Higher-order Aberrations Root Mean Square Research Articles

Effect of iris registration on outcomes of FEMTOLASIK for myopia and myopic astigmatism.

To compare the visual and refractive outcomes after FEMTOLASIK with and without iris registration. In this randomized, prospective, comparative, contralateral eye study, 118 eyes of 59 patients with myopia and myopic astigmatism underwent LASIK using the Femto LDV femtosecond laser (160µm) and the MEL80 with or without iris registration. For each patient, iris registration FEMTOLASIK was performed on one eye and non-iris registration FEMTOLASIK was performed on the other eye, assigned at random. Patients were evaluated before and 12months. Uncorrected visual acuity, best-corrected visual acuity, manifest refraction, contrast sensitivity, and higher-order aberrations (HOAs) were evaluated. At 12months, the mean UDVA was 0.002±0.07 logMAR (20/19) in iris registration eyes and 0.00±0.06 logMAR (20/24) in non-iris registration eyes (P=0.9). 61% of iris registration eyes and 71.2% of non-iris registration eyes achieved a UDVA of 20/20 or better (P=0.31); 98.3% of eyes with the iris registration FEMTOLASIK and 94.9% with the non-iris registration FEMTOLASIK were within ±0.50D from emmetropia (P=0.71). No statistically significant difference was found in postoperative contrast sensitivity between groups at 3, 6, 12, or 18 cycles/degree (P>0.05). There was significant increase in total HOA root mean square in two groups. The mean error magnitude of surgically induced astigmatism 12months postoperatively was -0.33 in iris registration eyes and -0.24 in the non-iris registration eyes (P=0.36). FEMTOLASIK with and without iris registration provides similar results in myopic and myopic astigmatism patients.

Corneal biomechanical data and biometric parameters measured with Scheimpflug-based devices on normal corneas

To analyze the correlations between ocular biomechanical and biometric data of the eye, measured by Scheimpflug-based devices on healthy subjects. Three consecutive measurements were carried out using the corneal visualization Scheimpflug technology (CorVis ST) device on healthy eyes and the 10 device-specific parameters were recorded. Pentacam HR-derived parameters (corneal curvature radii on the anterior and posterior surfaces; apical pachymetry; corneal volume; corneal aberration data; depth, volume and angle of the anterior chamber) and axial length (AL) from IOLMaster were correlated with the 10 specific CorVis ST parameters. Measurements were conducted in 43 eyes of 43 volunteers (age 61.24±15.72y). The 10 specific CorVis ST data showed significant relationships with corneal curvature radii both on the anterior and posterior surface, pachymetric data, root mean square (RMS) data of lower-order aberrations, and posterior RMS of higher-order aberrations and spherical aberration of the posterior cornea. Anterior chamber depth showed a significant relationship, but there were no significant correlations between corneal volume, anterior chamber volume, mean chamber angle or AL and the 10 specific CorVis ST parameters. CorVis ST-generated parameters are influenced by corneal curvature radii, some corneal RMS data, but corneal volume, anterior chamber volume, chamber angle and AL have no correlation with the biomechanical parameters. The parameters measured by CorVis ST seem to refer mostly to corneal properties of the eye.

Comparison of clinical outcomes between wavefront-optimized versus corneal wavefront-guided transepithelial photorefractive keratectomy for myopic astigmatism

To evaluate and compare the clinical outcomes, including visual acuity, refractive errors, and aberrations, between aberration-free transepithelial photorefractive keratectomy (PRK) and corneal wavefront-guided transepithelial PRK in eyes with myopic astigmatism. Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea. Retrospective comparative case series. Patients with myopic astigmatism were treated with aberration-free transepithelial PRK or corneal wavefront-guided transepithelial PRK using a 1050Hz high-repetition excimer laser.The safety, efficacy, predictability, and corneal aberrations were compared preoperatively and 1, 2, 3, and 6months postoperatively. The study comprised 188 patients (188 eyes); 91 eyes had aberration-free transepithelial PRK and 97 eyes corneal wavefront-guided transepithelial PRK. Six month after surgery, the mean uncorrected distance visual acuity was comparable (-0.06 logMAR±0.07 [SD] aberration-free group; -0.06±0.06 logMAR wavefront-guided group). The safety, efficacy, and predictability of refractive and visual outcomes were also comparable between groups. Corneal total root-mean-square (RMS) higher-order aberrations (HOAs) increased after treatment in both groups, although fewer RMS HOAs were induced in the corneal wavefront-guided group than in the aberration-free group. Spherical aberration increased similarly after treatment in both groups. However, coma and trefoil increased only in the aberration-free group. Aberration-free transepithelial PRK and corneal wavefront-guided transepithelial PRK were safe and effective for correction of myopic astigmatism without difference in visual acuity and refractive outcomes. However, the corneal wavefront-guided profile induced fewer corneal aberrations than the aberration-free profile.

