LADARWave wavefront measurement in normal eyes

PURPOSE: We evaluated the correlation of Alcon LADARWave wavefront measurements with clinical refraction and corneal topography. METHODS: In a retrospective, non-comparative case series, 60 eyes (30 patients) of healthy individuals evaluated by preoperative examination for refractive surgery were enrolled (manifest sphere, -11.00 to +4.50 D; manifest cylinder, 0 to -4.75 D; 45 eyes were myopic, 12 eyes were hyperopic, and 3 had mixed astigmatism). Correlation of manifest refraction, cycloplegic refraction, and topographic data with wavefront refraction and higher order aberration was assessed. Match percentage given by the wavefront was analyzed. This number represents how much of the wavefront refraction is due to sphere and cylinder (high percentage match) or is influenced by higher order aberration (low percentage match), in which case aberrometer refraction will not be close to phoropter refraction. Pearson's correlation coefficient was assessed for two continuous variables, adjusting for repeated measurements. RESULTS: The median match percentage was 91%. Mean values for all higher order aberration components in a 7.0-mm pupil were: coma = 0.35 +/- 0.29 microm, spherical aberrations = 0.36 +/- 0.31 microm, and other terms of higher order aberrations = 0.31 +/- 0.14 microm. Wavefront sphere, cylinder, and axis terms were highly correlated to manifest and cycloplegic measurements. The high match subgroup had a higher correlation coefficient than the low match subgroup for refraction. Topographic cylinder and axis were not strongly correlated to wavefront refraction, but manifest axis was significantly correlated to topographic axis. CONCLUSION: In 60 normal eyes, the Alcon LADARWave wavefront measurement was highly correlated with refraction, but less well with corneal topography.     

Effect of pharmacologic pupil dilation with tropicamide and phenylephrine on wavefront measurements

PurposeTo investigate the influence of tropicamide 1% (as a cycloplegic mydriatic) and phenylephrine 10% (as a noncycloplegic mydriatic) on mydriasis, wavefront refraction, and wavefront aberrations.MethodsIn this prospective study, 31 myopic eyes with a large mesopic pupil size were evaluated with an Allegretto Wave analyzer in a natural dilated state, after instillation of tropicamide 1% or phenylephrine 10%. Aberrations expressed as Zernike polynomials up to the sixth order were analyzed. Wavefront refractions were compared with subjective manifest refraction.ResultsBoth tropicamide and phenylephrine cause significant mydriasis (p < 0.001), but phenylephrine induced a larger pupil size than tropicamide under mesopic conditions (p = 0.029). Compared with the natural state, tropicamide induced a significant hyperopic shift in wavefront refraction (by +0.27 ± 0.09 D; p = 0.002). In contrast, wavefront refraction did not significantly change when using phenylephrine as the mydriatic (+0.03 ± 0.10 D; p = 0.75). Compared with the subjective manifest refraction, wavefront refraction before mydriatics and after phenylephrine showed a significant myopic shift (p < 0.0125), whereas the wavefront refraction after tropicamide was not significantly different from subjective refraction. Zernike coefficient C4 showed a less positive defocus after application of tropicamide (p = 0.0017). Other aberration coefficients of Zernike polynomials up to the sixth order did not change significantly from before to after tropicamide application. There was no significant difference in Zernike coefficients up to C27 before and after phenylephrine.ConclusionPhenylephrine preserves accommodation and provides a larger pupil under mesopic conditions, whereas tropicamide relaxes accommodation and provides an objective wavefront refraction that is closer to the subjective manifest refraction. Neither phenylephrine nor tropicamide causes a significant change in high-order aberrations from the natural state.     

