Zyoptix wavefront-guided versus standard photorefractive keratectomy (PRK) in low and moderate myopia: randomized controlled 6-month study

PURPOSE: To evaluate the refractive and aberrometric outcome of wavefront-guided photorefractive keratectomy (PRK) compared to standard PRK in myopic patients. METHODS: Fifty-six eyes of 56 patients were included in the study and were randomly divided into two groups. The study group consisted of 28 eyes with a mean spherical equivalent (SE) of -2.25+/-0.76 diopters (D) (range: -1.5 to -3.5 D) treated with wavefront-guided PRK using the Zywave ablation profile and the Bausch & Lomb Technolas 217z excimer laser (Zyoptix system) and the control group included 28 eyes with a SE of -2.35+/-1.01 D (range: -1.5 to -3.5 D) treated with standard PRK (PlanoScan ablation) using the same laser. A Zywave aberrometer was used to analyze and calculate the root-mean-square (RMS) of total high order aberrations (HOA) and Zernike coefficients of third and fourth order before and after (over a 6-month follow-up period) surgery in both groups. Preoperative and postoperative SE, un-corrected visual acuity (UCVA), and best-corrected visual acuity (BCVA) were evaluated in all cases. RESULTS: There was a high correlation between achieved and intended correction. The differences between the two treatment groups were not statistically significant for UCVA, BCVA, or SE cycloplegic refraction . Postoperatively the RMS value of high order aberrations was raised in both groups. At 6-month control, on average it increased by a factor of 1.17 in the Zyoptix PRK group and 1.54 in the PlanoScan PRK group (p=0.22). In the Zyoptix group there was a decrease of coma aberration, while in the PlanoScan group this third order aberration increased. The difference between postoperative and preoperative values between the two groups was statistically significant for coma aberration (p=0.013). No statistically significant difference was observed for spherical-like aberration between the two groups. In the study group eyes with a low amount of preoperative aberrations (HOA RMS lower than the median value; <0.28 microm) showed an increase of HOA RMS while eyes with RMS higher than 0.28 microm showed a decrease (p<0.05). CONCLUSIONS: Zyoptix wavefront-guided PRK is as safe and efficacious for the correction of myopia and myopic astigmatism as PlanoScan PRK. Moreover this technique induces a smaller increase of third order coma aberration compared to standard PRK. The use of Zyoptix wavefront-guided PRK is particularly indicated in eyes with higher preoperative RMS values.     

Wavefront- and topography-guided ablation in myopic eyes using Zyoptix

PURPOSE: To evaluate the results of wavefront- and topography-guided ablation in myopic eyes using Zyoptix (Bausch & Lomb). SETTING: Eye Research Center and Dr. Agarwal's Eye Hospital, Chennai, India. METHODS: This observational case study comprised 150 eyes with myopia and compound myopic astigmatism. Preoperatively, the patients had corneal topography with Orbscan IIz (Bausch & Lomb) and wavefront analysis with the Zywave aberrometer (Bausch & Lomb) in addition to the routine workup before laser in situ keratomileusis (LASIK). The results were assimilated using Zylink software (Bausch & Lomb), and a customized treatment plan was formulated. Laser in situ keratomileusis was performed with the Technolas 217 system (Bausch & Lomb). The patients were followed for at least 6 months. RESULTS: The mean preoperative best corrected visual acuity (BCVA) (in decimal equivalent) was 0.83 (20/25) +/- 0.18 (SD) (range 0.33 to 1.00) and the mean postoperative (6 months) BCVA, 1.00 (20/20) +/- 0.23 (range 0.33 to 1.50). Three eyes (2%) lost 2 or more lines of best spectacle-corrected visual acuity. The safety index was 1.20. The mean preoperative uncorrected visual acuity (UCVA) was 0.06 (20/350) +/- 0.02 (range 0.01 to 0.50) and the mean postoperative UCVA, 0.88 (20/25) +/- 0.36 (range 0.08 to 1.50). The efficacy index was 14.66. The mean preoperative spherical equivalent (SE) was -5.25 +/- 1.68 diopters (D) (range -0.87 to -15.00 D) and the mean postoperative SE (6 months), -0.36 +/- 0.931 D (range -4.25 to +1.25 D). At 6 months, the UCVA was 1.00 (6/6) or better in 105 eyes (69.93%) and 0.5 (6/12) or better in 126 eyes (83.91%). The postoperative aberrations were decreased compared with the preoperative aberrations. One eye (0.66%) had a free cap during LASIK with subsequent loss of 2 lines of BCVA and induced higher-order aberrations (HOAs). Nine patients (11.2%) complained of halos at night. CONCLUSIONS: Wavefront- and topography-guided LASIK leads to improve visual performance by decreasing HOAs. Scotopic visual complaints may be reduced with this method.     

Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up

PURPOSE: To evaluate the clinical outcomes 6 months after wavefront-guided laser in situ keratomileusis (LASIK) for myopia in Japan. SETTING: Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. METHODS: This prospective study comprised 22 eyes of 12 patients treated with wavefront-guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years +/- 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was -7.30 +/- 2.72 diopters (D) (range -2.75 to -11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer and the Technolas 217z flying-spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront-guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. RESULTS: At 6 months, 10 eyes had no change in best spectacle-correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd-order aberrations decreased and higher-order aberrations increased. In the 3rd order, aberrations increased in the high-myopia group (-6.0 D or worse) and decreased in the low to moderate-myopia group (better than -6.0 D). CONCLUSION: Wavefront-guided LASIK was a good option for refractive surgery, although a longer follow-up in a larger study is required.     

Laser in situ keratomileusis for myopia and compound myopic astigmatism using the Technolas 217 scanning-spot laser

PURPOSE: To evaluate the safety, efficacy, predictability, and visual results of laser in situ keratomileusis (LASIK) using the Bausch & Lomb Technolas(R) 217 scanning-spot laser for the treatment of myopia and compound myopic astigmatism. SETTING: Stanford Eye Laser Center, Stanford, California, USA. METHODS: In a prospective study, 110 eyes of 58 patients with a mean spherical equivalent (SE) of -4.87 diopters (D) +/- 2.5 (SD) (range -1.0 to -11.4 D) had LASIK for myopia and compound myopic astigmatism using the Technolas 217 scanning-spot laser. The primary outcome variables included preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), achieved versus attempted correction, vector analysis of astigmatism, and complications. RESULTS: One hundred ten eyes were available for analysis at 3 months. The mean SE refraction was reduced 95% (mean -0.23 +/- 0.4 D), and astigmatism was reduced 70% (mean 0.28 +/- 0.3 D). One day postoperatively, 100% of eyes had a UCVA of 20/40 or better, 96% had 20/25 or better, 77% had 20/20 or better, and 39% had 20/15 or better. At the 3-month examination, 100% of eyes had a UCVA of 20/40 or better, 95% had 20/25 or better, 83% had 20/20 or better, and 48% had 20/15 or better. Ninety percent of eyes were within +/-0.5 D of emmetropia. No eye lost 2 or more lines of BSCVA. CONCLUSIONS: The Technolas 217 scanning-spot laser produced excellent postoperative UCVA and BSCVA. It was predictable, safe, and effective for the treatment of myopia and compound myopic astigmatism. Long-term follow-up is needed to assess the stability of the procedure.     

Outcomes of laser in situ keratomileusis in a Refractive Surgery fellowship program

PURPOSE: The purpose of this study was to document the learning curve and evaluate the success of laser in situ keratomileusis (LASIK) performed by fellows in a Cornea/External Disease and Refractive fellowship program. METHODS: Two surgeons performed LASIK within a fellowship training program between July 2000 and August 2001. A retrospective review was conducted to determine the visual outcomes and operative complications from this non-comparative case series of 755 consecutive eyes. All LASIK procedures were performed using a Bausch & Lomb Technolas 217A laser and the Bausch & Lomb Hansatome or the Automated Corneal Shaper microkeratome. All eyes were evaluated for operative complications. Visual acuity was reported with a minimum of 1 month follow-up. RESULTS: Data analysis revealed that uncorrected visual acuity of 20/40 or better was attained in 99.4% of treated eyes, and 20/20 or better in 77.2%. With both eyes open, 100% of patients saw 20/30 or better, 94% saw 20/20 or better, 70% saw 20/15 or better, and 5.5% saw 20/10. Flap related complications occurred in 7 of 755 eyes (0.9%) and all were successfully treated. Forty-two eyes (5.6%) were lost to follow-up prior to the 1-month examination and were excluded from analysis of visual acuity. CONCLUSIONS: Favorable operative and visual acuity 1-month results in 755 eyes after LASIK with the Bausch & Lomb Technolas 217A laser were in part due to a well organized system of education, patient examination, execution of surgery, and postoperative care. A team approach was essential.     