Wavefront aberrations and accommodation in myopes and hyperopes

to comparatively investigate accommodation, pseudoaccommodation, and higher-order aberrations in children and young adults with myopia and hyperopia. A total of 39 myopic (the mean error of (-)5.2±1.5 diopters) and 53 hyperopic (the mean error of (+)3.1±1.15 diopters) eyes of 46 patients aged 5-20 years (11.6±0.6 years on average) were enrolled. Examination included evaluation of the objective accommodative response, relative accommodation reserves, pseudoaccommodation volume (calculated as the difference between the (+)3.0-diopter lens that is necessary for cycloplegic reading at a 33-cm distance and the weakest possible plus lens that enables reading), and higher-order aberrations (HOA), particularly the root mean square (RMS) value, vertical and horizontal trefoil, vertical and horizontal coma (coma7, coma8), and spherical aberration (SA). Both objective and subjective parameters of accommodation were reliably lower in myopia as compared to hyperopia, while wavefront aberrations (RMS HOA, vertical trefoil, coma7) and pseudoaccommodation - reliably greater. SA was found to be reliably more pronounced in those myopes, who demonstrated larger volume of pseudoaccommodation. At the same time, there was a mismatch in wavefront parameters of myopes and hyperopes at different levels of accommodation and pseudoaccommodation. In myopic eyes, vertical trefoil decreased down to negative values as the accommodative response improved. In contrast to that, in hyperopic eyes with large volume of pseudoaccommodation, SA decreased below zero. Myopia has been shown to be associated with reduced accommodation parameters as well as stronger HOA and pseudoaccommodation. Wavefront and accommodation parameters interrelations differ in myopic and hyperopic eyes. The nuances revealed should be taken into account when developing correction methods that purposefully influence refractogenesis.

Influence of Overnight Orthokeratology on Corneal Surface Shape and Optical Quality.

Purpose To investigate the changes of corneal surface shape and optical quality during orthokeratology. Methods 49 eyes of 26 patients (10.63 ± 2.02 years old) who underwent overnight orthokeratology for myopia were prospectively examined. The corneal surface shape parameters, including surface regularity index (SRI) and surface asymmetry index (SAI), were attained with an OPD-III SCAN. The higher-order aberrations and higher-order Strehl ratios were calculated under a 3 mm pupil diameter before orthokeratology, 1 month, 3 months, and 6 months after orthokeratology. A P value of less than 0.05 was statistically significant. Results Months after orthokeratology, SRI and SAI were both showing a significant increase in comparison with those before orthokeratology (P < 0.001). After orthokeratology, for a 3 mm pupil, the higher-order Strehl ratio presented a reduction of 0.217 μm (P < 0.001), and the higher-order aberration root mean square (HOA RMS) showed a mean increase of 0.100 μm (P < 0.001). There were significant increases in spherical aberration (P < 0.001) and coma (P = 0.044) after orthokeratology. Trefoil showed a slight reduction at month 6 after orthokeratology, but there was no statistical significance (P = 0.722). Conclusion Overnight orthokeratology for a correction of myopia resulted in a significant improvement in refractive error but increased corneal irregularity and ocular higher-order aberrations, especially in spherical aberration.

Comparison of visual outcomes and higher order aberrations of wavefront-optimized and wavefront-guided myopic laser in-situ keratomileusis

