Oculocardiac reflex in sedated patients having laser in situ keratomileusis.

PURPOSE: To eliminate stress as a variable in assessing the frequency of the oculocardiac reflex during laser in situ keratomileusis (LASIK). SETTING: Merida Ophthalmological Hospital and Oftalmedica, Mexico City, Mexico. METHODS: A pulse oximeter registered the heart rate of 30 sedated patients having LASIK. Sedation was accomplished with a combination of midazolam and fentanyl. The heart rate was noted before and during suction. The results in 1 eye of each patient were recorded. Oculocardiac reflex was defined as a decrease of 10% or more of the basal heart rate. RESULTS: Fourteen patients (46.7%) had a 10% or more decrease in heart rate when suction was applied. Ten of the 14 had a decrease in heart rate between 10% and 19%, 3 between 20% and 29%, and 1 of more than 30%. Two patients (6.6%) had an increase in the basal heart rate of more than 10%. CONCLUSIONS: The findings suggest that the oculocardiac reflex occurs more frequently in sedated patients than in nonsedated patients.     

Contact lens fitting in a patient with keratectasia after laser in situ keratomileusis

We present a case of unilateral iatrogenic keratectasia developing 15 months after bilateral laser in situ keratomileusis using a broad-beam excimer laser (Bausch & Lomb Keracor 116) to treat -3.5 -1.5 x 85 diopters of myopia. Preoperative pachymetry in the eye measured 450 microm without topographical changes suggesting keratoconus or forme fruste keratoconus. Contact lens fitting to provide 20/25 visual acuity is described.     

Intrastromal corneal ring segments in a patient with previous laser in situ keratomileusis

PURPOSE: Intrastromal corneal ring segments (ICRS; Intacs) were inserted in a patient with residual myopia of -3.375 D (spherical equivalent) 10 months after laser in situ keratomileusis (LASIK). METHODS: A standard intrastromal corneal ring segment implantation technique was used with the addition of intraoperative ultrasonic pachymetry in 4 quadrants at the 7-mm zone to insure adequate stromal thickness for segment insertion. RESULTS: Four months after ICRS surgery and 14 months after LASIK, the patient had uncorrected visual acuity of 20/20 and a cycloplegic refraction of plano -1.00 x 23 degrees. CONCLUSION: Implantation of intrastromal corneal ring segments in an eye with previous LASIK resulted in additional corneal flattening with a decrease in residual myopia and improved uncorrected visual acuity.     

Choroidal neovascularization after laser in situ keratomileusis in a patient with low myopia

We report a case of choroidal neovascularization after laser in situ keratomileusis in a 37-year-old man with low myopia.     

Visual experience and patient satisfaction with wavefront-guided laser in situ keratomileusis

PURPOSE: To determine the correlation between patient perception and clinical measurements after wavefront-guided laser in situ keratomileusis (LASIK). SETTING: Multicenter clinical trial. METHODS: In this retrospective analysis of clinical study results in 274 eyes, wavefront-guided LASIK procedures were performed in 274 myopic-astigmatic eyes at 6 sites. Comprehensive evaluations of vision and ocular health were conducted preoperatively and for 6 months postoperatively. Visual acuity and contrast sensitivity were measured, and questionnaires were administered. Questionnaire responses were compared with clinical measurements. RESULTS: The overall distribution shifted toward "more satisfied." The "very satisfied" population increased by as much as 70% in all areas. There was no significant change in frequency of visual symptoms. Patients were more expressive about visual decline than visual improvement. Perception of changes in vision appeared to be related to mesopic contrast sensitivity and mesopic contrast sensitivity under glare. Mesopic pupil diameter was not a major predictor of patient satisfaction. Contact lens wearers were more satisfied with postoperative vision than were spectacle wearers. Men were more likely to report visual symptoms and to complain about night vision, although their changes were the same as those of the women. Residual refractive error was a major predictor for most questionnaire items. CONCLUSION: Most patients were as satisfied or more satisfied with their postoperative uncorrected visual acuity than with their preoperative best corrected visual acuity. By continuing to minimize postoperative refractive error through the use of nomograms and improved technology, visual complaints such as night glare and halo could be diminished or even eliminated. The study shows that subjective experience affected satisfaction with results. Some dissatisfaction might be mitigated by being sure patients are educated and have realistic expectations before surgery.     

