Order Aberrations Root Mean Square Research Articles

Evaluation of the Agreement Between a New Pyramid Wavefront Sensor Aberrometer and Scheiner-Smirnov Aberrometers.

To assess agreement between a new aberrometer (Osiris-T; CSO) employing pyramid wavefront sensor technique and Scheiner-Smirnov aberrometer (OPD-Scan III; Nidek) on measuring ocular, corneal, and internal aberrations in healthy participants. The measurements were conducted three times consecutively by an experienced examiner. The total root mean square (RMS) aberrations, higher order aberration RMS, coma Z3±1, trefoil Z3±3, spherical aberration Z40, and astigmatism II Z4±2 up to 7th order were exported in both 4-and 6-mm pupil zones. The parameters between the two devices were statistically compared using the paired t-test, and the differences assessed with Bland-Altman plots and 95% limits of agreement. This prospective study included 70 right eyes of 70 healthy participants with an average age of 25.94 ± 6.59 years (range: 18 to 47 years). The mean difference in the two devices ranged from 0.01 µm for astigmatism II Z4±2 to 0.63 µm for total RMS in 4 mm and from 0.01 to 1.41 µm in 6-mm pupil size. The Bland-Altman analysis of ocular, corneal, and internal aberrations indicated high agreement between the two devices and the maximum absolute values for 95% limits of agreement ranged from 0.03 to 1.06 µm for 4-mm pupil diameters and 0.12 to 1.13 µm for 6-mm pupil diameters. The newly developed pyramid wavefront sensor technique aberrometer demonstrated a high agreement with a Scheiner-Smirnov aberrometer when measuring ocular, corneal, and internal aberrations in healthy participants. Thus, the two aberrometers may be considered interchangeable for clinical applications. [J Refract Surg. 2024;40(4):e218-e228.].

Spherical Aberration of Cataractous Eyes and Its Relationship With Age, Ocular Biometry, and Various IOL Platforms.

To determine the median spherical aberration (SA) of the cataractous population, how it relates to biometry, and the theoretical effect of different intraocular lens (IOL) platforms. A retrospective chart review of patients undergoing cataract surgery evaluation with a high quality Pentacam (Oculus Optikgeräte GmbH) were included. Age, gender, Q-value, mean total SA, higher order aberration root mean square wavefront error, and equivalent keratometry were collected from the Holladay report and axial length and anterior chamber depth (ACD) from the IOLMaster 700 (Carl Zeiss Meditec AG). Data from 1,725 eyes of 999 patients were collected. SA had a median of 0.37 µm (95% confidence interval: 0.36 to 0.38. Age (r = .136, P < .001), Q-factor (r = .743, P < .001), and higher order aberration root mean square wavefront error (r = .307, P < .001) were positively correlated with SA. Average equivalent keratometry (r = -.310, P < .001) was negatively correlated with SA. Axial length (r = -0.037, P = .120) and ACD (r = .004, P = .856) had no association with SA. Up to 1,499 (86.9%) theoretically had SA moved closer to zero with IOLs that had negative SA. Up to 102 (5.9%) had SA theoretically worsened. SA is not normally distributed, suggesting that there may be no "average" SA that IOLs should aim to correct. Patients might benefit from tailoring IOL choice to individual SA. Without access to SA data, eyes with steeper average keratometry or younger patients may have less SA, which could influence IOL choice. [J Refract Surg. 2023;39(2):89-94.].

Astigmatism Tolerance and Visual Outcomes After Bilateral Implantation of a Hybrid Continuous Transitional Focus IOL.

