binder PS, Lindstrom RL, Stulting RD, Donnenfeld E, Wu H, McDonnell P, Rabinowitz Y. Keratoconus and corneal ectasia after LASIK. J Cataract Refract Surg 2006; 31:2035-8. [PMID: 16412891 DOI: 10.1016/j.jcrs.2005.12.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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163
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Luger MH. March Consultation #2. J Cataract Refract Surg 2006. [DOI: 10.1016/j.jcrs.2006.01.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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164
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Abstract
In surface ablation, haze is the most frequent complication. After LASIK, microkeratome-related complications are rare today and usually resolve without sequelae, provided no ablation was done. Postoperative flap complications such as flap slippage usually occur during the first few days after surgery and should be treated as early whenever present. Interface complications are a new diagnostic entity as the interface between flap and stroma presents a space where fluid or cells can accumulate. Diffuse lamellar keratitis usually occurs within the first few postoperative days and should be treated aggressively to avoid scarring. Epithelial ingrowth is another rare complication usually requiring treatment. Corneal hydrops with fluid accumulation in the interface is a very rare but important phenomenon related to steroid-induced glaucoma but presenting with false low tonometry readings. Corneal ectasia is extremely rare and in most cases related to thin stromal beds. However, its pathogenesis is not yet completely understood, and it may occur in "normal" eyes, too. Dry eye syndrome is the most frequent complication after LASIK. It is usually benign but may cause significant visual impairment in rare cases.
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Affiliation(s)
- M C Knorz
- FreeVis LASIK Zentrum, Universitätsklinikum Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim.
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165
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O'Doherty M, O'Keeffe M, Kelleher C. Five year follow up of laser in situ keratomileusis for all levels of myopia. Br J Ophthalmol 2006; 90:20-3. [PMID: 16361660 PMCID: PMC1856914 DOI: 10.1136/bjo.2005.075127] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To assess the long term refractive and visual outcome of patients who have laser in situ keratomileusis (LASIK) surgery. METHODS This was a retrospective study of visual and refractive outcome of patients who had LASIK surgery performed in 1998 and 1999. All levels of myopia were included in the study. 49 patients attended for follow up. The main outcome measures were safety, predictability, efficacy, and stability. Postoperative complications and aberrations were also recorded. The mean preoperative spherical equivalent was -4.85. RESULTS At 2 months postoperatively 67% of eyes were within plus or minus 0.5D of attempted correction with 81% within plus or minus 1.0D. At 5 years postoperatively 60% of eyes were within plus or minus 0.5D of attempted correction with 83% within plus or minus 1.0D. 88% of eyes had a vision of 6/12 or better at 2 months compared to 89% of eyes at 5 years. Best spectacle corrected visual acuity (BSCVA) was unchanged or improved in 51%. No eye lost more than one line of BSCVA. Overall, there was regression towards myopia with a mean change in refraction of -0.5D over the 5 years. As expected, severely myopic patients regressed more with a mean change of -1.06D. However, there was a high level of patient satisfaction with the surgery. CONCLUSION LASIK surgery offers predictable results in terms of refractive and visual outcome with mild regression in refraction over time.
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Affiliation(s)
- M O'Doherty
- National University of Ireland, Mater Private Hospital, Dublin 7, Republic of Ireland
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166
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Binder PS, Lindstrom RL, Stulting RD, Donnenfeld E, Wu H, McDonnell P, Rabinowitz Y. Keratoconus and Corneal Ectasia After LASIK. J Refract Surg 2005; 21:749-52. [PMID: 16329368 DOI: 10.3928/1081-597x-20051101-15] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Perry S Binder
- Gordon Binder Weiss Vision Institute, San Diego, CA, USA.
