Pupil size measurements with a multifunctional aberrometer/coherence interferometer/tomographer and two infrared-based pupillometers.

PURPOSE: To compare precision of pupil size measurements of a multifunctional device (Pentacam AXL Wave [Pentacam]) and 2 infrared-based pupillometers (PupilX, Colvard) and to compare repeatability of Pentacam and PupilX. SETTING: Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany. DESIGN: Prospective, comparative trial. METHODS: Pupil diameter of healthy eyes was measured with Colvard once and Pentacam without glare (WO) and with glare (WG), PupilX in 0, 1, and 16 lux 3 times each. In a second series, measurements with Pentacam WO and PupilX in 0.06 and 0.12 lux were assessed. RESULTS: 36 eyes of participants aged 21 to 63 years were included. Mean pupil diameter was 6.05 mm with Colvard, 5.79 mm (first series), 5.50 mm (second series) with Pentacam WO, 3.42 mm WG, 7.26 mm PupilX in 0, 4.67 mm 1, 3.66 mm 16, 6.82 mm in 0.06, and 6.39 mm in 0.12 lux. Measurements with Pentacam WO were significantly different to PupilX in 0, 0.06, 0.12, and 1 lux (all P < .001), but not to Colvard ( P = .086). Pupil size measured with Pentacam WG and PupilX in 16 lux was not significantly different ( P = .647). Consecutive measurements with Pentacam WO and WG had mean SD of 0.23 mm and 0.20 mm, respectively, and with PupilX 0.11 in 0, 0.24 mm 1, and 0.20 mm in 16 lux. CONCLUSIONS: Pentacam provided good assessment of pupil size but was not equivalent to PupilX in low lighting conditions. Repeatability was more favorable for Pentacam.

Evaluation of a Portable Wavefront Aberrometer for Community Screening Refraction in the Elderly.

SIGNIFICANCE: The SVOne may prove useful to quickly and easily assess refractive correction needs in community screenings and low-resource settings, but not all subjects were testable with the device. PURPOSE: This study aimed to compare the SVOne handheld, smartphone-based wavefront aberrometer with a tabletop autorefractor in identifying refractive errors in elderly subjects. METHODS: Participants 50 years or older at community eye screenings with visual acuity worse than 20/40 in either eye underwent autorefraction followed by two SVOne trials. Power vectors of right eye data were analyzed. RESULTS: Of 84 subjects who underwent autorefraction, 67 (79.8%) were successfully autorefracted with the SVOne, of whom 82.1% (55/67) had a successful repeat reading. Mean M (spherical equivalent) values from tabletop and handheld autorefraction were -0.21 D (95% confidence interval [CI], -0.71 to +0.29 D) and -0.29 D (95% CI, -0.79 to +0.21 D), respectively (P > .05). Mean astigmatism values from tabletop and handheld devices were +1.06 D (95% CI, 0.87 to 1.26 D) and +1.21 D (95% CI, 0.99 to 1.43 D), respectively (P > .05). Intraclass correlation coefficients between devices were 0.95 (95% CI, 0.93 to 0.97) for M, 0.78 (95% CI, 0.66 to 0.86) for J0, and 0.45 (95% CI, 0.24 to 0.63) for J45 (P < .05 for all). Excellent test-retest correlation between SVOne measurements was noted for M (Pearson correlation [r] = 0.96; P < .05), but a weaker correlation was noted for J0 and J45 (r = 0.67 and r = 0.63 [P < .05 for both], respectively). CONCLUSIONS: The SVOne provided strong agreement for M, with the majority of readings within ±1.00 D of each other, when compared with the tabletop autorefractor. A weaker but still good correlation was noted for astigmatism. Similar findings were noted when assessing repeatability.

Visual quality observation of clear lens extraction by ultrasonic phacoemulsification and intraocular lens implantation in a child with microspherophakia: A case report.

