Jackson Cross-cylinder Research Articles

Subjective quasi-vector-based refraction with a conventional phoropter.

To introduce a novel methodology for subjective refraction based on power vectors with a conventional phoropter. A conventional phoropter was used to measure power vector components of refraction (M, J0 and J45) directly by using the sphere power (for M measurement) and the cylinder power combined with the Jackson cross-cylinders (for J0 and J45 measurements). Conventional subjective refraction was also performed, and this result was mathematically transformed into power vector notation for comparison purposes. Visual acuities with the conventional prescription and the quasi-vector-based prescription were compared. Refractive error from 40 healthy participants was measured by conventional and quasi-vector-based subjective refraction. No differences were found between methods for any of the power vector components of refraction (p > 0.21 in all cases). The visual acuity achieved with the prescriptions yielded similar values (p = 0.85). Subjective refraction can be measured directly in power vector notation using a conventional phoropter without any additional adaptation and computation.

Comparison of Spot Vision Screener and Tabletop Autorefractometer with Retinoscopy in the Pediatric Population.

Determining the accuracy of cycloplegic refractive error measurements made with the Spot Vision Screener (SVS, Welch Allyn Inc, Skaneateles Falls, NY, USA) is important for refractive assessment of uncooperative patients during optometric examinations. This study compared cycloplegic refractive errors measured by SVS and tabletop autorefractometer to cycloplegic retinoscopy in children. Eighty-eight eyes of 44 subjects were examined in the study. Refractive error measurements were obtained under cycloplegia using retinoscopy, SVS, and Nidek ARK-530 tabletop autorefractometer (ARK-530, Nidek, Japan). Spherical and cylindrical values, spherical equivalents (SE), and Jackson cross-cylinder values at axes of 0° (J0) and 45° (J45) were recorded. Correlations between methods were analyzed using intraclass correlation coefficient (ICC) and Bland-Altman analysis. The mean age was 7 years (range: 6 months-17 years). Sixteen (36%) of the subjects were female and 28 (64%) were male. For SE there was excellent agreement between retinoscopy and SVS (ICC: 0.924) and between retinoscopy and tabletop autorefractometer (ICC: 0.995). While there was a moderate correlation between retinoscopy and SVS for cylindrical values (ICC: 0.686), excellent correlation was detected between retinoscopy and autorefractometer (ICC: 0.966). J0 and J45 crosscylinder power values were not correlated between retinoscopy and SVS (ICC: 0.472) or retinoscopy and tabletop autorefractometer (ICC: 0.442). Retinoscopy was correlated with both SVS and tabletop autorefractometer for all parameters within ±1.96 standard deviations in Bland-Altman analysis. Cycloplegic retinoscopy is the gold standard for refractive error measurement in the pediatric population. However, it requires time and experienced professionals. This study revealed moderate to good agreement between SVS and retinoscopy, with better agreement in spherical errors than cylindrical errors. Although the SVS is intended for screening programs, it may also be useful in the pediatric eye office to estimate spherical refractive error in uncooperative patients.

Calculation of the total corneal astigmatism using the virtual cross cylinder method on the secondary principal plane of the cornea

This study aimed to establish a virtual cross cylinder method to calculate the total corneal astigmatism by combining the anterior and posterior corneal astigmatism on the secondary principal plane of the cornea based on Gaussian optics. The meridian with the least refractive power, namely, the flattest meridian of the virtual cross cylinder of a ± 0.5 × C diopter, is set as the reference meridian, and the power (F) at an angle of φ between an arbitrary meridian and the reference meridian is defined as F(φ) = − 0.5 × C × cos2φ. The magnitude and axis of the total corneal astigmatism were calculated by applying trigonometric functions and the atan2 function based on the combination of the virtual cross cylinders of the anterior corneal astigmatism and the posterior corneal astigmatism. To verify the performance of the virtual cross cylinder method, a verification experiment with two Jackson cross cylinders and a lensmeter was performed, and the measured and calculated values were compared. The limit of the natural domain of the arctangent function is circumvented by using the atan2 function. The magnitude and axis of the total corneal astigmatism are determined through generalized mathematical expressions. The verification experiment results showed good agreement between the measured and calculated values. Compared to the vector analysis method, the virtual cross cylinder method is mathematically sound and straightforward. A novel technique for calculating total corneal astigmatism, the virtual cross cylinder method, was developed and verified.

