Hartmann-Shack Aberrometer Research Articles

Effect of migraine attack on pupil size, accommodation and ocular aberrations.

To evaluate the pupil size, accommodation, and ocular higher-order aberrations (HOAs) in patients with migraine during migraine attacks and compare them with interictal period and healthy controls. This prospective, case-control study included 48 eyes of 24 patients with migraine and 48 eyes of 24 age and sex-matched healthy controls. Measurements were performed using a Hartmann Shack aberrometer. Accommodative responses to accommodative stimulus ranging from 0 to 5 diopters (D) in increments of 0.5 D were recorded. Spherical, coma, trefoil aberration, and root mean square (RMS) of total HOAs were assessed. Patients with migraine were measured twice during the interictal phase and during migraine attack. The mean pupil size significantly decreased during migraine attack (5.85 ± 0.19 mm) compared with the interictal phase (6.05 ± 0.19 mm) in the patients with migraine (p = 0.012). There was a significant increase in the accommodative response to accommodative stimulus of 1.5 to 5 D during migraine attack. No significant change was observed in HOAs during migraine attack. In addition, no ictal or interictal period measurements were statistically significantly different from the controls. Comparing symptomatic and non-symptomatic sides in 17 migraine patients with unilateral headache, no significant difference was found in any of the measurements in both ictal and interictal periods. Our results suggest the presence of a subtle oculosympathetic hypofunction in patients with migraine during the ictal period compared to the interictal period. The accommodation status of the eye seems to be affected by this autonomic dysfunction.

Higher order aberrations and axial elongation in combined 0.01% atropine with orthokeratology for myopia control.

To compare the changes in higher order aberrations (HOA's) for photopic and mesopic pupil diameters in children undergoing orthokeratology treatment (OK) or combined 0.01% atropine with orthokeratology treatment (AOK), and their association with axial elongation. Children aged 6 to <11years with 1.00-4.00 D of myopia were randomly assigned to each treatment group. Photopic and mesopic pupil diameters were quantified using automated pupillometry and HOA's were measured with a Hartmann-Shack aberrometer and Badal system to control for accommodation. HOA's were rescaled to photopic and mesopic pupil diameters and fitted with a 6th order Zernike polynomial expansion. Axial length was measured using an optical biometer under cycloplegia. Baseline and six-month data from 25 AOK and 28 OK participants were analysed. At the six-month visit, pupil diameter was larger in the AOK group under photopic conditions (3.70±0.42 vs 3.12±0.33mm, p<0.001), along with a range of HOA metrics [3rd to 6th order and higher order root mean square error values (HO RMS), all p≤0.003] and individual Zernike terms (primary spherical aberration, and oblique quadrafoil, both p≤0.03). Axial elongation was greater in the OK treatment group (0.05±0.08 vs -0.01±0.12mm, p=0.02). In the AOK group, axial elongation was correlated with the increase in photopic pupil diameter (r=-0.45, p=0.02) and with several HOA metrics; however, these associations were not observed in the OK group. AOK treatment resulted in increased photopic pupil size and HOA's, and significantly less axial elongation over a six-month period compared to OK treatment alone. The improved myopia control observed with combination 0.01% atropine and orthokeratology may be a result of an enhanced optical effect due to a larger photopic pupil size.

Optical Aberrations of Guinea Pig Eyes.