To evaluate the astigmatism tolerance and the visual outcomes after implantation of a premium intraocular lens (IOL) with a continuous transitional focus (Precizon Presbyopic; Ophtec BV) in pseudophakic presbyopia correction. This prospective study enrolled 20 patients (40 eyes) after bilateral phacoemulsification and IOL implantation. Corrected and uncorrected visual acuities at 4 m and 80, 67, and 40 cm (CDVA, UDVA, DCI80VA, UI80VA, DCI67VA, UI67VA, DCNVA, and UNVA), astigmatic and spheric defocus curve, mean reading speed (MRS), critical print size (CPS), contrast sensitivity, optical aberrations (modulation transfer function [MTF] cut-off, Strehl ratio, and higher order aberration root mean square [HOA RMS]), objective halometry, and National Eye Institute Refractive Error Quality of Life Instrument 42 [NEI RQL-42] questionnaire were evaluated 3 months after surgery. Astigmatic defocus curves revealed a tolerance up to -1.00 and +0.75 diopters (D) for with-the-rule astigmatism, and up to -1.00 and +1.00 D for against-the-rule astigmatism. Binocular spheric defocus curve showed that the mean visual acuity was greater than 0.15 logMAR from 1.00 to -1.00 D. MRS, CPS, MTF cut-off, Strehl ratio, and HOA RMS were 116.97 ± 21.94 words/min, 0.45 ± 0.06 logRDA, 20.03 ± 4.86 cycles/degree, 0.11 ± 0.07, and 0.28 ± 0.09, respectively. Contrast sensitivity was within the normal range for all tested light conditions. The NEI RQL-42 evidenced high subjective satisfaction for all subscales, especially for far vision, activity limitations, dependence on correction, suboptimal correction, appearance, and satisfaction with correction. The Precizon Presbyopic IOL allows good astigmatism tolerance and both objective and subjective high quality of vision. [J Refract Surg. 2023;39(1):33-39.].

Objective and Subjective Quality of Vision After SMILE for High Myopia and Astigmatism.

To report subjective and objective quality of vision (QoV) results for high myopic small incision lenticule extraction (SMILE) between -9.00 and -13.00 diopters (D). This was a prospective study recruiting 114 patients undergoing SMILE with attempted spherical equivalent refraction (SEQ) correction from -9.00 to -13.00 D, and cylinder up to 5.00 D. Patients were informed before surgery of the increased risk of QoV symptoms. Patients completed the Rasch validated QoV questionnaire. Objective QoV was assessed by corneal and whole eye aberrations, HD Analyzer Objective Scatter Index (OSI) (Keeler), and contrast sensitivity. Patient satisfaction was assessed on a scale from 0 (very dissatisfied) to 10 (very satisfied). Individual item and total Rasch-scaled scores for the three subscales (frequency, severity, and bothersomeness) of the QoV questionnaire were calculated before and 12 months after surgery. The mean patient satisfaction score was 9.27 ± 1.18 (range: 2 to 10), 8 or higher in 93%, and 7 or higher in 98% of patients. One patient with a satisfaction score of 2 had a simple refractive error re-treatment and then reported a satisfaction score of 10. The total mean ± standard deviation Rasch-scaled QoV score for the frequency, severity, and bothersomeness subscales before surgery was 24 ± 19, 20 ± 16, and 19 ± 18, respectively. Scores increased after surgery to 41 ± 18, 32 ± 16, and 30 ± 21, respectively (P < .001). Corneal aberrations (6 mm, OSI) increased on average by 0.39 µm for spherical aberration, 0.41 µm for coma, and 0.56 µm for higher order aberrations root mean square. OSI increased on average by 0.58. There was a small but statistically significant improvement in contrast sensitivity at 3, 6, 12, and 18 cycles per degree. There were no statistically significant correlations found between subjective scores for starbursts and objective measurements. Satisfaction was high following SMILE for high myopia. As expected, there was an increase in QoV symptoms, mainly glare and starbursts. The acceptance of QoV symptoms for high myopic SMILE was high, indicating that residual refractive error and visual acuity are the major drivers for patient satisfaction with appropriate preoperative informed consent. [J Refract Surg. 2022;38(7):404-413.].

Preliminary Characterization of Predictive Factors of the Visual Change after Epi-On and Epi-Off Corneal Collagen Crosslinking Techniques.

Purpose To investigate the potential predictive factors of the visual change achieved with accelerated epi-on and epi-off corneal collagen crosslinking (CXL) in keratoconus. Methods This retrospective comparative study analyzed 67 eyes treated with an accelerated epithelium-on (epi-on group) and epithelium-off (epi-off group) CXL. The clinical outcomes were evaluated and compared during a 1-year follow-up. Likewise, the relationship of the change achieved with both CXL techniques in the corrected distance visual acuity (CDVA) with different preoperative data was investigated. Results The mean CDVA change at 3 months postoperatively was −0.04 ± 0.19 and −0.07 ± 0.25 in the epi-on and epi-off groups, respectively (p = 0.809). In the epi-on group, this change was significantly correlated with the preoperative apical (r = −0.375, p = 0.045) and central corneal thickness (r = −0.402, p = 0.031). In the epi-off group, the CDVA change was significantly correlated with not only the preoperative apical (r = 0.402, p = 0.028) and central corneal thickness (r = 0.367, p = 0.046) but also with some topometric and aberrometric indices (r ≤ −0.374, p ≤ 0.042). Furthermore, the change in CDVA in the epi-on group could be predicted from age, preoperative refractive astigmatism J45 component, anterior corneal asphericity, and posterior corneal high order aberration root mean square (p = 0.002, R2 = 0.503). In the epi-off group, the CDVA change could be predicted from the preoperative minimum corneal thickness and magnitude of the vertical anterior corneal primary coma component (p = 0.001, R2 = 0.446). Conclusions Clearly, different predictive factors of the visual change induced with the accelerated epi-on and epi-off CXL techniques are present, suggesting a different mechanism of action for stiffening the cornea and inducing changes in this structure.