显然验光与不同瞳孔直径下波前像差验光的比较

目的采用波前像差仪进行客观验光,比较分析显然验光与不同瞳孔直径下含有不同高阶成分的波前像差验光的关系。方法横断面研究。选取近视及近视散光患者31例（62眼）,利用基于Hartmann．Shack原理的波前传感系统进行波前像差测量。根据所测数据计算出不同瞳孔直径下仅有离焦的屈光度,包含离焦及球差的屈光度和含有离焦、球差及二级球差的屈光度．并应用Friedman检验分析临床显然验光与这些波前像差验光屈光度的关系。结果2、3、4、5、6mm直径瞳孔下的波前客观屈光度分别与临床显然验光屈光度比较,仅含有离焦时的屈光度差异最小,球镜度差异的中位数分别为－0．540、－0．473、－0．422、－0．407、－0．290D,差异具有统计学意义（Z=99．29,P〈0．01）;柱镜度差异的中位数分别为0．193、0．142、0．119、0．078、0．065D,差异具有统计学意义（Z=30．25,P〈0．01）;平均散光轴差异的中位数分别为-2．41、-2．89、-3．03、-1．94、-2．40°,差异无统计学意义（Z=4．42,P〉0．05）。含有高阶成分的屈光度与临床显然验光差异较大。结论由波前像差计算得到的屈光度与瞳孔直径和高阶像差参与的多少有关。纳入较高阶球差后等效屈光度降低,较大瞳孔直径下无高阶像差参与的波前屈光度与临床显然验光较接近。波前验光散光轴向与主觉验光较接近。     

Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography

PURPOSE: To evaluate the information assessed with the LADARWave wavefront measurement device and correlate it with visual symptoms, refraction, and corneal topography in previously LASIK-treated eyes. PARTICIPANTS: One hundred five eyes (58 patients) of individuals who underwent LASIK surgery were evaluated. DESIGN: Retrospective, noncomparative case series. MAIN OUTCOME MEASURES: Complete ophthalmologic examination, corneal topography, and wavefront measurements were performed. Correlations were made between the examinations and symptoms. METHODS: Wavefront measurements were assessed with the LADARWave device. Manifest, cycloplegic refraction, and topographic data were compared with wavefront refraction and higher order aberrations. Visual symptoms were correlated to higher order aberrations in 3 different pupil sizes (5-mm, 7-mm, and scotopic pupil size). Pearson's correlation coefficient and generalized estimating equations were used for statistical analysis. RESULTS: In post-LASIK eyes, wavefront refraction components were poorly correlated to manifest and cycloplegic components. The comparison between manifest, cycloplegic, and wavefront refraction with total amount of higher order aberrations showed no strong correlation. The comparison between topography and manifest, cycloplegic, and wavefront refraction did not show strong correlation. Visual symptoms analysis showed correlation of double vision with total coma and with horizontal coma for the 5-mm and 7-mm pupil size; correlation between starburst and total coma for the 7-mm pupil size; and correlation of double vision with horizontal coma, glare with spherical aberrations and with total aberrations, and starburst with spherical aberrations for the scotopic pupil size. Scotopic pupil size had a positive association with starburst and a negative association with double vision. CONCLUSIONS: The LADARWave wavefront measurement device is a valuable diagnostic tool in measuring refractive error with ocular aberrations in post-LASIK eyes. A strong correlation between visual symptoms and ocular aberrations, such as monocular diplopia with coma and starburst and glare with spherical aberration, suggest this device is valuable in diagnosing symptomatic LASIK-induced aberrations. Horizontal coma was correlated with double vision, whereas vertical coma was not.     

Wavefront analysis in normal refractive surgery candidates

PURPOSE: To quantify the higher order aberrations of refractive surgery candidates and compare the wavefront-determined refractions with manifest refractions refined with a +/- 0.25 Jackson cross cylinder. METHODS: Results of 226 consecutive patients (418 eyes) were analyzed with the WaveScan WavePrint system (VISX, Santa Clara, Calif). Only patients with normal eyes without previous surgery were included. RESULTS: The mean spherical equivalent refraction determined with wavefront analysis was -3.40 +/- 3.14 diopters (D) (range: -10.72 to +5.41 D). The largest amount of higher order aberrations was detected with : a 6-mm pupil diameter (coma 0.14 +/- 0.08 microm; trefoil 0.10 +/- 0.07 microm; spherical aberrations 0.09 +/- 0.07 microm). The mean root-mean-square of higher order aberrations and total aberrations were 0.23 +/- 0.11 microm and 4.00 +/- 2.45 microm, respectively. No statistically significant correlation was noted between higher order aberrations and gender (P = 0.7) or between higher order aberration and refractive level (P > .59). The mean differences in spherical equivalent refraction, sphere, and cylinder between WaveScan measurements and manifest refraction were 0.36 +/- 0.41 D, 0.40 +/- 0.44 D, and 0.28 +/- 0.32 D, respectively. CONCLUSIONS: This study provides reference values for higher order aberrations in normal refractive surgery candidates. Wavefront analysis also proved to be a valuable tool for objectively measuring preoperative refractive error.     