PurposeThe guinea pig is widely used in studies of refractive error development and myopia which often involve experimental optical manipulations. The study described here investigated the optical quality of the guinea pig eye, for which there are limited data, despite its fundamental importance to understanding visually guided eye growth.MethodsThe ocular aberrations of eight adolescent New Zealand pigmented guinea pigs (6–11 weeks old) were measured after cycloplegia using a custom-built Shack–Hartmann aberrometer and fit with a Zernike polynomial function to the 10th order (65 terms). The optical quality of their eyes was assessed in terms of individual Zernike coefficients, and data were further analyzed to derive root-mean-square (RMS) wavefront errors, modulation transfer functions (MTFs), point spread functions (PSFs), Strehl ratios, and depth of focus. A 4-mm pupil was used in all computations. The derived data are compared with equivalent data from normal young adult human eyes.ResultsThe guinea pigs exhibited low hyperopia and a small amount of positive spherical aberration, with other aberration terms decreasing with increasing order. Their average depth of focus, estimated from through-focus modulation, was 3.75 diopters. The RMS wavefront error of the guinea pig eye was found to be larger than that of the human eye for the same pupil size, reflecting a higher degree of aberrations, although the PSF (area) on the retina was smaller and sharper due to its shorter focal length. The radial average best-focus MTF derived for the guinea pig eye showed good performance at very low spatial frequencies, with a steeper decline with increasing frequency than for the human eye, dropping below 0.3 at 9 cpd. When converted to linear units (cycles/mm), the guinea pig eye had a higher spatial frequency cutoff and a slight contrast advantage for low spatial frequencies compared to the human eye.ConclusionsThe optical quality of the guinea pig eye is far superior to their reported behavioral visual acuity. This implies a neuroanatomical limit to their vision, which contrasts with the close match of optical and neural limits to spatial resolution in human eyes. The significance for eye growth regulation of the relative optical advantages exhibited by guinea pig eyes, when optical quality is expressed in linear rather than angular retinal units, warrants further consideration.

A Comparison Between Refraction From an Adaptive Optics Visual Simulator and Clinical Refractions.

PurposeThe Visual Adaptive Optics (VAO) is an adaptive optics visual simulator with an embedded Hartmann–Shack aberrometer that can give objective and subjective refraction measures. The aim of the present study was to compare the findings of the objective and subjective refractions from the VAO with a commercial autorefractometer (Topcon Corp., Tokyo, Japan) and a subjective refraction by an optometrist. The influence of age, refractive error type, and presence of ocular diseases was ascertained.MethodsThe refractive error was obtained in 469 participants using the four techniques mentioned. Data were analyzed with power vectors mean spherical equivalent, the vertical Jackson-Cross-Cylinder, and the oblique Jackson-Cross-Cylinder. Age, refractive error type (myopia, emmetropia, hyperopia) and presence of ocular diseases (yes, no) were included as covariates. Agreement was assessed using the 95% interval of agreement.ResultsThe median spherical equivalent difference and the interval of agreement for all the participants with the VAO subjective, VAO objective, and autorefraction with the clinical subjective refraction were (+0.13, 1.80 diopters [D]), (+0.38, 1.80 D), and (−0.38, 2.10 D), respectively. When considering only healthy participants, the results were (+0.06, 1.70 D), (+0.38, 1.60 D) and (−0.25, 1.80 D), respectively. When considering only those participants with any ocular condition, the results with VAO subjective, VAO objective and autorefraction were (+0.13, 2.50 D), (+0.31, 2.70 D), and (−0.50, 4.80 D), respectively.ConclusionsThe VAO subjective refraction is more accurate than VAO objective refraction and autorefraction, regardless of refractive error, age, or the presence of ocular conditions. The presence of ocular conditions significantly deteriorates the accuracy of all refraction methods.Translational RelevanceReported clinical comparisons between different types of standard refraction methods and a new adaptive optics refraction instrument (VAO) are in good agreement and support the further development of this method to increase refraction accuracy and to refract quicker than standard procedures.

