Ocular Higher-order Aberrations Research Articles

Comparison of ocular wavefront aberrations in subluxated lenses before and after lens extraction with intraocular lens implantation

To compare the change in ocular higher-order wavefront aberrations (HOAs), visual acuity, and modulation transfer function (MTF) after lens extraction with intraocular lens (IOL) implantation in patients with subluxated lenses. Iladevi Cataract & IOL Research Centre, Ahmedabad, India. Prospective case series. Eyes with subluxated lenses having lens extraction with IOL implantation were included. Capsular bag fixation with in-the-bag IOL implantation or sutured or sutureless scleral fixation of the IOL was performed. Aberrometry was performed preoperatively and 6months postoperatively. The following were compared: root-mean-square (RMS) value for total ocular HOAs, coma aberration, spherical aberration, MTF, and corrected distance visual acuity (CDVA). Of the 39 eyes with subluxated lenses, 26 eyes had Cionni ring fixation, 9 had sutured scleral fixation, and 4 had intrascleral fixation of the IOL. The mean preoperative and postoperative values, respectively, were as follows: RMS HOAs, 10.5μm±9.5 (SD) and 4.73±4.6μm(P<.001); coma aberration, 2.46±2.4μm and 0.11±0.1μm(P=.03); and spherical aberration, 0.37±0.9μm and 0.02±0.06μm(P=.02). The MTF improved significantly in all eyes (mean 0.05±0.02 preoperatively and 0.32±0.16 postoperatively) (P=.005). The CDVA was statistically significant improved 6months postoperatively. Lens extraction with IOL fixation in eyes with subluxated lenses significantly reduced ocular HOAs and improved the MTF.

Precision and agreement of higher order aberrations measured with ray tracing and Hartmann-Shack aberrometers

BackgroundTo assess the precision and agreement of measurements of higher order aberrations (HOAs) obtained with a ray tracing aberrometer (iTrace) and a Hartmann-Shack aberrometer (Topcon KR-1 W).MethodsProspective evaluation of the diagnostic test. Data from the right eyes of 92 normal subjects obtained using the two devices were included in this study. Two observers performed 3 consecutive scans to determine the intraobserver repeatability and interobserver reproducibility. About one week later, one observer performed an additional 3 consecutive scans to obtain the intersession reproducibility. The within-subject standard deviation (Sw), test-retest repeatability (TRT) and intraclass correlation coefficient (ICC) were used to assess the precision, while Bland-Altman plots were performed to assess the agreement.ResultsFor intraobserver repeatability of the ocular, corneal and internal HOAs, Topcon KR-1 W showed a 2.77Sw of 0.079 μm or less and ICCs of 0.761 or more; and iTrace showed a 2.77Sw of 0.105 μm or less and ICCs of 0.805 or more. The ICCs of the internal HOAs of interobserver reproducibility were less than 0.75 except for spherical aberration (SA) (0.862), and interobserver reproducibility of the counterpart showed similar but lower results. For the ocular, corneal and internal HOA measurements, statistically significant differences existed between the Topcon KR-1 W and iTrace (all P < 0.05). No significant differences were observed in the ocular SA and internal coma.ConclusionsThe ray tracing and Hartmann-Shack method aberrometers provided excellent repeatability but less reliable reproducibility in the measurement of HOAs (except for SA). The two aberrometers should not be interchangeable in clinical application because of the significant differences in HOA measurements between them.

Effect of trabeculectomy on ocular higher-order aberrations in patients with open angle glaucoma.

OBJECTIVE:The aim of this study was to evaluate the effect of trabeculectomy on ocular higher-order aberrations following surgery in a group of patients with open angle glaucoma.METHODS:In this prospective study, patients with primary open angle glaucoma underwent wavefront aberrometry before trabeculectomy with mitomycin-C. Coma-like, spherical-like, and total ocular higher-order aberrations were measured as root mean square values. The measurements were repeated 1 month and 3 months after the procedure.RESULTS:A total of 20 eyes from 20 patients were examined. There was a significant decrease in intraocular pressure following surgery at 1 month and 3 months postoperatively. However, there was no statistically significant change in the spherical equivalent of the eyes. One month after surgery, a significant change in coma-like, spherical-like, and total higher-order aberrations of the eyes was observed. However, the repeated measurements performed 3 months after procedure revealed no significant difference compared to the baseline values.CONCLUSION:Ocular higher-order aberrations increased 1 month following trabeculectomy surgery. However, this effect seems to be transient, as the values returned to the preoperative measurement 3 months after the procedure.