Repeatability and validity of Zywave aberrometer measurements

PURPOSE: To study the repeatability of Zywave aberrometer (Bausch & Lomb) measurements and compare the measurements with those of subjective refraction and noncycloplegic and cycloplegic autorefractions in a clinical setting. SETTING: Department of Ophthalmology, University Hospital Maastricht, Maastricht, The Netherlands. METHODS: Subjective manifest refraction, noncycloplegic autorefraction, cycloplegic autorefraction, and Zywave aberrometer measurements were performed in 20 eyes of 20 myopic patients. Three consecutive Zywave measurements were performed with and without dilation of the pupil. The mean difference and 95% limits of agreement among the measurement methods were determined for dilated and 3.5 mm pupils. The repeatability coefficient of the Zywave aberrometer measurements was determined. RESULTS: The mean differences in spherical equivalent (SE), sphere, and cylinder between subjective refraction and Zywave predicted phoropter refraction (PPR) with a dilated pupil were -1.10 diopters (D) +/- 0.46 (SD) (P <.001), -1.08 +/- 0.44 D (P <.001), and -0.02 +/- 0.37 D (P =.87), respectively (paired Student t test). After the data were converted to a 3.5 mm pupil, the mean differences were -0.55 +/- 0.48 D (P <.001), -0.50 +/- 0.49 D (P <.001), and -0.16 +/- 0.50 D (P =.15), respectively. The mean difference in SE between autorefraction and cycloplegic autorefraction versus subjective refraction was +0.18 +/- 0.71 D (P =.27) and +0.35 +/- 0.62 D (P =.02), respectively. The mean difference in SE between cycloplegic autorefraction and Zywave PPR with a dilated pupil was -1.44 +/- 0.79 D (P <.001). The repeatability coefficient of Zywave PPR was +/-0.25 D for SE, +/-0.29 D for sphere, and +/-0.29 D for cylinder. CONCLUSIONS: Subjective refraction measurements are slightly more myopic than cycloplegic autorefraction measurements. With a dilated pupil, the Zywave measurements were significantly more myopic than subjective refractions and even more myopic than cycloplegic autorefractions. Zywave measurements and subjective refractions were in better agreement with a 3.5 mm pupil. The repeatability of Zywave aberrometer measurements is adequate for lower-order aberrations.     

In vivo and in vitro repeatability of Hartmann-Shack aberrometry

PURPOSE: To assess the in vivo and in vitro repeatability of objective refraction and higher-order aberrations (HOAs) measured by a commercially available Hartmann-Shack wavefront sensor. SETTING: Department of Ophthalmology, Johann-Wolfgang-Goethe University, Frankfurt am Main, Germany. METHODS: After pupil dilation of 40 myopic or myopic, astigmatic eyes of 20 patients, wavefront measurements were performed 6 times in each eye and in a test object provided by the manufacturer by 2 experienced examiners using a Hartmann-Shack wavefront sensor (Zywave, software version 3.21, Bausch & Lomb). The mean standard deviation (SD) and the coefficient of variation (CV) for sphere, cylinder, and each Zernike polynomial were computed for a 7.0 mm pupil diameter. Vector analysis was performed for the astigmatism. After the data were subdivided into 2 groups with 3 measurements in each, one measurement that best matched the subjective manifest refraction was chosen in each group and the difference between them was calculated. RESULTS: The mean SD (CV) was 0.15 diopter (D) (7%) for the sphere value of the predicted phoropter refraction and 0.16 D (22%) for astigmatism. Thirty-two eyes had an axis deviation of at least 10 degrees. Vector analysis revealed a mean SD of 0.24@109.8. Other results for mean SD and mean CV were as follows: total in vivo higher-order RMS, 0.097 microm, 13.4%; sphere in myopic test device, 0.034 D, 0.65%; sphere in hyperopic test object, 0.035 D, 0.72%. The difference between the 2 best-matched refractions was significantly different from zero (0.11 D, P<.001). The CV was significantly higher for HOAs than for the 2nd-order aberrations (defocus and astigmatism). CONCLUSIONS: Repeatability of Hartmann-Shack aberrometry by the Zywave wavefront sensor was not satisfactory, particularly for small amounts of HOAs. Under these conditions, aberrometry measurements should be repeated several times and outliers should be excluded in calculating the means.     