To compare the visual and refractive outcomes of wavefront-optimized (WFO) ablations (wavelight allegretto) and wavefront-guided (WFG) ablations (VISX Custom Vue). Overall, two consecutive groups of eyes were treated for myopia and myopic astigmatism with laser in-situ keratomileusis. One group was treated with WFO ablation and the other group was treated with WFG ablation. Preoperative and 1, 3 and 6 months postoperative refractive evaluation (efficacy, safety, predictability, accuracy, stability, and refractive astigmatism), higher order aberrations (HOAs), and contrast sensitivity were analyzed. The WFO group comprised 20 eyes of 11 patients and the WFG group comprised 34 eyes of 17 patients. Postoperatively, the mean refractive spherical equivalent was −0.21±0.30 D in WFO group and −0.23D±0.57 D in WFG group. The mean values for postoperative uncorrected distance visual acuity were 0.93±0.15 and 0.96±0.16 in WFO and WFG groups, respectively. Safety index was 1.11 in WFO group and 1.17 in WFG group. Six months postoperatively, in WFO group, the induced HOA root mean square (RMS) was 0.25±0.21 μm (P=0.007), induced coma RMS was 0.07±0.23 μm (P=0.84), and induced spherical aberration RMS was 0.03±0.12 μm (P=0.467), whereas induced trefoil RMS was −0.09±0.23 μm (P=0.003). In WFG group, induced HOA RMS was 0.9±0.11 μm (P=0.002), induced coma RMS was 0.01±0.30 μm (P=0.065), and induced spherical aberration RMS was 0.09±0.17 μm (P=0.214), whereas induced trefoil RMS was 0.04±0.15 μm (P=0.005). Contrast sensitivity testing showed a statistically significant improvement in both groups at low spatial frequencies test. Both WFG and WFO showed comparable accuracy, efficacy, and safety with nearly equal induction of all HOA.

Evaluation of visual and refractive outcomes of wavefront optimized versus wavefront guided laser-assisted in situ keratomileusis in patients with myopia and myopic astigmatism

Purpose The aim of this study was to compare the visual and refractive outcomes of wavefront optimized (WFO) ablations with wavefront guided (WFG) ablations in patients with myopia and myopic astigmatism. Patients and methods Two consecutive groups of eyes were treated for myopia and myopic astigmatism with laser insitu keratomileusis. One group was treated with WFO ablation, and the other group was treated with WFG ablation. Refractive evaluation (efficacy, safety, predictability, accuracy, stability, and refractive astigmatism), higher-order aberrations (HOAs), and contrast sensitivity were analyzed preoperatively and at 1, 3, and 6 months postoperatively. Results The WFO ablation group comprised 20 eyes of 11 patients who showed a change in the mean spherical equivalent refraction from − 3.34 ± 1.64 D preoperatively to − 0.21 ± 0.30 D at 6 months postoperatively, and the WFG ablation group comprised 34 eyes of 17 patients who showed a change in the mean spherical equivalent refraction from − 3.54 ± 1.50 D preoperatively to − 0.23 ± 0.57 D at 6 months postoperatively. A statistically significant difference was found when comparing within the group preoperatively versus 6 months postoperatively as regards contrast sensitivity, HOAs, trefoil root mean square (RMS), and spherical aberration. However, there was no significant difference in induced coma and spherical aberration RMS within each group preoperatively and at 6 months postoperatively. A statistically significant difference was found when comparing the two groups at 6 months postoperatively with respect to contrast sensitivity, induced HOA RMS, induced trefoil RMS, and spherical aberration. There was no significant difference between the two groups, except for induced coma and spherical aberration RMS. Conclusion Both the WFG group and the WFO showed comparable accuracy, efficacy, and safety with nearly equal induction of all HOAs.

Changes of ocular aberration stability after correction with adaptive optics system

Background The use of adaptive optics (AO) system in ophthalmic clinic and basic studies has increased in recent years.However, there are few reports on the stability of ocular aberrations after correction. Objective This study was to analyze the stability of aberration after correction by observing the repeatability of ocular aberration measurements. Methods Forty-one postgraduate school students and volunteers who meet the conditions were included from February to April 2014.The Zernike aberration coefficients including astigmatism (Z2-2, Z22), defocus (Z20), trefoil (Z33, Z3-3), coma (Z3-1, Z31), spherical aberration (Z40) and the value of root mean square (RMS) including 3rd-order to 7th-order aberrations, total higher-order aberrations (HOAs) and total ocular aberrations (TOAs) were measured by using AO system.The repeatability and stability of these data after corrected with AO system were analyzed.The repeatability was evaluated by ANOVA, within-subject standard deviation (Sw), repeatability (r) and intra-class correlation coefficients (ICC). The stability was evaluated by the nonparametric Friedman's rank test. Results AO system showed excellent repeatability on Z2-2, Z22, Z20 and TOA RMS (ICC>0.9), good repeatability on Z31, Z33, Z3-3, Z40, 3rd-order RMS, 4th-order RMS, HOA RMS (ICC>0.75), poor repeatability on Z3-1, 5th-order RMS, 6th-order RMS, 7th-order RMS (ICC<0.75). Repeatability (2.77 Sw) values ranged from 0.009 mm (7th-order RMS) to 0.163 mm (Z31). After low-order ocular aberrations were corrected, It was founded that Z2-2, Z22 reached stable state at the 4th second; Z20 was stable at the 6th second; Z3-3and Z33 reached stable state at the 4th second and third second, separately; Z31 was stable from 3rd-second to 9th-second, Z3-3 was stable at the 4th-second.Z40 and HOA RMS were stable at the third second and fifth second, respectively.The Z2-2, Z20, Z22, Z3-3, Z3-1, Z33, Z40 and HOA RMS were significantly different among different time points before and after low-order aberrations correction (all at P<0.05). Z2-2, Z22, Z20 reached stable state at the 4th-second, 3rd-second and 5th-second, respectively; Z3-3, Z33reached stable state at the 2nd-second and 3rd-second, respectively; Z3-1and Z40 reached stable state at the 2nd-second; HOA RMS reached stable state at the 5th-second. Conclusions After correcting the human ocular aberration, different aberrations can reach stable state at different time.The time of Z20, Z22, Z3-3, Z3-1, Z40 reaching stable state after 2nd-order to 5th-order ocular aberrations correction was earlier than those of lower-order aberrations correction. Key words: Adaptive optics; Wavefront aberration; Repeatability; Correction; Stability