Evaluation of Clinical Outcomes after LASIK for the Correction of Myopia Using the Advanced Customvue Excimer Laser Platform

-Purpose: To evaluate early visual, refractive and aberrometric outcomes after wave front-guided LASIK for the correction of low to moderate myopia and myopic astigmat is musing the excimer laser platform Advanced Custom Vue. Methods: A prospective, non-comparative study in 100 myopic eyes of 50 patients evaluating LASIK results over a period of 3 months. Main outcome variables included visual acuity, refraction, total higher-order aberrations (HOAs), spherical aberration (SA) and coma-like aberration. The surgery was performed using the VISX STAR S4 (Johnson and Johnson Vision) excimer laser and a wave front-guided ablation designed according to the iDesign aberrometer data (Johnson and Johnson Vision). Results: Mean preoperative sphere decreased from -4.07 ± 1.78 D to 0.32 ± 0.30 D at 3 months after surgery. Mean preoperative cylinder was reduced from -1.09 ± 0.88 D to -0.26 ± 0.28 D after the complete follow-up. Postoperative uncorrected distance visual acuity (UDVA) was 0.00 logMAR (20/20) or better in 100% of eyes, and 65.3% of eyes reached an UDVA of -0.20 logMAR (20/12.5) or better (p < 0.05). For a 6-mm pupil, the root mean square (RMS) for total ocular HOAs increased with surgery by 0.03 μm (p = 0.050), whereas the coma-like RMS increased by 0.05 μm (p < 0.001). The change in spherical aberration was +0.08 μm (p < 0.001). Conclusion: Wavefront-guided LASIK using the new generation excimer laser platform Advanced Custom Vue is safe and effective for treating myopia and myopic astigmatism, minimizing the postoperative level of HOAs.

Short-term change in higher-order aberrations after mitomycin-C-augmented trabeculectomy.

To investigate the changes in ocular higher-order aberrations (HOA) after trabeculectomy using mitomycin-C (MMC). We retrospectively reviewed data for 63 eyes from 63 glaucoma patients who had undergone MMC augmented trabeculectomy. We measured intraocular pressure (IOP), refractive errors, anterior chamber depth (ACD), and HOA before surgery and 1, 2, and 4weeks postoperatively. The patients were divided into two groups on the basis of preoperative lens status: phakic and pseudophakic group. We used a paired t test to compare preoperative and postoperative HOA values. Regression analysis was used to compare higher-order total (HOT) change and factors including ACD and age. For entire eye aberrations, coma-like and total HOT were significantly increased postoperatively at 1week (P=0.029, P=0.005, respectively), but not after 2 or 4weeks in the phakic group and were not significant at any time in the pseudophakic group. Corneal HOA were significantly increased postoperatively after 1, 2weeks, but not after 4weeks in the phakic group and were not significant in the pseudophakic group. For internal optics aberrations, HOA were significantly increased postoperatively at 1, 2, and 4weeks in the phakic group, but were not significant at any time in the pseudophakic group. However, HOT aberration change showed no correlation with age, ACD, IOP change in either group. Following trabeculectomy, HOA changes were significantly increased postoperatively at 1, 2weeks in the phakic group. Therefore, visual complaint-related HOA changes after trabeculectomy may be more profound in phakic patients.

OPD scan III accuracy: Topographic and aberrometric indices after accelerated corneal cross-linking