Impact of peripheral optical properties induced by orthokeratology lens use on myopia progression

The objective of the present retrospective comparative cohort study was to compare the impact of wearing glasses versus an orthokeratology (Ortho-K) lens on peripheral optical properties and myopia progression in a population of South Korean children. Participants included children with myopia, between 8 and 12 years of age (n = 22 eyes), and divided into two groups: those who used glasses (Group I, n = 9) and those who used an Ortho-K lens (Group II, n = 13). Myopia progression over one year was quantified by changes in the central axial length of the eye. Keratometry and corneal aberrations on both the anterior and posterior surfaces of the eye were obtained using a Scheimpflug camera. A custom-developed Shack-Hartmann aberrometer was also used to measure peripheral aberrations across the horizontal visual field, up to 30°, and along the nasal-temporal meridian in 10-degree steps. Central axial elongation was larger in Group I (0.59 ± 0.21 mm) than in Group II (0.34 ± 0.18 mm) (P = .01). Relative peripheral spherical refractions at 10 and 20° nasally and at 10° temporally (P = 0.04, 0.049, and 0.042, respectively) relative to the fovea were positively correlated with central axial elongation in Group II. Group II exhibited an increase in peripheral ocular high order aberrations, such as horizontal coma and asymmetric trefoil. The use of Ortho-K lenses was found to slow the rate of central axis elongation in children with myopia. This effect might be related to an increase in both peripheral spherical refraction and peripheral ocular higher order aberrations with Ortho-K lens use.

Artificial Tear Drops Influence on High Order Aberrations in Healthy Eye Subjects

Purpose: To gain more insight into tear film from a functional standpoint, we investigate artificial tear eye drops effect by assessing its influence on high order aberration in healthy eye subjects using a Shack-Hartmann aberrometer.&#x0D; Methods: An observational case-control study into which 20 young healthy participants were involved. High order aberrations were measured using Shack-Hartmann technology before; 1 hour and 3 hours after instillation of a 0.3% sodium hyaluronate eye drop.&#x0D; Main measured outcomes were root mean square of high order aberrations in central 5 mm (HOA 5) and in central 6 mm (HOA 6), spherical aberration, vertical coma, horizontal coma, vertical trefoil, horizontal trefoil.&#x0D; Results: The HOA 5 mean value was 0.21µ before the instillation of artificial tear eye drops and 0.185µ one hour after instillation with a significant statistical difference (p=0.01) and 0.186µ three hours after instillation with no significant statistical difference (p=0.057). No significant statistical difference was found for HOA 6 before and after tear eye drops application.&#x0D; Vertical coma was the only subset of high order aberrations that was significantly improved from 0.042µ to -0.003µ one hour after tear eye drops application (p=0.04). There was no statistical difference for all the other measurements.&#x0D; Conclusions: Some high order aberrations could arise from the tear film even in a healthy patient. Vertical coma could be used as a tool to point to the integrity of tear film. For wavefront-guided refractive surgery candidates, high order aberrations should be assessed 1 hour after artificial tear drop instillation.

Impact of monovision on dynamic accommodation of early presbyopes

To examine the impact of monovision on dynamic changes in accommodation, pupil responses, spherical aberration and resultant image quality in early presbyopes. Refractive state, pupil size and spherical aberration levels were monitored in nine early presbyopes who exhibited some accommodation (40-50years, mean=42±2.37years) using a Shack-Hartmann aberrometer as a binocularly viewed stimulus stepped closer (from 2m to 40cm), or farther (from 40cm to 2m). Comparison data from two fully presbyopic (i.e. non-accommodating) subjects (ages 46 and 61years) and two young adults (ages 26 and 29years) were also collected. Each subject was fit with four different refractive strategies: (1) both eyes corrected for 2m, (2) both eyes corrected for 40cm, (3) monovision with the measured right eye corrected for 2m and, (4) monovision with the right eye corrected for 40cm. Monochromatic image quality was quantified using the AreaMTF metric. When fit with monovision, the largest number of early presbyopes produce an accommodative response dominated by the right eye correction (distance or near) as the stimulus is abruptly changed from the retinal conjugate plane of one eye to that of the other eye. However, the accommodative responses in some early presbyopes were always dominated by the distance corrected eye, the near corrected eye, or by convergence. When the stimulus approached, the near corrected eye experienced high image quality only if there was no accommodative response. However, reduced image quality was observed if an accommodative response was initiated. Neither accommodation nor pupil response latencies were longer with monovision corrections compared with bilateral distance corrections (p>0.05). In the early presbyopes, spherical aberration was reduced during near viewing, but primarily due to pupil miosis and not lens shape changes. As the stimulus was abruptly changed from the retinal conjugate plane of the distance corrected eye to that of the near corrected eye, most early presbyopes fit with monovision accommodated, which resulted in a decline, not an increase in image quality in the near corrected eye. These results reveal a non-optimal accommodative strategy in early presbyopes fit with monovision.