Effect of intracorneal ring segment implantation on high order aberrations comparing patients with eccentric versus central keratoconus.

To assess potential differences between central and eccentric cones in the aberrometric corneal profile and in visual and keratometric outcomes 6 months after intracorneal ring segment (ICRS) implantation for keratoconus. This study compared two groups consisting of 12 patients each, with central or eccentric keratoconus who were treated with femtosecond laser-assisted Keraring implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, keratometric readings and higher order aberrations (HOAs) including high order aberrations root mean square (HOARMS), coma, spherical aberration and trefoil were measured preoperatively and 6 months after ICRS implantation. Trefoil and spherical aberration were significantly reduced after ICRS implantation compared to preoperative values in eccentric keratoconus (Trefoil, p = 0.0049; Spherical aberration, p < 0.0001). In central keratoconus spherical aberration was reduced not significantly after ICRS implantation compared to preoperative values (p = 0.087). Coma showed a significant reduction in central (p = 0.0001) and in eccentric keratoconus (p = 0.0001). The reduction of spherical aberration in central keratoconus was significantly positively correlated to improvement in UDVA (Pearson's correlation coefficient, r = -0.66; p = 0.02). In eccentric keratoconus there was a significant positive correlation between reduction of trefoil and improvement in UDVA (Spearmans R, r = -0.69; p = 0.01). Patients both with central and eccentric keratoconus benefit from ICRS implantation. Specifically, our data provide a slightly higher gain in visual performance for eccentric cones 6 month after ICRS implantation, which is accentuated by a greater reduction in spherical aberration and trefoil. Improvements in UDVA are positively correlated with reductions in HOAs.

Aspheric photorefractive keratectomy for myopia and myopic astigmatism with the SCHWIND AMARIS laser: 2 years postoperative outcomes

PurposeTo evaluate mid-term refractive outcomes and higher order aberrations of aspheric PRK for low, moderate and high myopia and myopic astigmatism with the AMARIS excimer laser system (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). MethodsThis prospective longitudinal study evaluated 80 eyes of 40 subjects who underwent aspheric PRK. Manifest refractive spherical equivalent (MRSE) of up to −10.00 diopters (D) at the spectacle plane with cylinder up to 3.25 was treated. Refractive outcomes and corneal wavefront data (6mm pupil to the 7th Zernike order) were evaluated out to 2 years postoperatively. Statistical significance was indicated by P<0.05. ResultsThe mean manifest spherical equivalent refraction (MRSE) was −4.77±2.45 (range, −10.00D to −0.75D) preoperatively and −0.12±0.35D (range, −1.87D to +0.75D) postoperatively (P<0.0001). Postoperatively, 91% (73/80) of eyes had an MRSE within ±0.50D of the attempted. No eyes lost one or more lines of corrected distance visual acuity (CDVA) and CDVA increased by one or more lines in 26% (21/80) of eyes. Corneal trefoil and corneal higher order aberration root mean square did not statistically change postoperatively compared to preoperatively (P>0.05, both cases). There was a statistical increase in postoperative coma (+0.12μm) and spherical aberration (+0.14μm) compared to preoperatively (P<0.001, both cases). ConclusionAspheric PRK provides excellent visual and refractive outcomes with induction in individual corneal aberrations but not overall corneal aberrations.