PurposeTo determine topographic and aberrometric changes after accelerated cross-linking (ACXL; 18 mW/cm2 for 5 min) as measured with OPD Scan III (Nidek Inc., Tokyo, Japan) and their repeatability in patients with mild and moderate keratoconus (KCN). MethodsIn this prospective study, 25 eyes with mild KCN [Ksteep = 47.24 ± 3.11 diopter (D)] and 20 moderate cases (Ksteep = 52.86 ± 4.39 D) were examined under mesopic conditions (20 lux) twice, 30–45 min apart, at baseline and 6 and 12 months afterwards. Extracted indices were Ksteep, Kflat, ocular and corneal irregularity, ocular and corneal total higher order aberrations (HOAs), coma, trefoil, and spherical aberration (SA). Repeatability index (RI) and intraclass correlation coefficients (ICCs) were determined. ResultsIn mild cases, Ksteep and corneal irregularity had lower RI, but Kflat and ocular irregularity had higher RI (all P > 0.050) at 1 year. The RI for ocular total HOAs, coma, and SA decreased and showed no significant change for trefoil (all P > 0.050). Moderate cases showed non-significant increases in RI for Ksteep, Kflat, ocular and corneal irregularity (all P > 0.050), and all aberrometry indices, and significant increases in RI for ocular coma (P = 0.046) and corneal trefoil (P = 0.037). At 1 year, ICC was >0.75 for all indices except ocular and corneal trefoil (ICC = 0.613 and 0.390) in moderate cases. ConclusionsAt one year after ACXL, OPD Scan III showed acceptable repeatability in mild cases. In moderate cases, topographic indices had acceptable repeatability but poorer compared to the mild group. Overall, ocular HOAs showed better repeatability than corneal ones. These changes should be considered in the interpretation of measurements.

Ocular higher-order aberrations changes after implantable collamer lens implantation for high myopic astigmatism

PurposeTo investigate the changes in higher-order aberrations (HOAs) induced by the implantation of implantable collamer lenses (ICLs) and Toric ICL (TICL) in eyes with high myopia and high myopic astigmatism. MethodsWe investigated 33 eyes of 18 consecutive patients (in a prospective, interventional case series study), with spherical equivalent errors of −6.00 to −21.09 diopters (D) and cylindrical errors of −0.5 to −4.75 D, who underwent ICL and TICL implantation. Before and after 5 days, 2 and 6 months of surgery, the uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), defocus and adverse events of the surgery were assessed. Ocular HOAs were also evaluated by Hartmann-Shack aberrometry (Technolas PV, Rochester, New York, USA) before and after 6 months of surgery. ResultsAt 6.0 months after surgery, the UCVA and BCVA in 40% and 66.7% of eyes were 20/20, respectively. Mean defocus refraction and astigmatism was reduced to −0.66 and 0.65 D from −12.79 and 2.18 at baseline, respectively. For a 6 mm pupil, HOAs were not significantly changed, merely from 0.417 ± 0.162 μ before surgery to 0.393 ± 0.119 μ after surgery (P = 0.45). Spherical aberration (Z400) increased significantly (P = 00.0). Surgical induced astigmatism was lower than 0.25 D, and there were no changes in trefoils and coma aberration. No vision-threatening complications occurred during the observation period. ConclusionThis study shows that the ICL and TICL performed well in correcting high myopic astigmatism without significant changes in HOAs during a 6-month observation period, although the spherical aberration (Z400) increased significantly.

The effect of soft contact lens thickness in visual function after intracorneal ring segments surgery.

To study the influence of soft contact lens (SCL) central thickness and material in keratoconus on visual function after intracorneal ring segment (ICRS) surgery. A pilot, experimental, prospective, cross-sectional and double-blind study was performed. Fourteen keratoconus patients with age range of 34.75±9.22years (7 males and 7 females) with ICRS implanted were involved in the study. Two different SCL materials [Hioxifilcon A (G-5X/p-GMA/HEMA) and Lucifilcon A (silicone-hydrogel)] with four different central thicknesses (0.1, 0.2, 0.3 and 0.4mm) were fitted in one eye per patient, selected randomly. High and low corrected distance visual acuity (CDVA) and contrast sensitivity (CS), corneal topography and corneal and total aberrometry were measured. Corneal spherical like, coma like and root mean square (RMS) decreased significantly for 0.3 and 0.4mm in both SCL materials (p<0.05). Total RMS decreased significantly for 0.4mm with both SCL materials (p<0.05). High and low CDVA improved for 0.4mm of thickness for both materials (p<0.05). Statistically increasing were found in all thicknesses studied for CS in both materials (p<0.05). A central thickness of the SCL equal or superior to 0.4mm seems to decrease the ocular high order aberration (HOA) and to improve the visual function in keratoconus patients implanted with ICRS. However, the modulus of rigidity of the SCL would not influence the HOA correction.