Corneal Densitometry and Higher Order Aberrations After Bowman Layer Transplantation: 1-Year Results.

To evaluate corneal densitometry and higher order aberrations (HOAs) up to 1 year after Bowman layer (BL) transplantation. This was a retrospective study carried out at a tertiary referral center. Fifteen eyes of 14 patients who underwent BL transplantation for advanced keratoconus and had at least 1 year of follow-up were examined before BL transplantation and postoperatively at 1 day, 1 week, and 1, 3, 6, and 12 months. Corrected distance visual acuity (CDVA) with spectacles and contact lenses, anterior and posterior HOAs, and corneal densitometry were analyzed. One year after surgery, average logarithm of the minimum angle of resolution of spectacle-CDVA changed from 1.35 (±0.46) preoperatively to 0.96 (±0.32, P < 0.001), whereas average logarithm of the minimum angle of resolution of CDVA with contact lens remained stable after surgery (P = 0.126). Anterior and posterior HOA root mean square decreased from 3.08 ± 0.59 to 2.67 ± 0.71 μm and 7.32 ± 2.20 to 6.30 ± 2.18 μm, respectively (P < 0.05). Spherical aberration ((Equation is included in full-text article.)) improved on both anterior and posterior corneal surfaces (P < 0.001). After 1 year, corneal backscattering values showed an increase as compared with preoperative values mostly involving the central and posterior layers of the cornea, with a peak 1 month after surgery (P < 0.005 in zones 2-6 and 6-10 mm). No correlation between HOAs or corneal backscatter and CDVA was found. Corneal HOAs, especially spherical aberration, decreased for both anterior and posterior corneal surfaces after BL transplantation, whereas corneal backscattering increased, mostly in the central and posterior layers, where the graft has been placed. Changes in HOAs and corneal backscattering did not correlate with CDVA.

Induced Higher-order aberrations after Laser In Situ Keratomileusis (LASIK) Performed with Wavefront-Guided IntraLase Femtosecond Laser in moderate to high Astigmatism.