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167
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Affiliation(s)
- Marcelo V Netto
- The Cole Eye Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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168
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Ueda T, Nawa Y, Masuda K, Ishibashi H, Hara Y, Uozato H. Posterior corneal surface changes after hyperopic laser in situ keratomileusis. J Cataract Refract Surg 2005; 31:2084-7. [PMID: 16412919 DOI: 10.1016/j.jcrs.2005.04.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2005] [Indexed: 11/19/2022]
Abstract
PURPOSE To evaluate posterior corneal surface topographic changes after hyperopic laser in situ keratomileusis (H-LASIK) using Orbscan I (Orbtek, Inc.). SETTING Department of Ophthalmology, Nara Medical University, Nara, Japan. METHODS In 25 eyes of 15 patients who had H-LASIK, the posterior corneal surface was measured with slit-scanning corneal topography (Orbscan I) preoperatively and 1 year postoperatively. The center as a fit zone and calculated posterior corneal surface changes were taken at 4 points: nasal, temporal, superior, and inferior sides in the 5.0 mm diameter. The posterior corneal topographic changes were analyzed using an analysis of variance. The postoperative:preoperative magnification ratio of the posterior corneal surface was calculated in a theoretical eye model. RESULTS When a "+" reading was defined as the forward displacement and "-" was defined as the backward displacement, the mean posterior corneal topographic changes were -2.8 microm +/- 27.9 (SD) at the nasal side, -4.5 +/- 27.8 microm at the temporal side, -3.9 +/- 20.1 microm at the superior side, and -2.3 +/- 20.1 microm at the inferior side. The posterior corneal surface between any 2 examined points showed no significant difference after H-LASIK. In addition, the hypothetical change in the posterior cornea was -8.3 microm after +3.0 diopter H-LASIK, which was approximately closer to the study results. In each side, the amount of the attempted correction was significantly correlated with the posterior corneal topographic change. CONCLUSIONS Clinical measurement of the posterior corneal displacement after H-LASIK with Orbscan revealed a backward shift. This change corresponded to the hypothetical artifactual changes with Orbscan; that is, changes in the magnification ratio.
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Affiliation(s)
- Tesuo Ueda
- Department of Ophthalmology, Nara Medical University, Nara, Japan.
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169
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Lifshitz T, Levy J, Klemperer I, Levinger S. Late Bilateral Keratectasia After LASIK in a Low Myopic Patient. J Refract Surg 2005; 21:494-6. [PMID: 16209448 DOI: 10.3928/1081-597x-20050901-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To report a rare case of late bilateral ectasia developing after LASIK for low myopia without preoperative risk factors. METHODS A 21-year-old man underwent bilateral uneventful LASIK for low myopia of -2.75 diopters in both eyes. Preoperative corneal pachymetry was 531 microm in the right eye and 526 microm in the left eye. The total ablation depth was 46.8 microm in the right eye and 42.2 microm in the left eye. Preoperative corneal topography was normal and did not reveal forme fruste keratoconus. RESULTS Twenty-four months postoperatively, the patient developed bilateral inferior keratectasia of +0.50 -3.00 x 72 degrees in the right eye and +1.00 -2.75 x 99 degrees in the left eye. CONCLUSIONS Late keratectasia may follow LASIK for low myopia despite a thorough preoperative work-up.
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Affiliation(s)
- Tova Lifshitz
- Department of Ophthalmology, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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170
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Rajan MS, Watters W, Patmore A, Marshall J. In vitro human corneal model to investigate stromal epithelial interactions following refractive surgery. J Cataract Refract Surg 2005; 31:1789-801. [PMID: 16246786 DOI: 10.1016/j.jcrs.2005.02.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2005] [Indexed: 11/21/2022]
Abstract
PURPOSE To develop an in vitro human corneal model to evaluate stromal epithelial interactions following corneal refractive surgical procedures. SETTING Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom. METHODS Fifty-six human donor corneas procured from the eye bank were placed in a specially designed acrylic corneal holder and were cultured using the air-interface organ culture technique for up to 4 weeks. Corneal refractive surgical procedures such as a simple epithelial defect, 4 diopter (D) and 9 D photorefractive keratectomy (PRK), 4 D and 9 D laser-assisted subepithelial keratectomy (LASEK), and 9 D laser in situ keratomileusis (LASIK) were performed on the model. Temporal events in epithelial and keratocyte cell kinetics were evaluated using digital imaging, confocal microscopy, and light microscopy. Two-way analysis of variance and Student t tests were used to assess statistical significance. RESULTS Epithelial healing following PRK was completed by 92 hours +/- 10 (SD) at a rate of 0.58 +/- 0.45 mm2/hour. In LASEK, the epithelial flap was replaced by regenerating peripheral epithelium that showed significant delay in epithelial closure (120 +/- 5 hours) with prolonged latency (24 +/- 4 hours, P<.0001) in comparison with PRK. The magnitude of keratocyte loss corresponded to ablation depth, and keratocyte regeneration was dependent on epithelial closure. In comparison, LASIK corneas showed a lesser percentage of keratocyte loss with poor recovery of keratocyte density in the stromal flap. Epithelial viability and keratocyte density were well preserved in the in vitro human model as observed in control corneas for up to 4 weeks. CONCLUSIONS The temporal events in stromal epithelial interactions in the in vitro human model closely mimicked in vivo observations. The human model further avoided species-specific variations and provided a suitable test bed for evaluating newer algorithms and therapeutic regimens following refractive surgery.