Comparison of tropicamide and cyclopentolate for cycloplegic refractions in myopic adult refractive surgery patients

PURPOSE: To compare tropicamide 1%, a shorter-acting cycloplegic agent, with cyclopentolate 1% for cycloplegic refractions in adult refractive surgery patients. SETTING: Navy Refractive Surgery Center, Ophthalmology, Naval Medical Center, San Diego, California. METHODS: The study was prospective, single center, with randomized sequencing of cycloplegic agent; each patient received both agents. Thirty consecutive myopic adult refractive surgery patients (mean age 35.4 years) participated. A complete preoperative examination, including cycloplegic refraction, was obtained twice, 1 week apart. The patient and the examiner were masked to the medication. Main outcome measures included cycloplegic and manifest refractions, best corrected distance acuity, near-point accommodation, pupil diameters, and subjective appraisal of experience with cycloplegic agents. RESULTS: Twenty-eight of 30 patients completed both examinations. Both eyes were measured, but comparisons were limited to right and left eyes, independently. No statistically significant difference was found between the tropicamide and cyclopentolate cycloplegic refractions (mean difference in MSE +/- SD, OD=0.054 +/- 0.214 diopters (D), t=1.33, P=.10; OS=0.054 +/- 0.253 D, t=1.12, P=.14). Five eyes of 3 patients had a difference of 0.50 D or greater between the 2 agents; less myopia with cyclopentolate. Near-point testing revealed less residual accommodation with cyclopentolate (difference in MSE, OD=-0.27 +/- 0.51 D, t=2.68, P=.006; OS=-0.32 +/- 0.49 D, t=3.46, P=.001). Subjectively, 24 of 28 (86%) patients preferred tropicamide, 1 (4%) preferred cyclopentolate, and 3 (10%) had no preference. CONCLUSIONS: There was no statistically significant difference in mean cycloplegic refractions. Cyclopentolate was more effective than tropicamide in reducing accommodative amplitude in adult myopes (near-point testing). Patients strongly preferred tropicamide.     

Higher order ocular aberrations after cycloplegic and non-cycloplegic pupil dilation

PURPOSE: Clinical aberrometry is commonly undertaken with the use of mydriatic agents, however there is no literature available on whether aberrometry results obtained under cycloplegia differ from those obtained without cycloplegia. METHODS: Higher order aberrations were measured over a 6-mm pupil with a Bausch and Lomb Technolas Zywave Aberrometer on the right eyes of 31 young subjects (average age 19.7 +/- 1.7 years; 5 females, 16 males). Two measurement conditions were used for each subject: 1) topical installation of 3 drops 1% cyclopentolate hydrochloride; and 2) topical installation of 1 drop 2.5% phenylephrine hydrochloride, prior to aberrometry measurements. RESULTS: For higher order aberrations (3rd to 5th order), average root mean square (RMS) after phenylephrine measurement (0.3852 microm) was significantly lower than after cyclopentolate (0.4259 microm). A small but statistically significant difference was found between the two conditions for average vertical and horizontal coma and, to a lesser extent, horizontal 5th order aberrations. Repeatability RMS, a measure of test-retest measurement repeatability, was similar for the two conditions at 0.15 microm, and significantly lower than the average RMS for the difference between the two conditions (residual RMS) of 0.22 microm. CONCLUSIONS: The difference between cycloplegic and non-cycloplegic aberration measurements has implications for surgical correction of higher order aberrations.     