Kaleidos-based binocular vision analyzer for the estimation of refractive errors and horizontal ocular deviation in children

ABSTRACT Clinical relevance Knowing the agreement and interobserver variability of the 2WIN-S photorefractometer with cycloplegic retinoscopy and prism cover test is important for judging the clinical usefulness of the device. Background This study aims to determine an agreement and interobserver reliability between 2WIN-S photorefractometer and cycloplegic retinoscopy for estimating refractive errors and between 2WIN-S and prism cover test for measuring horizontal ocular deviation in children. Methods Two groups of 129 and 64 participants (range, 5 to 16 years) were recruited for the agreement and interobserver reliability studies, respectively. Non-cycloplegic 2WIN-S refraction was compared with cycloplegic retinoscopy for low and moderate myopia and hyperopia. Similarly, corneal reflex-function (CR-function) of 2WIN-S was compared with prism cover test for horizontal ocular deviation. Bland-Altman plots were used to depict agreement, and the intraclass correlation coefficient (ICC) was used for determining interobserver reliability of repeated measures. Results The mean differences in spherical equivalent, J0 (Cartesian astigmatism) and J45 (oblique Jackson cross-cylinder) between cycloplegic retinoscopy and 2WIN-S were 1.10 (95% CI = 0.97 to 1.21, p < 0.001), −0.06 (95% CI = −0.09 to −0.03, p < 0.001) and 0.009 (95% CI = −0.01 to 0.03, p = 0.35), respectively. The overall median difference in the horizontal ocular deviation between prism cover test and 2WIN-S was −4.5 (Interquartile range = −12.0 to 4.0). For constant strabismus, this difference was insignificant (median= −2.0, interquartile range = −11.0 to 6.7, p = 0.19) between prism cover test and 2WIN-S. The ICC was high for the spherical equivalent (0.997; p < 0.001), J0 (0.932; p < 0.001) and J45 (0.901; p < 0.001), whereas it was low-to-moderate for horizontal ocular deviation (0.50; p < 0.001). Conclusion 2WIN-S refraction was in agreement with cycloplegic retinoscopy for low and moderate myopia and hyperopia, and requires an adjustment for the consistent differences between cycloplegic retinoscopy and 2WIN-S refraction. The measurement of constant strabismus with 2WIN-S is comparable to that of prism cover test.

Accuracy of an objective binocular automated phoropter for providing spectacle prescriptions

ABSTRACT Clinical relevance Currently eye examinations are usually based on autorefraction followed by subjective refraction (SR) with a phoropter. An automated phoropter that can also perform autorefraction may facilitate the optometric workflow. Background The efficiency and feasibility of an objective autorefraction and correction system are assessed by comparing objective refractive measurements with SR on the same subjects and evaluating the visual acuity (VA) values obtained after the objective refractive measurement and correction. Methods Objective autorefraction and correction was performed on 41 subjects using an automated binocular phoropter system. The auto-phoropter performs autorefraction by wavefront measurement and corrects the spherical and cylindrical errors with tunable fluidic lenses while the patient looks at a visual display inside the instrument. The instrument outputs are optometric constants of spherical and cylindrical aberrations. After measurement and automated correction of the refractive errors, the VA values were assessed by having the subjects look at an integrated Snellen chart. The objective measurement results were statistically compared with their SR. Results The correlations between SR and objective autorefraction and correction spherical equivalents (M) were 0.98 (0.97–0.99) and 0.96 (0.93–0.98), the vertical Jackson cross cylinder (J0) were 0.96 (0.92–0.98) and 0.95 (0.91–0.97), and the oblique Jackson cross cylinder (J45) were 0.73 (0.55–0.85) and 0.82 (0.69–0.90), for the right and left eyes, respectively, with the 95% confidence interval (CI) values in parentheses. 89.0% of the 82 eyes had at least 6/7.5 VA. Conclusions A significant agreement between the SR and objective autorefraction and correction was observed. An all-objective refractive assessment with instantaneous verification may improve the precision of eye prescriptions and possibly reduce the procedure time.

