Internal Aberrations Research Articles

Orofarenks kitlesinin nadir bir nedeni: İki taraflı aberan internal karotis arter

Bilateral pharyngeal internal carotid artery aberration is a rarely seen variation which poses a risk during the surgical interventions of this area. A 74-year-old male patient was admitted to our clinic with the complaints of a sensation of fullness in his throat and dysphagia. Oropharyngeal examination revealed bilateral smooth-surfaced masses in the posterior pharyngeal wall. Magnetic resonance imaging showed an aberrant internal carotid artery. The patient was followed up with necessary warnings. The pulsation on the pharyngeal masses should be definitely evaluated and aberrant internal carotid artery should be kept in mind, if present.

Intraocular Optical Quality of Phakic Intraocular Lenses: Comparison of Angle-Supported, Iris-Fixated, and Posterior Chamber Lenses

To evaluate internal aberrometric profiles following phakic intraocular lens (PIOL) implantation. Retrospective and consecutive case series. One hundred and five eyes of 65 patients were included. The optical aberrations were measured with the Topcon KR-1W aberrometer. Comparisons of internal aberrations for different models were made. Comparisons at 4 and 6 mm were made also within the same model for all the lenses. Comparisons regarding the implantation site were also performed: angle-supported (AS) anterior chamber (AC) (n = 47), iris-fixated (IF) (n = 27), and posterior chamber (PC) (n = 31). Root mean square (RMS) of internal optical higher-order aberrations (HOAs) changed significantly to higher values from 4-6 mm aperture diameter in each PIOL, as should be expected. However, this significant change was not detected in spherical aberration for Kelman Duet (P = .753) and in trefoil for Acrysoft (P = .059). Kelman lens showed significantly lower values of spherical aberration compared to Acrysoft at 4 mm (P = .022) and at 6 mm (P = .042). Acrysoft showed the lowest values at central zone for trefoil (P = .043) and tetrafoil (P = .002) in AC group. In the IF group, Artisan and Artiflex showed similar results for all internal aberrations. In the comparison between Visian Implantable Collamer Lens (ICL; STAAR Surgical Co, Monrovia, California, USA) and phakic refractive lens (PRL), both for posterior chamber, significantly lower values of coma were observed for ICL (P = .033). IF lenses showed clinical evidence, but not significant, of better centering capability than AS lenses (P = .096). The study of intraocular aberrations is an adequate method to identify the clinical optical behavior and could help the surgeon to identify the most frequent problems related with each model.

The Effects of Pharmacologic Pupil Dilatation on Ocular, Corneal, and Internal Aberrations

The Effects of Pharmacologic Pupil Dilatation on Ocular, Corneal, and Internal Aberrations

Effect of Age on Components of Peripheral Ocular Aberrations

To investigate the effect of age on the contributions of the anterior cornea and internal components to ocular aberrations in the peripheral visual field. Ocular aberrations were measured in 10 young emmetropes and 7 older emmetropes using a modified commercial Hartmann-Shack aberrometer across 42° × 32° of central visual field. Anterior corneal aberrations were estimated from anterior corneal topography using theoretical ray-tracing. Internal aberrations were calculated by subtracting anterior corneal aberrations from ocular aberrations. Anterior corneal aberrations of young subjects were reasonably compensated by the internal aberrations, except for astigmatism for which the internal contribution was small out to the 21° field limit. The internal coma and spherical aberration of the older subjects were considerably smaller in magnitude than those of the young subjects such that the compensation for anterior corneal aberrations was poorer. This can be explained by age-related changes in the lens shape and refractive index distribution. Loss of balance between anterior cornea and internal components of higher order aberrations with increasing age, found previously for on-axis vision, applies also to the peripheral visual field.