Clinical outcome of wavefront-guided laser in situ keratomileusis in eyes with moderate to high myopia with thin corneas

PURPOSE: To evaluate the clinical outcome of wavefront-guided laser in situ keratomileusis (LASIK) for the treatment of moderate to high myopia associated with a thin cornea. SETTING: Enaim Laser Medical Center, Tel Aviv, Israel. METHODS: This retrospective study included 98 eyes of 49 patients with moderate to high myopia (-5.20 to -10.35 diopters [D]) and thin corneas (456 to 498 mum) treated with wavefront-guided LASIK (Zyoptix, Bausch & Lomb) and followed for 36 months. Preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer, and treatment was performed with the Technolas 217 z excimer laser system (Bausch & Lomb). Final refraction data, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), optic zone size, ablation depth, optical aberrations, and night glare complaints were evaluated. RESULTS: Mean patient age was 28 years +/- 7 (SD), and mean preoperative spherical equivalent refraction was -7.06 D (range -5.20 to -10.35 D). Final UCVA ranged between 6/6 and 6/30. The safety index of the technique was 1.03, and the efficacy index was 0.67. Undercorrection of more than 0.50 D was observed in 41.3% of the high-myopic eyes (-7.00 to -10.35 D, n = 58) compared with 10% in the moderately myopic eyes (-5.00 to -6.75 D, n = 40). A significant reduction in spherical aberration (Z(4)0) was found 12 months postoperatively in all eyes. Night glare was documented in 4 eyes (4%) in the high myopia group. There were no cases of corneal ectasia. CONCLUSION: Zyoptix was safe in eyes with moderate to high myopia with relatively thin corneas (<498 microm). For myopia between -7.00 D and -10.35 D, a small optical zone (4.3 to 5.6 mm) may be applied as night glare was relatively rare, but significant undercorrection should be expected.     

Bitoric laser in situ keratomileusis for astigmatism

PURPOSE: To evaluate the efficacy, predictability, and safety of bitoric laser in situ keratomileusis (LASIK) for the correction of mixed astigmatism. SETTING: Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: This prospective study included 28 eyes of 21 patients with mixed astigmatism who had bitoric LASIK using the Hansatome microkeratome (Bausch & Lomb Surgical) and the Chiron Technolas 217 excimer laser (Bausch & Lomb Surgical). The main outcome measures were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), defocus equivalent, blur strength, and refraction. RESULTS: Six months after bitoric LASIK, the mean UCVA was 0.70 +/- 0.23 (SD). The percentage of eyes with a UCVA of 20/40 or better was 78.6% and of 20/20, 21.4%. There was a statistically significant increase in the mean BCVA from 0.71 +/- 0.19 before surgery to 0.83 +/- 0.15 at 6 months (P =.0004). Three eyes (10.7%) lost 1 line of BCVA; 19 eyes (67.9%) gained 1 or more lines. The mean preoperative astigmatism of -4.04 +/- 1.13 diopters (D) was reduced to -0.67 +/- 0.79 D after surgery. The defocus equivalent was less than 1.00 D in 75.0% of eyes and less than 0.50 D in 64.3%. Vector analysis showed that the mean achieved correction was 97.4% of the intended correction. CONCLUSIONS: Bitoric LASIK was a safe, effective, and predictable procedure in the treatment of mixed astigmatism. It is a means to improving BCVA in a significant percentage of patients.     