BackgroundWavefront-guided Laser-assisted in situ keratomileusis (LASIK) is a widespread and effective surgical treatment for myopia and astigmatic correction but whether it induces higher-order aberrations remains controversial. The study was designed to evaluate the changes in higher-order aberrations after wavefront-guided ablation with IntraLase femtosecond laser in moderate to high astigmatism.MethodsTwenty-three eyes of 15 patients with moderate to high astigmatism (mean cylinder, −3.22 ± 0.59 dioptres) aged between 19 and 35 years (mean age, 25.6 ± 4.9 years) were included in this prospective study. Subjects with cylinder ≥ 1.5 and ≤2.75 D were classified as moderate astigmatism while high astigmatism was ≥3.00 D. All patients underwent a femtosecond laser–enabled (150-kHz IntraLase iFS; Abbott Medical Optics Inc) wavefront-guided ablation. Uncorrected (UDVA), corrected (CDVA) distance visual acuity in logMAR, keratometry, central corneal thickness (CCT) and higher-order aberrations (HOAs) over a 6 mm pupil, were assessed before and 6 months, postoperatively. The relationship between postoperative change in HOA and preoperative mean spherical equivalent refraction, mean astigmatism, and postoperative CCT were tested.ResultsAt the last follow-up, the mean UDVA was increased (P < 0.0001) but CDVA remained unchanged (P = 0.48) and no eyes lost ≥2 lines of CDVA. Mean spherical equivalent refraction was reduced (P < 0.0001) and was within ±0.50 D range in 61 % of eyes. The average corneal curvature was flatter by 4 D and CCT was reduced by 83 μm (P < 0.0001, for all), postoperatively. Coma aberrations remained unchanged (P = 0.07) while the change in trefoil (P = 0.047) postoperatively, was not clinically significant. The 4th order HOAs (spherical aberration and secondary astigmatism) and the HOA root mean square (RMS) increased from −0.18 ± 0.07 μm, 0.04 ± 0.03 μm and 0.47 ± 0.11 μm, preoperatively, to 0.33 ± 0.19 μm (P = 0.004), 0.21 ± 0.09 μm (P < 0.0001) and 0.77 ± 0.27 μm (P < 0.0001), six months postoperatively. The change in spherical aberration after the procedure increased with an increase in the degree of preoperative myopia.ConclusionsWavefront-guided IntraLASIK offers a safe and effective option for vision and visual function improvement in astigmatism. Although, reduction of HOA is possible in a few eyes, spherical-like aberrations are increased in majority of the treated eyes.

Keratoconic Cone using its Keratometry, Decentration, and Thickness as Staging Parameters

ABSTRACT Aim To propose a new system of keratoconus staging using a set of parameters describing the keratoconic cone. Materials and methods Retrospective case series study of 101 keratoconic eyes of 58 patients was undertaken. They all had complete eye examination including corneal topography (Oculus Pentacam). Kmean, Kmax, higher order aberrations (HOAs) root mean square (HOARMS) value, pachymetry at thinnest point and steepest corneal meridian were obtained from Pentacam. Apex to thinnest pachymetry distance (D) was calculated using trigonometry. Pearson correlation coefficients between Kmax and HOARMS, between D on the one hand and the adjusted angle of steepest meridian, Kmean and Kmax respectively on the other, were calculated. Results There is a statistically significant positive correlation between Kmax and HOARMS (p &lt; 0.00001). There is a negative correlation, a “horizontalization,” of the steep meridian with D increase, although it fell short of statistical significance (p = 0.07). D and Kmean (p = 0.003), and D and Kmax (p = 0.005) are significantly negatively correlated. Conclusion Kmax correlates with significant changes in HOAs. D correlates with corneal astigmatic meridian change and has a divergent path to Kmean and to Kmax. We propose a new keratometry, decentration, and thinnest pachymetry staging using the parameters Kmax (K), distance from the corneal apex to the thinnest pachymetry point (D), and corneal thickness at its thinnest point (T) to give a better, detailed description of a keratoconic cornea which could lead to improvements in assessment of its severity and treatment outcomes. How to cite this article Tu KL, Tourkmani AK, Srinivas S. Keratoconic Cone using its Keratometry, Decentration and Thickness as Staging Parameters. Int J Kerat Ect Cor Dis 2016;5(3):99-104.

Comparison of Higher Order Aberrations after Wavefront-guided LASIK and PRK: One Year Follow-Up Results.

Purpose:To evaluate the changes and predictability of higher order aberrations (HOAs) after personalized laser in situ keratomileusis (LASIK) and personalized photorefractive keratectomy (PRK) for simple myopia and compound myopic astigmatism.Methods:In this prospective cross-sectional study, 100 eyes were included. A total of 50 eyes underwent personalized LASIK and 50 eyes underwent personalized PRK. Preoperative and postoperative wavefront data were compared between the two groups. The influential factors and predictability of HOAs were also assessed.Result:Total HOA increased in the amount of 0.01 ± 0.14 μm for the 5 mm pupil (P = 0.55) and 0.08 ± 0.22 μm for the 6 mm pupil (P = 0.02) after PRK; however after LASIK the corresponding values for the 5 and 6 mm pupil sizes were 0.05 ± 0.12 and 0.15 ± 0.18 μm, respectively (P < 0. 001). Mean changes were not significantly different between the PRK and LASIK groups for both 5 and 6 mm pupil sizes (P = 0.21 and P = 0.13, respectively). Spherical aberration increased following LASIK more than following PRK (P < 0.001). Changes in the root mean square (RMS) of total HOA had a statistically significant negative correlation (P < 0.001) with its preoperative value. HOA and spherical aberration reduced in majority of eyes when the preoperative spherical equivalent refraction was low.Conclusion:For the 6mm pupil size, the total HOA increased following both personalized PRK and LASIK with no significant difference between the two groups. Change of the total HOA RMS was influenced by the preoperative values. The known influencing factors could predict nearly 50% of the changes in total HOA.

