Ocular Aberrations Research Articles

Comparisons of amplitude of pseudoaccommodation with aspheric yellow, spheric yellow, and spheric clear monofocal intraocular lenses

PurposeTo determine the amplitude of pseudoaccommodation and higher-order aberrations with three types of implanted monofocal intraocular lenses (IOLs): aspheric yellow (IQ); spheric yellow (NT); and spheric clear (AT).SettingDepartment of Ophthalmology, Nara Medical University, Nara, Japan.MethodsWe studied 60 patients who underwent small incision phacoemulsification with the implantation of a monofocal IQ, NT, or AT IOL. The pseudoaccommodation was measured by the lens-loading method, and the postoperative ocular higher-order aberrations were measured with a Hartmann–Shack wavefront analyzer through natural and 4 mm pupils.ResultsSixty eyes of 60 patients were studied. The average amplitude of the pseudoaccommodation was 0.45±0.24 D with the IQ IOL, which was significantly lower than that with the AT IOL at 0.81±0.37 D (Tukey’s test; P<0.01). The differences in the amplitude of the pseudoaccommodation between the IQ and the NT IOLs, and between the NT and the AT IOLs were not significant (Tukey’s test; P>0.05). The degree of spherical aberration was significantly different for the IQ, NT, and AT lenses (analysis of variance, P=0.016). The spherical aberration through the IQ IOL was significantly lower than that through the NT and the AT IOLs (Tukey’s test; P<0.01). The fourth-order RMS (root mean square) aberration of the IQ lens was also significantly lower than that of the NT and AT IOLs (Tukey’s test; P<0.01).ConclusionOur results suggest that the spherical aberration and selective spectral transmission of IOLs may work together to increase the amplitude of the pseudoaccommodation.

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

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

Changes in Spherical Aberration after Various Corneal Surface Ablation Techniques

PurposeThe corneal change induced by refractive procedures influence both the postoperative refractive status and the ocular spherical aberration (SA). We evaluated changes in corneal SA after three types of surface ablation: phototherapeutic keratectomy (PTK), myopic photorefractive keratectomy (PRK), and myopic wavefront-guided laser epithelial keratomileusis (LASEK).MethodsTwenty-six eyes (25 patients) were subjected to PTK 26 eyes (14 patients) to PRK, and 34 eyes (17 patients) to wavefront-guided LASEK. Corneal SA was measured with the iTrace in all patients both preoperatively and 6 months postoperatively.ResultsSix months after surgery, mean corneal SA was -0.173 ± 0.171 µm in the PTK group, 0.672 ± 0.200 µm in the PRK group, and 0.143 ± 0.136 µm in the wavefront-guided LASEK group. The mean difference between the preoperative and postoperative corneal SA (ΔSA) was -0.475 µm in the PTK group, 0.402 µm in the PRK group, and -0.143 µm in the wavefront-guided LASEK group.ConclusionsSurgically induced changes in corneal SA vary with procedure. The prediction of the pattern of SA change induced by various surface ablation procedures may be helpful for developing future surgical procedures.

Preoperative Ocular Aberrations Measured by Zywave® II Aberrometer in Individuals Screened for Refractive Surgery

Preoperative Ocular Aberrations Measured by Zywave® II Aberrometer in Individuals Screened for Refractive Surgery

Short-term stability in refractive status despite large fluctuations in glucose levels in diabetes mellitus type 1 and 2.

PurposeThis work investigates how short-term changes in blood glucose concentration affect the refractive components of the diabetic eye in patients with long-term Type 1 and Type 2 diabetes.MethodsBlood glucose concentration, refractive error components (mean spherical equivalent MSE, J0, J45), central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), axial length (AL) and ocular aberrations were monitored at two-hourly intervals over a 12-hour period in: 20 T1DM patients (mean age ± SD) 38±14 years, baseline HbA1c 8.6±1.9%; 21 T2DM patients (mean age ± SD) 56±11 years, HbA1c 7.5±1.8%; and in 20 control subjects (mean age ± SD) 49±23 years, HbA1c 5.5±0.5%. The refractive and biometric results were compared with the corresponding changes in blood glucose concentration.ResultsBlood glucose concentration at different times was found to vary significantly within (p<0.0005) and between groups (p<0.0005). However, the refractive error components and ocular aberrations were not found to alter significantly over the day in either the diabetic patients or the control subjects (p>0.05). Minor changes of marginal statistical or optical significance were observed in some biometric parameters. Similarly there were some marginally significant differences between the baseline biometric parameters of well-controlled and poorly-controlled diabetic subjects.ConclusionThis work suggests that normal, short-term fluctuations (of up to about 6 mM/l on a timescale of a few hours) in the blood glucose levels of diabetics are not usually associated with acute changes in refractive error or ocular wavefront aberrations. It is therefore possible that factors other than refractive error fluctuations are sometimes responsible for the transient visual problems often reported by diabetic patients.