LASEK治疗LASIK术后屈光欠矫

目的 :探讨准分子激光上皮下角膜磨镶术 (LASEK)治疗准分子激光原位角膜磨镶术 (LASIK)术后屈光欠矫的疗效。方法 :对LASIK术后屈光欠矫的 11例 (2 0只眼 )施行LASEK。结果 :术后 6个月视力和屈光度趋于稳定 ,术后 3个月角膜Haze 0级者 15只眼 ,0 5级者 4只眼 ,1级者 1只眼。术后 6个月 ,裸眼视力≥ 0 6、≥ 1 0者分别为 2 0只眼 (10 0 % )、14只眼 (70 % )。屈光度≤± 1 0 0D者为 19只眼 (95 % )。结论 :LASEK治疗LASIK术后屈光欠矫安全 ,有效。     

准分子激光原位角膜磨镶术适应证的选择

准分子激光原位角膜磨镶术是目前临床最常用的角膜屈光手术.术前应当严格把握适应证,特别是对角膜厚度薄、瞳孔大、顿挫型圆锥角膜或其他角膜扩张、自身免疫性疾病、单纯疱疹病毒角膜炎、青光眼、角膜的生物力学异常以及角膜屈光术后、白内障术后和穿透性角膜移植术后残留屈光不正等一些特殊患者的手术方式选择及相应处理,才能更好地提高手术成功率,并减少术后并发症.     

二次LASIK手术治疗近视欠矫

评价再次ＬＡＳＩＫ矫正残余近视的效果,可预测性、安全性。方法对４０只眼ＬＡＳＩＫ术后屈光欠矫的患者行二次手术,两次手术间隔时间３－２４个月。分别在二次术后３天、１、３和６个月随访观察。结果术后各随访时间患眼平均裸眼视力较术前明显提高,最佳矫正视力与术前无显著差异,术后后平均屈光度较术前减,差异有显著性,切削直径适量增大可减术后屈光回退;结论二次ＬＡＳＩＫ手术是必要、安全、可行的。     

准分子激光原位角膜磨镶术的并发症

准分子激光原位角膜磨镶术是目前最常见的一种角膜屈光手术,但是它仍然存在并发症,如角膜瓣相关并发症、准分子激光消融的并发症、弥漫性角膜炎、感染性角膜炎、角膜瓣下上皮植入、干眼、医源性圆锥角膜及视网膜病变等,只有尽早作出诊断并进行相关处理,才能提高手术成功率.     

Cyclotorsion during laser in situ keratomileusis

PURPOSE: To determine the magnitude of cyclotorsion during excimer laser ablation using a dynamic iris eye tracker. SETTING: Guy Hugh Chan Refractive Surgery Centre, Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong, China. METHODS: This retrospective study comprised 245 eyes (137 patients) that had laser in situ keratomileusis (LASIK) for myopia with or without astigmatism by the same surgeon. The magnitude of cyclotorsion during LASIK was recorded as the maximum, average, and minimum positions according to the angle of deviation displayed on the excimer laser computer screen. Measurements of cyclotorsion were performed during laser ablation. RESULTS: The mean total cyclotorsion was 2.181 degrees +/- 1.392 (SD) (range 0.0 to 13.3 degrees). The mean average position (AP) was +0.134 +/- 1.851 degrees (range -7.0 degrees [excyclotorsion] to +12.6 degrees [incyclotorsion]). Forty-five eyes (18.4%) had an AP greater than +/-2 degrees, and 168 eyes (68.6%) deviated from the zero position at the onset of laser ablation. The mean incyclotorsion was 2.136 +/- 1.440 degrees (78 eyes, 31.8%) and the mean excyclotorsion, 1.772 +/- 0.809 degrees (78 eyes, 31.8%). Eighty-six eyes (35.1%) had cyclotorsion in both directions (mixed cyclotorsion). The mean cyclotorsion was 2.670 +/- 1.588 degrees. Eight (3.3%) of the 109 patients having simultaneous bilateral LASIK had bilateral incyclotorsion or bilateral excyclotorsion. CONCLUSIONS: Cyclotorsion occurs before and during laser ablation. An active rotational eye tracker is fundamental to compensate for cyclotorsion and to enable greater precision in excimer laser ablation delivery.     

Ectasia after laser in situ keratomileusis

Eighty-five cases of post laser in situ keratomileusis ectasia were reviewed and analyzed. Cases of keratoconus or forme fruste keratoconus were eliminated; many remaining case reports lacked key information. The current literature is unable to define a specific residual corneal thickness or a range of preoperative corneal thickness that would put an eye at risk for developing ectasia. The most logical cause for eyes without preexisting pathology to develop ectasia is a postablation stromal thickness that is mechanically unstable; this "minimal" thickness is probably specific to each eye. The preoperative and postoperative corneal thickness, measured flap thickness, and microkeratome and laser parameters used in a given case are required to determine the range of residual corneal thickness that puts the eye at risk for developing ectasia. Other as yet undetermined factors may play a role in the development of this complication.     