RATIONALE: Microspherophakia is characterized by a small, spherical crystalline lens with increased sagittal diameter. Because of the uncertainty about the outcome, as well as the complexity of the operation and development of complications, the management and timing of surgical intervention for microspherophakia are still debated. Lens extraction is effective for avoiding the risk of pupillary blockage, but the outcome after operation is controversial. The iTrace (Tracey, USA) report shows the influence of low-order aberrations (LOA) and high-order aberrations (HOA), which may be valuable in predicting postoperative outcome. Our report concerns a child with microspherophakia who underwent lens extraction via the analysis of visual quality by iTrace. PATIENT CONCERNS: Our report is on the case of a 7-year-old girl whose parents observed she had to bring her papers and books extremely close to her face to read. On examination, the girl was bilaterally diagnosed microspherophakia with a small tremble lens. The objective refraction was -15.0 diopter of spherical power (DS)/-1.00 diopter of cylindrical power (DC) × 180 right eye (OD) and -12.5 DS/-1.50 DC × 20 left eye (OS). The HOA of OD and OS were high up to 0.926 and 0.659, respectively by iTrace. The visual quality remained terrible after correcting LOA (high myopia and astigmatism). According to iTrace report, the patient would get a good visual quality by extracting the clear lens with HOA from cornea after correcting LOA. The girl's parent opted for surgery on the left eye. DIAGNOSIS: Due to the patient's symptoms, examination results, she was diagnosed with microspherophakia. INTERVENTIONS: The patient underwent clear lens extraction by ultrasonic phacoemulsification and intraocular lens implantation. OUTCOMES: The first day after operation, total HOA was decreased to 0.077. Total LOA was 0.713. Corrected distance visual acuity (CDVA) is 20/20. One week after surgery, HOA was 0.110 and LOA was 0.328. CDVA was 20/25. CDVA was still 20/25 one month after surgery. The total HOA was 0.110 and the LOA was 0.334 by iTrace. LESSONS: ITrace not only plays an important role in analyzing potential reasons of undesirable preoperative visual quality but also can predict postoperative outcomes. All these functions are helpful for determining surgical intervention of microspherophakia cases.

Accuracy of the Hand-held Wavefront Aberrometer in Measurement of Refractive Error.

PURPOSE: To compare refractive error measured by hand-held wavefront aberrometers with postcycloplegic autorefraction (AR) and cycloplegic refraction (CR). METHODS: The medical records of patients who received refractive measurements using the wavefront aberrometer, postcycloplegic AR, and CR between January 2014 and January 2016 were retrospectively analyzed. The mean differences, 95% confidence intervals, and limits of agreement (LOA) were calculated for the refractive vector components (M, J0, and J45 ). RESULTS: Fifty-one patients (9.0 ± 5.5 years, male 41.2%) were enrolled in this study, and only the right eye of each was included. Refractive errors ranged from -9.25 to +7.25 diopters (D) for spherical equivalent (median, 0.75 D). The M component was not significantly different among the three methods (p = 0.080). However, the J0 vector component was significantly different (p < 0.001). After post hoc analysis, the wavefront aberrometer obtained more positive values for J0 compared to the other methods. The J45 component was not significantly different among the three methods (p = 0.143). The mean difference between the wavefront aberrometer and postcycloplegic AR was -0.115 D (LOA, -1.578 to 1.348 D) for M, 0.239 D (LOA, -0.371 to 0.850 D) for J0, and -0.015 D (LOA, -0.768 to 0.738 D) for J45 . The mean difference between the wavefront aberrometer and CR was -0.220 D (LOA, -1.790 to 1.350 D) for M, 0.300 D (LOA, -0.526 to 1.127 D) for J0, and -0.079 D (-0.662 to 0.504 D) for J45 . CONCLUSIONS: The wavefront aberrometer showed good agreement with postcycloplegic AR and CR in spherical equivalents, but tended to produce slightly myopic results. The wavefront aberrometer also overestimated with-the-rule astigmatism. Therefore, we recommend that the device be used for estimations of refractive error, which may be useful for patients who have postural difficulties, live in undeveloped countries, or are bedridden.

Validation of an Affordable Handheld Wavefront Autorefractor.