Repeatability of Internal Aberrometry with a New Simultaneous Capture Aberrometer/Corneal Topographer

To compare repeatability of internal eye aberrations derived from aberrometry and corneal topography (CT) measured simultaneously by the Innovative Visual Systems Discovery, against time displaced but same instrument measurement (Nidek OPD-Scan 3), and time displaced different instrument measurement (Medmont E300 and Imagine Eyes irx3). Three aberrometry and CT measurements were captured with each instrument, except for the OPD-Scan 3 where three aberrometry scans were followed by a single CT. Measurements were repeated across 2 days. Corneal surface Zernike coefficients were derived from CT and subtracted from aberrometry to establish internal aberration coefficients. For the OPD-Scan 3, internal Zernike coefficients were derived by the instrument's software. Repeatability for second-order root mean square (RMS), spherical aberration, coma RMS, trefoil RMS, and the refraction components M, J0, and J45 were assessed using intraclass correlation coefficient (ICC). Intrasession repeatability was similar between the Discovery and E300/irx3, with the E300/irx3 slightly more repeatable for second-order RMS. Across days, the Discovery was most repeatable for second-order RMS (ICC 0.98) followed by the E300/irx3 (ICC 0.96) and OPD-Scan 3 (ICC 0.88). All instruments were less repeatable for higher order aberrations with only the Discovery moderately repeatable for spherical aberration and trefoil RMS (both ICC ≥ 0.75). The Discovery was highly repeatable for all derived refractive components (ICC ≥ 0.96). The E300/irx3 was highly repeatable for M (ICC 0.98) and moderately repeatable for J0 (ICC 0.89). The OPD-Scan 3 was highly repeatable for the M component (ICC 0.98) but not repeatable for the cylindrical components. The Discovery was highly repeatable for second-order RMS and derived refractive components. The lower repeatability for internal higher order aberrations measured with all instruments suggests caution in their use until further work is carried out to investigate sources of error and to develop methods to improve repeatability.

Aberrations and Topography in Normal, Keratoconus-Suspect, and Keratoconic Eyes

This study was designed to compare higher order aberrations of the cornea and of the eye with inferior-superior (I-S) corneal topographic values in keratoconic eyes. We studied 92 eyes from 78 subjects: 21 eyes of 14 subjects with suspected keratoconus, 23 eyes of 16 subjects with manifest keratoconus, and 48 eyes of 48 subjects without keratoconus using the L80 wave+, an instrument which can measure corneal topography and aberrations simultaneously with a large dynamic range making it possible to evaluate higher order aberrations to the seventh order of the Zernike polynomial function series. All ocular and corneal higher order aberrations were found to be significantly higher for keratoconic than normal eyes, but for suspected keratoconus the results were mixed. Corneal aberrations were higher than ocular aberrations due to compensation from the internal aberrations. For manifest keratoconus, the corneal and ocular vertical coma displayed the largest difference being 38.6 and 78.5 times higher, respectively, than normal eyes, while the largest differences for suspected keratoconus were only 5.3 and 4.0 times higher, respectively. On the other hand, inferior-superior dioptric asymmetry was 9.4 and 37.3 times higher for suspected keratoconus and keratoconic eyes, respectively, than normal eyes. The separation of normality curves between suspected keratoconus and normal eyes was 28.6% for I-S and 14.3% for both corneal vertical coma and corneal total coma. Although corneal vertical coma and, to a lesser extent, ocular vertical coma were found to be good indicators for the detection of keratoconic eyes, the traditional corneal topographic value such as the inferior-superior dioptric asymmetry remains an important predictor for identifying suspected keratoconus. However, ocular vertical coma and ocular higher order total root mean square also represent a good means of identifying suspected keratoconus.

Internal Aberrations and Optical Quality After Femtosecond Laser Anterior Capsulotomy in Cataract Surgery

To compare ocular and internal aberrations after femtosecond laser anterior capsulotomy and continuous curvilinear capsulorrhexis in cataract surgery. In this prospective study, anterior capsulotomy was performed during cataract surgery with an intraocular femtosecond (FS) laser (Alcon LenSx Inc) in 48 eyes. As a control group, continuous curvilinear capsulorrhexis (CCC) was performed in 51 eyes. Wavefront aberrometry, corneal topography, and objective visual quality were measured using the OPD-Scan (NIDEK Co Ltd). Vertical and horizontal tilt, coma, and visual quality metrics were evaluated separately to determine whether the source of aberrations was ocular or internal. Main outcome measures included postoperative residual refraction, uncorrected and corrected visual acuities, ocular and internal aberrations, Strehl ratio, and modulation transfer function (MTF). No statistically significant differences were noted between the FS and CCC groups, respectively, in postoperative sphere (-0.60 ± 1.50 vs -0.50 ± 1.40 diopters [D]), postoperative cylinder (1.30 ± 1.01 vs 1.10 ± 1.10 D), uncorrected distance visual acuity (0.86 ± 0.15 vs 0.88 ± 0.08), or corrected distance visual acuity (0.97 ± 0.08 vs 0.97 ± 0.06). The FS group had significantly lower values of intraocular vertical tilt (-0.05 ± 0.36 vs 0.27 ± 0.57) and coma (-0.003 ± 0.11 vs 0.1 ± 0.15), and significantly higher Strehl ratios (0.02 ± 0.02 vs 0.01 ± 0.01) and MTF values at all measured cycles per degree, compared to the CCC group. Capsulotomy performed with an intraocular FS laser induced significantly less internal aberrations measured by the NIDEK OPD-Scan aberrometer compared to eyes that underwent CCC, which may result in better optical quality after the procedure.