Comparison of visual acuity, higher-order aberrations and corneal asphericity after refractive lenticule extraction and wavefront-guided laser-assisted in situ keratomileusis for myopia

AimTo compare postoperative visual acuity, higher-order aberrations (HOAs) and corneal asphericity after femtosecond lenticule extraction (FLEx) and after wavefront-guided laser-assisted in situ keratomileusis (wfg-LASIK) in myopic eyes.MethodsWe examined 43 eyes...

Adaptive Optics for Visual Simulation

A revision of the current state-of-the-art adaptive optics technology for visual sciences is provided. The human eye, as an optical system able to generate images onto the retina, exhibits optical aberrations. Those are continuously changing with time, and they are different for every subject. Adaptive optics is the technology permitting the manipulation of the aberrations, and eventually their correction. Across the different applications of adaptive optics, the current paper focuses on visual simulation. These systems are capable of manipulating the ocular aberrations and simultaneous visual testing though the modified aberrations on real eyes. Some applications of the visual simulators presented in this work are the study of the neural adaptation to the aberrations, the influence of aberrations on accommodation, and the recent development of binocular adaptive optics visual simulators allowing the study of stereopsis.

Three different aspheric treatment algorithms of laser-assisted sub-epithelial keratectomy in patients with high myopia

To compare visual outcomes and quality in high myopia patients treated using one of three aspheric treatment algorithms based on the NIDEK Advanced Vision Excimer Laser System. Sixty eyes of 60 high myopia patients (>-6 diopter) underwent topography-guided (CATz) (20 eyes), wavefront-guided (OPDCAT) (20 eyes), or topography and wavefront-guided (OPA) (20 eyes) laser-assisted sub-epithelial keratectomy. Visual acuity, manifest refraction spherical equivalent (MRSE), ocular and corneal higher order aberrations, corneal asphericity, point spread function (Strehl ratio) and modulation transfer function (MTF) were compared preoperatively and 1, 3 and 6months postoperatively. Six months after surgery, logMAR uncorrected visual acuity was 0.02±0.09 in the CATz group, 0.02±0.07 in the OPDCAT group and 0.02±0.08 in the OPA group, and there were no statistically significant differences (P=0.5355). No statistical differences were found among the three groups in MRSE (P=0.3541). Induced spherical aberrations and the change of corneal asphericity were less in the OPA group than in the others (P<0.0001). The MTF was slightly better in the OPA group than in the others. The Strehl ratio showed no statistically significant differences among the three groups. All three aspheric treatment algorithms were safe and effective in correcting high myopia. Among them, the OPA algorithm maintained optical quality and physiologic cornea longer than the others.

Change in Efficiency of Aspheric Intraocular Lenses Based on Pupil Diameter

To measure the effect of spherical aberration correction by aspheric intraocular lenses (IOLs) based on pupil diameter, and to determine the minimum pupil diameter for each aspheric IOL. Retrospective cross-sectional study. Eight-six patients (169 eyes) who were implanted with a HOYA AF-1 NY-60 (HOYA Corporation) or Tecnis ZCB00 1-piece IOL (Abbott Medical Optics Inc) were enrolled. Ocular, corneal, and internal spherical aberrations were measured at the 1-month postoperative visit using the Wavefront Analyzer KR-1W (Topcon). Minimum pupil diameter, which is required for each aspheric IOL to be effective, was calculated using a regression equation. The mean value of internal spherical aberration of the Tecnis ZCB00 group (-0.09 ± 0.094 μm) was lower than that of the HOYA NY-60 group (-0.05 ± 0.072 μm) (P = .005). The original negative spherical aberrations of the HOYA NY-60 (-0.18 μm) were measured at a pupil diameter of 5.6 mm, and for the Tecnis ZCB00 (-0.27 μm) at a pupil diameter of 6.1 mm. The aspheric IOL efficiency dropped to 0% when the pupil diameter was 3.47 mm for the Tecnis ZCB00 group and 3.71 mm for the HOYA NY-60 group. When the pupil diameters of patients are smaller than 3.4 mm for the Tecnis ZCB00 and 3.7 mm for the HOYA NY-60, the spherical aberration correction using these aspheric IOLs seems to be ineffective. Approximately 10% of the eyes showed smaller pupil size than the minimum effective diameter under mesopic conditions.