Corneal wavefront-guided ablation with the Schwind ESIRIS laser for myopia

PURPOSE: To evaluate the outcome of corneal wavefront-guided LASIK for the treatment of myopia and myopic astigmatism. METHODS: This study included 56 myopic virgin eyes of 28 patients with a mean spherical equivalent refraction of -4.40 +/- 1.83 diopters (D) (range: -1.25 to -9.75 D) and astigmatism < 2.50 D. The corneal wavefront aberrations were analyzed using a corneal topography system. The preoperative corneal wavefront aberration data obtained from the above analyses combined with manifest refraction were used to generate a customized ablation profile. The safety, efficacy, and predictability of the correction, contrast sensitivity, and corneal higher order wavefront aberrations were evaluated. RESULTS: At 1-year follow-up, the mean residual spherical equivalent refractive error was -0.15 +/- 0.3 D (range: 0 to -1.25 D) and mean cylinder was -0.54 +/- 0.34 D (range: 0 to -1.50 D). Ninety-five percent of eyes were in the residual refractive error range of +/- 0.50 D and uncorrected visual acuity improved by 1.00 D or better in 94% of eyes. The safety index and efficacy index were 1.13 and 0.92, respectively. After treatment, corneal higher order wavefront aberrations with a 6-mm pupil diameter increased significantly (paired sample t test, P < .01), and contrast sensitivity with glare had small reductions at high spatial frequencies. Changes in spherical-like aberration (R = 0.708, P < .001) and higher order wavefront aberration (R = 0.449, P = .001), except for coma-like aberration (P = .238), were positively correlated with the amount of achieved correction. CONCLUSIONS: Evaluation of clinical results showed that corneal wavefront-guided LASIK for the correction of myopia and myopic astigmatism was safe and effective. There was an increase in all higher order aberrations postoperatively.     

Influence of age on ocular wavefront aberration changes with accommodation

PURPOSE: To perform a quantitative analysis of high order wavefront aberrations of the entire optical system of the eye that accompanies accommodation demands in the healthy and emmetropic eye. METHODS: Fifty-six healthy emmetropic eyes of 30 patients were separated into three groups according to age: group 1, 20 to 29 years; group 2, 30 to 39 years; and group 3, 40 to 49 years. Using iTrace ray-tracing technology, pupil diameter, objective refraction, and wavefront aberrations at accommodation demands of 0 to 4.00 diopters (D) in five 1.00-D increments were determined. In analyzing higher order aberrations in the central 4-mm diameter zone of the pupil, Zernike polynomials were used to study the changes associated with accommodation in the magnitude of total higher order aberrations, third order aberrations (coma-like aberrations), fourth order aberrations (spherical-like aberrations), and the spherical aberration component (C4(0)) of the fourth order aberrations. RESULTS: Pupil diameter decreased significantly (P < .05) with accommodation demand in each group. Total higher order aberrations in group 1 increased significantly (P < .05). No significant change was seen in third order aberrations in any group, but fourth order aberrations increased significantly (P < .05) in group 1. Spherical aberration (C4(0)) showed phase shifts from positive to negative in all groups, but the shift in group 3 was minimal, remaining positive even for a 4.00-D accommodation demand. CONCLUSIONS: Among higher order aberrations accompanying accommodation demands, spherical aberration (C4(0)) in particular showed characteristic changes; however, these changes showed age-related disparities. The changes were probably due to the effects of reduction in accommodation resulting from age-related changes in the crystalline lens.     

High-order aberrations and preoperative associated factors

PURPOSE: The purpose of this study was to determine which preoperative factors are associated with the presence of high-order aberrations. METHODS: A total of 93 eyes of 52 subjects were evaluated preoperatively between 1 January and 31 March 2003, using a Hartmann-Shack-based aberrometer. Age, gender, cycloplegic refraction, pupil size, keratometry readings, anterior chamber depth, white-to-white tests, intraocular pressure and basic secretion tests were evaluated. RESULTS: Factors associated with high-order aberrations included age > or = 40 years (mean 4.39 +/- 2.95 microm; p = 0.03, Mann-Whitney test), higher keratometry values (44.96 +/- 1.57 D) (r = 0.447, p < 0.001, Spearman's correlation coefficient), higher degrees of myopia (> or = - 6.1 D) (p < 0.001, Kruskall-Wallis test) and increasing pupil size (p < 0.001, anova). Other factors including anterior chamber depth, white-to-white results, intraocular pressure and basic secretion test results did not correlate with the presence of high-order aberrations preoperatively. CONCLUSIONS: Ocular wavefront aberrations varied greatly from subject to subject. Treatment should be customized for each laser based on patient characteristics in order to ensure the optimal treatment profile for the aberration.     

Wavefront aberration and its relationship to the accommodative stimulus-response function in myopic subjects.