Custom vs Conventional PRK: A Prospective, Randomized, Contralateral Eye Comparison of Postoperative Visual Function

To determine whether VISX S4 (VISX Inc) custom photorefractive keratectomy (PRK) results in better visual outcomes than VISX S4 conventional PRK. Photorefractive keratectomy was performed on 80 eyes from 40 patients in this randomized, prospective, contralateral eye study. Dominant eyes were randomized to one group with the fellow eye receiving the alternate treatment. Primary outcome measures included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, and root-mean-square (RMS) higher order aberrations. Mean UDVA was -0.023±0.099 (20/19) in the custom group and -0.044±0.080 (20/18) in the conventional group 6 months after surgery (P=.293). Mean CDVA was -0.073±0.067 (20/17) in the custom group and -0.079±0.071 (20/17) in the conventional group 6 months after surgery (P=.659). Total higher order aberration RMS and spherical aberration increased in both groups compared to preoperative values (P<.05). Coma increased in the conventional group (P<.05) whereas it was similar to preoperative values in the custom group. No significant differences were noted in induction of trefoil. Custom and conventional PRK were shown to be safe and effective with excellent visual acuity and contrast sensitivity performance at 6 and 12 months. Conventional PRK induced more coma than custom PRK; however, this did not seem to correlate with clinical outcomes.

Intrasubject Repeatability of Internal Aberrometry Obtained With a New Integrated Aberrometer

To evaluate the intrasubject repeatability of the internal aberrometry obtained with a new integrated aberrometer in a sample of normal eyes to assess its clinical usefulness. Twenty-six healthy eyes of 26 participants, aged 20 to 50 years, were included in the study. All eyes achieved corrected distance visual acuity of 1.0 (Snellen decimal notation) and did not undergo previous ocular surgeries. Three consecutive measurements of internal aberrations were obtained with the KR-1W system (Topcon Corp) by an experienced examiner. Intrasubject repeatability for 4- and 6-mm pupils was evaluated by the within-subject standard deviation (S(w)) and intraclass correlation coefficient (ICC). Low values of S(w) and values of ICC close to 1 were found for the 4-mm pupil astigmatism and for several aberrometric coefficients: primary spherical aberration and higher order, third order, and trefoil root-mean-square (RMS). Significant correlations of the S(w) for the 4-mm pupil higher order aberrations RMS with the magnitude of different aberrometric coefficients were found (r≥0.611, P<.01). In addition, tetrafoil RMS for 4-mm pupils correlated significantly with the S(w) for some higher order errors (r≥0.675, P<.01). Significantly larger values of S(w) for 6-mm pupils were found for trefoil (P<.01) and secondary astigmatism RMS (P=.02). The KR-1W provided repeatable measurements of internal astigmatism and some higher order aberrations, although consistency of such measurements appears to be limited by the level of aberration.

Variability of Higher Order Wavefront Aberrations After Blinks

To investigate the rapid alterations in value and fluctuation of ocular wavefront aberrations during the interblink interval. Forty-two volunteers were examined with a WASCA Wavefront Analyzer (Carl Zeiss Meditec AG) using modified software. For each subject, 150 images (about 6 frames/second) were registered during an interblink period. The outcome measures were spherical and cylindrical refraction and root-mean-square (RMS) values for spherical, coma, and total higher order aberrations. Fifth order polynomials were fitted to the data and the fluctuation trends of the parameters were determined. We calculated the prevalence of the trends with an early local minimum (type 1). The tear production status (Schirmer test) and tear film break-up time (BUT) were also measured. Fluctuation trends with an early minimum (type 1) were significantly more frequent than trends with an early local maximum (type 2) for total higher order aberrations RMS (P=.036). The incidence of type 1 fluctuation trends was significantly greater for coma and total higher order aberrations RMS (P=.041 and P=.003, respectively) in subjects with normal results in the BUT or Schirmer test than in those with abnormal results. In the normal subjects, the first minimum of type 1 RMS fluctuation trends occurred, on average, between 3.8 and 5.1 seconds after blink. We suggest that wavefront aberrations can be measured most accurately at the time after blink when they exhibit a decreased degree of dispersion. We recommend that a snapshot of wavefront measurements be made 3 to 5 seconds after blink.