SIGNIFICANCE: There is a critical need for tools that increase the accessibility of eye care to address the most common cause of vision impairment: uncorrected refractive errors. This work assesses the performance of an affordable autorefractor, which could help reduce the burden of this health care problem in low-resource communities. PURPOSE: The purpose of this study was to validate the commercial version of a portable wavefront autorefractor for measuring refractive errors. METHODS: Refraction was performed without cycloplegia using (1) a standard clinical procedure consisting of an objective measurement with a desktop autorefractor followed by subjective refraction (SR) and (2) with the handheld autorefractor. Agreement between both methods was evaluated using Bland-Altman analysis and by comparing the visual acuity (VA) with trial frames set to the resulting measurements. RESULTS: The study was conducted on 54 patients (33.9 ± 14.1 years of age) with a spherical equivalent (M) refraction determined by SR ranging from -7.25 to 4.25 D (mean ± SD, -0.93 ± 1.95 D). Mean differences between the portable autorefractor and SR were 0.09 ± 0.39, -0.06 ± 0.13, and 0.02 ± 0.12 D for M, J0, and J45, respectively. The device agreed within 0.5 D of SR in 87% of the eyes for spherical equivalent power. The average VAs achieved from trial lenses set to the wavefront autorefractor and SR results were 0.02 ± 0.015 and 0.015 ± 0.042 logMAR units, respectively. Visual acuity resulting from correction based on the device was the same as or better than that achieved by SR in 87% of the eyes. CONCLUSIONS: This study found excellent agreement between the measurements obtained with the portable autorefractor and the prescriptions based on SR and only small differences between the VA achieved by either method.

Validation of a Clinical Aberrometer Using Pyramidal Wavefront Sensing.

SIGNIFICANCE: Measurement of ocular aberrations is a critical component of many optical corrections. PURPOSE: This study examines the accuracy and repeatability of a newly available high-resolution pyramidal wavefront sensor-based aberrometer (Osiris by Costruzione Strumenti Oftalmici, Firenze, Italy). METHODS: An engineered model eye and a dilated presbyopic eye were used to assess accuracy and repeatability of aberration measurements after systematic introduction of lower- and higher-order aberrations with calibrated trial lenses (sphere +10.00 to -10.00 D, and astigmatic -4.00 and -2.00 D with axis 180, 90, and 45°) and phase plates (-0.57 to 0.60 µm of Seidel spherical aberration defined over a 6-mm pupil diameter). Osiris aberration measurements were compared with those acquired on a previously calibrated COAS-HD aberrometer for foveal and peripheral optics both with and without multizone dual-focus contact lenses. The impact of simulated axial and lateral misalignment was evaluated. RESULTS: Root-mean-square errors for paraxial sphere (corneal plane), cylinder, and axis were, respectively, 0.07, 0.11 D, and 1.8° for the engineered model and 0.15, 0.26 D, and 2.7° for the presbyopic eye. Repeatability estimates (i.e., standard deviation of 10 repeat measures) for the model and presbyopic eyes were 0.026 and 0.039 D for spherical error. Root-mean-square errors of 0.01 and 0.02 µm, respectively, were observed for primary spherical aberration and horizontal coma (model eye). Foveal and peripheral measures of higher- and lower-order aberrations measured with the Osiris closely matched parallel data collected with the COAS-HD aberrometer both with and without dual-focus zonal bifocal contact lenses. Operator errors of focus and alignment introduced changes of 0.018 and 0.02 D/mm in sphere estimates. CONCLUSIONS: The newly available clinical pyramidal aberrometer provided accurate and repeatable measures of lower- and higher-order aberrations, even in the challenging but clinically important cases of peripheral retina and multifocal optics.

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

PURPOSE: 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). SETTING: IOA Madrid Innova Ocular, Madrid, Spain. DESIGN: Prospective comparative cohort study. METHODS: 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 4.0 mm 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). RESULTS: 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). CONCLUSION: Objective methods tend to yield more negative sphere values than manifest refraction.

Analysis of Intrasession Repeatability of Ocular Aberrometric Measurements and Validation of Keratometry Provided by a New Integrated System in Mild to Moderate Keratoconus.