Changes in Corneal Power After Descemet Stripping Automated Endothelial Keratoplasty.

To examine the optical effects of Descemet stripping automated endothelial keratoplasty (DSAEK) by evaluating changes in anterior and posterior corneal curvatures and aberrations. Eighty-three eyes treated using DSAEK combined with cataract surgery (the DSAEK group) and 41 control eyes of healthy patients (the control group) were included. Patients were examined before and 1 year after surgery with autokeratometry and Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany). The preoperative posterior corneal curvature was estimated from the anterior corneal curvature. The mean intended postoperative refraction in the DSAEK group was -0.75 ± 0.62 diopters (D), which was statistically different from the achieved refraction of +0.50 ± 0.93 D at the 1-year follow-up (P < .001). The average biometry prediction error was a hyperopic shift of +1.27 ± 0.80 D. Anterior corneal power was significantly higher before than after DSAEK with a difference of -0.63 ± 0.68 D (P = .03) correlating significantly with the hyperopic change (r(2) = 0.23, P < .01). The posterior corneal power after DSAEK showed a significant steepening of -0.69 ± 0.38 D (P < .01) from the estimated preoperative power and a difference of -0.64 ± 0.38 D (P < .01) from the posterior corneal power in the control group. The change correlated significantly with the hyperopic change (r(2) = 0.10, P < .01). The combined changes in anterior and posterior keratometry increased the correlation coefficient to r(2) = 0.34 (P < .01). Significant differences were observed for total higher-order aberrations root mean square and coma root mean square after DSAEK compared to controls. No significant changes were observed in spherical aberration. The hyperopic shift in the DSAEK group can be explained by changes in anterior and posterior corneal surfaces. Spherical aberration was not changed by DSAEK, suggesting that aspherical intraocular lenses may be implanted on the same indications as in normal cataract surgery.

Comparison of corneal power, astigmatism, and wavefront aberration measurements obtained by a point-source color light-emitting diode–based topographer, a Placido-disk topographer, and a combined Placido and dual Scheimpflug device

To evaluate and compare the performance of a point-source color light-emitting diode (LED)-based topographer (color-LED) in measuring anterior corneal power and aberrations with that of a Placido-disk topographer and a combined Placido and dual Scheimpflug device. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas USA. Retrospective observational case series. Normal eyes and post-refractive-surgery eyes were consecutively measured using color-LED, Placido, and dual-Scheimpflug devices. The main outcome measures were anterior corneal power, astigmatism, and higher-order aberrations (HOAs) (6.0 mm pupil), which were compared using the t test. There were no statistically significant differences in corneal power measurements in normal and post-refractive surgery eyes and in astigmatism magnitude in post-refractive surgery eyes between the color-LED device and Placido or dual Scheimpflug devices (all P > .05). In normal eyes, there were no statistically significant differences in 3rd-order coma and 4th-order spherical aberration between the color-LED and Placido devices and in HOA root mean square, 3rd-order coma, 3rd-order trefoil, 4th-order spherical aberration, and 4th-order secondary astigmatism between the color-LED and dual Scheimpflug devices (all P > .05). In post-refractive surgery eyes, the color-LED device agreed with the Placido and dual-Scheimpflug devices regarding 3rd-order coma and 4th-order spherical aberration (all P > .05). In normal and post-refractive surgery eyes, all 3 devices were comparable with respect to corneal power. The agreement in corneal aberrations varied. Drs. Wang, Koch, and Weikert are consultants to Ziemer Ophthalmic Systems AG. Dr. Koch is a consultant to Abbott Medical Optics, Inc., Alcon Surgical, Inc., and i-Optics Corp.