Higher order aberrations during accommodation in children

Background: In adults, higher order aberrations (HOAs) vary during accommodation [1] which reduces retinal image quality [2]. These changes may provide a mechanism linking near work and myopia development [3], however little is known about HOAs during accommodation in children. Methodology: HOAs of 90 children (mean age and spherical equivalent refraction: 8.2 ± 1.8 years; +0.63 ± 0.34 D) were measured at four accommodation demands (0, 3, 6 and 9 D) using a Hartmann-Shack aberrometer (COAS-HD). Individual Zernike term coefficients up to and including the 6th-order were analysed over a 4 mm pupil at each accommodation demand. Root mean square (RMS) errors were calculated for total (2nd-6th orders), higher order (3rd-6th orders) (HO), individual radial orders, coma (Z[3,-1], Z[3,1], Z[5,-1] and Z[5,1]), trefoil (Z[3,-3], Z[3,3], Z[5,-3] and Z[5,3]) and spherical aberration (Z[4,0] and Z[6,0]) (SA). Visual Strehl ratios based on the optical transfer function were determined from HOAs (VSOTF). Results: Total, HO, all individual orders, coma, trefoil, and SA RMS varied significantly with accommodation demand (p Conclusions: HOAs changed significantly during accommodation resulting in a significant reduction in retinal image quality at the 9 D accommodation demand. Longitudinal studies are required to examine the potential influence of these changes on eye growth.

Objective optical quality in eyes with customized selection of aspheric intraocular lens implantation

BackgroundTo compare the postoperative optical quality in eyes with customized selection and random selection of aspheric intraocular lens (IOL) implantation.MethodsA prospective, nonrandomized study was implemented in adult cataract patients who underwent unilateral phacoemulsification with aspheric IOL implantation. Patients were allocated into two treatment groups: a customized group and a control group. In the customized group, the aspheric IOL selection was based on the corneal spherical aberration to enable the postoperative target ocular spherical aberration closest to zero; in the control group, the aspheric IOLs were chosen using a random strategy. Primary outcome measurements included the following objective optical quality assessments: higher-order aberrations obtained by a Hartmann-shack aberrometer at 4 mm and 6 mm pupil diameters; objective scatter index (OSI), modulation transfer function (MTF) cut-off, Strehl ratio (SR) and a simulated contrast visual acuity—optical quality analysis system value (OV) obtained by a double-pass system with a 4-mm aperture. Subjective visual acuity was measured as secondary outcome. All the patients were followed up for 3 months.ResultsEighty-four patients in the customized group and 78 patients in the control group were evaluated. There was no significant difference in postoperative visual acuity between the two groups (P > 0.05). Significantly less ocular higher-order aberrations were shown in the customized group (P < 0.05). No significant difference was shown in OSI, MTF cut-off, SR and OV between the two groups (P > 0.05).ConclusionsAlthough customized selection of aspheric IOL implantation showed less postoperative ocular aberrations, it performed similarly to random selection of aspheric IOL implantation in terms of postoperative visual acuity, simulated contrast visual acuity, intraocular scatter, modulation transfer function and Strehl ratio.Trial registrationRetrospectively registered on 07/06/2019. Registration number: ChiCTR1900024356.