BACKGROUND: Autorefractors are increasingly used in myopia research because they are convenient tools to investigate aspects of the accommodation response. The degree to which the autorefractor measures are affected by ocular aberrations has been highlighted by studies that have shown changes in aberration levels through different parts of the pupil and with accommodation. We have compared accommodative accuracy as measured with a Shin-Nippon SRW 5000 autorefractor with wavefront error as measured with a Hartmann-Shack wavefront sensor to investigate how factors such as accommodation demand, ocular aberrations, and pupil size can influence autorefractor measures. METHODS: Accommodation stimulus-response curves were determined (using negative lenses) for 30 young healthy subjects (20 myopic [-0.75 to -6.00 D] and 10 emmetropic). Accommodation levels ranged from 0 to 4 D in 1 D steps. Wavefront aberrations were also determined for the same accommodation levels using a Hartmann-Shack wavefront sensor for both the subjects' natural pupil sizes and for a 2.9-mm pupil. RESULTS: For all subjects, there was a consistent increase in negative spherical aberration with increases in accommodative stimulus. However, there was no consistent change in paraxial spherocylindrical refractive correction with accommodation stimulus. For the emmetropic subjects, accommodation error as measured with the autorefractor was statistically similar to the total spherocylindrical correction for the eye as estimated by the Hartmann-Shack wavefront sensor, but only for a 2.9-mm pupil (the pupil size utilized by the autorefractor). For the myopic subjects, accommodation error as measured with the autorefractor was statistically similar to the higher-order aberrations, but only when measured for a natural pupil size. CONCLUSIONS: The relationship between the accommodation accuracy as measured with the autorefractor and the total wavefront aberration as measured with a Hartmann-Shack wavefront sensor is largely influenced by the higher-order (fourth and above) aberration levels. For the emmetropic subjects, the errors measured by the two methods agree when adjusted to measure at similar pupil sizes. For the myopic subjects with similar pupil sizes, however, the Hartmann-Shack wavefront sensor underestimates the accommodation error at higher accommodation levels (2 to 4 D) compared with the autorefractor.     

Changes of higher-order aberrations with the use of various mydriatics

Advances in corneal refractive surgery have allowed ophthalmologists to correct ocular higher-order aberrations. To obtain more information on the ocular aberrations generated from the optical axis, mydriasis is required. The aim of this study is to evaluate the changes in higher-order aberrations with the use of various mydriatics. Higher-order aberrations were measured in 21 eyes of 21 subjects (age range 24–37 years; 13 males, 8 females). Repeated measurements were conducted before and after the installation of three different mydriatics: 10% phenylephrine, 1% tropicamide, or 1% cyclopentolate. At a pupil size of 6 mm, the average root mean square value of higher-order aberrations (HO-RMS) was 0.430 μm in undilated eyes, and 0.413, 0.410, and 0.477 μm after installation of phenylephrine, tropicamide, and cyclopentolate, respectively. There were no statistically significant differences in the HO-RMS between the four conditions. There was a significant difference in the spherical aberration between the undilated or phenylephrine-treated eyes, compared to those treated with tropicamide or cyclopentolate. Cycloplegic mydriatics seemed to shift spherical aberration in a positive direction. These results suggest that mydriatics may affect higher-order aberrations, especially spherical aberration, and this should be considered when performing wavefront analysis and when correcting wavefront errors.     

Wavefront-guided excimer laser vision correction after multifocal IOL implantation