Ocular higher-order aberrations in patients with various refractive errors

Introduction:. Higher-order aberrations (HOAs) are small optical irregularities or imperfections of the eye which cannot be corrected by simple sphere and cylinder corrections. Many authors believe that HOAs are the reason many patients complain of halo, glare and decreased contrast sensitivity after successful corneal refractive surgery.(Baily et al., 2003) Many studies in the past showed significant variability of HOAs among the individuals of same population. Popularization of laser corneal refractive surgery and its potential to induce or remove optical aberrations (both low order and higher order aberrations) is the main reason behind better understanding of the nature of aberrations as well as their influence on visual quality. (Bisneto et al., 2007) Aim of the work:To measure and evaluate the distribution of HOAs among various refractive errors in individuals screened for refractive surgery and compare them .correlation with errors. Patients and Methods: prospective cross sectional analytical study was conducted at ophathalmology center for refactive surgery ,sohag started in February 2016. two hundred eyes of patients with age ranging from 18-40 years were included in the study. Results: Patients in hypermetropia group had statistically significant higher amount of HOA than other three groups followed by mixed group.No significant correlation of HOAs with amount of refractive error in all the groups except in mixed error group. Conclusion: In overall comparison we noticed the mean RMS of total HOAs were significantly higher in hypermetropia group and there was a statistically significant correlation between SE of Mixed group and RMS of Total HOAs.

Age-Related Changes in Ocular Aberrations and the Yamagata Study (Funagata).

Human vision quality is influenced by ocular aberrations, including astigmatism and higher-order aberrations (HOAs), in combination with other optical factors. In this study, we introduce the results and perceptions of previous studies investigating these aberrations. We also introduce our results obtained as part of the Yamagata Study (Funagata), a population-based epidemiologic study. To investigate the astigmatic change with age, researchers have used the power vector analysis, allowing incorporation of the magnitude and axis of astigmatism into statistical analyses. It was found that the axes of refractive astigmatism shift from with-the-rule toward against-the-rule with aging. It was demonstrated that the change in corneal curvature causes this shift. It was further reported that HOA increase is associated with deterioration of visual function. Some authors described that HOA increases with age in adults and that aging disrupts compensation between corneal and internal aberrations. Our study confirmed these results after considering possible confounding factors. HOA decreased from childhood to early adulthood and then increased with age, as modeled by a second-order polynomial regression. It is possible that the reduction in HOA is involved in emmetropization. In addition to age, HOA is known to be influenced by several factors, including pupil diameter, accommodation, and pupil shift. Although HOA increases with aging, the increase may be compensated by decreasing the pupil diameter. Better understanding of the causes of optical alterations with aging will improve the maintenance of vision quality.

Effects of higher-order aberrations on contrast sensitivity in normal eyes of a large myopic population.

To study the relation between higher-order aberrations (HOAs) and contrast sensitivity (CS) in normal eyes among a population of laser in situ keratomileusis (LASIK) candidates. In 6629 eyes of 3315 LASIK candidates, CS were measured under dark environment at the spatial frequencies of 1.5, 3, 6, 12 and 18 cycles per degree (c/d), respectively, using an Optec 6500 visual function tester. Meanwhile, ocular HOAs were measured for a 6.0 mm pupil with a Hartmann-Shack wavefront analyzer. In the study, the subjects with an average spherical equivalent of -4.86±2.07 D were included. HOAs decreased from the third to the sixth order aberrations with predominant aberrations of third-order coma, trefoil and fourth-order spherical aberration. At low and moderate spatial frequencies, CS was negatively correlated with the third-order coma and trefoil aberrations, and decreased with increasing Z31, but increased with increasing Z3-3 and Z5-1. At high spatial frequencies, CS decreased with increasing Z3-3 and increased with increasing Z5-1. At a large pupil size of 6.0 mm, the third-order aberrations, but not the total aberrations, are the main factors affecting CS. Vertical coma is negatively correlated with CS.