Repeatability of wavefront measurements in pseudophakic eyes

Higher- as well as lower-order aberrations influence uncorrected visual quality after successful cataract surgery. Different techniques are used for measuring ocular wavefront aberrations, such as Hartmann–Shack aberrometers, laser ray tracing aberrometers, and automatic retinoscopy. The aim of our study was to assess the repeatability of a Hartmann–Shack aberrometer measurement in a pseudophakic study population. This prospective study included patients who underwent cataract surgery 1 month prior to recruitment. Three consecutive Hartmann–Shack measurements (WASCA, Carl Zeiss Meditec AG, Germany) were performed after pharmacological dilation of the pupil. In total, 156 eyes of 156 patients were included. Repeatability of measurements was good in pseudophakic eyes for all Zernike polynomials up to the fourth order. The median values of the SD of all three measurements ranged between 0.042 and 0.125 for the Tecnis intraocular lens (IOL) and 0.028 and 0.148 for the CT Asphina 409MP IOL. Intraclass correlation coefficients ranged between 0.793592 and 0.97955 for the Tecnis IOL and between 0.673894 and 0.989172 for the CT Asphina 409MP IOL. Postoperative unsatisfactory image quality, sometimes reported by patients, despite good defocus and astigmatism values calls for examination of higher-order aberrations. Hartmann–Shack measurements with the WASCA offers good repeatability in pseudophakic patients and, therefore, fulfills this task.

Alterations in optical higher order aberrations after implantable contact lens for high myopia in Indian eyes

Aim: To evaluate the changes in the higher order aberrations and correlation with visual acuity improvement in eyes operated with implantable contact lens (ICL) for high myopia in Indian population. Materials and Methods: 15 eyes of 10 patients underwent ICL implantation. Main outcomes measured were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), contrast sensitivity and optical higher order aberrations (HOA). Optical higher order aberrations were measured with Hartmann shack aberro meter postoperatively at 4 weeks. Results: Five patients had ICL implantation in both eyes and 5 patients in one eye. The mean preoperative and postoperative UCVA were 0.012±0.009 and 0.762±0.359 respectively. The mean preoperative TRMS and HRMS was 5.16±7.47 and 0.11±0.8 respectively at 6mm pupil. The mean postoperative TRMS and HRMS was 1.17±2.42 and 0.17±0.14 respectively. There was a significant change (p=0.001) in Z40, Z3-3 (p=0.026) and total trefoil (Z3-3 and Z33) (p=0.009) at 6mm pupil. In eyes with postoperative BCVA of ≥1 Snellen decimal equivalent, there was significant change in the mean Z33 (p=0.028) and Z40 (p&lt;0.001) at 6mm pupil. In eyes with post-operative BCVA improvement ≥3 lines, there was significant difference in the Z40 (p=0.014) and (Z5-3 + Z53) (p=0.004) at 6mm pupil. There was no significant change in Z40 at 4mm pupil. Conclusion: ICL implantation produces significant changes in third and fourth optical higher order aberrations. Alteration in spherical aberration was observed to be high at 6mm than at 4mm pupil.

Ocular high-order aberrations in monocular anisometropic amblyopia

Objective The aim of this study was to investigate the relationship between high-order aberrations (HOAs) and monocular anisometropic amblyopia with or without strabismus. Patients and methods The medical records of 391 patients with monocular anisometropic amblyopia presenting to Sohag Refractive Center (Sohag, Egypt) were reviewed retrospectively in the period from May 2014 to December 2016. Ocular HOAs were measured using a Hartmann–Shack aberrometer and were used to compare the amblyopic eyes with the fellow eye on one hand and a control group of 380 individuals on the other hand. Results The study included 391 (190 men and 201 women) eyes of patients with anisometropic amblyopia. There was a significant difference between the amblyopic eyes and the control group regarding the total HOA, coma, and trefoil. In addition, hypermetropic amblyopes displayed higher HOA. Conclusion Anisometropic amblyopic eyes revealed higher ocular HOAs than fellow nonamblyopic eyes and the control group. Thus, HOAs should be incorporated in the treatment plan of amblyopia.