Laser in situ keratomileusis for residual myopia after primary LASIK

PURPOSE: To analyze the results of secondary laser in situ keratomileusis (LASIK) for residual myopia after primary LASIK. SETTING: Dr. Agarwal's Eye Hospital, Chennai, India. METHODS: A retrospective study of 50 eyes of 29 patients who had a secondary LASIK procedure was carried out. After a mean follow-up of 5.84 months +/- 3.24 (SD) after the primary procedure, the mean myopic residual refraction was -4.30 +/- 1.83 diopters (D). In 10 eyes, the primary corneal flap was lifted by blunt dissection. In 40 eyes, the flap was made with a second cut. The secondary LASIK was performed using the Chiron Technolas Keracor 217 excimer laser and the Automated Corneal Shaper microkeratome (Bausch & Lomb). RESULTS: The mean follow-up was 16.58 +/- 3.06 months. At 12 months, the mean spherical equivalent was -0.45 +/- 0.68 D (P <.05). Thirty-one eyes were emmetropic, 13 eyes were within +/-1.00 D of emmetropia, and 5 eyes were within +/-2.00 D. The mean uncorrected visual acuity improved from 20/80 (range 20/60 to 20/200) to 20/40 (range 20/20 to 20/200) (P <.005). Seventeen eyes gained 1 line of best spectacle-corrected visual acuity; 1 eye lost 1 line because of a decentered ablation with an induced postoperative astigmatism of -3.50 D cylinder. No sight-threatening complications such as a free cap, flap irregularity, corneal ectasia, or retinal complication occurred postoperatively. Epithelial ingrowth developed in 5 eyes and corneal thinning, in 1 eye. Three eyes had night glare. CONCLUSION: Secondary LASIK was a safe, stable, and effective method for the treatment of residual myopia after primary LASIK.     

Outcomes after laser in situ keratomileusis retreatment in high myopes

PURPOSE: To evaluate the refractive and visual performance after laser in situ keratomileusis (LASIK) retreatment. METHODS: A retrospective study was performed on 33 eyes of 23 patients who underwent LASIK (Bausch & Lomb Technolas 217C) retreatment for residual myopia with or without astigmatism. Parameters evaluated were uncorrected and best spectacle-corrected visual acuity, spherical equivalent refraction, contrast sensitivity, glare acuity, and pachymetry, preoperatively and at 1, 3, and 6 months postoperatively. RESULTS: The mean spherical equivalent refraction before primary LASIK was -9.89 +/- 4.00 D and before retreatment was -2.85 +/- 2.17 D. Although contrast sensitivity and glare acuity decreased significantly after primary LASIK (P<.05), no significant change in these parameters was observed after retreatment. Smaller ablation zones were associated with decreased contrast sensitivity and glare acuity after primary LASIK as well as following retreatment. Contrast sensitivity and glare acuity following primary LASIK were significantly better in eyes with ablation zones > or = 5 mm than those with < 5 mm (P<.05). Eyes in which the ablation zone was the same as that for primary LASIK had significantly better contrast sensitivity than those with different ablation zones (increased or decreased) during retreatment. Attempted refractive correction during primary LASIK and retreatment had a significant negative correlation with contrast sensitivity and glare acuity following primary LASIK as well as retreatment. CONCLUSION: The ablation zones following primary LASIK and retreatment should be > or = 5.00 mm and remain unchanged to improve visual performance.     

Wavefront-guided laser in situ keratomileusis with the Bausch & Lomb Zyoptix system

PURPOSE: To evaluate the clinical results of wavefront-guided laser in situ keratomileusis (LASIK) with the Zyoptix system. METHODS: Twelve patients (24 eyes) underwent wavefront-guided LASIK with the Bausch & Lomb Zyoptix system. Uncorrected and best spectacle-corrected visual acuity and manifest refraction were measured at postoperative day 1, week 1, and months 1 and 3. A subjective vision quality questionnaire evaluated light sensitivity, dryness, tearing, glare, halos, ghost images, and difficulties in night driving, preoperatively and 3 months postoperatively. RESULTS: Preoperatively, mean sphere was -3.70 +/- 2.33 D (range -0.50 to -8.00 D), mean cylinder was -0.90 +/- 0.98 D (range 0 to -3.00 D), and mean spherical equivalent refraction was -4.15 +/- 2.16 D (range -1.38 to -8.25 D). Three-month postoperative spherical equivalent refraction was within +/- 0.50 D of emmetropia in 17 eyes (70.8%) and within +/- 1.00 D in 22 eyes (91.7%). At 3 months postoperatively, no eyes lost any lines of BSCVA and eight eyes (33.3%) gained 2 lines. The ratio of postoperative BSCVA to preoperative BSCVA (safety) was 1.05 +/- 0.09 (range 1.00 to 1.20) at 1 month and 1.07 +/- 0.10 (range 1.00 to 1.29) at 3 months. The ratio of postoperative UCVA to preoperative BSCVA (efficacy) was 0.96 +/- 0.12 (range 0.80 to 1.20) at 1 month and 0.95 +/- 0.12 (range 0.8 to 1.2) at 3 months. The subjective vision quality questionnaire revealed less tearing, fewer halos, and less difficulty in night driving after wavefront-guided LASIK. Comparison of higher order optical aberrations before and after surgery was not done. CONCLUSIONS: Wavefront-guided LASIK with the Bausch & Lomb Zyoptix system was safe and effective in correcting low to moderate myopic refractive error.     