The Expanding Spectrum of Refractive Surgery

illustrates that concept better than this month’s issue of the Journal, with articles encompassing nearly every available anterior-segment approach now considered refractive surgery. Among the diverse topics presented herein, the safety and effi cacy of femtosecond cataract surgery, the advanced analysis of subclinical ectatic corneal disease, and the evolution of corneal collagen cross-linking (CXL) techniques provide essential information for all ophthalmologists. Perhaps the hottest topic in ophthalmology currently is femtosecond laser‐assisted cataract surgery. A prime concern about new technologies is that “hype” may speak louder than facts; therefore, surgeons need hard data from which to make educated decisions about this new technology. In this issue, Mihaltz and colleagues 2 report potential visual aberration benefi ts for femtosecond laser cataract surgery. Although standard visual acuity outcomes did not differ between femtosecond or manual capsulotomy groups, more subtle markers of visual quality, including internal aberrations, Strehl ratios, and modulation transfer functions favored the femtosecond laser group. Members of the same research group also reported favorable outcomes regarding macular thickness in the early postoperative period, suggesting that the suction ring utilized for femtosecond laser cataract surgery has minimal adverse effect on the retina. 3 With femtosecond laser cataract surgery still in its infancy, more studies are essential to evaluate the technique, benefi ts, and potential complications. Improved identifi cation of subclinical ectatic corneal disease in refractive surgery candidates remains of utmost importance. Wei and colleagues 4 com

Temporal evolution of ocular aberrations following laser in situ keratomileusis

To study the temporal evolution of ocular aberrations after standard LASIK to correct myopia. The ocular, corneal and internal aberrations for a 6-mm pupil were measured in 22 young myopic eyes (n = 12 subjects; range -2.0 to-7.6 D) before and during a 9-month follow-up after standard myopic LASIK. Ocular aberrations were measured with a Hartmann-Shack wavefront sensor, while corneal aberrations were estimated from the elevation data obtained by corneal topography. For every patient and condition the eye's modulation transfer function (MTF) and Strehl ratio (SR) were calculated. Compared to preoperative results, we found that standard myopic LASIK produced a significant increase of ocular high-order aberrations at 1 month after surgery. During the next 8 months, we found a small increase of ocular and corneal positive spherical aberration (SA), although with a large inter-subject variability. However, all eyes treated for myopia higher than -5 D showed a significant increase of positive SA during the first 6 months after surgery. Standard myopic LASIK decreases ocular optical quality. For most subjects, the increase in aberrations induced by the surgery was stable during the next 9 months after LASIK. However, further changes of the ocular SA after myopic LASIK are possible in patients treated for higher amounts of myopia. The changes in aberrations mainly appeared between the first and the sixth month after surgery, which suggests the need to wait at least 6 months after myopic LASIK before comparing outcomes, especially for patients treated for higher myopias.