Correlation between iris-registered static and dynamic cyclotorsions with preoperative refractive astigmatism in PRK candidates

PurposeTo evaluate static and dynamic cyclotorsions during photorefractive keratotomy (PRK) surgery in refractive surgery candidates and their correlations with preoperative factors. MethodsThis cross-sectional case series was performed in 138 eyes of 77 patients who underwent PRK surgery by Technolas 217z100. Iris registration was used to evaluate the degree of static and dynamic cyclotorsion. Wavefront measurements were performed in sitting position using Zywave (versions 3.1 and 3.2, Bausch & Lomb) Hartmann Shack aberrometer (Bausch & Lomb), and the cyclotorsion from upright to supine position was measured using iris image comparison. Dynamic cyclotorsions were measured by Advanced Cyclotorsional Eye Tracker (ACE) mounted on Excimer laser machine Technolas 217z100 during surgery. ResultsThe mean absolute static cyclotorsion that was captured in surgery time was 3.37 ± 2.38° (range, 0.00 to 11.30), and the mean absolute dynamic cyclotorsion was 2.54 ± 2.50° (range, 0.00 to 13.60). There was a significant correlation between dynamic cyclotorsions and static cyclotorsions (P < 0.001 and R = 0.704). There was a strong association between preoperative refractive astigmatism and range dynamic cyclotorsion. Total pulses (P = 0.009), ablation depth (P = 0.012), gender (P = 0.008) had significant correlations with cyclotorsional movements. ConclusionThe measurements of static and dynamic cyclotorsions are highly recommended for refractive surgery candidates with significant preoperative refractive astigmatism.

A comparative study between manifest, cycloplegic and wavefront refraction in myopia

Aim. to compare between manifest, cycloplegic and wavefront refraction in different grades of myopia. Methods. 100 myopic eyes were included. The data collected included: age, sex, manifest refraction, cycloplegic refraction, wavefront refraction and pupil diameter. Manifest refraction was acquired by autorefractometer ( NideK). Cycloplegic refraction was acquired after applying cyclopentolate eye drops 1% for an hour. Wavefront refraction was acquired by the iDesign aberrometer ( Hartmann Shack Aberrometer) (Visx, USA) using a 32 × 32 lenslet array and near infra-red light with a wavelength of 780 nm. Results. The study showed that the wavefront refraction using the iDesign aberrometer (Hartmann-Shack aberrometer) gives higher values for each of sphere, cylinder and spherical equivalent followed by the manifest autorefraction using the Nidek autorefractometer and lastly cycloplegic refraction in all grades of myopia. Conclusions. Regarding the three methods of refraction (manifest, cycloplegic and wavefront), our results showed that the wavefront refraction acquired by the iDesign aberrometer (Hartmann Shack Aberrometer) shows higher values for each of sphere, cylinder and spherical equivalent, followed by manifest refraction acquired by autorefractometer (NideK) and lastly cycloplegic refraction in all grades of myopia.

Profile of off-axis higher order aberrations and its variation with time among various refractive error groups

Peripheral higher order aberrations (HOA) of 646 children at 30° temporal, nasal and inferior visual field were measured under cycloplegia (5 mm pupil diameter) using a commercially available Shack-Hartmann aberrometer in the Sydney Myopia Study [age, 12.7 ± 0.4 years (mean ± standard deviation)] and five years later in the Sydney Adolescent Vascular and Eye Study. At baseline, 176 eyes were emmetropic, 95 were myopic and 375 were hyperopic. Coma, 3rd order and RMS of coma increased with eccentricity for all eyes and no difference was observed for 4th order and RMS of C(4,0) among refractive error groups. More positive C(4,0) was observed for hyperopic eyes at periphery. At follow up, 26% had ‘myopic change’ and 70% had ‘no change’ in refractive error. At follow-up, horizontal coma became more negative at nasal field and more positive at temporal field for all eyes. More positive C(4,0) for hyperopic eyes at baseline may indicate variation in optical characteristics of peripheral cornea and crystalline lens. An increase in horizontal coma with time, irrespective of refractive error change, may be attributed to variation in the shape factor of peripheral cornea and crystalline lens and/or misalignment of optical surfaces/components relative to the visual axis (angle kappa) as the eye grows in axial length.