Higher order ocular aberrations in eyes with myopia in a Chinese population

PURPOSE: To describe the characteristics of higher order ocular aberrations of adult Chinese eyes with myopia. METHODS: Higher order aberrations in consecutive right eyes of 166 Chinese patients with myopia who enrolled for preoperative assessment for LASIK were retrospectively reviewed. Wavefront aberrations were measured with the Bausch & Lomb Zywave over a 6-mm dilated pupil. The correlations between higher order aberrations and myopia, astigmatism, and age, respectively, were analyzed. RESULTS: Mean patient age was 32.1 +/- 6.2 years, the mean refractive error was sphere -5.23 +/- 1.79 diopters (D) and cylinder -1.29 +/- 0.98 D. The mean of the total higher order root-mean-square (RMS) (third to fifth order) was 0.49 +/- 0.16 microm. Third-order RMS was largest (mean 0.37 +/- 0.16 microm), followed by fourth-order RMS (mean 0.29 +/- 0.11 microm). For individual higher order Zernike coefficients, spherical aberration (C4(0)) predominated with a mean of 0.23 +/- 0.14 microm. No correlation was found between total higher order RMS and myopia or between total higher order RMS and age. Small but statistically significant relationships were found in the following groups: age and vertical primary coma (C3(-1))(r=-0.206, P=.008); age and spherical aberration (C4(0)) (r=0.196, P=.012); and myopia and horizontal trefoil (C3(3)) (r=-0.158, P=.042). CONCLUSIONS: Higher order aberrations varied among individuals with myopia. Third-order RMS was the predominant higher order aberration. Spherical aberration and vertical primary coma increased slightly with age. Our study helps establish ocular aberration standards for Chinese refractive surgery candidates.     

Zyoptix节约角膜个体化LASIK治疗近视的疗效分析

目的:观察博士伦Zyoptix节约角膜个体化LASIK治疗近视的临床效果,同时分析术后高阶像差的变化。方法:因角膜相对较薄不适宜接受常规LASIK手术,而采用Zyoptix节约角膜个体化LASIK治疗的患者32例64眼,分析节约角膜的程度、术后1a余视力的恢复和6mm瞳孔直径下高阶像差的变化。结果:手术平均节约角膜组织29.27μm,节约组织达21.36%;术后1a余,裸眼视力为0.93±0.24,较术前裸眼视力显著提高(P<0.01),与术前最佳矫正视力0.96±0.09相似,比较无统计学差异;81%的眼裸眼视力≥术前最佳矫正视力,无1眼最佳矫正视力下降。在6mm瞳孔直径下,总体高阶像差、三阶彗差、四阶球差较术前分别增大1.76倍、2.10倍、3.90倍,与常规LASIK术相似。结论:Zyoptix节约角膜个体化LASIK可以节约角膜组织20%～25%,扩大近视治疗度数范围,临床上有良好的安全性、有效性和预测性。     

Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study

PURPOSE: To compare the outcomes of wavefront-guided and wavefront-optimized treatment in fellow eyes of patients having laser in situ keratomileusis (LASIK) for myopia. SETTING: Medical and Vision Research Foundation, Tamil Nadu, India. METHODS: This prospective comparative study comprised 27 patients who had wavefront-guided LASIK in 1 eye and wavefront-optimized LASIK in the fellow eye. The Hansatome (Bausch & Lomb) was used to create a superior-hinged flap and the Allegretto laser (WaveLight Laser Technologie AG), for photoablation. The Allegretto wave analyzer was used to measure ocular wavefront aberrations and the Functional Acuity Contrast Test chart, to measure contrast sensitivity before and 1 month after LASIK. The refractive and visual outcomes and the changes in aberrations and contrast sensitivity were compared between the 2 treatment modalities. RESULTS: One month postoperatively, 92% of eyes in the wavefront-guided group and 85% in the wavefront-optimized group had uncorrected visual acuity of 20/20 or better; 93% and 89%, respectively, had a postoperative spherical equivalent refraction of +/-0.50 diopter. The differences between groups were not statistically significant. Wavefront-guided LASIK induced less change in 18 of 22 higher-order Zernike terms than wavefront-optimized LASIK, with the change in positive spherical aberration the only statistically significant one (P= .01). Contrast sensitivity improved at the low and middle spatial frequencies (not statistically significant) and worsened significantly at high spatial frequencies after wavefront-guided LASIK; there was a statistically significant worsening at all spatial frequencies after wavefront-optimized LASIK. CONCLUSION: Although both wavefront-guided and wavefront-optimized LASIK gave excellent refractive correction results, the former induced less higher-order aberrations and was associated with better contrast sensitivity.     

Laser in situ keratomileusis for the correction of hyperopia from +0.50 to +11.50 diopters with the Keracor 117C laser

PURPOSE: To evaluate excimer laser in situ keratomileusis (LASIK) for the correction of hyperopia. METHODS: We reviewed retrospectively the medical records of 46 patients treated with LASIK for hyperopia. All patients had a complete ophthalmologic evaluation. The corneal bed was ablated using the Bausch & Lomb Chiron Keracor 117C excimer laser to create a paracentral annular ablation under a nasally hinged 160-microm corneal flap with the Chiron Automatic Corneal Shaper microkeratome. Follow-up was a minimum of 6 months. RESULTS: Eighty eyes of 46 patients (23 males and 23 females) were included. Age ranged from 18 to 65 years (mean, 42 yr). The range of preoperative spherical equivalent refraction was +0.50 to +11.50 D (mean, +3.40 D). Mean postoperative spherical equivalent refraction at 6 months was +0.26 D. Six months after surgery, 35 eyes (44%) achieved uncorrected visual acuity of 20/20 or better and 78 eyes (97.5%) achieved 20/40 or better. Forty-six eyes (58%) had a postoperative spherical equivalent refraction within +/-0.50 D of attempted correction, and 67 eyes (84%) were within +/-1.00 D of attempted correction. When using the Bausch & Lomb Chiron Keracor 117C excimer laser to correct hyperopia, eyes with a spherical equivalent refraction less +2.00 D should be overcorrected by 25%, +2.00 to +4.00 D by 30%, and over +4.00 by 40%. The positive cylinder should be overcorrected by 10%. CONCLUSIONS: LASIK was safe and effective in the treatment of hyperopia from +0.50 to +11.50 D. Regression following LASIK for hyperopia remains a problem. A special nomogram was required to achieve results comparable with those for myopia.     

Effect of flap thickness on higher order wavefront aberrations induced by LASIK: a bilateral study

PURPOSE: To investigate the effect of flap thickness on wavefront aberrations induced by LASIK. METHODS: LASIK was performed on 56 eyes of 28 patients with refraction errors that were well matched between the right and left eyes. For each patient, a planned 160-microm flap was created for one randomly selected eye using the Moria M2 microkeratome (130-microm head; thick flap group), and a 110-microm flap was created for the contralateral eye with the same microkeratome (90-microm head; thin flap group). Flap thickness was measured using ultrasonic pachymetry. Wavefront aberrations were measured in the anterior cornea using the Orbscan II (Bausch & Lomb) and in the whole eye using the Wavefront Supported Custom Ablation (WASCA) aberrometer (Carl Zeiss Meditec) preoperatively and at 1 month and 1 year postoperatively. RESULTS: Mean flap thickness was 155 +/- 13 microm in the thick flap group and 112 +/- 11 microm in the thin flap group. Mean root-mean-square of higher order wavefront aberrations were changed for the different test times in the cornea (F = 29.9, P < .0001) and the whole eye (F = 48.0, P < .0001). There was no significant difference between the two flap groups for the cornea (F = 0.76) or for the whole eye (F = 0.07). Similar results were observed for higher order Zernike aberrations such as spherical aberration and comas. CONCLUSIONS: The results suggest higher order wavefront aberrations induced by LASIK are independent of flap thickness. Complications in visual outcome for patients with different flap thickness should be attributed to factors other than aberrations.     