Optical aberrations and alignment of the eye with age

We explored the relative changes in ocular, corneal, and internal aberrations associated with normal aging with special emphasis in the role of ocular alignment and lens shape factor in the balance of aberrations. Ocular and corneal aberrations together with the angle kappa were measured for a 5-mm pupil diameter in 46 eyes with low refractive errors and ages ranging between 20 and 77 years. The root mean square (RMS) of the higher order ocular and corneal aberrations increased with age at a rate of 0.0032 μm/year and 0.0015 μm/year, respectively. While in young eyes the partial compensation of aberrations by the internal surfaces was clear, no significant difference was found between corneal and ocular RMS in the older group. The ocular spherical aberration (0.0011 μm/year) and horizontal coma (0.0017 μm/year) increased moderately with age. This is not due to changes in the optical alignment, since angle kappa did not vary significantly with age. Age-related variations in the radii of curvature of the crystalline lens modify slightly its shape factor, reducing the compensation of lateral coma. This suggests that geometrical changes in the crystalline lens with age contribute to modify its aberration structure, reducing the compensation mechanism and explaining most of the measured increment of ocular aberrations with age.

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.

The change in internal aberrations following myopic corneal laser refractive surgery

In virgin eyes, the internal aberrations compensate corneal aberrations, and it has been suggested that the compensation may be feedback-driven and developmental, with active or passive adaptive mechanisms potentially responsible for the aberration auto-compensation. The purpose of this study is to investigate the internal higher order aberrations (HOA) following laser in situ keratomileusis (LASIK). Prospective corneal and internal HOA were measured pre-operatively and 6 months post-operatively on 50 consecutive LASIK patients with the OPD-Scan. There were increases to corneal HOA terms Z⁰₄ (0.215 ± 0.092 μm to 0.381 ± 0.180 μm), Z⁰₆ (0.002 ± 0.018 μm to 0.049 ± 0.034 μm) and Z⁴₆ (0.010 ± 0.017 μm to 0.018 ± 0.016 μm) with corresponding increases to internal HOA terms Z⁰₄ (-0.176 ± 0.102 μm to -0.218 ± 0.121 μm), Z⁰₆ (0.004 ± 0.022 μm to -0.010 ± 0.036 μm) and Z⁴₆ (0.008 ± 0.106 μm to -0.015 ± 0.054 μm). The increases in internal aberrations attenuated the increase in corneal aberrations, providing an overall lower quantity of total aberration. A greater increase in corneal spherical aberration and associated compensation was found to occur with greater degrees of attempted myopic correction. Corneal spherical aberration and Z⁴₆increased with corresponding increases in the internal spherical aberration and Z⁴₆ following LASIK. This may be an active compensatory mechanism of the internal optics to change, in order to reduce the effect of induced corneal HOA.

Comparison of Corneal and Total Ocular Aberrations Before and After Myopic LASIK

To assess the compensation of total ocular and corneal wavefront aberrations after conventional myopic LASIK. This study comprised 57 eyes of 57 patients. Total and corneal aberrations were measured preoperatively and 3 months postoperatively using the OPD-Scan (NIDEK Co Ltd) aberrometer. Total and corneal aberrations root-mean-square (RMS) was calculated out to the 6th Zernike order for a 6.0-mm pupil diameter. The percentage increase postoperatively was defined by the ratio of RMS pre- and postoperatively for each corneal and total eye group. The compensation between corneal and internal aberrations for a given aberration group was defined as: (corneal aberration group RMS - total eye aberration group RMS)/corneal aberration group RMS. Postoperatively, higher order aberrations increased by a factor of 1.77+/-1.26 (total) and 2.47+/-2.25 (corneal) (P<.05). Coma aberration increased by a factor of 2.43+/-2.61 (total) and 2.56+/-2.66 (corneal). Spherical aberration increased by a factor of 1.46+/-1.83 (total) and 2.64+/-2.24 (corneal). The values of the ratio of compensation did not change significantly before and after LASIK for individual aberrations (P>.05). Although myopic LASIK induced significant corneal aberrations, the level of partial compensation of corneal aberrations by internal structures remained unchanged. These results suggest that the previously described emmetropization that is effective during development may also be effective with acquired variations in corneal shape.