Combined Effect of Ocular and Multifocal Contact Lens Induced Aberrations on Visual Performance: Center-Distance Versus Center-Near Design.

To evaluate the combined effects of inherent ocular aberrations and induced aberrations with a multifocal soft contact lens (MFCL) after 15 days of lens wear in presbyopic participants and their influence on visual performance at distance and near under high and low contrast conditions. Forty presbyopic participants (mean age, 48.7±3.4) presenting a mean addition of 1.53±0.58 D were fitted with Biofinity Multifocal (CooperVision) and included in the study. Measurements comprised distance and near monocular high (100%) and low contrast (10%) logMAR visual acuity (VA). Ocular aberrations were obtained with Hartmann-Shack aberrometer (IRX3, Imagine Eyes) and analyzed for 2 mm and maximum round natural pupil. Distance VA was significantly higher in dominant eye, whereas near VA was significantly better in the non-dominant eye (P<0.05 in all conditions). For a 2-mm pupil in the dominant eye fitted with MFCL, spherical-like aberration significantly increased (P=0.027) so as higher-order aberrations (HOA) (P=0.002). A significant increase was also observed in spherical-like aberrations (P=0.001), coma-like aberrations (P=0.006) and HOA (P=0.004) in non-dominant eye. For the maximum round natural pupil size, a significant decrease in vertical coma was observed (P=0.018) in dominant eye, whereas a significant increase in spherical-like (P<0.001) and coma-like aberrations (P=0.007) was observed in non-dominant eye. A negative significant correlation was found between vertical coma and high contrast VA (Rho=-0.405, P=0.011) in dominant eye; whereas in non-dominant eye, a significant correlation was found between induced secondary astigmatism and distance VA under high (Rho=0.556, P<0.001) and low contrast (Rho=0.448, P=0.005). On-eye visual performance of MFSCL is dependent on the high-order aberrations induced by dominant and non-dominant design coupled with the wearer's inherent aberrations.

Accommodative Behavior of Young Eyes Wearing Multifocal Contact Lenses.

The effectiveness of multifocal contact lenses (MFCLs) at slowing myopia progression may hinge on the accommodative behavior of young eyes fit with these presbyopic style lenses. Can they remove hyperopic defocus? Convergence accommodation as well as pupil size and the zonal geometry are likely to contribute to the final accommodative responses. The aim of this study was to examine the accommodation behavior of young adult eyes wearing MFCLs and the effectiveness of these MFCLs at removing foveal hyperopic defocus when viewing near targets binocularly. Using a high-resolution Shack-Hartmann aberrometer, accommodation and pupil behavior of eight young adults (27.25 ± 2.05 years) were measured while subjects fixated a 20/40 character positioned between 2 m and 20 cm (0.50 to 5.00 diopters [D]) in 0.25-D steps. Refractive states were measured while viewing binocularly and monocularly with single-vision and both center-distance and center-near +2.00 D add MFCLs. Refractive state was defined using three criteria: the dioptric power that would (1) minimize the root mean square wavefront error, (2) focus the pupil center, and (3) provide the peak image quality. Refractive state pupil maps reveal the complex optics that exist in eyes wearing MFCLs. Reduced accommodative gain beyond the far point of the near add revealed that young subjects used the added plus power to help focus near targets. During accommodation to stimuli closer than the far point generated by the add power, a midperipheral region of the pupil was approximately focused, resulting in the smallest accommodative errors for the minimum root mean square-defined measures of refractive state. Paraxial images were always hyperopically or myopically defocused in eyes viewing binocularly with center-distance or center-near MFCLs, respectively. Because of zone geometry in the concentric MFCLs tested, the highly aberrated transition zone between the distance and near optics contributed a significant proportion and sometimes the majority of light to the resulting images. Young eyes fit with MFCLs containing significant transition zones accommodated to focus pupil regions between the near and distance optics, which resulted in less than optimal retinal image quality and myopic or hyperopic defocus in either the pupil center or pupil margins.