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Affiliation(s)
- Madhavan S Rajan
- Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
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171
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Duffey RJ. Thin flap laser in situ keratomileusis: flap dimensions with the Moria LSK-One manual microkeratome using the 100-microm head. J Cataract Refract Surg 2005; 31:1159-62. [PMID: 16039490 DOI: 10.1016/j.jcrs.2004.10.056] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE To determine the predictability and consistency of corneal flap thickness, flap diameter, and hinge length with the modern 100 microm head of the Moria LSK-One manual microkeratome. SETTING Private clinic, office-based practice. METHODS Forty-two consecutive eyes with no previous surgery having thin flap laser in situ keratomileusis with the Moria LSK-One manual microkeratome had a new 100 microm (predicted flap thickness) head used for flap creation. Flap thickness was measured intraoperatively by subtraction ultrasound pachymetry (difference between central corneal thickness before flap cutting and residual stromal bed thickness after flap lifting). Vertical flap diameter and nasal hinge length were measured with calipers. RESULTS Mean flap thickness was 107 microm +/- 14 (SD) (range 82 to 137 microm). Standard deviation for mean vertical flap diameter was +/-0.24 mm. The cord length of the nasal hinge was variable with a mean of 4.26 +/- 0.63 mm (range 3.12 to 5.75 mm) in length. Postoperatively, there were no slipped flaps, flap striae, diffuse lamellar keratitis, or epithelial defects; there was 1 epithelial slide. At 1 day, the visual acuity was 20/20 or better in 76% of eyes. CONCLUSIONS The 100 microm head of the Moria LSK-One manual microkeratome cut a very predictable flap thickness and diameter but with variable length hinges. This flap thickness predictability was superior to that in other series with thicker intended flaps cut with mechanical microkeratomes and is comparable to that reported with the IntraLase FS femtosecond laser. Visual recovery was rapid, epithelial risks minimal, efficiency superior, and cost nominal relative to femtosecond laser technology.
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172
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Lifshitz T, Levy J, Rosen S, Belfair N, Levinger S. Central corneal thickness and its relationship to the patient's origin. Eye (Lond) 2005; 20:460-5. [PMID: 15877086 DOI: 10.1038/sj.eye.6701911] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES To report central corneal thickness (CCT) measurements on patients requesting refractive surgery and to search for possible associations between CCT and patient's origin, age, sex, and preoperative data. SETTING Department of Ophthalmology, Soroka University Medical Center, and Enaim Refractive Center, Beer-Sheva, Israel. METHODS Subjects were patients undergoing preoperative examination at our refractive centre during 2003. Patient's age, sex, preoperative CCT, refractive status, keratometry, and intraocular pressure (IOP) were obtained together with country of origin of the patients and their parents. Main outcome measures were CCT measurements and relationship between CCT and patient's origin and preoperative data. RESULTS A total of 204 patients were included in the study. Patients of North African origin had statistically significantly thinner corneas than patients of other origins (518.9+/-31.5 vs. 545.4+/-30.4 microm in the right eye and 518.4+/-32.1 vs. 546.3+/-29.7 microm in the left eye; P<0.00001). Patients of North African origin were significantly older than patients of other origins (P=0.028). No differences were found when comparing for sex, intraocular pressure, refractive status, and keratometry. When multivariate analysis was performed patient's origin was the only independently associated factor associated with CCT. CONCLUSIONS This is the first work in reporting lower CCT in people of North African origin examined in a refractive surgery centre. Studies from similar populations are needed to confirm our results.