Agreement between Two Swept-Source Optical Coherence Tomography Biometers and a Partial Coherence Interferometer.

PurposeTo evaluate the level of agreement between ANTERION (Heidelberg Engineering, Heidelberg, Germany), OA-2000 (Tomey, Nagoya, Japan), and IOLMaster 500 (Carl Zeiss AG, Jena, Germany).MethodsFifty-one eyes of 51 patients were included in the study. Flat keratometry (K) and steep K, vector component of astigmatism (Jackson cross-cylinder at 0° and 90° [J0] and Jackson cross-cylinder at 45° and 135° [J45]), anterior chamber depth, and axial length were compared using the three devices. Repeated measures analysis of variance was conducted to compare the mean values of the biometrics. Pearson correlation test was conducted to analyze the correlations of the measured values, and a Bland-Altman plot was used to assess the agreement between the three devices. The predicted intraocular lens power of each device was compared to the others using the SRK/T, Haigis, Barrett Universal II, and Kane formulas.ResultsAll K values measured using ANTERION were flatter than those of other instruments. However, good agreement was observed for flat K (ANTERION - OA-2000; 95% limits of agreement [LoA], 0.86 diopters [D]) and steep K (ANTERION - OA-2000; 95% LoA, 0.93 D) and OA-2000 - IOLMaster 500 (95% LoA, 0.93 D). J0 and J45 vector components of astigmatism were not statistically different; however, the agreements were poor between the devices (95% LoA ≥1.97 D). Anterior chamber depth values of ANTERION and OA-2000 were interchangeable (95% LoA, 0.15 mm). The axial length showed a high agreement (95% LoA ≤0.17 mm) among the three devices. The predicted intraocular lens powers of the three devices were not interchangeable regardless of formulas (95% LoA ≥1.04 D).ConclusionsSignificant differences in ocular biometrics were observed between ANTERION and the other two devices. This study demonstrated that only axial length showed good agreement among devices.

Comparison of Anterior Segment Measurements between Scheimpflug-Placido Camera and New Swept-source Optical Coherence Tomography

Purpose: We compared anterior segment measurements obtained using a Scheimpflug-Placido topographer (SIRIUS®, Costruzione Strumenti Oftalmici, Florence, Italy) and a new anterior module for a swept-source optical coherence tomography system (ANTERION®, Heidelberg Engineering Inc., Heidelberg, Germany).Methods: Anterior segment measurements were evaluated in 74 eyes of 101 patients with the two devices. Central corneal thickness (CCT), anterior chamber depth (ACD), corneal refractive power (K), J0 (Jackson cross-cylinder with axes at 180° and 90°), J45 vector (Jackson cross-cylinder with axes at 45° and 135°), and white-to-white corneal diameter (WTW) measurements obtained using the SIRIUS® system and the new anterior segment module of ANTERION® were compared.Results: The mean CCTs measured by SIRIUS® and ANTERION® were 558.69 ± 44.65 and 540.26 ± 36.57 μm, respectively. The difference was statistically significant (p &lt; 0.005), and there were high correlations between the two methods (r = 0.915, p &lt; 0.001). The mean ACD measurements were 3.34 ± 0.53 and 3.34 ± 0.51 mm (p = 0.856), respectively, for SIRIUS® and ANTERION®. The measurements were strongly correlated (r = 0.966, p &lt; 0.001). The measurements of WTW, total mean K, and J0 obtained with the two systems differed significantly (p &lt; 0.005, p = 0.017, and p &lt; 0.005, respectively), with high correlations between the two systems (r = 0.875, r = 0.967, and r = 0.933, respectively; all p &lt; 0.001).Conclusions: There were significant differences in measurements of K, CCT, WTW, and J0 between the two devices. Agreement analysis suggests that SIRIUS® and ANTERION® should not be used interchangeably.