Immediate effect of a tear enhancer and meibomian gland expression on the corneal surface and whole eye higher order aberrations

PurposeTo investigate changes in higher order ocular aberrations (HOA) induced by the administration of 0.15% sodium hyaluronate tear enhancer (TE) and meibomian gland expression (ME) on the tear film of normal subjects. MethodsHOA values were obtained from the corneal surface (CS) and whole eye (WE), using a corneal topographer and Shack–Hartmann aberrometer, from both eyes of 50 subjects (25 females, mean age±sd 32.5±11.0 years, and 25 males, 33.88±11.2 years) for two pupil sizes (3 and 6mm) in a dark environment. One drop of Blink Contacts™ (Abbott Medical Optics) was instilled into the right eye and HOA measurements repeated after 30s. After 1h, the meibomian glands of the left lower eyelid were gently squeezed and HOA measurements repeated after 30s. ResultsThere was no significant difference for CS and WE root mean square (RMS) HOAs between right and left eyes before (both pupil sizes) and after TE use or ME (3mm pupil). For 6mm pupil, TE use significantly reduced the WE RMS HOA (p<0.05, mean±sd) for Z40 (0.297±0.136 to 0.053±0.069), and Z55 (0.221±0.372 to 0.098±0.121) while ME significantly increased CS RMS HOA (p<0.05, mean±sd) for Z3−3 (0.799±1.178 to 1.302±1.991) and Z44 (0.594±1.184 to 0.988±1.463). In general, the change in HOA was significantly correlated with the initial value before TE use or ME (p<0.05). ConclusionThere were no detectable differences between right and left eyes. For the 6mm pupil, the tear enhancer tended to improve optical performance of the WE and meibomian gland expression tended to reduce the optical performance at the CS.

Evaluation of Optical Quality: Ocular Scattering and Aberrations in Eyes Implanted with Diffractive Multifocal or Monofocal Intraocular Lenses

ABSTRACTPurpose: To compare objective optical quality, ocular scattering and aberrations of eyes implanted with an aspheric monofocal intraocular lens (IOL) or an aspheric apodized diffractive multifocal IOL three months after surgery.Methods: Prospective consecutive nonrandomized comparative cohort study. A total of 80 eyes from 57 cataract patients were bilaterally or unilaterally implanted with monofocal (AcrySof IQ SN60WF) or multifocal (AcrySof IQ ReSTOR SN6AD1) IOLs. Respectively, 40 eyes of 27 patients were implanted with monofocal IOLs, and 40 eyes of 30 patients were implanted with multifocal IOLs. Ocular high-order aberration (HOA) values were obtained using Hartmann–Shack aberrometer; objective scatter index (OSI), modulation transfer function (MTF) cutoff, Strehl ratio (SR), and contrast visual acuity OV at 100%, 20%, and 9% were measured using Objective Quality Analysis System II (OQAS II).Results: Ocular aberrations performed similar in both groups (p > 0.05). However, significantly higher values of OSI and lower values of MTF cutoff, SR and OV were found in the SN6AD1 group (p < 0.05).Conclusions: Both ocular scattering and wave-front aberrations play essential role in retinal image quality, which may be overestimated when only aberrations were taken into account. Combining the effect of ocular scattering with HOA will result in a more accurate assessment of the visual and optical quality.

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.