Through‐focus performance with multifocal contact lenses: effect of binocularity, pupil diameter and inherent ocular aberrations

To evaluate the effects of the wearer's pupil size and spherical aberration on visual performance with centre-near, aspheric multifocal contact lenses (MFCLs). The advantage of binocular over monocular vision was also investigated. Twelve young volunteers, with an average age of 27 ± 5 years, participated in the study. LogMAR Visual Acuity (VA) was measured under cycloplegia for a range of defocus levels (from +3.0 to -3.0 D, in 0.5 D steps) with no correction and with three aspheric MFCLs (Air Optix Aqua Multifocal) with a centre-near design, providing correction for 'Low', 'Med' and 'High' near demands. Measurements were performed for all combinations of the following conditions: (1) artificial pupils of 6 and 3 mm diameter, (2) binocular and monocular (dominant eye) vision. Depth-of-focus (DOF) was calculated from the VA vs defocus curves. Ocular aberrations under cycloplegia were measured using iTrace. VA at -3.0 D defocus (simulating near performance) was statistically higher for the 3 mm than for the 6 mm pupil (p = 0.006), and for binocular rather than for monocular vision (p < 0.001). Similarly, DOF was better for the 3 mm pupil (p = 0.002) and for binocular viewing conditions (p < 0.001). Both VA at -3.0 D defocus and DOF increased as the 'addition' of the MFCL correction increased. Finally, with the centre-near MFCLs a linear correlation was found between VA at -3.0 D defocus and the wearer's ocular spherical aberration (R(2) = 0.20 p < 0.001 for 6 mm data), with the eyes exhibiting the higher positive spherical aberration experiencing worse VAs. By contrast, no correlation was found between VA and spherical aberration at 0.00 D defocus (distance vision). Both near VA and depth-of-focus improve with these MFCLs, with the effects being more pronounced for small pupils and for binocular rather than monocular vision. Coupling of the wearer's ocular spherical aberration with the aberration profiles provided by MFCLs affects their functionality.

The Change in Ocular Higher-Order Aberrations After Pterygium Excision With Conjunctival Autograft

To investigate the effects of pterygium excision with conjunctival autograft plus corneal polishing on ocular higher-order aberrations (HOAs) and to monitor the changes throughout the first postoperative year. A total of 18 eyes of 16 patients with primary pterygium who had an indication for surgical excision were included in the study. All patients underwent a detailed ophthalmologic examination preoperatively and at the third and twelfth postoperative months. Pterygium excision with conjunctival autograft plus corneal polishing was performed by the same surgeon (K.G.). Corneal topography and ocular HOAs were measured by NIDEK optical path difference scanning system ARK-10000 refractive power/corneal analyzer. Root mean square values of total aberrations and total HOAs were found to be significantly decreased both at 3 and 12 months after an uneventful pterygium surgery. Although solely root mean square values of coma and trefoil revealed a statistically significant reduction in the third postoperative month (P=0.043 and P=0.018, respectively), after 1 year, all parameters (total coma: P<0.001; total trefoil: P=0.004; total quatrefoil: P=0.010; and total high astigmatism: P=0.016) except for total spherical aberration (P=0.236) were found to be lower when compared with the preoperative values. Uneventful pterygium excision with conjunctival autograft plus corneal polishing can significantly reduce most of the pterygium-induced HOAs. Moreover, the reduced postoperative aberrations continue to change beyond the early postoperative period even into the 1-year postoperative period. Therefore, any refractive procedures should be postponed at least 1 year after the pterygium surgery until corneal stability occurs.

Objective evaluation of spherical aberration induced by soft contact lenses with spherical and aspherical optics and its effect on visual quality

Purpose: To measure, in mesopic luminance, the effects on ocular spherical aberration (OSA) of soft CLs with spherical optic (SOCL) and aspherical optic (AOCL) and to evaluate the impact on visual quality (VQ).

High Resolution Retinal Imaging Based on Ocular Aberration Measurement and Compensation

Ocular retinal imaging is a major diagnostic modality for retinal disease, and can play a critical role for diagnosing systemic diseases such as diabetes and eye-specific diseases such as macular degeneration and diabetic retinopathy, the leading causes of blindness. In order to get high-resolution retinal imaging and develop the low-cost and compact retinal imaging system, we employ micro adaptive optics, which is consisted of wavefront sensor, wavefront corrector and control system. In this paper, the theory, design and testing of the ocular retinal microscopy is detailed, with an emphasis on the eye wavefront aberration describing, aberration detecting method with Hartmann-Shack wavefront sensing and close-loop aberration compensating by micromachined membrane deformable mirrors(MMDM).The ocular retinal microscopy experimental setup is built, the retinal cell imaging had been snapped. It is showed in this work that the ocular retinal microscopy based on adaptive optics system can enable diffraction-limited imaging of micro-scale features of the retina, through real-time compensation of aberrations introduced by the eye.