Comparison of Higher-Order Aberration Values between Different Aberrometry Technologies in Preoperative Laser Refractive Surgery Patients

Introduction: Purpose of this study was to evaluate the inter-device agreement of ocular and corneal higher-order aberration measurements using various aberrometers. Materials and method: Ocular and corneal higher-order aberrations were measured from 57 eyes. For ocular aberration, the measurements were obtained from WASCA Analyzer (Carl Zeiss Meditec, Jena, Germany), i-Profiler Plus (Carl Zeiss Meditec, Jena, Germany) and OPD-Scan III (NIDEK Co. Ltd., Tokyo, Japan). Whereas for corneal aberration, an additional measurement was obtained from Atlas Corneal Topographer 9000 (Carl Zeiss Meditec, Jena, Germany). All the measurements were displayed by the Zernike algorithm. Root mean squares of total, 3rd and 4th order of higher-order aberrations were compared between any three devices using repeated measured analysis of variance. The Bland-Altman analysis and Pearson's correlation were employed to assess agreement and strength of relationship between measurements. Results: For ocular aberrations, there were no significant difference (P &gt; 0.05) in all comparisons except for total higher-order aberration, oblique and horizontal trefoil. Whereas for corneal aberrations, vertical coma, spherical aberration and with-therule/against-the-rule secondary astigmatism between devices were found to be significantly different (P &lt; 0.05). The most agreeable device pairs for ocular and corneal aberrations were demonstrated by i-Profiler Plus - OPD Scan III (95% limit of agreement: -0.340 to 0.730) and Atlas Corneal Topographer 9000 - i-Profiler Plus (limit of agreement: 0.196 to 0.520) respectively. The r-values are stronger than 0.70. Conclusion: There were differences in the value of higher-order aberrations between different aberrometry technologies. Clinical impact due to the differences in wavefront measurement between skiascopy, Placido-based and laser technologies need to be investigated further.

Evaluation of the effect of corneal collagen cross-linking for keratoconus on the ocular higher-order aberrations.

BackgroundCorneal collagen cross-linking (CXL) is the only treatment currently available to arrest the progression of keratoconus. The procedure consists of photopolymerization of stromal collagen fibers induced by combined action of a photosensitizing substance (riboflavin or vitamin B2) and ultraviolet-A light.PurposeTo determine changes in the ocular higher-order aberrations (HOAs) after CXL and its correlation with changes in visual acuity.DesignProspective interventional study.Subjects and methodsThis study was conducted on 30 eyes of 16 patients with progressive keratoconus documented between 2012 and 2014. Patients were treated with epithelium-off CXL and followed for a minimum of 6 months. The following ocular HOAs were measured and analyzed using I-Tracey Aberrometer: coma, trefoil, spherical aberration, astigmatism, and total HOAs.ResultsThere was statistically significant improvement in uncorrected visual acuity and best-corrected visual acuity between the preoperative and 6-month evaluations (P<0.001). Total HOAs and total coma were statistically significantly reduced at 6 months by 25% and 18%, respectively. Significant improvement was seen in spherical aberration by 8.71% (P<0.001), while no significant change was observed in trefoil and high order astigmatism (P=0.405 and 0.329, respectively). There was a statistically significant change in the average (K) value at the apex between the preoperative values and the 6-month values (P<0.05).ConclusionTotal HOAs, total coma, and spherical aberrations decreased after CXL. Coma has a direct relationship with the improvement of visual function.

Quality of Vision in Eyes With Epiphora Undergoing Lacrimal Passage Intubation

To investigate visual function and optical quality in eyes with epiphora undergoing lacrimal passage intubation. Prospective case series. Thirty-four eyes of 30 patients with lacrimal passage obstruction were enrolled. Before and 1month after lacrimal passage intubation, functional visual acuity (FVA), higher-order aberrations (HOAs), lower tear meniscus, and tear clearance were assessed. An FVA measurement system was used to examine changes in continuous visual acuity (VA) over time, and visual function parameters such as FVA, visual maintenance ratio, and blink frequency were obtained. Sequential ocular HOAs were measured for 10 seconds after the blink using a wavefront sensor. Aberration data were analyzed in the central 4mm for coma-like, spherical-like, and total HOAs. Fluctuation and stability indices of the total HOAs over time were calculated. Lower tear meniscus was assessed by anterior segment optical coherence tomography. After lacrimal passage intubation, visual function significantly improved, as indicated by improved FVA (P= .003) and visual maintenance ratio (P < .001). Blink frequency decreased significantly after treatment (P= .01). Optical quality significantly improved, as indicated by a decrease in coma-like aberrations (P= .003), spherical-like aberrations (P= .018), and total HOAs (P= .001). Stability index increased (P< .001) and fluctuation index decreased (P= .019), and tear meniscus dimension decreased (P < .001). Lacrimal passage intubation for eyes with epiphora significantly improved visual function andoptical quality via patency of the lacrimal passage.