Repeatability of topographic and aberrometric measurements at different accommodative states using a combined topographer and open-view aberrometer

To evaluate the repeatability of corneal first-surface aberrations and aberrometric measurements of a combined aberrometer-topographer (iTrace Visual Function Analyzer) for 5 accommodative stimuli. Department of Ophthalmology, Goethe-University, Frankfurt, Germany. Prospective case series. Eyes of young adults with low to moderate myopia or hyperopia were examined in 2 measurement series comprising 3 corneal topography measurements and wavefront measurements focusing on targets at 5 distances (0.4, 0.5, 0.6, 1.0, and 4.0 m). Repeatability was analyzed using the standard deviation (SD) within 6 measurements and the coefficient of repeatability (CoR) by Bland-Altman analysis of the means of the 2 measurement series. Fifty eyes (50 subjects) were evaluated. The lowest calculated mean SD/CoR measurements using the aberrometer function at 5 target distances were 0.07 μm/0.14 μm for total ocular aberrations root mean square (RMS), 0.07 μm/0.16 μm for lower-order aberrations (LOAs) RMS, 0.03 μm/0.66 μm for higher-order aberrations (HOAs) RMS, 0.10 diopter (D)/0.22 D for sphere, 0.08 D/0.13 D for cylinder, and 0.09 D/0.21 D for the spherical equivalent (SE). Repeatability of the total RMS, LOAs RMS, sphere, and SE measurements improved with increasing target distance (P < .01 for aberrometric values; P < .03 for refractive values). Measurement reproducibility using the corneal topographer showed mean SDs/CoRs of 0.19 μm/0.41 μm for total RMS, 0.19 μm/0.39 μm for LOAs RMS, and 0.08 μm/0.23 μm for HOAs RMS. The aberrometer showed satisfactory results for measurement repeatability at all target distances and declining repeatability with increasing accommodation effort. No author has a financial or proprietary interest in any material or method mentioned.

Predictive Analysis Between Topographic, Pachymetric and Wavefront Parameters in Keratoconus, Suspects and Normal Eyes: Creating Unified Equations to Evaluate Keratoconus

ABSTRACTPurpose: To perform prediction analysis between topographic, pachymetric and wavefront parameters in keratoconus, suspects, and normal cases and to look at the possibility of a unified equation to evaluate keratoconus.Methods: This cross-sectional, observational study was done in cornea services of a specialty hospital. Fifty eyes of 50 candidates with a diagnosis of normal, keratoconus suspect, and keratoconus were included in each group (total 150 eyes). All eyes underwent detailed analysis on Scheimplug + Placido device (Sirius, CSO, Italy). Main parameters evaluated were topographic [maximum keratometry (Max Km), average keratometry and astigmatism at 3, 5, and 7 mm], pachymetric [central and minimum corneal thickness (MCT) and their difference, corneal volume] and corneal aberrations [higher order aberrations root-mean-square (HOARMS), coma, spherical, residual].Central tendency, predictive fits and regression models, were computed.Results: The measured variables had a significant difference in mean between the three groups (Kruskal–Wallis, p < 0.001). Max Km, MCT, and HOARMS had significant fits with other topographic, pachymetric and wavefront parameters, respectively. Inter-relations between these three (Max Km, MCT, and HOARMS) were also stronger for keratoconus (R2 from 0.75 to 0.33) compared to suspect/normal eyes (R2 from 0.15 to 0.003). These three variables (Max Km, MCT and HOARMS) were used as representative variables to create the unified equations. The equation for the pooled data was (Kmax = 59.5 + 2.3 × HOARMS−0.03 × MCT; R2 = 0.7, p < 0.001).Conclusions: Major variables used for grading keratoconus (MaxKm, MCT, HOARMS) can be linked by linear regression equations to predict the pathology’s behavior.

Clinical results with a supplementary toric intraocular lens for the correction of astigmatism in pseudophakic patients.

To evaluate the visual outcomes of pseudophakic patients who underwent supplementary toric intraocular lens (IOL) implantation to correct astigmatic refractive errors. Pseudophakic patients referred for the implantation of a supplementary toric IOL (Sulcoflex Toric 653T) were evaluated. Uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively), spherical equivalent (SE) refraction, rotational stability, higher order aberrations (HOA), and photopic glare and no-glare contrast sensitivity (CSV-1000, VectorVision) were evaluated. A total of 10 eyes of 10 patients were included. The mean age was 56.42 ± 5.9 years (range 45-65 years). Mean follow-up was 6.99 ± 5.1 months (6-18 months). Postoperatively, UDVA improved to 0.10 ± 0.12 (0.3 to -0.1) (p = 0.004) and CDVA to 0.07 ± 0.12 (0.3 to -0.1) (p = 0.021). Mean SE was -0.30 ± 0.56 D (-1.00 to +0.75) (p = 0.001). Mean toric IOL axis rotation at 6-month follow-up was 3.0° ± 2.45° (0-6). Ocular aberrometry values decreased after surgery (for average HOA root mean square, p = 0.008). Photopic contrast sensitivity (for all spatial frequencies) showed a trend for improvement after surgery; however, this was not borne out from the analysis (p&gt;0.05). The implantation of the Sulcoflex Toric IOL to correct astigmatism in pseudophakic patients provided excellent visual outcomes, predictability of refractive results, rotational stability, and optical performance. The implantation of this IOL is a safe and effective technique to correct pseudophakic cylindrical refractive errors and reduce spectacle dependence in these patients.