Stability of Wavefront Aberrations During the Daytime After 6 Months of Overnight Orthokeratology Corneal Reshaping

To evaluate the stability of wavefront aberrations during the daytime after 6 months of overnight orthokeratology corneal reshaping. A prospective study of 26 eyes using the Ultravision BE lens design during 6 months of overnight wear. Uncorrected visual acuity (UCVA), cycloplegic refraction, and wavefront aberrometry were measured at 8 AM (within 1 hour after awakening and removing lenses), 1 PM (5 to 6 hours after lens removal), and 6 PM (10 to 12 hours after lens removal). There was no significant difference in UCVA between 8 AM, 1 PM, and 6 PM (P=.383). Spherical power from wavefront aberrometry showed significant regression from 8 AM to 1 PM (P<.001) and stabilized near zero diopters. Total root-mean-square (RMS) increased and higher order aberration RMS and defocus (Z4) decreased between 8 AM and 1 PM (P<.001) but did not change for the rest of the day (P>.001). There was no statistically significant change in astigmatism (Z3 and Z5) (P=.449) and coma (Z7 and Z8) (P=.145) between 8 AM, 1 PM, and 6 PM. Spherical aberration (Z12) showed regression throughout the day (P<.001). After 6 months of overnight orthokeratology wear, some optical aberrations showed regression during the day. Despite no significant change in UCVA during 10 to 12 hours, there was a significant increase in defocus (Z4) within the first 5 hours after removing the orthokeratology lens and a decrease in spherical aberration (Z12) throughout the day.

The Effect of Lubricant Eye Drops on Ocular Wavefront Aberrations

To study the effect of lubricant eye drop instillation on ocular wavefront aberrations. The wavefront aberrations of the entire optical path of 30 eyes of 15 patients before and following instillation of lubricant eye drops (Bion Tears; Alcon Laboratories Inc, Ft Worth, Tex) were obtained over a 6-mm pupil using a Hartmann-Shack wavefront sensor (WaveScan; VISX Inc, Santa Clara, Calif). Additional computation of root-mean-square (RMS) errors of higher order aberrations from third to sixth order were done using Zernike Tool Software (VISX Inc). Main outcome measures include the mean changes of total higher order aberrations RMS, higher order aberrations, and point spread function (PSF) of the higher order aberrations. The mean changes of total higher order aberrations following instillation of lubricant eye drops on the right eyes were -0.07 microm (95% confidence interval [CI], -0.11 to -0.03) and -0.03 microm on the left eyes (95% CI, -0.07 to 0.01). Significant mean changes were noted for coma and trefoil aberrations with a magnitude of -0.08 microm (95% CI, -0.12 to -0.03) and -0.09 (95% CI, -0.13 to -0.05), respectively, as well as a mean change of the PSF of the higher order aberrations (-0.05 diopters, 95% CI, -0.08 to -0.02) on the right eyes. Although no significant changes in these parameters were demonstrated on the left eyes, a similar trend of changes was observed. Ocular wavefront aberrations may change following eye drop instillation as measured objectively by the WaveScan system. This effect should be taken into consideration in the assessment of patients for wavefront-guided laser vision correction procedures.

Changes in Wavefront Aberration With Pharmaceutical Dilating Agents

Finding the best way to capture the wavefronts of small pupils for refractive surgery has become a more pressing issue as the general population ages. This study explores whether pharmaceutical dilation impacts wavefront measurement and pupil centroid. Baseline measurements were performed on 32 eyes using the VISX WaveScan Wavefront system. Pupils were dark adapted. One drop of 0.05% tropicamide was placed in each eye, and wavefront measurements were conducted at 10, 20, and 30 minutes. One drop each of 0.5% tropicamide and 2.5% phenylephrine were administered after the measurements. Wavefronts were captured again 30 minutes after the last eye drop. All patients returned for repeated procedures. Wavefront analysis was performed using the same pupillary area as the smallest capture from the same visit. Pupil center shift was taken into account. Mean patient age was 40 +/- 12 years (range: 20 to 59 years). Mean dark-adapted pupil was 6.40 +/- 1.17 mm. Pupil centers shifted randomly after pharmacological dilation compared to the dark-adapted condition. Pupil centers of 45% of the population shifted by > or = 0.2 mm. Repeatability coefficients were established for the wavefront measurements. After controlling for pupil diameter and pupil center, total high order aberrations root-mean-square (RMS) had changed significantly in 18% of the population. The diluted tropicamide formula, which caused less dilation effect, also induced less high order aberration RMS change. Pharmaceutical dilation agents cause random shifts of the pupil centroid from the dark-adapted pupil condition and could induce changes in wavefront measurements. Caution is required when resorting to dilation to obtain a wavefront measurement of smaller pupils.