Clinical course of severe central epithelial defects in laser in situ keratomileusis

PURPOSE: To report the clinical outcome of laser in situ keratomileusis (LASIK) cases complicated by severe central intraoperative epithelial defects (EDs) caused by the microkeratome cut. SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: In a retrospective study of 1650 LASIK cases at 1 center, the preoperative data, surgical procedures, and postoperative course in 22 eyes of 14 patients who experienced severe central EDs during the LASIK procedure (1.3%) were reviewed. The surgery was performed using a Technolas C-LASIK 217 excimer laser (Bausch & Lomb) and a Hansatome microkeratome (Bausch & Lomb). A follow-up of at least 12 months was available in all but 1 case. The median follow-up was 13.5 months (range 12 to 25 months). In the postoperative period, the following parameters were reviewed: course of refraction, best spectacle-corrected visual acuity (BSCVA), slitlamp findings, and corneal topography. RESULTS: The mean patient age was 42 years (range 27 to 61 years). Eight patients were affected bilaterally. Fifteen eyes (68%) had moderate to severe dry-eye symptoms preoperatively. Almost all eyes lost BSCVA in the postoperative period, and visual acuity improved slowly. By the last follow-up visit, no eye had lost more than 1 line of BSCVA. Diffuse lamellar keratitis (DLK) was observed in 20 eyes (91%), irregular astigmatism in 17 (77%), and microfolds in 12 (55%). In unilaterally affected patients, the refractive outcome was better in the nonaffected eye. CONCLUSIONS: A large central ED is a severe intraoperative complication of LASIK that may lead to DLK, irregular astigmatism, flap microfolds, clearly prolonged visual rehabilitation, and temporary loss of BSCVA. The improvement in BSCVA may take several months.     

Correction of presbyopia in hyperopia with a center-distance, paracentral-near technique using the Technolas 217z platform

PURPOSE: To analyze the results of hyperopic patients treated with a peripheral presbyLASIK algorithm for the correction of presbyopia. METHODS: The study included 44 eyes of 22 hyperopic patients treated with a peripheral presbyLASIK technique using a Technolas 217z excimer laser. Mean patient age was 56 years (range: 47 to 72 years), mean preoperative spherical equivalent refraction was +1.21 +/- 0.77 diopters (D) (range: +0.50 to +4.00 D), and mean spectacle near addition was +1.76 +/- 0.42 D (range: +1.00 to +2.75 D). The Peripheral Multifocal LASIK (PML) ablation pattern creates a multifocal corneal profile over a 6.5-mm diameter, performing the distance correction first in a 6-mm optical zone and then near correction in a 6.5-mm zone. Main outcome measures were uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA) for near and distance, spherical equivalent refraction, contrast sensitivity, and corneal aberrations. RESULTS: Six months postoperatively, mean binocular UCVA was 1.06 +/- 0.13 for distance and 0.84 +/- 0.14 for near. Mean postoperative spherical equivalent refraction was -0.42 D (range: -1.12 to +0.87 D). Two (4.5%) eyes lost 1 line of BSCVA for distance and near vision, and 20 (45%) eyes gained 1 line of distance BSCVA. Contrast sensitivity decreased for 3, 6, 12, and 18 cycles/degree. Corneal aberration analysis showed a slight increase in coma and decrease in spherical aberration. CONCLUSIONS: The peripheral presbyLASIK technique used in this study is a safe and efficient treatment that may improve functional near vision in presbyopic patients with low and moderate hyperopia (from +0.50 to +3.00 D).     

不同方式角膜准分子激光手术对人眼波前像差的影响

目的研究不同方式的角膜准分子激光手术(LASIK、LASEK)对术后高阶像差的影响。设计病例对照研究。研究对象行LASIK及LASEK患者各22例(各43眼)。方法对行LASIK或LASEK的患者术前、术后1、3、6个月进行波前像差检查。主要指标视力、屈光、波前像差的变化。结果两种手术方式的术后视力与等效球镜度相近。6mm瞳孔直径下,术后1个月时,总波前像差的RMS值比术前减少61%,高阶像差增加110%。术后高阶像差的主要成分大部分增加;其中,球差增加最大,1个月时比术前增加285%。术后1、3个月,LASIK术式组高阶像差RMS值稍低于LASEK术式组;术后6个月,LASIK术式组高阶像差RMS值稍高于LASEK术式组(P>0.05)。其中,两组的三阶彗差、三叶草、球差RMS值改变无统计学意义(P>0.05)。结论LASIK与LASEK患者术后视力与屈光结果相近。术后总波前像差和低阶像差降低,高阶像差增加。不同手术方式对术后高阶像差无显著性影响。(眼科,2006,15:191-194)     