Refractive outcomes of table-mounted and hand-held auto-refractometers in children: an observational cross-sectional study

BackgroundTo compare the refractive results of hand-held and table-mounted autorefractors.MethodsWe designed this study as an observational, cross-sectional study. We compared the mean spheric and cylinder power, spherical equivalent, Jackson cross-cylinder values, determined the limits of agreement (LoA), and evaluated the reliability of two autorefractors.ResultsWe evaluated 256 eyes of 256 pediatric patients (mean age, 9.12 ± 2.26 years; range, 5–16 years). 49% of the patients were female, and 51% were male. The Nidek HandyRef-K autorefractor measured relatively more astigmatism (P < 0.001) and less hyperopia (P = 0.024). The mean differences and 95% LoA were 0.06 D ± 0.47 D (− 0.82 D to 0.98 D) in spherical power, 0.08 D ± 0.28 D (− 0.47 D to 0.64 D) in cylindrical power, 0.11 D ± 0.47 D (− 0.81 D to 1.01 D) in spherical equivalent, 0.02 D ± 0.36 D (− 0.73 D to 0.69 D) in Jackson cross-cylinder power at 0°, 0.005 D ± 0.54 D (− 1.07 D to 1.06 D) in Jackson cross-cylinder power at 45°. We found the difference within 0.50 D in 244 (95%) eyes for spherical power, in 245 (96%) eyes for cylindrical power, 228 (89%) eyes for spherical equivalent, 224 (87%) eyes for Jackson cross-cylinder power at 0°, 213 (83%) eyes for Jackson cross-cylinder power at 45°. When comparing devices, there were strong correlations for spherical power (Spearman’s rho = 0.99, P < 0.001), cylindrical power (Spearman’s rho = 0.88, P < 0.001), and spherical equivalent (Spearman’s rho = 0.98, P < 0.001).ConclusionTwo autorefractors showed clinically applicable agreement limits; excellent reliability for spherical power and spherical equivalent and good reliability for cylindrical power; high positive percent agreement for spherical and cylindrical power, spherical equivalent, Jackson cross-cylinder power at 0°and 45°. These results showed that both devices might be used interchangeably for screening of refractive error in children.

Bearing fixing: A new computer algorithm method for subjective determination of astigmatism.

This article aims to illustrate the principles of bearing fixing, a new computer-controlled procedure for subjective determination of astigmatism, and to compare it with conventional clinician-controlled Jackson crossed-cylinder refraction. The principles and method for bearing fixing are described. Astigmatism was measured using bearing fixing and Jackson cross-cylinder twice on 20 visually normal participants aged between 18 and 34years. After final sphere adjustment, acuity measurements were made with each refraction estimate. Bearing fixing results could be obtained for all participants. Mean bearing fixing cylinder magnitude was slightly higher than Jackson cross-cylinder measures of cylinder magnitude, by 0.05D. Using vector analysis to take into account cylinder power and axis, mean bearing fixing astigmatism was not significantly different from cross-cylinder astigmatism, but did have higher test-retest variability (p<0.05). Acuity with bearing fixing and cross-cylinder corrections did not significantly differ in average value or repeatability. Bearing fixing is a feasible method for subjective determination of astigmatism, and there are a number of potential improvements to the method which could make it faster and more precise.

Centrality of Hirschberg Reflex in Young Emmetropic Population of Pakistan

Purpose: To find out the Centrality of Hirschberg reflex in young emmetropic females and to correlate it with asthenopia.&#x0D; Study Design: Cross-sectional study&#x0D; Place and Duration of Study: Outpatients department of Khalid Eye Hospital, Karachi, from January to December 2019.&#x0D; Methods: Six hundred young emmetropic females 10 to 25 years of age were included. We performed the Hirschberg test and Jackson cross cylinder to assess the astigmatism and observed near point of convergence to find out convergence insufficiency.&#x0D; Results: Out of 600 young emmetropic females only one hundred and ninety had a central Hirschberg corneal reflex along with an astigmatism of 0.25 to 0.50 which was observed in one hundred and sixty five patients. One hundred and twenty five had a receded near point of convergence.&#x0D; Conclusion: Acentrality of Hirschberg can be a cause of asthenopia among young emmetropic females.&#x0D; Key Words: Asthenopia, Astigmatism, Emmetropia, Hirschberg corneal reflex.