PURPOSE: To evaluate the intrasession repeatability and validity of corneal curvature measurements provided by a new multifunctional device and to assess the intrasession repeatability of its ocular aberrometric measures. METHODS: This prospective study comprises 37 mild to moderate keratoconus eyes of 37 patients. In all cases, 3 repeated measures of corneal topography and ocular aberrometry were performed with the iDesign 2 system (iD2; Johnson & Johnson Vision Care Inc, Jacksonville, FL) and one keratometric measurement was performed with the intraocular lens-(IOL) Master 500 (Carl Zeiss Meditec Inc, Dublin, CA) and Sirius (CSO) (SIR) systems. RESULTS: The within-subject SD (Sw) was <0.50 D for all iD2 keratometric measurements, with intraclass correlation coefficient (ICC) >0.980. Sw and ICC for the keratometric axis were 2.60 degrees and 0.992, respectively. Concerning aberrations, all Sw values for high-order Zernike terms were ≤0.11 µm (ICC > 0.900), and all Sw values for refraction data were <0.75 D (ICC > 0.95), except for J45. No statistically significant differences were found between the devices in any keratometric parameter evaluated (P ≥ 0.222), but the limits of agreement between the devices were clinically relevant. The magnitude of K readings and astigmatism correlated significantly with the difference in these parameters between iD2 and SIR (0.432 ≤ r ≤ 0.489, P ≤ 0.041). CONCLUSIONS: The iD2 system provides consistent measures of keratometry and ocular aberrometry in eyes with mild to moderate keratoconus. Keratometric data obtained with this system in these eyes cannot be considered as interchangeable with data provided by intraocular lens-Master 500 and SIR.

Corneal power measurement with a new aberrometer/corneal topographer in eyes after small incision lenticule extraction for myopia.

PURPOSE: To assess corneal power measurements obtained by the OPD SCAN III Topographer in eyes with prior myopic small incision lenticule extraction (SMILE) surgery. METHODS: Sixty untreated myopic eyes of sixty subjects and forty previous myopic SMILE surgery eyes of forty subjects were consecutively enrolled in the present study. Manifest refraction, OPD SCAN III and Pentacam HR were performed. Keratometric measurements assessed by OPD SCAN III-simulated keratometry, average pupil power and effective central corneal power (ECCP) were compared with mean keratometry (Km) obtained by Pentacam HR in the untreated group and the clinical history method (CHM) in the treated group. RESULTS: In the untreated group, no statistically significant differences were revealed between all corneal power measurements obtained with OPD SCAN III and Km. In the treated group, all the corneal power measurements were statistically different from the CHM except for the Haigis method and the Shammas method, while ECCP had a statistically but not clinically significant overestimation of 0.42 D with 95% limit of agreement (LOA) of - 0.81 D to 1.64 D. The three modified ECCP had better prediction performance with narrower 95% of LOA lying in (- 1.20, 1.20 D) (- 1.22, 1.23 D) and (- 0.90, 1.00 D), respectively. CONCLUSIONS: The ECCP provided with OPD SCAN III could be used as an alternative option for the CHM after specific modifications in eyes with previous myopic SMILE surgery when the preoperative data are unavailable considering the narrowest agreement between the modified ECCP and the CHM. Otherwise, caution must be raised considering the wide LOA.

Assessment of subjective refraction with a clinical adaptive optics visual simulator.

PURPOSE: To clinically validate an adaptive optics visual simulator (VAO) that measures subjective refraction and visual acuity. SETTING: Optics Laboratory, University of Murcia, Murcia, Spain. DESIGN: Prospective case series. METHODS: Using 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). RESULTS: Seventy-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). CONCLUSION: Subjective 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.

Clinical evaluation of the repeatability of ocular aberrometry obtained with a new pyramid wavefront sensor.