PURPOSE: To investigate the use of wavefront-guided LASIK after multifocal intraocular lens (IOL) implantation to correct residual ametropia and higher order aberrations. METHODS: In a prospective, nonrandomized case series, wavefront-guided LASIK was performed in 27 eyes (19 patients) after multifocal IOL implantation (Tecnis diffractive IOL, n = 20; ReSTOR diffractive IOL, n = 4; ReZoom refractive IOL, n = 3) using the VISX STAR S4 IR excimer laser. Visual acuity, manifest refraction, and wavefront error were examined pre- and 3 months postoperatively. RESULTS: In the Tecnis group, results before (after) LASIK were: sphere +1.06 +/- 0.77 diopters (D) (-0.03 +/- 0.28 D; P = .0001), cylinder -1.13 +/- 0.73 D (-0.14 +/- 0.25 D; P = .00004), distance uncorrected visual acuity (UCVA) 20/45 +/- 0.09 (20/29 +/- 0.16; P = .00004), near UCVA 20/30 +/- 0.24 (20/25 +/- 0.16; P = .001), and higher order aberrations (4-mm pupil) 0.14 +/- 0.05 microm (0.18 +/-0.03 microm; P = .02). Distance and near best spectacle-corrected visual acuity (BSCVA) did not change. In the ReSTOR group, results before (after) LASIK were: sphere +0.75 +/- 0.56 D (+0.13 +/- 0.22 D), cylinder -1.50 +/- 0.47 D (-0.13 +/- 0.22 D), distance UCVA 20/40 +/- 0.07 (20/26 +/- 0.07), near UCVA 20/44 +/- 0.05 (20/25 +/- 0.0), and higher order aberrations (4-mm pupil) 0.14 +/- 0.03 microm (0.20 +/- 0.02 microm). Distance and near BSCVA did not change. In the ReZoom group, results before (after) LASIK were: sphere +0.08 +/- 1.20 D (0.00 D), cylinder -0.83 +/- 0.120 D (0.00 D), distance UCVA 20/40 +/- 0 (20/25 +/- 0), near UCVA 20/60 +/- 0.09 (20/150 +/- 0.18), and higher order aberrations (4-mm pupil) 0.43 +/- 0.04 microm (0.39 +/- 0.03 microm). Patients lost one line of distance BSCVA and two lines of near BSCVA. CONCLUSIONS: Wavefront-guided LASIK is safe and effective in diffractive multifocal IOLs to correct residual refractive error, but higher order aberrations did not improve. It is not recommended in refractive multifocal IOLs, as these cannot be measured reliably with current wavefront sensors.     

两种睫状肌麻痹剂对像差影响的对照研究

目的评价环喷托酯和托吡卡胺散瞳前后对像差测量的影响。方法选取准分子激光原位角膜磨镶术患者随机分为环喷托酯组15例(30眼)和托吡卡胺组15例(29眼)。两组患者测量像差后,分别给予1%环喷托酯及0.5%托吡卡胺,散瞳后再次测量像差,并比较两组散瞳前后像差球镜值(6mm)和高阶像差的均方根(MRS)值。结果两组暗室瞳孔下像差球镜值均小于综合验光值和散瞳后像差测量值,差异有统计学意义(P<0.05)。两组在暗室下或是散瞳后,随着分析瞳孔的增大,三阶(RMS3)、四阶(RMS4)、五阶(RMS5)、总高阶像差(RMSh)和球差C12逐渐增大,差异有统计学意义(P<0.05),而慧差C7、C8差异无统计学意义(P>0.05)。而在同一分析瞳孔直径下,散瞳前后各阶高阶像差和RMSh、C7、C8差异无统计学意义,散瞳后C12增大,与暗室下C12比较,差异有统计学意义(P<0.05)。在同一瞳孔直径下,环喷托酯组球差值与托吡卡胺组相比,差异无统计学意义(P>0.05)。结论睫状肌麻痹剂影响像差的测量,使球差值增大。     

Technical Note: Comparison of the wavefront aberrations between natural and pharmacological pupil dilations

Ocular wavefront aberrations were tested with the wavefront-supported corneal ablation (WASCA) aberrometer when the pupil was dilated naturally under scotopic illumination levels, and pharmacologically using tropicamide. Wavefront aberrations were measured across a 5-mm pupil in one eye of each of 58 subjects. There was a significant difference in the pupil diameter between the scotopic and cycloplegic conditions (p < 0.001). For higher order aberrations (HOAs), no significant difference was found in Zernike coefficients between the scotopic and cycloplegic conditions. There was no significant difference in the spherical equivalent refraction. Accommodation can be neglected during the wavefront aberration measurement with the WASCA aberrometer. In view of the shift of the pupil centre caused by pharmacological pupil dilation, obtaining measurements under natural conditions rather than using mydriatics is recommended for customized laser in situ keratomileusis (LASIK) surgery.     