The Survey on Refraction Protocol for Optical Aids to be More Accurate

Purpose : This study was to investigate the refraction protocal ongoing in the clinics when conducted dispensing, refraction and prescribing contact lens optical aids to be more accurate. Methods : A questionnaire covered three items refraction, dispensing and prescription of contact lenses and was conducted by 53 optometrists in Gyeonggi-do. Results : In the item refraction, 50(94.3%) optometrists answered checking visual acuity with habitual correction. When asked measuring the interpupillary distance, 24(45.3%) optometrists used a P.D. meter and 21(39.6%) used the value measured by the auto-refractometer. 23(43.4%) optometrists did not use the Jackson cross-cylinder after correcting astigmatism. The reasons were diverse; ‘not aware of the methods’(17.4%), ‘unnecessary to do(52.2%)’, ’not enough time(26.1%)’ and ‘unspecified(4.3%)’. 8(15.1%) optometrists did not doublecheck after prescribing contact lenses. Conclusion : In order to provide the best correction, the accurate refraction, dispensing and prescribing contact lenses must be fulfilled as well as the eye examinations required in the clinic.

Comparison of open-field autorefraction, closed-field autorefraction, and retinoscopy for refractive measurements of children and adolescents in Taiwan

To evaluate the accuracy and effectiveness of noncycloplegic and cycloplegic autorefraction using two types of autorefractors (ARs) compared with retinoscopy in children and adolescents. This cross-sectional study included 308 students (6-17 years old) from eastern Taiwan. Noncycloplegic and cycloplegic refractive measurements were obtained using open-field AR (Shin-Nippon NVision-K 5001), closed-field AR (Topcon KR-800), and cycloplegic retinoscopy. Three optical components emerged from the measurements: spherical equivalent (M) and two Jackson cross-cylinder values (J0 and J45). Agreement between both ARs and retinoscopy was evaluated using intraclass correlation coefficient. Measurement discrepancies from retinoscopy among different ARs and cycloplegic status were compared using repeated measures ANOVA and receiver operating characteristic curve analysis. Compared with retinoscopy, measurements obtained before and after cycloplegia with both ARs showed excellent reliability for evaluating M and J0 and fair to good results for J45. More myopic results were obtained using KR-800 before cycloplegia; more hyperopic results were obtained using KR-800 and NVision-K 5001 after cycloplegia(all p<0.05). J45 data obtained using NVision-K 5001 were closest to those obtained by retinoscopy; J0 data obtained using both ARs were comparable with retinoscopy after cycloplegia. NVision-K 5001 outperformed KR-800 in refractive measurements, particularly in hyperopia diagnosis among younger children. Both autorefractors showed great agreement with retinoscopy. Results obtained using NVision-K 5001 without cycloplegia were most similar to those by retinoscopy, especially for oblique astigmatism and hyperopia detection in younger children. For large vision screening in elementary school, Shin-Nippon NVision-K 5001 might be a more suitable autorefractor.

Global-flash mfERG responses to local differences in spherical and astigmatic defocus across the human retina.

Emmetropisation is essentially a visually guided, within-eye process. We investigated differences in global-flash multifocal electroretinogram (gmfERG) responses to naturally occurring differences in spherical and astigmatic defocus across the retina, which might provide a basis for guiding eye growth. Experiment 1: The gmfERG responses (direct, DC, and induced, IC, amplitudes and latencies) recorded simultaneously from six retinal areas (15° eccentricity, spaced at 60°, areas 3.2°2 ) were correlated with the uncorrected retinal defocus measured at the six corresponding retinal locations in 20 adults with foveal refractive errors (-4.75 to +1.25D). No correcting lenses were used to avoid introduction of lens-induced aberrations and magnification. Experiment 2 investigated the effect of superimposing astigmatic defocus (+2.00/-4.00D Jackson Cross Cylinder presented at four orientations) on gmfERG responses. Experiment 1: DC and IC response amplitudes were greater in retinal regions naturally exposed to more hyperopic spherical defocus (DC: rho=0.26, p=0.005; IC: rho=0.29, p=0.001), but response latencies were unaffected by sign or magnitude of spherical defocus (DC: p=0.34; IC: p=0.40). Response amplitudes and latencies were unaffected by astigmatic defocus. Experiment 2: Rotating the JCC axis to four different orientations had no effect on the gmfERG responses (DC amplitude, p=0.39; DC latency, p=0.10; IC amplitude, p=0.51; IC latency, p=0.64). The gmfERG responses from discrete retinal areas varied with the sign and magnitude of local spherical defocus, but we found no evidence that retinal responses were affected by astigmatic defocus. Therefore, local astigmatism is unlikely to provide cues for controlling eye growth, whereas differences in response to spherical defocus between different retinal regions could potentially provide cues for controlling eye growth in emmetropisation.