PURPOSE: To evaluate the intrasubject repeatability of the ocular aberrometry obtained with a new ocular pyramidal aberrometer technology in a sample of normal eyes. METHODS: A total of 53 healthy eyes of 53 subjects with ages ranging from 18 to 45 years were included in this study. In all cases, three consecutive acquisitions were obtained. Intrasubject repeatability of the measurements with a pyramidal aberrometer was calculated. Intrasubject repeatability for 4.0- and 6.0-mm pupils was evaluated within the subject standard deviation (Sw) and intraclass correlation coefficient. RESULTS: Low values of the Sw and intraclass correlation coefficient outcomes close to 1 were observed for the sphere and cylinder at 3.0-mm pupil size. Most low Sw and intraclass correlation coefficient values close to 1 were observed for total, low-order aberrations and higher-order aberrations root mean square and for each Zernike coefficient analysis (intraclass correlation coefficient ⩾0.798) at 4.0-mm pupil size, with more limited outcomes for the aberrometric coefficient of Z(4, 4) with an intraclass correlation coefficient of 0.683. For a 6.0 mm pupil diameter, low Sw and intraclass correlation coefficient values close to 1 were observed for all aberrometric parameters or Zernike coefficients analyzed (intraclass correlation coefficient ⩾0.850). CONCLUSION: The new pyramidal aberrometer Osiris provides repeatable and consistent measurements of ocular aberrometry measurements in normal eyes.

Portable Autorefractors for Detecting Axial Length Changes in Space.

INTRODUCTION: We evaluated the reproducibility of two portable, self-administered autorefractors (Netra and SVOne Pro) to assess the time course of visual changes on the ISS. METHODS: We measured cycloplegic refractive error at 5 visits at least a week apart in 13 subjects (6 women, 7 men, 30 ± 9 yr) using both devices seated and also prone with lower body positive pressure (LBPP) applied. Axial length was measured with an optical biometer. Subjects completed a questionnaire on device preferences. RESULTS: The SVOne seated intrasession reproducibility coefficient (RPC) was 0.37 diopters (D), while the Netra's was 0.41 D. Intersession seated results were: RPC = 0.67 D for the SVOne and RPC = 0.54 D for the Netra. The average seated to prone LBPP differences were significantly different from zero for both the SVOne and Netra. The SVOne was preferred in four out of five categories on the questionnaire and took half the time to complete a measurement set compared to the Netra. DISCUSSION: Users preferred the SVOne and it took less time. An SVOne refraction change of 0.67 D from baseline would happen by chance less than 5% of the time. If multiple separate measurements were taken, the detection limit could be reduced (e.g., three repeated measurements could reduce it to 0.38 D). Since astronauts with visual changes show spherical equivalent changes of 0.5 to 1.0 D, in-flight autorefractors could help determine the time course of refractive changes in space from which changes in axial length could be inferred.Masterova KS, Anderson AP, Cowan DR, Fellows AM, Zegans ME, Buckey JC. Portable autorefractors for detecting axial length changes in space. Aerosp Med Hum Perform. 2018; 89(8):724-730.

Real-Time Measurement of Ocular Wavefront Aberrations in Symptomatic Subjects.

The purpose of this work was to study the real-time changes of the optical properties of the eye with accommodation in subjects with symptoms of accommodative disorders. From ocular aberrations, it is possible to compute several parameters like the response and lag of accommodation. The ocular aberrations were measured in 4 subjects, with different accommodative disorders, during several cycles of accommodation/disaccommodation and for different accommodative stimuli. The measurement was done continuously and in real time during different accommodative stimuli. It was possible to see the changes in accommodative response during the several stimuli of accommodation. Subjects with accommodative disorders showed different accommodative responses. The use of wavefront ocular aberrations can be a tool to diagnose accommodative disorders. In some subjects with complaints, this method showed irregularities even when the results of the usual clinical exams were normal.

Corneal topography with an aberrometry-topography system.