OPTICAL AND FUNCTIONAL PERFORMANCE OF PHAKIC ANGLE-SUPPORTED INTRAOCULAR LENS FOR THE CORRECTION OF HIGH MYOPIA IN 18-MONTHS FOLLOW-UP STUDY

To investigate the safety, the efficacy and stability of the AcrySof phakic angle-supported intraocular lens (IOL) (Alcon Laboratories, Inc., Fort Worth, TX) for correction of moderate-to-high myopia in adults. 12 patients (18 eyes) with moderate-to-high myopia underwent implantation of the AcrySof phakic angle-supported IOL. Best spectacle-corrected visual acuity (BSCVA), uncorrected distance visual acuity (UCVA), predictability and stability of mean manifest refraction spherical equivalent (MRSE), adverse events, endothelial cell density, corneal and total ocular aberrations and rotation of the IOL were measured. The mean follow-up was 18 months (± 4 months). At 18 months, the mean UDVA was 0.83 and the mean BSCVA was 0.97. The mean MRSE was -0.29 D. The mean percentage change in central endothelial cell density 18 months after surgery was -3.4%. No adverse events were observed. Wavefront measurements revealed a significant reduction in terms of high order aberrations between pre-operative and post-operative 18 months values. The analysis of the rotation showed a little variation (mean rotation of 5.4°) between postoperative 1 month and postoperative 18 months visits. The AcrySof phakic angle-supported IOL yielded excellent refractive correction and predictability with optimal safety. The study demonstrates preliminary support for an high stability of the IOL at 18 months follow-up.

OPTICAL AND FUNCTIONAL PERFORMANCE OF PHAKIC ANGLE-SUPPORTED INTRAOCULAR LENS FOR THE CORRECTION OF HIGH MYOPIA IN 18-MONTHS FOLLOW-UP STUDY

To investigate the safety, the efficacy and stability of the AcrySof phakic angle-supported intraocular lens (IOL) (Alcon Laboratories, Inc., Fort Worth, TX) for correction of moderate-to-high myopia in adults. 12 patients (18 eyes) with moderate-to-high myopia underwent implantation of the AcrySof phakic angle-supported IOL. Best spectacle-corrected visual acuity (BSCVA), uncorrected distance visual acuity (UCVA), predictability and stability of mean manifest refraction spherical equivalent (MRSE), adverse events, endothelial cell density, corneal and total ocular aberrations and rotation of the IOL were measured. The mean follow-up was 18 months (&plusmn; 4 months). At 18 months, the mean UDVA was 0.83 and the mean BSCVA was 0.97. The mean MRSE was -0.29 D. The mean percentage change in central endothelial cell density 18 months after surgery was -3.4%. No adverse events were observed. Wavefront measurements revealed a significant reduction in terms of high order aberrations between pre-operative and post-operative 18 months values. The analysis of the rotation showed a little variation (mean rotation of 5.4&deg;) between postoperative 1 month and postoperative 18 months visits. The AcrySof phakic angle-supported IOL yielded excellent refractive correction and predictability with optimal safety. The study demonstrates preliminary support for an high stability of the IOL at 18 months follow-up.

Measurement of ocular anterior segment dimension and wavefront aberration simultaneously during accommodation

In order to understand the relationship between accommodation and vision quality, a custom-built ultra-long scan depth spectral domain optical coherence tomography (UL-SDOCT) and a Shack-Hartmann wavefront sensor (HSWFS) were combined. The resolution and scan depth of UL-SDOCT are 6 μm and 15.6 mm, respectively, which allow for high-resolution imaging of the whole anterior segment. The HSWFS consists of a 32 × 32 microlens array, and is able to measure first 35th-order Zernike aberrations with (1/20)λ measurement accuracy. The integrated system succeeded in measuring the ocular anterior segment dimension parameters and the ocular monochromatic high-order aberrations simultaneously under the conditions of nonaccommodative and accommodative stimuli. This may help understand the regulatory mechanism of image quality control in the human eye.

Multimodal adaptive optics retinal imager: design and performance

Optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) are complementary imaging modalities, the combination of which can provide clinicians with a wealth of information to detect retinal diseases, monitor disease progression, or assess new therapies. Adaptive optics (AO) is a tool that enables correction of wavefront distortions from ocular aberrations. We have developed a multimodal adaptive optics system (MAOS) for high-resolution multifunctional use in a variety of research and clinical applications. The system integrates both OCT and SLO imaging channels into an AO beam path. The optics and hardware were designed with specific features for simultaneous SLO/OCT output, for high-fidelity AO correction, for use in humans, primates, and small animals, and for efficient location and orientation of retinal regions of interest. The MAOS system was tested on human subjects and rodents. The design, performance characterization, and initial representative results from the human and animal studies are presented and discussed.