Influence of trifocal intraocular lenses on standard autorefraction and aberrometer-based autorefraction

To study the agreement between manifest refraction and objective refraction measured with two autorefractor models and an aberrometer in eyes implanted with a trifocal diffractive intraocular lens (IOL). IOA Madrid Innova Ocular, Madrid, Spain. Prospective comparative cohort study. An autorefractor keratometer (KR-8800), based on a Scheiner double pinhole, and a 3-dimension wavefront topography aberrometer system (OPD-Scan III), based on the scanning-slit retinoscopy principle, were used to obtain objective refraction readings. In addition, lower-order Zernike coefficients (Z) were used to calculate objective refraction. A set of 7 different results was obtained in power vector notation (spherical equivalent [SE], Jackson cross-cylinder, axes at 180 degrees and 90 degrees [J0] and Jackson cross-cylinder, axes at 45 degrees and 135 degrees [J45]) for 7 different methods: manifest refraction, autorefraction obtained with the autorefractor keratometer, WF-P (Z-based objective refraction for the photopic pupil), WF-M (Z-based objective refraction for the mesopic pupil), WF-4 (Z-based objective refraction for a 4.0mm pupil), OPD-C (autorefraction measured with the 3-dimension wavefront topography aberrometer system under photopic conditions), and OPD-M (autorefraction measured with the 3-dimension wavefront topography aberrometer system under mesopic conditions). The study comprised 102 eyes from 51 cataract patients who underwent binocular implantation of a diffractive trifocal IOL (FineVision POD F). All 6 objective methods yielded more negative SE values than manifest refraction (P<.001). As for the astigmatism components (J0 and J45), only autorefraction (P=.003) and OPD-M (P<.001) differed significantly from manifest refraction. The best and worst correlation for the SE component were intraclass correlation coefficient (ICC)=0.70 (for WF-M) and ICC=0.48 (for WF-4). Objective methods tend to yield more negative sphere values than manifest refraction.

Comparative analysis of 2 swept-source optical coherence tomography biometers

To report the level of agreement, repeatability, and correlation of axial length (AL), mean keratometry, central corneal thickness, anterior chamber depth, lens thickness, and corneal diameter measurements of 2 swept-source optical coherence tomography (SS-OCT) biometers, the IOLMaster 700 (reference biometer) and the Argos (new biometer). Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Retrospective case series. Each patient had SS-OCT biometry with the reference biometer and new biometer. In addition to reporting the statistical results derived from both eyes, this study included a subgroup analysis of right eyes and left eyes. The level of agreement between the biometers was represented with the Bland-Altman method. Power vector analysis of the J0 (Jackson cross-cylinder, axes at 0 degrees and 90 degrees) and J45 (Jackson cross-cylinder, axes at 45 degrees and 135 degrees) vectorial components of astigmatism was performed. Internal consistency was assessed with the Cronbach α coefficient of reliability. The dispersion of probability distribution was computed with the coefficient of variation. The intraoperator repeatability was calculated using the intraclass correlation coefficient (ICC). The study comprised 112 patients (218 eyes). There was a statistically significant difference between the 2 biometers in all measurements (P<.05) except AL. The level of correlation between the reference biometer and the new biometer was very high for all the parameters except corneal diameter, and the agreement was high. The ICC and internal consistency were excellent with both biometers. The new biometer provided good agreement and repeatability compared with the reference biometer.