PURPOSE: To investigate the agreement between the central corneal radii and corneal eccentricity measurements generated by the new Wave Analyzer 700 Medica (WAV) compared to the Keratograph 4 (KER) and to test the repeatability of the instruments. METHODS: 20 subjects (10 male, mean age 29.1 years, range 21-50 years) were recruited from the students and staff of the Cologne School of Optometry. Central corneal radii for the flat (rc/fl) and steep (rc/st) meridian as well as corneal eccentricity for the nasal (enas), temporal (etemp), inferior (einf) and superior (esup) directions were measured using WAV and KER by one examiner in a randomized order. RESULTS: Central radii of the flat (rc/fl) and steep (rc/st) meridian measured with both instruments were statically significantly correlated (r = 0.945 and r = 0.951; p < 0.001). Comparison between the WAV and KER showed that rc/fl and rc/st measured with WAV were significantly steeper than those measured with KER (p < 0.001). Corneal eccentricities were statistically significantly correlated in all meridians (p < 0.05). Compared to KER, etemp and esup measured with WAV were greater (p < 0.05), while there were no statistically significant differences for enas and einf (p = 0.350 and p = 0.083). For the central radii, repeated measurements were not significantly different for the KER or WAV (p > 0.05). Limits of agreement (LoA) indicate a better repeatability for the KER compared to WAV. CONCLUSIONS: Corneal topography measurements captured with the WAV were strongly correlated with the KER. However, due to the differences in measured corneal radii and eccentricities, the devices cannot be used interchangeably. For corneal topography the KER demonstrated better repeatability.

Clinical outcomes with distance-dominant multifocal and monofocal intraocular lenses in post-LASIK cataract surgery planned using an intraoperative aberrometer.

IMPORTANCE: Studies evaluating the clinical benefits of intraoperative aberrometry (IA) in cataract surgery are limited. BACKGROUND: The study was designed to determine whether IA improved clinical outcomes of post-laser in situ keratomileusis (LASIK) cataract surgery with different intraocular lenses (IOLs) implanted. DESIGN: A retrospective chart review of clinical outcomes from one surgeon at one surgical centre was conducted. It included post-LASIK cataract surgeries where IA was used for the confirmation of IOL power, with either a distant-dominant multifocal IOL or a monofocal IOL implanted. PARTICIPANTS: Records for 44 eyes of 31 patients were analysed. METHODS: Differences in visual acuity (VA) and refractions by lens type were compared, and the effects of IA were evaluated. MAIN OUTCOME MEASURES: Uncorrected distance VA and the percentage of eyes with a spherical equivalent refraction within 0.5D of the intended correction were the primary outcome measures. RESULTS: There was no statistically significant difference in the percentage of eyes with uncorrected distance VA of 20/25 or better between IOL groups (P = 0.41). More eyes in the multifocal group had a refraction within 0.50D of intended (P = 0.03). In 39% of cases, the preoperative and IA power calculations suggested the same IOL power. When not equal, the IA results were not significantly more likely to be 'best' (P = 0.08). CONCLUSIONS AND RELEVANCE: Results suggest that a history of previous LASIK is not a contraindication to use of distant-dominant multifocal IOLs. IA did not appear to improve clinical outcomes in post-LASIK eyes, although a positive trend was evident.

Precision and agreement of higher order aberrations measured with ray tracing and Hartmann-Shack aberrometers.

BACKGROUND: To 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). METHODS: Prospective 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. RESULTS: For 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. CONCLUSIONS: The 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.

Repeatability of a Commercially Available Adaptive Optics Visual Simulator and Aberrometer in Normal and Keratoconic Eyes.

PURPOSE: To evaluate the repeatability of aberration measurement obtained by a Hartmann-Shack aberrometer combined with a visual adaptive optics simulator in normal and keratoconic eyes. METHODS: One hundred fifteen normal eyes and 92 eyes with grade I and II keratoconus, as per the Amsler-Krumeich classification, were included in the study. To evaluate the repeatability, three consecutive measurements of ocular aberrations were obtained by a single operator. Zernike analyses up to the 5th order for a pupil size of 4.5 mm were performed. Statistical analyses included the intraclass correlation coefficient (ICC) and within-subject standard deviation (SD). RESULTS: For intrasession repeatability, the ICC value for sphere and cylinder was 0.94 and 0.93 in normal eyes and 0.98 and 0.97 in keratoconic eyes, respectively. The ICC for root mean square of higher order aberrations (HOARMS) was 0.82 in normal and 0.98 in keratoconic eyes. For 3rd order aberrations (trefoil and coma), the ICC values were greater than 0.87 for normal eyes and greater than 0.92 for keratoconic eyes. The ICC for spherical aberration was 0.92 and 0.90 in normal and keratoconic eyes, respectively. CONCLUSIONS: Visual adaptive optics provided repeatable aberrometry data in both normal and keratoconic eyes. For most of the parameters, the repeatability in eyes with early keratoconus was somewhat better than that for normal eyes. The repeatability of the Zernike terms was acceptable for 3rd order (trefoil and coma) and spherical aberrations. Therefore, visual adaptive optics was a suitable tool to perform repeatable aberrometric measurements. [J Refract Surg. 2017;33(11):769-772.].