Ocular, corneal, and internal aberrations in eyes with keratoconus, forme fruste keratoconus, and healthy eyes.

The purpose of this study is to evaluate ocular, corneal, and internal aberration parameters in eyes with keratoconus (KC), forme fruste keratoconus (FFKC), and normal eyes. In a prospective study, one eye of 110 patients with KC, 60 FFKC patients, and 150 healthy participants was evaluated using OPD-Scan II. Ocular, corneal, and internal higher-order aberrations were measured through a sixth-order Zernike polynomial decomposition. Receiver operating characteristic analysis was performed to evaluate the diagnostic ability of the aberration parameters in discriminating KC and FFKC from normal eyes. The root mean square of the all ocular aberration measurements was significantly higher in the KC and FFKC patients than that of normal participants (p<0.05). All of the corneal aberration measurements were significantly higher in KC patients than those of normal patients (p<0.05); however, only corneal total higher-order aberration (HOA), vertical and total coma, and higher-order astigmatism were significantly higher in the FFKC patients than normal participants (p<0.05). The results also showed that internal aberration lower-order astigmatism, total trefoil, and total higher-order spherical aberration were significantly different between KC and normal groups (p<0.05). In comparison, internal total HOA, lower and higher-order astigmatism, total trefoil, and vertical coma were significantly different between FFKC and normal groups (p<0.05). Ocular vertical and total coma had the highest ability in discriminating keratoconic from normal eyes. Ocular total higher aberration and total coma had the highest diagnostic ability in discriminating FFKC from normal eyes. The diagnostic ability of internal aberration, on the other hand, was moderate to poor in discriminating KC and FFKC from normal eyes. Ocular aberration especially vertical and total coma and total HOA were found to be suitable parameters to discriminate KC and FFKC from normal patients. These two parameters could be used as discriminating factors in evaluating the patient for refractive surgery in an attempt to avoid iatrogenic ectasia.

Changes in meibomian gland morphology and ocular higher-order aberrations in eyes with chalazion.

PurposeTo examine the changes in meibomian gland morphology and ocular higher-order aberrations (HOAs) in eyes with chalazion and its excision.MethodsSeven male patients with previous history of chalazion excision and seven control male subjects were enrolled. Changes in meibomian gland morphology (meiboscores, gland dropout, and shortening) were evaluated by using meibography equipped in a wavefront analyzer KR-1W and in a slit-lamp device BG-4M. Ocular HOAs were measured sequentially with KR-1W. The tear film breakup time (BUT) was measured.ResultsBoth KR-1W and BG-4M visualized meibomian gland as clear similar images. The tear film BUT (mean ± SD, 5.6±3.0 vs 9.4±2.3 seconds, P=0.025), the total meiboscore (median [interquartile range], 2 (2−3) vs 0 (0−1), P=0.007) as well as the meibomian gland dropout rate (86% vs 14%, P=0.008) and shortening rate (100% vs 29%, P=0.031) differed significantly between the patient and control groups. The first total ocular HOAs (0.142±0.063 vs 0.130±0.015, P=0.80) were similar in both groups, whereas the stability index of the total HOAs over time (0.0041±0.0048 vs −0.0012±0.0020, P=0.030) differed significantly between the patient and control groups.ConclusionsChalazion and its excision were associated with dropout and shortening rate of meibomian glands. The morphological changes of meibomian glands in chalazion may be associated to instability of the tear film, which was suggested by the tear film BUT and the stability of ocular HOAs.

Comparison of ocular higher-order aberrations after SMILE and Wavefront-guided Femtosecond LASIK for myopia