Comparison of anterior segment measurements obtained using a swept-source optical coherence tomography biometer and a Scheimpflug–Placido tomographer

To assess the repeatability and agreement of anterior segment measurements between an optical biometer (IOLMaster 700) using swept-source optical coherence tomography and a Scheimpflug-Placido tomographer (Sirius) in patients scheduled for corneal refractive surgery. Eye Hospital of Wenzhou Medical University, Zhejiang, China. Prospective case series. The parameters, including the central corneal thickness (CCT), anterior chamber depth (ACD), aqueous depth, keratometry (K) values, astigmatism, J0 (Jackson cross-cylinder with axes at 180 degree and 90 degrees) and J45 vectors (Jackson cross-cylinder with axes at 45 degrees and 135 degrees), and horizontal corneal diameter, were measured 3 times per instrument. The intraobserver repeatability was assessed using test-retest repeatability, the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Paired t tests were used to compare the difference between the 2 methods. Agreement was evaluated using Bland-Altman analyses. The study enrolled 100 right eyes. All measurements of the 2 devices showed high repeatability. The CoV of all measured parameters was less than 0.93 and the ICC value was more than 0.85. The paired t test did not show a significant difference in CCT, astigmatism, J0 or J45 vector. The mean ACD and aqueous depth were statistically lower with the optical biometer; however, the 95% limits of agreement (LoA) were low (from -0.20 to -0.03mm). The K and corneal diameter values obtained using the optical biometer were higher by 0.1 diopter and 0.1mm, respectively, but with narrow 95% LoA. The optical biometer and the Scheimpflug-Placido tomographer showed high repeatability for all anterior segment measurements. The measured parameters showed good agreement and could be used interchangeably.

Assessment of subjective refraction with a clinical adaptive optics visual simulator

PurposeTo clinically validate an adaptive optics visual simulator (VAO) that measures subjective refraction and visual acuity.SettingOptics Laboratory, University of Murcia, Murcia, Spain.DesignProspective case series.MethodsUsing the adaptive optics visual simulator, 2 examiners measured the subjective refraction and visual acuity in healthy eyes of volunteers; 1 examiner also used a trial frame as a gold standard. The interexaminer reproducibility and agreement with the gold standard were estimated using the following statistical parameters: limits of agreement from Bland-Altman analysis, significance between differences (P value), and intraclass correlation coefficient (ICC).ResultsSeventy-six eyes of 38 volunteers were measured. Interexaminer reproducibility for subjective refraction was excellent (ICC ≥0.96; P > .05), with low 95% confidence interval (CI) values for the power vectors M (spherical equivalent of the given refractive error), J0 (Jackson cross-cylinder, axes at 180 degrees and 90 degrees), and J45 (Jackson cross-cylinder, axes at 45 degrees and 135 degrees) (±0.51 diopter [D], ±0.14 D, and ±0.14 D, respectively). No significant differences in subjective refraction and visual acuity were found between the visual simulator and gold standard (P > .05), with 95% CIs for M, J0, and J45 (subjective refraction) of ±0.67 D, ±0.14 D, and ±0.16 D, respectively, and a ±0.10 logarithm of the minimum angle of resolution (visual acuity).ConclusionSubjective refraction results using the adaptive optics visual simulator agreed with those of the gold standard and can be used as the baseline for visual simulation of any optical corneal profile or intraocular lens design for refractive surgery patients.

A contralateral eye study comparing characteristics of corneal endothelial cells in bilateral keratoconus patients with unilateral corneal Vogt's striae

PurposeThe aim of this study was to analyze and compare corneal endothelial cell morphology and characteristics in bilateral keratoconus (KCN) patients with unilateral Vogt's striae. MethodsFifty patients aged 20–38 years were recruited in this cross-sectional contralateral eye study. In this study, corneal endothelial cell parameters were evaluated in patients with bilateral KCN and unilateral Vogt's striae using the Topcon SP2000P specular microscope (Topcon, Tokyo, Japan). ResultsIn the current study, there were no significant differences in corneal endothelial cell parameters including endothelial cell density (ECD), hexagonal cell ratio (HEX), and coefficient of variance of cell size (CV) between the KCN groups with and without Vogt's striae, [(2968.34 ± 276.65 vs. 2980.05 ± 253.30, P = 0.618), (51.88 ± 13.57 vs. 53.24 ± 9.31, P = 0.658), and (32.50 ± 5.40 vs. 32.97 ± 4.07, P = 0.467), respectively]. Also, among study groups with and without Vogt's striae, ECD did not correlate with anterior chamber depth (ACD) [(P = 0.564, r = 0.09), (P = 0.219, r = −0.18), respectively], maximum keratometry (Kmax) [(P = 0.215, r = 0.18), (P = 0.898, r = 0.02), respectively], and central corneal thickness (CCT) [(P = 0.989, r = −0.02), (P = 0.643, r = −0.07), respectively].Our results showed significant differences in corrected and uncorrected distance visual acuity (UDVA), cycloplegic refractive error components (calculated by vectorial analysis), CCT, and Kmax between two study groups (all P < 0.05) except for J45 (Jackson cross cylinder, axes at 45 and 135°) (P = 0.131). ConclusionsWe were not able to find the statistically significant differences in ECD, HEX, and CV between KCN eyes with and without Vogt's striae. Despite clinical and tomographic results, it seems that Vogt's striae cannot cause deterioration in the corneal endothelial morphology.