Opto-mechanical design of a dispersive artificial eye.

We present an opto-mechanical artificial eye that can be used for examining multi-wavelength ophthalmic instruments. Standard off-the-shelf lenses and a refractive-index-matching fluid were used in the creation of the artificial eye. In addition to dispersive properties, the artificial eye can be used to simulate refractive error. To analyze the artificial eye, a multi-wavelength Hartmann-Shack aberrometer was used to measure the longitudinal chromatic aberration and the possibility of inducing refractive error. Off-axis chromatic aberrations were also analyzed by imaging through the artificial eye at two discrete wavelengths. Possible extensions to the dispersive artificial eye are also discussed.

Evaluation of the SVOne Handheld Autorefractor in a Pediatric Population.

PURPOSE: The SVOne is a portable, Hartmann-Shack wavefront aberrometer, which can be attached to a smartphone to determine the refractive error of the eye objectively. Previous results have shown the device to provide measurements equivalent to those of standard clinical techniques in young, healthy adults. The aim of the present study was to compare the findings of the SVOne with retinoscopy, subjective refraction, and two commercially available autorefractors (Retinomax-3 and WAM-5500) in a pediatric population. METHOD: The refractive error of the right eye was assessed both without and with cycloplegia in 40 visually normal children between 5 and 17 years of age (mean age = 11.3 years) using the five techniques described above. Further, to assess repeatability of the instruments, the entire procedure was repeated in a subgroup of five subjects. All data were analyzed in terms of power vectors (M, J0, and J45). RESULTS: No significant difference was observed between the mean values of M (spherical equivalent) for the different techniques. Retinoscopy showed the best agreement with subjective refraction, both without and with cycloplegia, followed by the open-field WAM-5500. The most repeatable procedures, when measured without and with cycloplegia, were the WAM-5500 and retinoscopy, respectively. Measurements with the SVOne showed a decline in repeatability under cycloplegia. CONCLUSIONS: The results indicate that the SVOne provides measurements of refractive error in a normal, pediatric population that are not significantly different from other subjective and objective procedures. Accurate alignment along the visual axis, especially when measuring through a dilated pupil, is critical. This instrument is valuable for vision screenings, for examinations taking place outside the clinical office, and a starting point for the refractive assessment.

Comparison of the Orbscan II topographer and the iTrace aberrometer for the measurements of keratometry and corneal diameter in myopic patients.

BACKGROUND: The purpose of this study was to compare corneal power and horizontal corneal diameter (white-to-white [WTW] distance) readings obtained by the Orbscan II topographer and the iTrace aberrometer. METHODS: Keratometry readings in the flat (Kf) and steep (Ks) meridians and WTW distance were measured with the Orbscan II and iTrace systems in 100 myopic patients. Statistical evaluation was performed using the paired t test, Pearson correlation, and Bland-Altman analysis for comparison of measurement techniques. RESULTS: The mean keratometry values with the Orbscan II and iTrace were 43.16 ± 1.44 and 42.64 ± 1.43 diopter (D), respectively (P < 0.0001). The mean WTW distance measurements with the Orbscan II and iTrace were 11.57 ± 0.34 and 11.33 ± 0.36 mm, respectively (P < 0.0001). For the measurement of corneal power, the 95 % limits of agreement (LoA) between the Orbscan II and iTrace were - 0.21 to 1.21 D for the flat meridian and - 0.15 to 1.25 D for the steep meridian. For the measurement of WTW distance, the range of the 95 % LoA between the two devices was 0.47 mm. CONCLUSIONS: For some clinical applications, the keratometry and WTW distance measurements obtained by the Orbscan II topographer and the iTrace aberrometer differed greatly and therefore were not interchangeable. TRIAL REGISTRATION: Clinical trials number: ChiCTR-OCS-14005077 (August 2nd, 2014).