Total, Corneal, and Internal Ocular Optical Aberrations in Patients With Keratoconus

To measure and compare total, corneal, and internal ocular aberrations using combined wavefront analysis and corneal topography in eyes with keratoconus and eyes with normal corneas. This prospective study comprised eyes of patients with keratoconus and myopic patients seeking refractive surgery. Patients diagnosed with keratoconus and with a classification of "normal" or "keratoconus" on the NIDEK Corneal Navigator corneal disease screening software were selected for inclusion in this study. The normal group comprised eyes with a "normal" classification with 99% similarity. In the normal group, only one eye per patient was randomly selected based on a randomization schedule. Corneal, internal, and total wavefront measurements were provided by the NIDEK OPD-Scan II. One hundred eyes with keratoconus and 155 normal eyes were enrolled in the study. Statistically significant higher corneal and internal higher order aberrations were observed in the eyes with keratoconus (P<.05). However, an increase in ocular higher order aberrations proportional to corneal higher order aberrations was not observed in the keratoconus group. A compensatory effect of increased anterior corneal aberrations by internal aberrations in keratoconic eyes was present for some aberrations. The origin of this compensation and the optical mechanism behind it requires further study.

Spherical Aberration, Contrast Sensitivity and Depth of Focus With Three Aspherical Intraocular Lenses

Purpose: To evaluate postoperative spherical aberration, contrast sensitivity and depth of focus after implanting 3 different aspheric intraocular lenses. Methods: Fifty-six eyes (18 eyes for Akreos adapt Advanced Optics (AO), 20 eyes for AcrySof IQ SN60WF and 18 eyes for Tecnis Acrylic IOL ZA9003) of 48 patients were evaluated. Internal ocular aberration including spherical aberration and higher-order aberration and contrast sensitivity were evaluated 3 months after lens implantation. In addition, visual acuities at 33 cm and 1 m distance were measured with the far vision corrected state to calculate depth of focus. Results: The total and internal ocular spherical aberration of the AO implanted group was slightly higher than the other groups with statistical significance. However, there was no statistically significant difference of contrast sensitivity and depth of focus among the 3 groups. Conclusions: A subtle difference of spherical aberration among the 3 groups without a statistically significant difference in other factors may not induce the differences of contrast sensitivities and depths of focus in each group.

The Use of NIDEK OPD Scan II Wavefront Aberrometry in Toric Intraocular Lens Implantation

To present case examples outlining the use of wavefront aberrometry for toric intraocular lens (IOL) implantation pre- and postoperatively. Twelve eyes that underwent AcrySof Toric IOL (Alcon Inc Laboratories) implantation were assessed pre- and postoperatively using the NIDEK OPD Scan II (NIDEK Co Ltd). Wavefront aberrometry, corneal topography, and objective visual quality were measured using the OPD Scan II with OPD-Station software. The internal and corneal aberrations were evaluated separately to determine whether the source of astigmatism was corneal, internal, or a combination of both. All IOLs were implanted using a 2.75-mm incision. Wavefront aberrometry was used to determine the position of the incision to minimize postoperative astigmatism. The postoperative objective visual quality and wavefront maps were used to determine the effect of residual irregular or regular astigmatism. The OPD Scan II determines whether irregular or regular astigmatism is due to the corneal surface or to the internal aberrations of the eye. The magnitude, type, and location of astigmatism can guide the proper placement of toric IOLs.

Importance of fixation, pupil center, and reference axis in ocular wavefront sensing, videokeratography, and retinal image quality

To examine the impact of the location of the fixation target, pupil center, and reference axis of ophthalmic aberrometers and videokeratographers on the measurement of corneal aberrations relevant to vision. Clinical Research, Visual Optics Institute, College of Optometry, University of Houston, Houston, Texas, USA. The design features of a generic aberrometer and videokeratographer and their interaction with the eye were examined. The results provided a theoretical framework for experimental assessment of pupil translation errors on corneal aberrations relevant to vision and their correction in 129 eyes. Two key principles emerged. First, the aberrometer's measurement axis must coincide with the eye's line-of-sight (LoS). Second, the videokeratographer's measurement axis (the vertex normal) must be parallel with the eye's LoS. When these principles are satisfied, the eye will be in the same state of angular rotation and direct comparison of measurements is justified, provided any translation of the pupil from the vertex normal is taken into account. The error incurred by ignoring pupil displacement in videokeratography varies between eyes and depends on the type of aberration and amount of displacement, with the largest residual correction root-mean-square wavefront error being 1.26 mum over a 6.0 mm pupil, which markedly decreases retinal image quality. Translation of the pupil center with respect to the vertex normal in videokeratography should not be ignored in the calculation of the corneal first-surface, internal aberrations of the eye relevant to vision, or the design of refractive corrections based on videokeratography.