Assessment of aberrations and visual quality differences between myopic and astigmatic eyes before and after contact lens application.

OBJECTIVE:To evaluate the aberration and visual quality differences between myopic and astigmatic eyes before and after contact lens application by using corneal aberrometer and low- contrast sensitivity chart.METHODS:Eighty eyes of 40 patients were included in this study. Patients were divided into two groups as myopic (40 eyes, n=20) and astigmatic groups (40 eyes, n=20). We used aspheric Balafilcon A (Purevision and Purevision Toric Bausch&Lomb, Rochester, USA) lenses for each group. Corneal aberrations and low-contrast sensitivity values were measured and compared for each patient in both groups.RESULTS:There were no statistically significant differences between myopic and astigmatic groups when we compared low-contrast sensitivity values for both on- and off-eyes. Mean total higher-order aberration (HOA) values for off-eye, were 0.29±0.10 μm, and 0.33±0.10 μm for on-eye in the myopic group, while they were 0.42±0.14 μm in off-eye and 0.37±0.23 μm in on-eye in the astigmatic group. Off-eye mean coma, irregular astigmatism and total higher-order aberration RMS (root-mean-square) values were significantly higher in the astigmatic group compared to the myopic group (p=0.006, p=0.001, p=0.001) but mean on-eye RMS values were not.CONCLUSION:Myopic and astigmatic patients differ in terms of high-order aberrations and these differences cannot be equalized after contact lens application, but visual quality can be improved in both patients by using contact lenses.

Clinical Results and Higher-Order Aberrations after 1.4-mm Biaxial Cataract Surgery and Implantation of a New Aspheric Intraocular Lens

Purpose: The purpose of this study was to analyze the clinical outcome and higher-order aberrations (HOAs) after 1.4-mm biaxial microincision cataract surgery (B-MICS) and implantation of a new aspheric intraocular lens (IOL). Material and Methods: A total of 157 eyes of 106 patients were enrolled in this prospective, single-center study. The B-MICS (1.4 mm, 26 eyes) was followed by an implantation of a microincision aspheric Incise® IOL MJ14T (Bausch & Lomb, Rochester, N.Y., USA). The control groups consisted of patients operated with 1.8-mm (coaxial MICS, Akreos MI60, 41 eyes), 2.2-mm (small incision cataract surgery, Tecnis ZCB00, 44 eyes) and 2.2-mm (small incision cataract surgery, CT Asphina, 46 eyes) coaxial phacoemulsification with implantation of an aspheric IOL. Intraoperative and postoperative complications, best-corrected visual acuity, HOAs for a 5.0-mm pupil using the iTrace aberrometer (Tracey Technologies, Houston, Tex., USA) and endothelial cell loss were evaluated. The difference among the groups was evaluated by analysis of variance. Results: In the Incise group, the mean best-corrected visual acuity improved significantly from 0.4 ± 0.27 logMAR preoperatively to 0.05 ± 0.07 postoperatively. The root mean square of total ocular HOAs was measured at 0.419 ± 0.191 µm, spherical aberration was measured at 0.168 ± 0.072 µm and coma was measured at 0.213 ± 0.200 µm. The best-corrected visual acuity (p = 0.097), total ocular HOA (p = 0.630) and coma (p = 0.193) showed no statistically significant difference between the 4 groups. Conclusion: The aspheric microincision IOL was safely implanted through a 1.4-mm incision and showed similarly good postoperative outcome in comparison to 1.8- and 2.2-mm coaxial phacoemulsification. © 2014 S. Karger AG, Basel

Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: A comparison of two fitting approaches

PurposeTo evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. MethodsThirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-point-touch fitting approach. The lens’ back optic zone radius (BOZR) was 0.4mm and 0.1mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. ResultsA statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p<0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p<0.05). Significant reduction was found over time in CCA (p=0.001) and anterior corneal asphericity in both groups (p<0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p<0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p<0.05). ConclusionShort-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apical-touch was associated with greater corneal flattening in comparison to three-point-touch lens wear.