Autorefractometry after laser in situ keratomileusis

PURPOSE: To correlate cycloplegic subjective refraction with cycloplegic autorefractometry in eyes that have had laser in situ keratomileusis (LASIK). SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Subjective refraction and autorefractometry under cycloplegia were performed in 73 eyes of 46 patients 1, 6, and 12 months after LASIK to correct myopia or myopic astigmatism. The preoperative subjective refraction and autorefractometry under cycloplegia in the same eyes served as controls. RESULTS: A statistically significant difference between subjective refraction and autorefraction was found in the sphere and cylinder at all postoperative times. No statistically significant difference was found in the axis. There was no statistically significant difference in the control eyes. CONCLUSIONS: Automated refractometry in eyes that had had LASIK was reliable in the axis only. Retreatments after LASIK should always be based on subjective refraction.     

Retreatment after laser in situ keratomileusis

ObjectiveTo evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment for correcting residual myopia.DesignRetrospective noncomparative case series.Participants and interventionFifty-nine consecutive eyes (43 patients) underwent LASIK retreatment at 3 or 6 months after the primary LASIK procedure. Lifting the corneal flap and reablating the stromal bed with a VISX 20/20 excimer laser was the procedure used for LASIK enhancement.Main outcome measuresThe following parameters were studied before and after retreatment: visual acuity, refraction, videokeratography, applanation tonometry, and corneal thickness. Complications after LASIK enhancement also were evaluated. Follow-up was 12 months.ResultsBefore retreatment, only 3.38% of eyes (2 of 59) had an uncorrected visual acuity of 0.5 (20/40) or better, and after retreatment, this percentage increased to 60% (30 of 50) at 6 months and 61.8% (34 of 55) at 12 months. After reoperation, mean best-corrected visual acuity improved by half a line over the values before retreatment. The preretreatment refraction of −2.92 ± 1.22 diopters (D) (mean ± standard deviation) decreased significantly to −0.44 ± 0.80 D at 6 months and to −0.61 ± 0.82 D at 12 months (P < 0.001). In 82% of eyes (41 of 50) at 6 months and 81.8% (45 of 55) at 12 months, the spherical equivalent was within 1.00 D of emmetropia. There was a significant regression of effect (0.38 D) between 3 and 12 months (P < 0.01). Postretreatment refraction was related to the original refraction before the primary LASIK, the preretreatment refraction, and the ablation diameter used. Although no vision-threatening complications were found, epithelial ingrowth and flap melting were more common after than before LASIK retreatment, with 31% of eyes at 12 months with epithelial ingrowth and 10.9% with flap melting. However, LASIK enhancement improved decentration and night-vision problems.ConclusionsLASIK retreatment was an effective and predictable procedure for correcting residual myopia. Epithelial ingrowth and flap melting were more frequent after than before LASIK retreatment, whereas decentration and night-vision symptoms improved.     

Ptosis after laser in situ keratomileusis

We present a patient who developed partial ptosis after laser in situ keratomileusis.     

Ectasia after laser in situ keratomileusis

PURPOSE OF REVIEW: The potential for litigation has resulted in increased interest in ectasia after laser in situ keratomileusis. This article summarizes papers written during this past year on this subject. RECENT FINDINGS: A panel of refractive surgery experts have summarized the current state of knowledge on this subject and provided guidelines to minimize risk. Because ectasia may occur in the absence of risk factors, there may be corneas with biomechanical factors not detectable with present technology which are at risk. Several articles point out the limitations of the Orbscan (Bausch & Lomb, Rochester, New York, USA), in particular its accuracy and reproducibility with regard to data generated from the posterior surface of the cornea. A biomechanical model of the cornea is proposed which suggests that each cornea's response to laser in situ keratomileusis is unique. Several case reports are also reviewed which provide insight into pathogenesis and potential new treatment options; these include reports on histopathology, topographic pseudokeratectasia, ectasia from transient raised intraocular pressure, poor response to laser in situ keratomileusis after incisional surgery, intracorneal rings, collagen cross-linking and conductive keratoplasty to stabilize and sphericize the cornea with ectasia. SUMMARY: Our knowledge about ectasia is still in evolution. Insights into the biomechanics and genetics of the cornea may allow us to further reduce its occurrence.     

准分子激光原位角膜磨镶术适应证的选择

准分子激光原位角膜磨镶术是目前临床最常用的角膜屈光手术.术前应当严格把握适应证,特别是对角膜厚度薄、瞳孔大、顿挫型圆锥角膜或其他角膜扩张、自身免疫性疾病、单纯疱疹病毒角膜炎、青光眼、角膜的生物力学异常以及角膜屈光术后、白内障术后和穿透性角膜移植术后残留屈光不正等一些特殊患者的手术方式选择及相应处理,才能更好地提高手术成功率,并减少术后并发症.     

LASIK术后继发性圆锥角膜研究进展

继发性圆锥角膜是激光原位角膜磨镶术(LASIK)后最严重的并发症之一,临床表现为最佳矫正视力下降、散光增加、屈光回退、暗视力问题、角膜地形图异常、角膜前凸、进行性的角膜变薄等,本文就其病因、诊断、预防和治疗作一综述。