Changes in shape and astigmatism of total, anterior, and posterior cornea after long versus short clear corneal incision cataract surgery

To compare changes in the shape and astigmatism of the total, anterior, and posterior cornea between eyes with long-length clear corneal incisions (CCIs) and eyes with short-length CCIs in cataract surgery. Hayashi Eye Hospital, Fukuoka, Japan. Prospective case series. Both eyes of patients having phacoemulsification with temporal CCIs were randomized to have a long-length (≥1.75mm) or short-length (<1.75mm) CCI. Corneal astigmatic changes were decomposed to vertical/horizontal (Jackson cross-cylinder, axes at 180 degrees and 90 degrees [J0]) and oblique changes (Jackson cross-cylinder, axes at 45 degrees and 135 degrees [J45]) using power vector analysis. Corneal shape changes were assessed using the average of the difference map on videokeratography 2days and 2, 4, and 8weeks postoperatively. The mean J0 and J45 values of the total cornea in the 120 eyes evaluated were significantly greater in the long CCI group than in the short CCI group at all follow-ups (P≤.0290). The videokeratography showed a wedge-shaped flattening in the total and anterior cornea and a steepening in the posterior cornea around the CCI 2days postoperatively in both groups. This wound-related flattening of the total and anterior cornea rapidly reduced but persisted until 8weeks, whereas the steepening of the posterior cornea disappeared within 4weeks. These changes extended closer to the central cornea in the long CCI group than in the short CCI group. Corneal astigmatic changes were significantly greater after long CCI than after short CCI. The wound-related shape changes occurred immediately postoperatively but rapidly diminished.

Inability of Open-Field Autorefraction to Eliminate Accommodation in Preschoolers.

To evaluate the effectiveness of the Shin-Nippon NVision-K 5001 autorefractometer (Rexxam Co. Ltd., Osaka, Japan) (also branded as the Grand Seiko WR-5100K; Grand Seiko Co. Ltd., Hiroshima, Japan) based on the open-field refractometry principle in refractive measurements of preschool children and to determine its ability to eliminate accommodation adequately. The refractive results of 114 preschool children who presented to the ophthalmology outpatient department for screening were evaluated. The measurements were obtained before and after cycloplegia with the Shin-Nippon NVision-K 5001 autorefractometer and after cycloplegia with retinoscopy, which is the gold standard. The results underwent vectorial transformation to produce the spherical equivalent (M) and two Jackson cross-cylinder (J0 and J45) values. All results were then subjected to statistical analysis. The difference between the measurements was evaluated with repeated measures analysis of variance. Included in the study were 106 preschool children (51 boys and 55 girls). The mean age was 5.3 ± 0.9 years (range: 3 to 6 years). Although statistically significantly more myopic results were obtained with non-cycloplegic measurements using the Shin-Nippon NVision-K 5001 autorefractometer (P < .001), no difference was observed in cylindrical values (P > .05). Cycloplegic J0 measurements were significantly lower (P < .001), but no difference was found between J45 values before and after cycloplegia (P > .05). The Shin-Nippon NVision-K 5001/Grand Seiko WR-5100K open-field autorefractometer seems to be inadequate in eliminating accommodation in childhood. Measurements under cycloplegia continue to be the best method to ensure accurate results. [J Pediatr Ophthalmol Strabismus. 2017;54(5):311-318.].