Corneal higher order wavefront aberrations after hyperopic laser in situ keratomileusis

PURPOSE: To evaluate the changes in corneal higher order wavefront aberrations after hyperopic laser in situ keratomileusis (LASIK). METHODS: In a prospective case series, 15 eyes of 12 patients who had hyperopic LASIK were evaluated. Corneal topography was obtained before and after hyperopic LASIK with a Nidek EC 5000 laser using 5.5/8.0 ablation zones. Using anterior corneal height data, the changes in corneal higher order wavefront aberrations were calculated. RESULTS: The surgery significantly increased both corneal coma-like aberration (preoperative/6 months postoperative, 0.054/0.147 [172% increase] for 3-mm pupil and 0.381/1.076 [182% increase] for 6-mm pupil) and corneal spherical-like aberration (preoperative/6 months postoperative, 0.039/0.067 [72% increase] for 3-mm pupil and 0.297/0.959 [223% increase] for 6-mm pupil). The surgery significantly decreased Zernike coefficient 12 and the polarity of corneal spherical aberration changed from preoperative positive value to negative postoperatively. For a 3-mm pupil, the achieved changes in spherical equivalent refraction significantly correlated with the induced changes in the corneal coma-like aberration (R = 0.629, P = .010), but not with those in corneal spherical-like aberration (R = 0.408, P=.133) or Zernike coefficient 12 (R = -0.301, P = .282). For a 6-mm pupil, the achieved changes in spherical equivalent refraction significantly correlated with the induced changes in the corneal spherical-like aberration (R = 0.862, P < .0001) and Zemike coefficient 12 (R = -0.872, P < .001) but not with those in corneal coma-like aberration (R = 0.449, P = .094). CONCLUSIONS: Hyperopic LASIK significantly increases corneal coma-like and spherical-like aberrations and changes corneal spherical aberration from a positive to negative value.     

Aberrometry due dilated pupils--Which mydriatic should be used?

BACKGROUND: For a wavefront-based LASIK procedure aberrometric measurements are necessary via a dilated pupil. The more dilated the pupil is the more aberrations can be identified. There are different mydriatic eyedrops used to dilate the pupil. It is unclear so far which mydriatic is best for measuring aberrations before LASIK. METHODS: We performed aberrometry measurements on 50 eyes under the following different conditions: physiological mydriasis under mesopic environment, tropicamide-induced dilation, phenylephrine-induced dilation, and cyclopentolate-induced dilation. The wavefront measurements were compared with the respective subjective refraction (sr). RESULTS: The refractive myopic error measured by aberrometry was less than after subjective refraction depending on the mydriatic used. Phenylephrine-induced mydriasis resulted in 0.19 D less myopia, tropicamide induced 0.35 D less myopia, and cyclopentolate 0.42 D less on the average. The aberrometry measurements under mesopic conditions led to 0.24 D less myopia than measured subjectively. CONCLUSION: Using cyclopentolate eyedrops wavefront analysis results in a considerable difference in the preoperative refractive error compared to the standard subjective refraction. Regarding the average differences in refraction the aberrometry measurements after neosynephrine-induced dilation of the pupil usually resemble the subjective refractive error. For practical reasons we would like to recommend aberrometry measurements under mesopic conditions without applying mydriatics provided the pupillary diameter is at least 6 mm.     

Apparent accommodation and corneal wavefront aberration in pseudophakic eyes

PURPOSE: To assess the relationship between apparent accommodation in pseudophakic eyes, multifocal corneal effects, and wavefront aberrations of the cornea. METHODS: In 102 eyes of 86 patients who had undergone phacoemulsification and posterior chamber intraocular lens implantation, the amount of apparent accommodation was measured with an accommodometer. The degree of corneal multifocality was determined on the corneal topography by measuring the maximum and minimum corneal refractive powers within the pupillary area. Wavefront aberrations of the cornea were calculated by expanding the height data of the corneal topography into Zernike polynomials for individual pupil size. The influence of higher-order aberration on the retinal image quality was simulated by computing the point-spread function (PSF) and modulation-transfer function (MTF) from the aberration function. RESULTS: There was a significant positive correlation between the amount of apparent accommodation and corneal multifocality (Pearson correlation coefficient, r = 0.451, P < 0.001). The coma-like aberration showed a significant positive correlation with the amount of apparent accommodation (r = 0.440, P < 0.001), but the spherical-like aberration did not (r = 0.001, P = 0.993). Among the coma-like aberrations, the component representing vertically asymmetrical distribution of corneal refractive power with greater refraction located in the lower part of the eye was most relevant to apparent accommodation. Computer simulation of PSF and MTF indicated that a focus shift of 0.5 D deteriorated the retinal image significantly more in eyes without higher-order aberrations than in eyes with a moderate amount of coma-like aberrations. CONCLUSIONS: Coma-like aberration of the cornea, along with corneal multifocality, contributes to apparent accommodation in pseudophakic eyes.