Ocular aberrations and visual function with multifocal versus single vision soft contact lenses

To investigate differences in ocular aberrations induced by centre-near multifocal soft contact lenses (SCL) relative to single vision SCLs and their effect on contrast sensitivity function (CSF). Ocular aberrometry was measured in 18 cyclopleged subjects (19-24 years) while wearing Ciba Air Optix low (AOlow) and high (AOhigh) add, Bausch & Lomb PureVision low (PVlow) and high (PVhigh) add multifocals, and a Bausch & Lomb PureVision single vision (PVsv) control with the same -3.00 D distance back vertex power. Zernike polynomials were scaled to 4, 5 and 6 mm pupils. CSF was measured at equivalent distances of 6 m, 1 m and 40 cm while fully corrected with spherical trial lenses at 6m. AOlow, AOhigh and PVhigh induced a negative shift in primary spherical aberration (Z12) from PVsv and all multifocal SCLs induced a positive shift in secondary spherical aberration (Z24) (all p<0.01), without significantly increasing coma. Area under the CSF (AUCSF) reduced at 40 cm for all multifocals relative to PVsv (p<0.05), but was not significantly different at 6 m or 1 m. A moderate correlation (r = -0.80, p<0.005) was found between changes in Z12 and AUCSF at 40 cm for AOhigh, with an increase in negative Z12 reducing multifocal-induced loss of CSF. Centre-near multifocal SCLs induced a negative shift in Z12 and a positive shift in Z24. Although CSF was unaffected at 6 m and 1m it was reduced at 40 cm, possibly because changes in Z12 and Z24 were not great enough to induce a significant shift in centre of focus and increase in depth of field.

Precision of higher-order aberration measurements with a new Placido-disk topographer and Hartmann-Shack wavefront sensor

To assess the intrasession and intersession precision of ocular, corneal, and internal higher-order aberrations (HOAs) measured using an integrated topographer and Hartmann-Shack wavefront sensor (Topcon KR-1W) in refractive surgery candidates. IOBA-Eye Institute, Valladolid, Spain. Evaluation of diagnostic technology. To analyze intrasession repeatability, 1 experienced examiner measured eyes 9 times successively. To study intersession reproducibility, the same clinician obtained measurements from another set of eyes in 2 consecutive sessions 1 week apart. Ocular, corneal, and internal HOAs were obtained. Coma and spherical aberrations, 3rd- and 4th-order aberrations, and total HOAs were calculated for a 6.0 mm pupil diameter. For intrasession repeatability (75 eyes), excellent intraclass correlation coefficients (ICCs) were obtained (ICC >0.87), except for internal primary coma (ICC = 0.75) and 3rd-order (ICC = 0.72) HOAs. Repeatability precision (1.96 × S(w)) values ranged from 0.03 μm (corneal primary spherical) to 0.08 μm (ocular primary coma). For intersession reproducibility (50 eyes), ICCs were good (>0.8) for ocular primary spherical, 3rd-order, and total higher-order aberrations; reproducibility precision values ranged from 0.06 μm (corneal primary spherical) to 0.21 μm (internal 3rd order), with internal HOAs having the lowest precision (≥0.12 μm). No systematic bias was found between examinations on different days. The intrasession repeatability was high; therefore, the device's ability to measure HOAs in a reliable way was excellent. Under intersession reproducibility conditions, dependable corneal primary spherical aberrations were provided. No author has a financial or proprietary interest in any material or method mentioned.

Binocular visual performance and summation after correcting higher order aberrations

Although the ocular higher order aberrations degrade the retinal image substantially, most studies have investigated their effect on vision only under monocular conditions. Here, we have investigated the impact of binocular higher order aberration correction on visual performance and binocular summation by constructing a binocular adaptive optics (AO) vision simulator. Binocular monochromatic aberration correction using AO improved visual acuity and contrast sensitivity significantly. The improvement however, differed from that achieved under monocular viewing. At high spatial frequency (24 c/deg), the monocular benefit in contrast sensitivity was significantly larger than the benefit achieved binocularly. In addition, binocular summation for higher spatial frequencies was the largest in the presence of subject’s native higher order aberrations and was reduced when these aberrations were corrected. This study thus demonstrates the vast potential of binocular AO vision testing in understanding the impact of ocular optics on habitual binocular vision.