Laser in situ keratomileusis for myopia and the contrast sensitivity function

PURPOSE: To characterize the clinical effects of laser in situ keratomileusis (LASIK) on the cornea and visual performance by the contrast sensitivity function (CSF). SETTING: Clinique d'Ophtalmologie IRIS, Laval, Quebec, Canada. METHODS: Thirty-four patients aged 18 to 50 years volunteered for this prospective study. All patients had bilateral LASIK to correct myopia between -1.00 and -6.75 diopters (D) and refractive astigmatism less than 2.50 D. The mean spherical equivalent (SE) refractive error in the 68 eyes was -3.93 D +/- 1.67 (SD). A Hansatome microkeratome (Bausch & Lomb) and a Technolas 217C excimer laser (Bausch & Lomb) driven by the PlanoScan program were used. The monocular CSF for spatial frequencies of 3, 6, 12, and 18 cycles per degree (cpd) for both day and night vision simulations were made with a CSV-1000E system (Vector Vision) before and 1 month and up to 9 months after LASIK. All patients wore their best spectacle correction for the baseline CSF. RESULTS: The group (n = 68) averaged preoperative and postoperative CSFs did not differ at 1 month (analysis of variance [ANOVA], P>.05). In a subgroup of 11 eyes that had corneal microstriae, however, there was a significant reduction in the photopic and mesopic CSF at 6, 12, and 18 cpd (ANOVA, P<.05) despite normal Snellen visual acuities. The CSF normalized in 6 to 9 months as the microstriae became less visible. CONCLUSIONS: Subtle central corneal microstriae after LASIK can reduce the baseline CSF at medium to high spatial frequencies even with 20/20 visual acuity. The CSF normalizes as the microstriae fade over time.     

Customized LASIK treatment for myopia based on preoperative manifest refraction and higher order aberrometry: the Rochester nomogram

PURPOSE: To develop and test the efficacy of myopic treatment, based on preoperative manifest refraction and higher order aberrations, in enhancing the postoperative refractive error following customized LASIK treatment and compare results with the manufacturer-recommended sphere offset Zyoptix treatment nomogram, which does not account for the preoperative higher order aberrations. METHODS: One hundred seventy-five myopic eyes (89 patients) were treated based on the Rochester nomogram, which specified the amount of myopia to be treated based on preoperative manifest refraction and higher order aberrations, including third order aberrations and spherical aberration. Postoperative refractive error was measured at 1 month and compared to that theoretically estimated with the Zyoptix nomogram. RESULTS: The mean preoperative sphere and cylinder were -4.52 +/- 2.05 diopters (D) and -0.81 +/- 0.70 D, respectively. The mean postoperative spheres were +0.04 +/- 0.33 D and +0.31 +/- 0.54 D, using the Rochester and Zyoptix nomograms, respectively. The mean postoperative spherical equivalent refractions were -0.11 +/- 0.34 D and +0.15 +/- 0.53 D using the Rochester and Zyoptix nomograms, respectively. The Rochester nomogram reduced the range of postoperative spherical equivalent to +/- 1.00 D, which was significantly better than that using the Zyoptix nomogram (t = 5.46, P < .0001), which would have resulted in 8% of eyes with a postoperative spherical equivalent refraction > +/- 1.00 D. Using the Rochester nomogram, 93.1% of eyes attained a postoperative UCVA > or = 20/20. The percentage of postoperative hyperopic overcorrection decreased to 2.8% in the Rochester nomogram group from 22.3% using the Zyoptix nomogram, which only adjusts spherical values based on preoperative sphere and does not account for preoperative aberrations. CONCLUSIONS: The Rochester nomogram compensates for the effect of preoperative higher order aberrations on sphere and provided reduced range of postoperative spherical equivalent refraction.