BackgroundTo compare changes in higher-order aberrations (HOAs) following small incision lenticule extraction (SMILE) and wavefront-guided femtosecond laser-assisted in situ keratomileusis (WFG FS-LASIK), and to investigate correlations between preoperative spherical equivalence (SE) and components of HOAs affecting visual quality.MethodsSixty-five myopic eyes from 38 patients were enrolled in the study retrospectively, either having undergone SMILE or WFG FS-LASIK. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, and individual Zernike coefficients of 3rd- to 6th-order HOAs were measured before and 3 months after the surgeries and were compared using the Mann-Whitney test or Student’s t-test. Additional generalized estimating equation analyses (GEE) were used to control for within-subject biases in individual Zernike coefficients between the right and left eyes of the same patients.ResultsThere was no significant difference in UDVA or CDVA after WFG FS-LASIK (Mean ± SD: −0.02 ± 0.07 and −0.04 ± 0.22 respectively, in logMAR) and after SMILE (−0.01 ± 0.06 and −0.04 ± 0.04 respectively). However, greater vertical coma aberration was found after SMILE (p = 0.036). Preoperative SE was correlated to induced horizontal coma (r = −0.608, p = 0.001) in WFG FS-LASIK, and correlated to induced vertical coma (r = −0.459, p = 0.003) in SMILE.ConclusionsBoth SMILE and WFG FS-LASIK can achieve planned visual outcomes in correcting myopia and myopic astigmatism. However, higher vertical coma was shown in SMILE than WFG FS-LASIK which might be a potentially impact factor for patients’ vision under certain lighting conditions and needs further investigation.

Mesopic Quality of Vision after Accelerated 18 mW/cm2 Corneal Cross-linking: Mid-term Results.

PURPOSE:The purpose of the study was to determine 2-year changes in mesopic higher-order aberrations (HOAs) and contrast sensitivity (CS) after accelerated corneal cross-linking (CXL) in keratoconus patients.MATERIALS AND METHODS:In this before-after interventional case series, patients with progressive keratoconus were subjected to accelerated CXL (18 mW/cm2, 5 min). Patients were examined with the OPD-Scan III and CVS-1000 grating charts under mesopic conditions at baseline and at 12 and 24 months after CXL.RESULTS:At 24 months after CXL, compared to baseline, mesopic CS in spatial frequencies of 3, 6, 12, and 18 cycle per degree reduced respectively to 0.09 ± 0.27, 0.09 ± 0.32, 0.11 ± 0.19, and 0.02 ± 0.10; these changes were not statistically significant (all P > 0.05). The reduction in ocular HOAs was 0.11 ± 0.43; ocular coma, trefoil, and spherical aberration (SA) decreased by 0.09 ± 0.36, 0.05 ± 0.35, and 0.00 ± 0.13 microns, respectively (all P > 0.05). Reductions in corneal HOAs (0.89 ± 7.08) including coma (0.99 ± 3.55), SA (1.14 ± 3.92), and trefoil (1.28 ± 5.53) were not statistically significant (all P > 0.05). Coma had the highest share of corneal HOAs before and 24 months after CXL and the largest 24-month decrease was seen in corneal SA.CONCLUSION:At 2 years after accelerated CXL, despite reduced keratometry and corneal flattening, mesopic CS as well as ocular and corneal HOA remained unchanged, and the procedure did not cause a reduction in patients' vision quality.

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.

Higher-order aberration 4 years after corneal collagen cross-linking.

Purpose:Corneal collagen cross-linking (CXL) is a treatment strategy used in keratoconic eyes. Evaluation of long-term changes of higher-order aberrations (HOAs) after CXL is useful in understanding the efficacy of this procedure in improving optical, refractive, and visual acuity. This study aims to investigate the long-term effect of CXL on ocular HOA in patients with progressive keratoconus (KC).Methods:Using an OPD-Scan II aberrometer, ocular HOAs measurements of 56 eyes of 56 patients that underwent CXL was evaluated at the baseline, 1, 2, and 4 years after the procedure. All OPD-Scan measurements were decomposed into Zernike coefficients from 3rd to 6th order.Results:The results revealed that except for a few parameters, most of the aberration parameters continuously decreased during the study. In the 4-year postoperative period, a statistically significant improvement in all HOA parameters except 5th order Zernike polynomials (Z51, Z5−1, Z53, Z5−3, Z55, and Z5−5) was observed. All the values significantly decreased compared to the preoperative measurements (P < 0.05). The mean ± standard deviation (SD) root mean square of the 3rd, 4th, and the 5th order as well as coma, coma like, and total HOA parameters were significantly decreased compared to both preoperative and previous visits (P < 0.001). There were significant correlations between preoperative measurements of HOAs parameters with best-corrected visual acuity (BCVA) including Z31, Z3−1, Z40, Z51, and Z42. Moreover, all the HOAs parameters in 4 years after the CXL were significantly correlated with BCVA (P < 0.05).Conclusion:CXL is effective in improving HOA parameters in eyes with progressive KC during a long-term follow-up.