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Affiliation(s)
- T Lifshitz
- Department of Ophthalmology, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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173
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Jaycock PD, O'Brart DPS, Rajan MS, Marshall J. 5-year follow-up of LASIK for hyperopia. Ophthalmology 2005; 112:191-9. [PMID: 15691550 DOI: 10.1016/j.ophtha.2004.09.017] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Accepted: 09/02/2004] [Indexed: 11/19/2022] Open
Abstract
PURPOSE To assess the long-term efficacy and stability of LASIK for hyperopia (+0.75 to +7.00 diopters [D]). DESIGN Retrospective follow-up study of a previous phase III multicenter clinical trial (unpublished data). PARTICIPANTS Patients who had been treated for hyperopia (33 individuals, 47 eyes) attended follow-up 5 years after surgery. The preoperative mean spherical equivalent at the spectacle plane was +3.58 D (range, +0.75 to 7.00 D), and the attempted mean spherical correction at the corneal plane was +3.18 D (range, +1.00 to +6.00 D). INTERVENTION Treatments were performed using a Moria LSK One microkeratome and a Summit Technology SVS Apex Plus excimer laser fitted with an Axicon. MAIN OUTCOME MEASURES Manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity, corneal transparency, complications, and patient satisfaction were recorded. RESULTS At 5 years, for treatments between +1.00 to +3.00 D, 71.0% of eyes were within +/-1.00 D of the intended correction, and for treatments between +3.5 to +6.0 D, 37.5% of eyes were within +/-1.00 D of intended correction. From 12 to 54 months after surgery for all patients, there was a hyperopic shift of +0.53 D (range, -0.13 to +3.13 D), with 51.1% of eyes experiencing an increase of +0.50 D or more and 27.7% of eyes showing a hyperopic shift of more than +1.00 D. This hyperopic shift was +0.67 D (range, 0 to +1.125 D) for patients younger than 40 years of age and +0.44 D (range, -1.33 to +1.50 D) for patients between 43 and 55 years of age. CONCLUSIONS LASIK was moderately effective for the correction of low degrees of hyperopia. However, there was regression throughout the 5-year follow-up that was greater than would be expected as a result of aging. Long-term stability of hyperopic LASIK refractive corrections, therefore, is uncertain.
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Affiliation(s)
- Philip D Jaycock
- Rayne Institute, Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom
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174
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Flanagan GW, Binder PS. The Theoretical vs. Measured Laser Resection for Laser in situ Keratomileusis. J Refract Surg 2005; 21:18-27. [PMID: 15724681 DOI: 10.3928/1081-597x-20050101-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To measure the excimer laser resection during and after laser in situ keratomileusis (LASIK) and to determine the rate of stromal ablation and factors predicting its measurement. METHODS A retrospective, comparative, interventional case study of 6010 eyes undergoing LASIK surgery was performed. In vivo ultrasonic pachymetry was performed as a measure of the laser resection (1'MLR). The theoretical laser resection generated by one of three separate excimer lasers (Summit Apex Plus, Alcon LadarVision, VISX) was recorded. The change in central comeal thickness measured at enhancement surgery (2'MLR) and the change in the residual stromal thickness prior to the laser ablation at the primary and enhancement procedure (3'MLR) were recorded as separate measures of the laser resection. Paired sample t test and regression analysis was performed to determine the relationships and to develop a model predictive of laser resection for each laser. RESULTS For all lasers, 1'MLR produced the highest estimate compared to 3'MLR. Laser-induced stromal desiccation, microkeratome effects, and change in measured flap thickness were the most likely causes for the differences. Laser resection was overestimated in the Alcon theoretical laser resection group, but underestimated in the Summit and VISX groups. The difference between 2'MLR and 3'MLR was due to epithelial hyperplasia, which measured 8.3, 17.8, and 10.8 microm in the Alcon, Summit, and VISX enhancement groups, respectively. Stromal ablation rates were 11.79, 8.26, and 12.71 microm per spherical equivalent diopter laser setting for the Alcon, Summit, and VISX lasers, respectively, when measured with 3'MLR. Multiple pre- and perioperative factors were associated with laser resection. CONCLUSIONS To accurately predict residual corneal thickness, the expected laser resection for an attempted refractive change must be known. As the laser resection can be laser-specific, the surgeon needs to establish the mean and range of tissue removal for a given attempted correction.
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175
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Versace P, Watson SL. Cornea-sparing laser in situ keratomileusis: Ablation on the flap. J Cataract Refract Surg 2005; 31:88-96. [PMID: 15721700 DOI: 10.1016/j.jcrs.2004.10.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE To evaluate the safety and efficacy of laser ablation on the flap as a treatment for a refractive error. SETTING Laser Sight Centres, Sydney, Australia. METHODS In this noncomparative case series, 142 treatments were performed in 98 patients using cornea-sparing laser in situ keratomileusis (LASIK) with ablation of the corneal flap and, in some cases, also the stromal bed for spherical equivalent (SE) refractive errors from -0.50 diopter (D) to -12.38 D. The procedure was performed as a primary treatment in 104 eyes, an initial enhancement in 32 eyes, and a second enhancement in 6 eyes. Data were extracted for analysis by retrospective review of patients' charts. RESULTS After LASIK, the mean SE was -0.20 D +/- 0.47 (SD) (range +0.87 to -2.35 D) excluding eyes with monovision. The 6 eyes with monovision had a mean SE of -1.90 D with myopia of -1.70 D (range -1.00 to -3.00 D) and mean astigmatism of -0.37 D (range 0 to -0.75 D). Excluding eyes with monovision, 97% of eyes achieved an uncorrected visual acuity of 6/12 or better and 64% of eyes, better than or equal to 6/6. Ninety-six percent were within +/-1.0 D of the intended correction (SE). The safety index was 1.02 and the efficacy index, 0.8. CONCLUSIONS Laser ablation of the corneal flap achieved good visual results and enabled preservation of the posterior corneal stroma. This technique may aid the prevention of corneal keratectasia following LASIK.