Laser In Situ Keratomileusis Disrupts the Aberration Compensation Mechanism of the Human Eye

To study how changes induced on corneal optics by myopic and hyperopic laser in situ keratomileusis (LASIK) refractive surgery affect the aberration compensation mechanism. Interventional case series and modeling theory. We measured ocular, corneal, and internal aberrations for a 6-mm pupil in 15 myopic and 6 hyperopic eyes with similar age range before and 6 months after standard LASIK. Ocular aberrations were measured using our own developed Hartmann-Shack wavefront sensor, whereas corneal aberrations were calculated by using the elevation data obtained by corneal topography. Ocular, corneal, and internal root mean square (RMS), spherical aberration (SA), coma, and compensation factor were compared for each patient. After myopic LASIK, we obtained an average 1.6-fold increase in ocular RMS, mainly positive SA, and coma, associated with a similar increase in corneal aberrations. In the hyperopes, we found a higher (2.3-fold) induction of ocular aberrations after surgery, mainly negative SA and coma, but without net increases of corneal aberrations. Aberration compensation clearly decreased or even inverted after hyperopic LASIK, decreasing the ocular optical quality in a higher level than myopic LASIK. Although ocular aberrations after myopic LASIK usually were smaller than corneal aberrations because of partial compensation of SA, after hyperopic LASIK, because of induction of negative SA and change in coma, disruption of the compensation mechanism lead to a larger increase of ocular aberrations. Customized procedures should maintain the natural compensation to achieve improved visual outcomes.

Comparison of higher order aberrations in eyes with aspherical or spherical intraocular lenses

To compare ocular, internal, corneal aberrations, and contrast sensitivity in patients implanted with aspheric or spherical intraocular lenses (IOLs). Total, corneal, and internal aberrations were measured using ray-tracing technology in 23 eyes implanted with aspheric (Tecnis ZA9003) IOLs, and in 25 eyes implanted with spherical (AcrySof SA60AT) IOLs. Spherical aberration (SA), coma, trefoil, and RMS of higher order aberrations (HOAs) were analysed for 4.0 and 6.0 mm optical zones. Best-corrected visual acuities (BCVAs), contrast sensitivity under photopic and mesopic conditions, and modulation transfer function (MTF) were evaluated to compare visual performances. The mean internal SA was -0.06/-0.35 microm in the aspheric IOL group and 0.04/0.17 microm in the spherical IOL group (at 4 mm/6 mm pupil). Total SA was near to zero in the aspheric IOL group, and was 0.11+/-0.034/0.48+/-0.13 microm in the spherical IOL group. The internal Z(3)(-1) and total Z(3)(-1) were more negative in the spherical IOL group. The internal Z(3)(-3) was more negative in the aspheric IOL group. The two groups were similar in terms of other Zernike values and RMS of HOA. There were no differences in BCVA between groups. The aspheric IOL group showed better contrast sensitivity at 3-6 cpd in photopic and 1.5-6 cpd in mesopic conditions. The MTF curve was better for the aspheric IOL group at 5-10 cpd. The aspheric IOL with a negative SA reduced total SA by compensating for positive corneal SA. These effects resulted in improved contrast sensitivity.

Lokalisation und altersabhängige Verteilung von Aberrationen des Auges

The aim of this study was to analyze the distribution of total, corneal, and mainly internal human third- to sixth-order aberrations (HOA) and investigate possible correlations between wavefront errors and patient age. For this study 140 eyes of 140 subjects (age range 17-77 years) were measured three times each using Nidek Optical Path Difference scan. Mean value and standard deviation for each Zernike polynomial was computed for a 5-mm pupil diameter, and six different age groups were formed. There was wide individual variation in the internal wavefront aberrations. The mean root-mean-square value for HOA was 0.4563 microm+/-0.296 microm. No positive correlation was found between Zernike polynomials and increasing age. In total spherical aberration however a significant difference was found between the 26-35-year and > or =56-year age groups (p=0.0002), as well as to internal and total coma (Z8) (p=0.0487 and p=0.0117, respectively). The internal, corneal, and total wavefront aberrations varied widely among patients. Some significant differences were found between the age groups. No correlation between age and the internal, corneal, or total aberrations was found.