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Baumeister M, Bühren J, Kohnen T. Position of angle-supported, iris-fixated, and ciliary sulcus-implanted myopic phakic intraocular lenses evaluated by Scheimpflug photography. Am J Ophthalmol 2004; 138:723-31. [PMID: 15531305 DOI: 10.1016/j.ajo.2004.06.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2004] [Indexed: 11/29/2022]
Abstract
PURPOSE To examine postoperative positional stability of myopic phakic intraocular lenses (IOLs). DESIGN Prospective, nonrandomized clinical study. METHODS The study included 46 eyes which received an anterior chamber angle-supported (Bausch & Lomb NuVita; 10 eyes), anterior chamber iris-fixated (Ophtec Artisan; 20 eyes) or ciliary sulcus-implanted phakic IOL (Staar ICL; 16 eyes). The distance between the phakic IOL and the crystalline lens and the cornea as well as rotation around the optical axis was evaluated using Scheimpflug photography at 1, 3 to 6, and 12 months postsurgery. RESULTS The anterior chamber phakic IOLs showed no significant movement in anteroposterior direction. The posterior chamber phakic IOL showed a significant movement toward the crystalline lens between postoperative months 3 and 12. The median amount of rotation around the optical axis between the 3- and the 12-month evaluation was 1.9 degrees (range = 0.0-33.5 degrees) for the NuVita, 0.6 degrees (range = 0.0-3.5 degrees) for the Artisan, and 0.9 degrees (range = 0.2-2.3 degrees) for the ICL. Four NuVita IOLs rotated more than 10 degrees. CONCLUSIONS The angle-supported anterior chamber phakic IOLs showed a generally stable position regarding distance to cornea and natural lens, but rotation was observed in four IOLs. The iris-fixated phakic IOL showed the highest overall stability. The posterior chamber phakic IOL was stable in terms of rotation but had a tendency to decrease in distance toward the crystalline lens. Intraocular lenses implanted in phakic eyes followed for 12 months demonstrate stable IOL position overall.
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Affiliation(s)
- Martin Baumeister
- Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
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178
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Sekundärglaukom nach LASIK — Fallbericht. SPEKTRUM DER AUGENHEILKUNDE 2004. [DOI: 10.1007/bf03163176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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179
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Abstract
PURPOSE We describe ten patients who developed progressive keratectasia following laser in situ keratomileusis (LASIK) and identify possible factors that may lead to ectasia. METHODS In this retrospective study, we reviewed the files of 3,634 patients (6941 eyes) who had LASIK between March 2000 and April 2003. Ten patients (14 eyes, 0.2%) developed progressive keratectasia. We also evaluated consequent therapeutic measures and final visual status of these patients. RESULTS Patients were examined at a mean 24.9 +/- 8.1 months after LASIK. Ectasia developed within a mean 14 +/- 0.3 months after surgery. At baseline, mean keratometric power was 44.7 +/- 2.30 D, mean corneal thickness was 516 +/- 18.9 microm, and mean attempted correction was -10.85 +/- 3.20 D. We found a statistically significant correlation between residual stromal thickness, attempted correction, and occurrence of progressive keratectasia. We also found that preexisting abnormal corneal topography was a risk factor for progressive keratectasia. Ultimately, most patients had reasonable visual acuity after penetrating keratoplasty. CONCLUSION Progressive keratectasia is a vision threatening complication of LASIK that may occur in previously healthy or diseased eyes. The most important risk factors are residual stromal thickness and preexisting abnormal corneal topography. Penetrating keratoplasty may be a reasonable therapeutic measure for severe cases of progressive keratectasia.
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Affiliation(s)
- Ahmad Salamat Rad
- Cornea and Refractive Section, Novin Didegan Eye Center, Tehran, Iran.
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Nichamin LD. Incomplete flap with characteristics similar to corneal ectasia. J Cataract Refract Surg 2004; 30:1821-2. [PMID: 15342031 DOI: 10.1016/j.jcrs.2004.06.079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Laser literature watch. Photomed Laser Surg 2004; 22:261-76. [PMID: 15315736 DOI: 10.1089/1549541041438588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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